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How did life become so diverse? The dynamics of diversification according to The fossil record and molecular phylogenetics
Abstract
The long-term diversification of life probably cannot be modelled as a simple equilibrial process: the time scales are too long, the potential for exploring new ecospace is too large and it is unlikely that ecological controls can act at global scales. The sum of many clade expansions and reductions, each of which happens according to its own dynamic, probably approximates more a damped exponential curve when translated into a global-scale species diversification curve. Unfortunately, it is not possible to plot such a meaningful global-scale species diversification curve through time, but curves at higher taxonomic levels have been produced. These curves are subject to the vagaries of the fossil record, but it is unlikely that the sources of error entirely overwhelm the biological signal. Clades radiate when the external and internal conditions are right: a new territory or ecospace becomes available, and the lineage has acquired a number of characters that open up a new diet or mode of life. Modern high levels of diversity in certain speciose clades may depend on such ancient opportunities taken. Dramatic climatic changes through the Quaternary must have driven extinctions and originations, but many species responded simply by moving to more favourable locations. Ecological communities appear to be no more than merely chance associations of species, but there may be real interactions among species. Ironically, high species diversity may lead to more speciation, not, as had been assumed, less: more species create more opportunities and selective pressures for other species to respond to, rather than capping diversity at a fixed equilibrium level. Studies from the scale of modern ecosystems to global long-term patterns in the fossil record support a model for the exponential diversification of life, and one explanation for a pattern of exponential diversification is that as diversity increases, new forms become ever more refinements of existing forms. In a sense the world becomes increasingly divided into finer niche space. Organisms have a propensity to speciate freely, species richness within ecosystems appears to generate opportunities for more speciation, clades show all kinds of patterns from sluggish speciation rates and constant diversity through time to apparently explosive speciation, and there is no evidence that rapidly speciating clades have reached a limit, nor that they are driving other clades to extinction. A corollary of this view is that current biodiversity must be higher than it has ever been. Limits to infinite growth are clearly local, regional, and global turnover and extinction events, when climate change and physical catastrophes knock out species and whole clades, and push the rising exponential curve down a notch or two.
... A simple look at the major diversification and extinction events is convincing in this respect (Sepkoski, 1978;Sepkoski, 1984;Benton, 1995). And if there are still debates about the existence of a generic shape for large scale diversification (Benton et al., 2007), there is not much of a conundrum behind punctuated equilibriums, as it follows from three well identified processes, one being biotic while the others are mostly independent from life. ...
... 2.1. BOUNDLESS DIVERSITY AS THE ULTIMATE OUTCOME OF EVOLUTION dawn of dinosaurs had finally occurred (Benton et al., 2007;Barnosky et al., 2011), according to the idea of creative destruction, used in economics to describe coevolutionary processes through which innovative companies disrupt the market and lead to the collapse of lame ducks 8 (Schumpeter, 1942(Schumpeter, (rev. 2010 Another abiotic factor comes from pure geological events, and, contrary to the previous one, may be damaging but also fruitful. ...
... ). What still remains unclear at this stage is whether their occurrence impacts the global trend of diversity, or if it only triggers a short transient period with an abrupt decline followed by a quick bouncing effect that only modifies which organisms sustain the overall diversification trend(Benton et al., 2007) -for instance, mammals replacing non-avian dinosaurs in several ecological niches. Did biodiversity completely recover after each crisis and get back to what it would have been were the crisis not to have wiped it out? ...
Since Life was born, its Evolution has created an exceptional diversity of entities spanning an extravagant range of sizes from tiny microscopic molecules to the giant organisms that embody Megafauna. This broad variability, which exists both between and within classes of biological entities (eg. proteins), has often been theoretically explained by assuming the existence of biological trade-offs – impossibility to optimise many traits at once - and/or specific niches (eg. two different nutrients in the environment). However, how these trade-offs build up at the cellular level has mostly remained elusive because models of specialisation overlook the very mechanistic underpinnings of cells, that is to say how they actually work. Here, we develop a model where the fitness of cells emerges from a sequence of enzyme-substrate reactions that each produce a specific metabolite like ATP, and first show that accounting for physical, ecological and cellular constraints sheds light on the reasons why enzyme properties resemble a zoo although they seemingly evolve under a similar directional selective pressure – and should thus, at first glance, all look the same. Based on these landscapes of metabolic fitness and adaptive dynamics, we then simulate cell competition to demonstrate how the simple and intrinsic physical constraint of membrane permeability can explain the emergence of cross-feeding in an environment where only one ecological niche seems to exist, thus violating Gause's principle of competitive exclusion. This form of specialization sees one of the types specializing at the exploitation of a waste product released by the other, and it has generally been explained through considerations on the cost of processing metabolites, but this does not allow one to explain why certain metabolites seem more often associated with cross-feeding (acetate, glycerol). Our model specifically makes it possible to predict which intermediate metabolites should give rise to cross-feeding interactions and we emphasize that the available data seems to match our predictions. Yet, in this model, the enzymatic properties cannot evolve and the optimization simply concerns their levels of expression. If enzyme kinetics could be easily improved, cross-feeding would probably not emerge, but this not what the data shows. Hence, we then develop a quantitative genetic model intended to clarify the mechanistic underpinnings of metabolic epistasis and its consequences on the fitness reached at the mutation-selection-drift equilibrium. Because of these consequences, optimising enzymes above a given level may be compromised. Finally, we discuss the open perspectives whose vocation would be to combine these approaches in order to bring the fields of systems biology closer to those of quantitative genetics, and, thereby, to feed the field of quantitative evolution.
... A simple look at the major diversification and extinction events is convincing in this respect (Sepkoski, 1978;Sepkoski, 1984;Benton, 1995). And if there are still debates about the existence of a generic shape for large scale diversification (Benton et al., 2007), there is not much of a conundrum behind punctuated equilibriums, as it follows from three well identified processes, one being biotic while the others are mostly independent from life. ...
... 2.1. BOUNDLESS DIVERSITY AS THE ULTIMATE OUTCOME OF EVOLUTION dawn of dinosaurs had finally occurred (Benton et al., 2007;Barnosky et al., 2011), according to the idea of creative destruction, used in economics to describe coevolutionary processes through which innovative companies disrupt the market and lead to the collapse of lame ducks 8 (Schumpeter, 1942(Schumpeter, (rev. 2010 Another abiotic factor comes from pure geological events, and, contrary to the previous one, may be damaging but also fruitful. ...
... ). What still remains unclear at this stage is whether their occurrence impacts the global trend of diversity, or if it only triggers a short transient period with an abrupt decline followed by a quick bouncing effect that only modifies which organisms sustain the overall diversification trend(Benton et al., 2007) -for instance, mammals replacing non-avian dinosaurs in several ecological niches. Did biodiversity completely recover after each crisis and get back to what it would have been were the crisis not to have wiped it out? ...
Since Life was born, its tireless evolution has created an exceptional diversity of entities spanning an extravagant range of sizes, from the microscopic molecules underlying heritability and the expression of phenotypes to multicellular organisms and their societies. This great variety of the living world, present both between classes of biological entities and within these classes (e.g. proteins), has often been explained theoretically by assuming the existence of trade-offs – impossibility to optimize multiple traits at once – and / or specific niches as produced by the co-occurrence of multiple nutrients. However, the way in which these internal compromises emerge at the cellular level has remained in general elusive, especially since models of evolution most often overlook the mechanistic foundations and the very functioning of cells. Across this thesis, I try to build mechanistic evolutionary models by studying one of the most fundamental property of living things: how to produce energy, and grow, faster than others? This property is based at the cellular level on the structure and expression of enzymes. Rather than the extreme optimization this role suggests, enzymes have extremely diverse characteristics – some are close to achievable physical limits while others are very far from them – that should be explained. Through a modeling approach of the kinetic processes involved, I have shown that these differences can be explained by different selective contexts, characterizing in particular the reactions in which these enzymes are involved. Furthermore, the expression of an enzyme is the result of a complex selective process involving the obvious interest of catalyzing a given reaction but also overall costs for the cell, both in terms of production of the enzyme and of crowding within the cytoplasm. These constraints can promote the evolution of a selective (partial) expression of a metabolic pathway, leading to the release into the medium of metabolites, which can be used as an energetic source. In turn,this can give rise to the evolution of organisms specialised at these metabolites through a process called cross-feeding. Taking into account these processes in an adaptive dynamic model while also integrating an ecological dimension allowed me to establish the restricted conditions in which the cross-feeding may evolve, shedding light on the preponderant implication of certain metabolites (acetate, glycerol). In a last part, outside the strictly mechanistic framework of the thesis, I develop a model of population genetics intended to clarify the mainsprings of metabolic (weakest link) epistasis and its deleterious consequences on fitness at the mutation-selection-drift equilibrium. Finally, I discuss the perspectives opened up by this whole work, the vocation of which would be to contribute to the development of more realistic genotype- phenotype-fitness maps and to document their quantitative influence on evolution, through the combination of population genetics and systems biology.
... Ecological theory states that as diversity grows and ecological niches are filled, the strengthening of biological interactions imposes limits on diversity [5][6][7] . However, the extent to which biological interactions have constrained the growth of diversity over evolutionary time remains an open question 1-4, [8][9][10][11][12] , largely because of the incompleteness and spatial heterogeneity of the fossil record [13][14][15] . Here we present a regional diversification model that reproduces surprisingly well the Phanerozoic trends in the global diversity of marine invertebrates after imposing mass extinctions. ...
... The question of whether or not there is an equilibrium diversity that the biota, or portions of the biota, cannot exceed has led to decades of debate between those who think that there is a limit to the global diversity that the Earth can carry 2,3,11,18 (i.e., a carrying capacity or saturation level) and those who think that diversity can increase in an unlimited fashion over time or, alternatively, that the biosphere is so far from the equilibrium diversity (i.e., its carrying capacity) that we can ignore the existence of any limit 8,9,12 . This question has traditionally been addressed by examining the shape of global fossil diversity curves 3,19 . ...
... With the possible exception of well-developed diversity hotspots, our results indicate that the diversity of marine benthic animals has remained well below saturation levels throughout their evolutionary history, shedding light on one of the most controversial questions in evolutionary ecology 2,3,8,9,11,12,18,34 . A taxonomic diversification model operating widely within the exponential growth regime of the logistic function implies a concave-upward relationship between the magnitude of diversity loss (x-axis) and the subsequent rebuilding time. ...
The fossil record of marine invertebrates has long fueled the debate on whether or not there are limits to global diversity in the sea1–4. Ecological theory states that as diversity grows and ecological niches are filled, the strengthening of biological interactions imposes limits on diversity5–7. However, the extent to which biological interactions have constrained the growth of diversity over evolutionary time remains an open question1–4,8–12, largely because of the incompleteness and spatial heterogeneity of the fossil record13–15. Here we present a regional diversification model that reproduces surprisingly well the Phanerozoic trends in the global diversity of marine invertebrates after imposing mass extinctions. We find that the dynamics of global diversity is best described by a diversification model that operates broadly within the exponential growth regime of a logistic function. A spatially resolved analysis of the diversity-to-carrying capacity ratio reveals that only < 2% of the global flooded continental area exhibits diversity levels approaching ecological saturation. We attribute the overall increase in global diversity during the Late Mesozoic and Cenozoic to the development of diversity hotspots under prolonged conditions of Earth system stability and maximum continental fragmentation. We call this the "diversity hotspots hypothesis", which is proposed as a non-mutually exclusive alternative to the hypothesis that the Mesozoic marine revolution led this macroevolutionary trend16,17.
... For decades, paleobiologists have emphasized 'biodiversity through time' at the largest spatial scales 2,4,7-10 , primarily focusing on long-term changes in the total number of species on Earth or proxies thereof (but see 3, [11][12][13][14]. Long-standing controversies have centered on whether diversity has increased exponentially (or 'essentially exponentially' [15][16][17] or was characterized by long intervals of stationary dynamics, punctuated by abrupt diversity increases, which has been taken as evidence for diversitydependent or logistic diversification 2,4, 18 . ...
... The implications of this face-value, global pattern for understanding the drivers of biodiversity have been intensely debated, with the same curve seeming to support both logistic and exponential interpretations 4,15,17 . Global-scale, face-value studies of land vertebrate families 69 ( Figure 1D), insects 70 and land plants 26 have been also interpreted by some authors as providing strong evidence for exponential diversification on land 16 . ...
... The same concern applies to interpretation of global diversification inferred from molecular phylogenies. Therefore, the debate over process as inferred from global diversity through time curves 2,4, [15][16][17]22 may be unresolvable, because global curves cannot distinguish between fundamentally different causal mechanisms that operate at different levels of the spatial hierarchy (Figure 2). ...
The fossil record is the primary source of information on how biodiversity has varied in deep time, providing unique insight on the long-term dynamics of diversification and their drivers. However, interpretations of fossil record diversity patterns have been much debated, with a traditional focus on global diversity through time. Problems arise because the fossil record is spatially and temporally patchy, so 'global' diversity estimates actually represent the summed diversity across a set of geographically and environmentally distinct regions that vary substantially in number and identity through time. Furthermore, a focus on global diversity lumps the signal of ecological drivers at local and regional scales with the signal of global-scale processes, including variation in the distribution of environments and in provincialism (the extent of subdivision into distinct biogeographic regions). These signals cannot be untangled by studying global diversity measures alone. These conceptual and empirical concerns necessitate a shift away from the study of 'biodiversity through time' and towards the study of 'biodiversity across time and space'. Spatially explicit investigations, including analyses of local- and regional-scale datasets, are central to achieving this and allow analysis of geographic scale, location and the environmental parameters directly experienced by organisms. So far, research in this area has revealed the stability of species richness variation among environments through time, and the potential climatic and Earth-system drivers of changing biodiversity. Ultimately, this research program promises to address key questions regarding the assembly of biodiversity, and the contributions of local-, regional- and global-scale processes to the diversification of life on Earth.
... T he fossil record of Phanerozoic marine biodiversity has long been a model system for understanding animal diversification through deep time (1)(2)(3)(4)(5)(6). Numerous hypotheses have been proposed to explain these patterns. ...
... Numerous hypotheses have been proposed to explain these patterns. Some invoke long-term environmental change (7)(8)(9) or tectonic drivers (10), whereas others emphasize time-dependent processes, ranging from unconstrained, exponential diversification (3,11) to diversitydependent diversification constrained by biotic interactions (2,5,12). Inferred diversity patterns may also reflect the structure of the fossil record, including geological factors, such as rock amount (13) and lithification trends (4), or research practices, such as sampling variation resulting from worker interest or taxonomic culture (4,5). ...
... Exploratory analyses suggested that explanations for diversity change through time may differ between low and midpaleolatitudes, which were therefore modeled separately. Insufficient data were available Close (3,14) and categorical variables describing equilibrial diversification phases (2) and short-term postextinction decreases], and variables related to research activity (including sampling variables and modern continental region identity). Modern continental region identity was specified as a random effect to control for geographic variation in research practices (e.g., taxonomic splitters versus lumpers) and to permit us to model time series autocorrelation (22). ...
Across time, but also across space
Fossils, especially those from marine systems, have long been used to estimate changes in patterns of diversity over time. However, fossils are patchy in their occurrence, so such temporal estimates generally have not included variations due to space. Such a singular examination has the potential to simplify, or even misrepresent, patterns. Close et al. used a spatially explicit approach to measure diversity changes in marine fossils across time and space. They found that, like modern systems, diversity varies considerably across space, with reefs increasing diversity levels. Accounting for this spatial-environmental variation will shed new light on the study of diversity over time.
Science , this issue p. 420
... However, this challenge has long been hampered by controversies over how much reliable the fossil record is (Erwin, 2009). It has been demonstrated that taking the fossil record at face value to estimate diversity variations produces inaccurate palaeodiversity reconstructions due to several geological and sampling biases that affect its direct reading (Raup, 1976;Peters and Foote, 2001;Smith, 2001;Peters, 2005Peters, , 2006Benton and Emerson, 2007). Over the past decade however, a number of analytical approaches have been developed to circumvent these biases and produce more reliable estimates of deep-time diversity variations based on fossil data (Norell, 1993;Alroy et al., 2008;Alroy, 2014;Silvestro et al., 2014). ...
... It is likely that the positive correlation found with marine actinopterygians and elasmobranchs reflects the dominance of shallow water taxa in the clades analyzed here. Numerous studies have suggested or found a link between sea level (or continental flooding) and sampling bias metrics (Sepkoski, 1976;Peters and Foote, 2001;Smith, 2001;Peters, 2005Peters, , 2006Benton and Emerson, 2007), which led to establishing the "common cause" hypothesis (Peters, 2005). However, our results indicate a lower fit for models that include a sampling proxy, suggesting that sea level has a genuine biological effect and represents an important driver of the longterm fluctuations of marine biodiversity. ...
... An analysis of the fish family-level diversity dynamics demonstrated that both marine actinopterygians and elasmobranchs follow a similar equilibrium model of diversity variation (Guinot and Cavin, 2015). This apparent contradiction with the present analyses may relate to the use of different taxonomic levels as it has been proposed that logistic diversity curves prevail for higher taxonomic ranks and gradually change toward an exponential distribution when lower levels are considered (Benton, 1997;Lane and Benton, 2003;Benton and Emerson, 2007). Although post-Paleocene genus-level diversity data are lacking for actinopterygians, our pre-Eocene data ( Figure 1B) suggest that such contrasting taxonomic-level patterns might occur in marine ray-finned fishes. ...
Both biotic and abiotic factors likely played a role in influencing the diversification patterns of clades. Although the role of environmental forcing on the long-term evolution of biodiversity has been explored for invertebrate clades, little is known about how vertebrate groups responded to environmental changes. Among vertebrates, fishes (ray-finned fishes and elasmobranchs) have a long, rich, and complex evolutionary history comprising numerous diversification and extinction events. Yet, knowledge on the causes for the diversity fluctuations of these most speciose aquatic vertebrate clades in modern marine and continental ecosystems were restricted to qualitative interpretations. Here we use multiple regression methods to quantitatively examine the role of six abiotic parameters over the long-term variations of elasmobranch and actinopterygian genus-level diversity. We find that marine actinopterygian diversity is mainly controlled by temperature while continental fragmentation is the primary driver of the diversity fluctuations of elasmobranchs. Sea-level variations correlate positively with the diversity variations of both marine groups, whereas none of the tested proxies explains the diversity variation of freshwater ray-finned fishes. Our results indicate that such contrasting responses are mainly due to ecological and life-history trait differences between these groups.
... In paleobiology, the issue of diversity limits has been independently explored concurrently with the debates in the ecological literature, and in a similarly contentious manner 13,14 . Some authors have argued that the diversification process is unbounded [15][16][17][18] , whereas other authors favored the existence of strong limits to diversity, such that speciation rates would decrease and extinction rates would increase as the number of species in a region approaches its maximum, a phenomenon known as equilibrial dynamics of diversification [19][20][21][22][23] . Three major sources of evidence have been proposed in favor of equilibrial dynamics 24 . ...
... 20,32-34). It is also important to note that, even though these ideas involve negative-diversity dependence in diversification rates, some authors have in fact argued the opposite: as new life forms are continuously being added to a given biota, they would provide new niches, habitats, and potential interactions with other species, such that the overall result could be a positive influence on diversification, i.e., "diversity begets diversity" 17,35,36 . However, one should be cautious when interpreting these results. ...
The assumption of an ecological limit to the number of species in a given region is frequently invoked in evolutionary studies, yet its empirical basis is remarkably meager. We explore this assumption by integrating data on geographical distributions and phylogenetic relationships of nearly six thousand terrestrial vertebrate species. In particular, we test whether sympatry with closely-related species leads to decreasing speciation rates. We introduce the concept of clade density, which is the sum of the areas of overlap between a given species and other members of its higher taxon, weighted by their phylogenetic distance. Our results showed that, regardless of the chosen taxon and uncertainty in the phylogenetic relationships between the studied species, there is no significant relationship between clade density and speciation rate. We argue that the mechanistic foundation of diversity-dependent diversification is fragile, and that a better understanding of the mechanisms driving regional species pools is sorely needed.
... Ecological theory states that, as diversity grows and ecological niches are filled, the strengthening of biological interactions imposes limits on diversity 6,7 . However, the extent to which biological interactions have constrained the growth of diversity over evolutionary time remains an open question [1][2][3][4][5][8][9][10][11] . Here we present a regional diversification model that reproduces the main Phanerozoic eon trends in the global diversity of marine invertebrates after imposing mass extinctions. ...
... With the possible exception of diversity hotspots, our results indicate that the diversity of marine invertebrates has remained below saturation throughout their evolutionary history, shedding light on one of the most controversial topics in evolutionary ecology [1][2][3][4][5][8][9][10][11] . A model of taxonomic diversification operating within the exponential growth regime of a logistic function implies that diversity will recover faster than it would if it operated near saturation, with important consequences for post-extinction recovery dynamics. ...
The fossil record of marine invertebrates has long fuelled the debate as to whether or not there are limits to global diversity in the sea1–5. Ecological theory states that, as diversity grows and ecological niches are filled, the strengthening of biological interactions imposes limits on diversity6,7. However, the extent to which biological interactions have constrained the growth of diversity over evolutionary time remains an open question1–5,8–11. Here we present a regional diversification model that reproduces the main Phanerozoic eon trends in the global diversity of marine invertebrates after imposing mass extinctions. We find that the dynamics of global diversity are best described by a diversification model that operates widely within the exponential growth regime of a logistic function. A spatially resolved analysis of the ratio of diversity to carrying capacity reveals that less than 2% of the global flooded continental area throughout the Phanerozoic exhibits diversity levels approaching ecological saturation. We attribute the overall increase in global diversity during the Late Mesozoic and Cenozoic eras to the development of diversity hotspots under prolonged conditions of Earth system stability and maximum continental fragmentation. We call this the ‘diversity hotspots hypothesis’, which we propose as a non-mutually exclusive alternative to the hypothesis that the Mesozoic marine revolution led this macroevolutionary trend12,13. The diversity hotspots hypothesis attributes the overall increase in global diversity during the Late Mesozoic and Cenozoic eras to the development of diversity hotspots under prolonged conditions of Earth system stability and maximum continental fragmentation.
... Extinction is a fundamental ecological process. However, the long-term increase in diversity observed in the fossil record ( Fig. 1.2) [2]) offers strong support to the idea that, in general, the number of new species evolving from existing ones should compensate or exceed the number of species going extinct. The problem is that the estimated current extinction rate might be about one thousand times the "background extinction rate", that is, the percentage of species expected to go extinct per year during a geological period in between two mass extinction events, which is ≈0.0001%. ...
... Note that the plots for orders (C), families (D) and genera (E) are counts based on empirical data, while the plot for species (F) is based on a combination of real and simulated data, and its values are expressed as a percentage of modern diversity. Adapted from [2], with kind permission from John Wiley and Sons globally, of which around two million are marine [4]. If we combine this number with the yearly extinction rate, we obtain a back-of-the-envelope estimate of around 9000 species extinctions per year, which means at least one species loss per hour. ...
The world is collapsing at breakneck speed. The detrimental effects of human presence and activities are so widespread that finding “naturalness” is becoming more challenging every day. This calls for the fundamental question of whether we can halt or, at least, slow down this process. From a pessimistic yet realistic perspective, we have to recognize that averting the ongoing planetary crisis would be, at best, extremely challenging and, at worst, infeasible. Yet, from a more optimistic view, there are potential actions that might cushion the fall. Conservation alone cannot do miracles, so that a global change in human attitude is urgently needed before it is too late. Identifying achievable targets—both to advance scientific knowledge and reduce the impact of our daily lives—is a fundamental step we must take. But before we do that, we need first to get a glimpse of the overarching diversity and complexity of the mechanisms which are dismantling natural systems worldwide. The most transparent processes currently identified as the lead drivers of diversity loss might represent the tip of an enormous extinction iceberg. This book will take readers on a profound journey to see what is hidden below the water surface.
... In turn, this has permitted investigation of the drivers of diversification, broadly divided into intrinsic regulation of taxonomic richness by diversity-dependent mechanisms (the Red Queen Hypothesis) 8-12 versus extrinsic, abiotic forcings imposed by the Earth-Solar system (the Court Jester Hypothesis) 4,13,14 . The influence of the Red Queen remains contentious due to the difficulty of establishing whether biodiversity has ever truly entered a curtailed, diversitydependent regime 15-20 , with the additional observation that interactions between life and the Earth-Solar system through geological time have dynamically altered Earth's carrying capacity 21,22 . By contrast, a series of Court Jester mechanisms are repeatedly hypothesised to have driven patterns of diversification in individual clades to entire biotas, for example, the linked effects of atmospheric CO 2 concentration and temperature, the configuration of the continents, or eustatic sea-level variations 19,23-29 . ...
Palaeontologists have long sought to explain the diversification of individual clades to whole biotas at global scales. Advances in our understanding of the spatial distribution of the fossil record through geological time, however, has demonstrated that global trends in biodiversity were a mosaic of regionally heterogeneous diversification processes. Drivers of diversification must presumably have also displayed regional variation to produce the spatial disparities observed in past taxonomic richness. Here, we analyse the fossil record of ammonoids, pelagic shelled cephalopods, through the Late Cretaceous, characterised by some palaeontologists as an interval of biotic decline prior to their total extinction at the Cretaceous-Paleogene boundary. We regionally subdivide this record to eliminate the impacts of spatial sampling biases and infer regional origination and extinction rates corrected for temporal sampling biases using Bayesian methods. We then model these rates using biotic and abiotic drivers commonly inferred to influence diversification. Ammonoid diversification dynamics and responses to this common set of diversity drivers were regionally heterogeneous, do not support ecological decline, and demonstrate that their global diversification signal is influenced by spatial disparities in sampling effort. These results call into question the feasibility of seeking drivers of diversity at global scales in the fossil record.
... There has been a debate whether or not biodiversification follows an equilibrium model (Benton & Emerson, 2007;Sepkoski Jr, 1978). ...
The equilibrium theory of island biogeography (ETIB) is a widely applied dynamic theory proposed in the 1960s to explain why islands have coherent differences in species richness. The development of the ETIB was temporarily challenged in the 1970s by the alternative static theory of ecological impoverishment (TEI). The TEI suggests that the number of species on an island is determined by its number of habitats or niches but, with no clear evidence relating species richness to the number of niches however, the TEI has been almost dismissed as a theory in favour of the original ETIB. Here, we show that the number of climatic niches on islands is an important predictor of the species richness of plants, herpetofauna and land birds. We therefore propose a model called the niche‐based theory of island biogeography (NTIB), based on the MacroEcological Theory on the Arrangement of Life (METAL), which successfully integrates the number of niches sensu Hutchinson into ETIB. To account for greater species turnover at the beginning of colonisation, we include higher initial extinction rates. When we test our NTIB for resident land birds in the Krakatau Islands, it reveals a good correspondence with observed species richness, immigration and extinction rates. Provided the environmental regime remains unchanged, we estimate that the current species richness at equilibrium is ~45 species (range between 38.39 and 61.51). Our NTIB provides better prediction because it counts for changes in species richness with latitude, which is not considered in any theory of island biogeography.
... The fossil record provides empirical evidence on which to base estimates, offering insight to the processes of extinction, recovery, expansion and faunal and floral turnover, while setting the context in which drivers of biodiversity change are interpreted [1][2][3][4][5] . Fundamental questions in evolutionary biology such as whether or not there are global limits to biodiversity 6,7 , or how biodiversity has evolved, shaped by environmental change, mass extinctions, and biotic interactions [8][9][10][11][12] rely on our ability to infer diversity patterns in deep time. ...
Understanding how biodiversity has changed through time is a central goal of evolutionary biology. However, estimates of past biodiversity are challenged by the inherent incompleteness of the fossil record, even when state-of-the-art statistical methods are applied to adjust estimates while correcting for sampling biases. Here we develop an approach based on stochastic simulations of biodiversity and a deep learning model to infer richness at global or regional scales through time while incorporating spatial, temporal and taxonomic sampling variation. Our method outperforms alternative approaches across simulated datasets, especially at large spatial scales, providing robust palaeodiversity estimates under a wide range of preservation scenarios. We apply our method on two empirical datasets of different taxonomic and temporal scope: the Permian-Triassic record of marine animals and the Cenozoic evolution of proboscideans. Our estimates provide a revised quantitative assessment of two mass extinctions in the marine record and reveal rapid diversification of proboscideans following their expansion out of Africa and a >70% diversity drop in the Pleistocene.
... One obvious discrepancy of real data compared to basic BDPs is that diversification rate shifts must surely have occurred repeatedly through time, as a single homogeneous BDP cannot possibly capture the true patterns of diversification reflected in evolutionary history (c.f. [7]). Rate shifts have largely been addressed in one of two ways: either by assuming rate shifts occur at significant rare points (the "key innovation" concept), or by assuming broad secular variation, e.g. with declining rates through time across the entire tree [8] [9]. ...
Rate shifts in speciation and extinction have been recognised as important contributors to the creation of evolutionary patterns. In particular, the distribution of modern clade sizes is difficult to reconcile with models that do not include them. Although recent advances have allowed rate shifts to be integrated into evolutionary models, these have largely been for the purpose of inferring historical rate shifts across phylogenetic trees. In addition, these models have typically assumed an independence between patterns of diversification and rates of molecular and morphological evolution, despite there being mounting evidence of a connection between them. Here, we develop a new model with two principal goals: first, to explore the general patterns of diversification implied by constantly changing rates, and secondly to integrate diversification, molecular and morphological evolution into a single coherent framework. We thus develop and analyse a covariant birth-death process in which rates of all evolutionary processes (i.e. speciation, extinction and molecular and morphological change) covary continuously, both for each species and through time. We use this model to show that modern diversity is likely to be dominated by a small number of extremely large clades at any historical epoch; that these large clades are expected to be characterised by explosive early radiations accompanied by elevated rates of molecular evolution; and that extant organisms are likely to have evolved from species with unusually fast evolutionary rates. In addition, we show that under such a model, the amount of molecular change along a particular lineage is essentially independent of its height, which further weakens the molecular clock hypothesis. Finally, our model predicts the existence of "living fossil" sister groups to large clades that are both species poor and have exhibited slow rates of morphological and molecular change. Although our model is highly stochastic, it includes no special evolutionary moments or epochs. Our results thus demonstrate that the observed historical patterns of evolution can be modelled without invoking special evolutionary mechanisms or innovations that are unique to specific times or taxa, even when they are highly non-uniform: instead they could emerge from a process that is fundamentally homogeneous throughout time.
... When datasets span many strata, taxa, or time periods, manually correcting for the individual influences of fossilization, excavation, and publication practices becomes prohibitively timeconsuming. Consequently, many analyses bypass these steps with the assumption that stochasticity and sampling structure contribute less signal to results than does original biological signal (e.g., Sepkoski et al. 1981;Benton and Emerson 2007). However, fossil data violate this assumption frequently, leading to imprecise or inaccurate results. ...
The fossil record is spatiotemporally heterogeneous: taxon occurrence data have patchy spatial distributions, and this patchiness varies through time. Large-scale quantitative paleobiology studies that fail to account for heterogeneous sampling coverage will generate uninformative inferences at best and confidently draw wrong conclusions at worst. Explicitly spatial methods of standardization are necessary for analyses of large-scale fossil datasets, because nonspatial sample standardization, such as diversity rarefaction, is insufficient to reduce the signal of varying spatial coverage through time or between environments and clades. Spatial standardization should control both geographic area and dispersion (spread) of fossil localities. In addition to standardizing the spatial distribution of data, other factors may be standardized, including environmental heterogeneity or the number of publications or field collecting units that report taxon occurrences. Using a case study of published global Paleobiology Database occurrences, we demonstrate strong signals of sampling; without spatial standardization, these sampling signatures could be misattributed to biological processes. We discuss practical issues of implementing spatial standardization via subsampling and present the new R package divvy to improve the accessibility of spatial analysis. The software provides three spatial subsampling approaches, as well as related tools to quantify spatial coverage. After reviewing the theory, practice, and history of equalizing spatial coverage between data comparison groups, we outline priority areas to improve related data collection, analysis, and reporting practices in paleobiology.
... While gradual adaptation is important, it cannot explain the explosion of biological diversity and innovation-particularly over the past 10 000 years 1 -that are evident from the evolutionary record through to the modern economy (e.g., De Beaune, 2004;Benton and Emerson, 2007;Read and Van Der Leeuw, 2008;Arthur, 2009;Kauffman, 2016;Bar-On et al., 2018;Gatti et al., 2020;Grinin et al., 2020). Explaining this explosive growth and innovation-including varied niches, tools, technologies, institutions, and ways of "making a living"-is especially puzzling in the context of human evolution. ...
We explore the limitations of the adaptationist view of evolution and propose an alternative. While gradual adaptation can explain some biological and economic diversity, it cannot account for radical innovation (especially during the past 10,000 years). We argue that ubiquitously available but dormant “functional excess” provides the raw material for evolutionary disruptions. Harnessing this excess requires directed experimentation and what we call “protoscientific” problem solving. We highlight the implications of these arguments for evolutionary theory, including evolutionary economics and strategy.
... When datasets span many strata, taxa, or time periods, manually correcting for the individual influences of fossilization, excavation, and publication practices becomes prohibitively timeconsuming. Consequently, many analyses bypass these steps with the assumption that stochasticity and sampling structure contribute less signal to results than does original biological signal (e.g., Sepkoski et al. 1981;Benton and Emerson 2007). However, fossil data violate this assumption frequently, leading to imprecise or inaccurate results. ...
The fossil record is spatiotemporally heterogeneous: taxon occurrence data have patchy spatial distributions, and this patchiness varies through time. Inferences from large-scale quantitative paleobiology studies that fail to account for heterogeneous sampling coverage will be uninformative at best and confidently wrong at worst. Explicitly spatial methods of standardization are necessary for analyses of large-scale fossil datasets, because non-spatial sample standardization, such as diversity rarefaction, is insufficient to reduce the signal of varying spatial coverage through time or between environments and clades. Spatial standardization should control both geographic area and dispersion (spread) of fossil localities. In addition to spatial standardization, other factors may be standardized, including environmental heterogeneity or the number of publications or field collecting units that report taxon occurrences. Using a case study of published global Paleobiology Database occurrences, we demonstrate the strong signals of sampling that could be misinterpreted as biologically meaningful, and which spatial standardization accounts for successfully. We discuss practical issues of implementing spatial standardization via subsampling and present the new R package "divvy" to improve the accessibility of spatial analysis. The software provides three spatial subsampling approaches, as well as related tools to quantify spatial coverage. After reviewing the theory, practice, and history of equalizing spatial coverage between data comparison groups, we outline priority areas to improve related data collection, analysis, and reporting practices in paleobiology.
... Some authors suggested a relationship between the utilization of ecospace and change in diversity (Bambach, 1983). However, most of these previous studies emphasized the effect of niche partitioning as a global long-term pattern in the fossil record to explain the exponential diversification of life (Benton and Emerson, 2007). The main explanation for a pattern of exponential diversification is that as diversity increases, the world becomes increasingly divided into finer niche spaces. ...
A long tradition explains technological change as recombination. Within this tradition, this Element develops an innovative combinatorial model of technological change and tests it with 2,000 years of global GDP data and with data from US patents filed between 1835 and 2010. The model explains 1) the pace of technological change for a least the past two millennia, 2) patent citations and 3) the increasing complexity of tools over time. It shows that combining and modifying pre-existing goods to produce new goods generates the observed historical pattern of technological change. A long period of stasis was followed by sudden super-exponential growth in the number of goods. In this model, the sudden explosion of about 250 years ago is a combinatorial explosion that was a long time in coming, but inevitable once the process began at least two thousand years ago. This Element models the Industrial Revolution as a combinatorial explosion.
... The most important development in our NTIB is, in our opinion, the consideration of the number of niches (here the climatic niches) that can be recalculated as island environment changes, making our NTIB a nonequilibrium model at the time scale of an island's life cycle. There has been a debate whether or not biodiversi cation follows an equilibrium model 73,74 . A recent molecular phylogenetic survey of the Avian communities at four Macaronesian archipelagos (e.g. ...
The Equilibrium Theory of Island Biogeography (ETIB) is a widely applied dynamic theory proposed in the 1960s to explain why islands have coherent differences in species richness. The development of the ETIB was temporarily challenged in the 1970s by the alternative static Theory of Ecological Impoverishment (TEI), which suggests that the number of species on an island is determined by its number of niches or habitats. With no clear evidence relating species richness to the number of niches however, the TEI has been almost dismissed as a theory in favour of the original ETIB. Here, we show that the number of climatic niches on islands is an important predictor of the species richness of plants, herpetofauna and land birds, and we therefore propose a model called the Niche-based Theory of Island Biogeography (NTIB) that successfully, merges the ETIB and TEI into a unifying concept. To account for greater species turnover at the beginning of colonisation, we include higher initial extinction rates. When we test our NTIB for resident land birds in Krakatau Islands it reveals a good correspondence with observed species richness, immigration and extinction rates. We estimate that current species richness at equilibrium is ~48 species (range between 47.76 and 51.36) provided the environmental regime remains unchanged.
... While gradual adaptation is important, it cannot explain the explosion of biological diversity and innovation-particularly over the past 10,000 years 1 -that are evident from the evolutionary record through to the modern economy (e.g., Arthur, 2009;Bar-On et al., 2018;Benton and Emerson, 2007;De Beaune, 2004;Gatti et al., 2020;Kauffman, 2016;Read and Leeuw, 2008). Explaining this explosive growth and innovation-including varied niches, tools, technologies, and ways of "making a living"-is especially puzzling in the context of human evolution. ...
We explore the limitations of the adaptationist view of evolution and propose an alternative. While gradual adaptation can explain some biological and economic diversity, it cannot account for radical innovation (especially during the past 10,000 years). We argue that ubiquitously available but dormant “functional excess” provides the raw material for evolutionary disruptions. Harnessing this excess requires directed experimentation and what we call “protoscientific” problem solving. We highlight the critical implications of these arguments for evolutionary economics and strategy.
... Although most such compilations of fossil taxonomic diversity and turnover have yielded broadly similar temporal patterns that suggest a biological signal is present, it is well known that sampling effort and fossil preservation can significantly distort macroevolutionary patterns (Raup 1972(Raup , 1976Benton and Emerson 2007). Indeed, overcoming sampling-related biases was one of the primary motivations for the creation of the Paleobiology Database (PBDB), a geographically and taxonomically explicit global compilation of fossil occurrences that allowed for the development and application of sampling standardization approaches, among other things (e.g., Alroy et al. 2001Alroy et al. , 2008Finnegan et al. 2015;Bush et al. 2016;Klompmaker et al. 2017;Sansom et al. 2018;Chiarenza et al. 2020;Song et al. 2021;Raja et al. 2022;Siqueira et al. 2022;Spiridonov and Lovejoy 2022). ...
Geographically explicit, taxonomically resolved fossil occurrences are necessary for reconstructing macroevolutionary patterns and for testing a wide range of hypotheses in the Earth and life sciences. Heterogeneity in the spatial and temporal distribution of fossil occurrences in the Paleobiology Database (PBDB) is attributable to several different factors, including turnover among biological communities, socioeconomic disparities in the intensity of paleontological research, and geological controls on the distribution and fossil yield of sedimentary deposits. Here we use the intersection of global geological map data from Macrostrat and fossil collections in the PBDB to assess the extent to which the potentially fossil-bearing, surface-expressed sedimentary record has yielded fossil occurrences. We find a significant and moderately strong positive correlation between geological map area and the number of fossil occurrences. This correlation is consistent regardless of map unit age and binning protocol, except at period level; the Neogene and Quaternary have non-marine map units covering large areas and yielding fewer occurrences than expected. The sedimentary record of North America and Europe yields significantly more fossil occurrences per sedimentary area than similarly aged deposits in most of the rest of the world. However, geographic differences in area and age of sedimentary deposits lead to regionally different expectations for fossil occurrences. Using the sampling of surface-expressed sedimentary units in North America and Europe as a predictor for what might be recoverable from the surface-expressed sedimentary deposits of other regions, we find that the rest of the globe is approximately 45% as well sampled in the PBDB. Using age and area of bedrock and sampling in North America and Europe as a basis for prediction, we estimate that more than 639,000 occurrences from outside these regions would need to be added to the PBDB to achieve global geological parity in sampling. In general, new terrestrial fossil occurrences are expected to have the greatest impact on our understanding of macroevolutionary patterns.
... Additionally, and with broader implications, our findings identify advection driven by geological activity as a general mechanism shaping the microbial biogeography and diversity in deep-subsurface hard-rock aquifers. The limited hydraulic communication between heterogeneous geological compartments (e.g., isolated fractures in crystalline rocks) allows the formation of distinct microbial communities (8); geological activity can then induce rapid advection outpacing environmental selection, exposing translocated microbial communities to new environmental conditions and/or disparate biological communities, both of which could promote community diversification (11,54,55). Given that geological activity is a ubiquitous process across space and time not only on Earth, but on other planets as well (56,57), this mechanism may have fundamental implications for understanding the evolution and history of life. ...
Subsurface environments host diverse microorganisms in fluid-filled fractures; however, little is known about how geological and hydrological processes shape the subterranean biosphere. Here, we sampled three flowing boreholes weekly for 10 mo in a 1478-m-deep fractured rock aquifer to study the role of fracture activity (defined as seismically or aseismically induced fracture aperture change) and advection on fluid-associated microbial community composition. We found that despite a largely stable deep-subsurface fluid microbiome, drastic community-level shifts occurred after events signifying physical changes in the permeable fracture network. The community-level shifts include the emergence of microbial families from undetected to over 50% relative abundance, as well as the replacement of the community in one borehole by the earlier community from a different borehole. Null-model analysis indicates that the observed spatial and temporal community turnover was primarily driven by stochastic processes (as opposed to deterministic processes). We, therefore, conclude that the observed community-level shifts resulted from the physical transport of distinct microbial communities from other fracture(s) that outpaced environmental selection. Given that geological activity is a major cause of fracture activity and that geological activity is ubiquitous across space and time on Earth, our findings suggest that advection induced by geological activity is a general mechanism shaping the microbial biogeography and diversity in deep-subsurface habitats across the globe.
... Consistent with the perspective that evolution and speciation have long been constrained by universal interspecific trade-offs (Tilman, 2011), palaeontologists have found no evidence that the emergence of a new taxonomic group, or of new species within a group, had caused the extinction of pre-existing species (Benton & Emerson, 2007). Similarly, the fossil record suggests that migration of species that evolved in one biogeographical realm into a novel realm had resulted in coexistence, be it among resident and invading species of molluscs (Vermeij, 1989(Vermeij, , 1991, mammals, birds or plants (Benton, 1996;Flannery, 2001;Marshall et al., 1982;Vrba, 1992;Webb, 1991). ...
Because of human domination, the world faces two major environmental problems—species extinctions and climate change.
The still‐elusive solutions to these global problems must address interlinked ecological, economic, political, ethical and cultural constraints and trade‐offs, and will require unprecedented international cooperation. Major advances in ecological research will be essential and will require that ecology become a more mechanistic and predictive science.
Research advances in disciplines ranging from evolution and population ecology to community and ecosystem ecology could greatly contribute to the formulation of viable, sustainable solutions.
Synthesis. Because solutions must also be equitable, ethical, economically viable and societally sustainable, it will be increasingly important for ecologists to be part of multidisciplinary teams that evaluate the full range of interlinked environmental and societal impacts of alternative potential policies.
... Equilibrium is a theoretical, idealized concept that depends on the exact definition of state space as well as respective processes, so it is meaningless to ask whether nature by itself is equilibrial or not. 1) Paleontological time series. Although classical analyses of biodiversity changes during the Phanerozoic indicated a continuous increase of diversity at least since the mass extinction at the Cretaceous-Paleogene boundary (Benton and Emerson 2007), scholars have subsequently argued that these findings may reflect the 'pull of the recent' and unequal sampling of different geological periods , Alroy 2010. Sophisticated analyses accounting for these biases have demonstrated that taxonomic diversity is remarkably stable during long periods (Close et al. 2020a, b), although shifts in these equilibria do occur in times of major biota rearrangements (Close et al. 2019). ...
We are living in a time of rapid environmental changes caused by anthropogenic pressures. Besides direct human exploitation of plant and animal populations and habitat transformation, biodiversity changes in the Anthropocene are affected by less trivial processes including rapid spreading of non‐native species, emergence of novel communities and modifications of ecosystem functioning due to changing nutrient cycles and climate changes. These processes are so complex that confident predictions and effective biodiversity conservation cannot be obtained without a suitable theory of biodiversity dynamics. We argue that such dynamics have particular attractors, i.e. stable equilibria, that are determined by environmental conditions. These stable equilibria set biodiversity limits, i.e. carrying capacities for biodiversity, from local to global scales. We point out the evidence of such limits at various spatiotemporal scales and show, using the new equilibrium theory of biodiversity dynamics (ETBD), how dynamics of diversity depend on non‐linear relationships between number of species, community abundance and population size‐dependent processes of species extinction and origination (speciation or colonization). We show that non‐linear effects of biodiversity on ecosystem functioning can lead to multiple biodiversity equilibria and tipping points. Various human activities, including species introductions, human appropriation of primary production and trophic downgrading, can change local, regional and global diversity equilibria by affecting processes that set equilibrium diversity levels. The existence of equilibrium and out‐of‐equilibrium states has important implications for conservation, restoration and reconciliation ecology. It highlights the need to more effectively and intentionally balance the historical focus on the preservation of natural habitats with management specifically directed towards the processes responsible for long‐term maintenance of biodiversity equilibria. The Anthropocene represents a unique situation in which people make decisions concerning the dynamics of the natural world, and we argue that ecological restoration requires wisely deciding which of the alternative equilibria are worth maintaining.
... The x-axis is artificially truncated in both graphs, as small sample sizes produce substantial random noise as size class increases reflects a state where species richness has increased to the point that the addition of further species to the ecosystem accelerates extinction by reducing the resources available to them (Rabosky & Hurlbert, 2015). This theory is controversial: Opponents argue that fossil evidence in favor of ecological limits is flawed (Benton & Emerson, 2007), that apparent slowdowns in diversification rate over time are not good evidence of limits to diversity (Moen & Morlon, 2014), and that experimental evidence, including that from biological invasions (Sax et al., 2002), supports the idea that diversity is not, in practice, limited by simple equilibria, but that ecosystems tend to be able to accommodate more species than they naturally contain (Harmon & Harrison, 2015). Nevertheless, proponents of ecological limits argue that it is supported by both paleontological and modern ecological evidence. ...
It has often been suggested that the productivity of an ecosystem affects the number of species that it can support. Despite decades of study, the nature, extent, and underlying mechanisms of this relationship are unclear. One suggested mechanism is the “more individuals” hypothesis (MIH). This proposes that productivity controls the number of individuals in the ecosystem, and that more individuals can be divided into a greater number of species before their population size is sufficiently small for each to be at substantial risk of extinction. Here, we test this hypothesis using REvoSim: an individual‐based eco‐evolutionary system that simulates the evolution and speciation of populations over geological time, allowing phenomena occurring over timescales that cannot be easily observed in the real world to be evaluated. The individual‐based nature of this system allows us to remove assumptions about the nature of speciation and extinction that previous models have had to make. Many of the predictions of the MIH are supported in our simulations: Rare species are more likely to undergo extinction than common species, and species richness scales with productivity. However, we also find support for relationships that contradict the predictions of the strict MIH: species population size scales with productivity, and species extinction risk is better predicted by relative than absolute species population size, apparently due to increased competition when total community abundance is higher. Furthermore, we show that the scaling of species richness with productivity depends upon the ability of species to partition niche space. Consequently, we suggest that the MIH is applicable only to ecosystems in which niche partitioning has not been halted by species saturation. Some hypotheses regarding patterns of biodiversity implicitly or explicitly overlook niche theory in favor of neutral explanations, as has historically been the case with the MIH. Our simulations demonstrate that niche theory exerts a control on the applicability of the MIH and thus needs to be accounted for in macroecology. We use simulation experiments to test the predictions of the more‐individuals hypothesis of biodiversity. We find that many of these predictions are supported, but that interspecific competition and limits to niche diversity can provide additional complexity not predicted by the more‐individuals hypothesis.
... On the other hand, some authors suggest that diversity trajectories might be better described by an unlimited increase in the number of species (Benton & Emerson, 2007;Harmon & Harrison, 2015;Stanley, 2007Stanley, , 2008, or that the signal of a diversification slowdown might in fact be generated by statistical artifacts, taxon sampling, or given the prolonged nature of speciation (at least when analyzing molecular phylogenies, see Harmon & Harrison, 2015). Therefore, different macroevolutionary patterns can be expected if lower-level processes interact in a world where diversity is bounded or unbounded. ...
Although speciation dynamics have been described for several taxonomic groups in distinct geographic regions, most macroevolutionary studies still lack a detailed mechanistic view on how or why speciation rates change. To help partially fill this gap, we suggest that the interaction between the time taken by a species to geographically expand and the time populations take to evolve reproductive isolation should be considered when we are trying to understand macroevolutionary patterns. We introduce a simple conceptual index to guide our discussion on how demographic and microevolutionary processes might produce speciation dynamics at macroevolutionary scales. Our framework is developed under different scenarios: when speciation is mediated by geographical or resource‐partitioning opportunities, and when diversity is limited or not. We also discuss how organismal intrinsic properties and different overall geographical settings can influence the tempo and mode of speciation. We argue that specific conditions observed at the microscale might produce a pulse in speciation rates even without a pulse in either climate or physical barriers. We also propose a hypothesis to reconcile the apparent inconsistency between speciation measured at the microscale and macroscale, and emphasize that diversification rates are better seen as an emergent property. We hope to bring the reader's attention to interesting mechanisms to be further studied, to motivate the development of new theoretical models that connect microevolution and macroevolution, and to inspire new empirical and methodological approaches to more adequately investigate speciation dynamics either using neontological or paleontological data.
... Many classic cases of clade diversification have been in response to a morphological innovation or ecological opportunity (Benton & Emerson, 2007;Gavrilets & Losos, 2009;Mahler et al., 2010;Yoder et al., 2010). On the one hand, the emergence of phenotypic similarities between species can point to predictable responses to ecological challenges and selection pressures (Marques et al., 2017). ...
Aim
Climatic variation has long been regarded as a primary source of morphological variation. However, there is mixed support for the adherence of reptiles to ecogeographical hypotheses, such as Bergmann’s rule (body size decreases with temperature) and Allen’s rule (limb length increases with temperature). We quantified body and limb morphology among the diverse Australian gecko fauna (4 families, 30 genera, 226 of the 231 described species) to investigate environmental correlates of morphological variation in this radiation.
Location
Australia.
Major taxa studied
Geckos (Squamata: Gekkota; the families Gekkonidae, Carphodactylidae, Diplodactylidae and Pygopodidae).
Methods
We measured 20 external features of ethanol‐preserved museum specimens. We investigated whether principal component axes of morphology were correlated with three key environmental variables, and the microhabitat occupied by each species.
Results
Morphology varied greatly among Australian gecko families and genera, although there was a strong phylogenetic signal in morphology. After accounting for phylogeny, morphology was correlated with a species’ microhabitat use. Saxicolous species and species with variable microhabitat requirements (i.e., generalists) had larger body dimensions than terrestrial species. Saxicolous species also had longer proportional forelimbs and hindlimbs than terrestrial species.
Main conclusions
Our results highlight the importance of phylogeny and microhabitat use in shaping the morphology of Australian geckos. We find little evidence that Australian geckos adhere to Bergmann’s rule or Allen’s rule, suggesting that these ecogeographical hypotheses provide limited insight into the adaptive potential of lizard species to altered environmental conditions.
... Rabosky (2013). See also, Benton and Emerson (2007)). ...
In this work, we consider a two-type species model with trait-dependent speciation, extinction and transition rates under an evolutionary time scale. The scaling approach and the diffusion approximation techniques which are widely used in mathematical population genetics provide modeling tools and conceptual background to assist in the study of species dynamics, and help exploring the analogy between trait-dependent species diversification and the evolution of allele frequencies in the population genetics setting. The analytical framework specified is then applied to models incorporating diversity-dependence, in order to infer effective results from processes in which the net diversification of species depends on the total number of species. In particular, the long term fate of a rare trait may be analyzed under a partly symmetric scenario, using a time-change transform technique.
... Looking at the future of aquaculture diversity, the expansionistic idea of an unpredictable limit must be 448 abandoned instead a clear quantification of limit must be accepted. Even considering that the logistic model of land 449 species diversity, here proposed as general model of domesticated species diversification model could be considered an 450 artifact of taxonomic scale as shown in paleontological studies (Benton and Emerson, 2007), logistic model is correct 451 here as aquaculture is in its early stage. Thus, logistic growth and Pareto principle, indicate that aquaculture has recently 452 reached its climax and in the future global aquaculture diversity will oscillate around 428 species, within these, 116 will 453 produce the 99% of annual production and only 29 species the 80%. ...
Aquaculture diversity is universally considered one of the main aspects that make aquaculture different from land animal farming. A retrospective analysis on 68 years of FAO data on world aquaculture production shows that this aquaculture diversity study is the most powerful and exhaustive theoretical tool to investigate aquaculture origin, evolution and connections with the surrounding world. Aquaculture diversity investigated with Shannon index and Pareto principle shows its thermodynamic nature and reveals an unexpectable regularity that sheds new light on aquaculture, thus putting aquaculture in a perfect theoretical context together with fisheries. Species dominance, vicariance and redundancy must be considered for a functional description of aquaculture diversity. Aquaculture diversity is not biological diversity as an aquaculture species is not necessarily a biological species. Aquaculture diversity shows that aquaculture is a modern colonization of aquatic domain and it has recently reached its maximum value that is 428 ± 11 species, of which 29 ± 1 will produce 80% of global annual production. A temporal and geographical analysis of global aquaculture diversity reveals an original and hopefully enlightening vision of modern aquaculture and its perspectives.
... Some authors suggested a relationship between the utilization of ecospace and change in diversity (Bambach 1983). However, most of these previous studies emphasized the effect of niche partitioning as a global long-term pattern in the fossil record to explain the exponential diversification of life (Benton and Emerson 2007). The main explanation for a pattern of exponential diversification is that as diversity increases, the world becomes increasingly divided into finer niche spaces. ...
In the original publication of the article, equation 2 was published incorrectly.
... Some authors suggested a relationship between the utilization of ecospace and change in diversity (Bambach 1983). However, most of these previous studies emphasized the effect of niche partitioning as a global long-term pattern in the fossil record to explain the exponential diversification of life (Benton and Emerson 2007). The main explanation for a pattern of exponential diversification is that as diversity increases, the world becomes increasingly divided into finer niche spaces. ...
The origin of economic niches, conceived as potential markets, has been mostly
neglected in economic theory. Ecological niches emerge as new species evolve and fit
into a web of interactions, and the more species come into existence, the more
(exponentially or power-law distributed) ecological niches emerge. In parallel fashion,
economic niches emerge with new goods, and niche formation in economics is also
exponentially or power-law distributed. In economics and ecology alike, autocatalytic
processes drive the system to greater and greater diversity. Novelty begets novelty in a
positive feedback loop. An autocatalytic set of self-enabling transactions feed back
upon one another in combinatoric fashion to generate progressive diversity. While
these combinatorial dynamics cannot be prestated, the model explains the “hockeystick
of economic growth”—a pattern of prolonged stasis followed by a sudden takeoff,
such as occurred during the Industrial Revolution or the Cambrian explosion in ecology.
Several implications derive from our niche emergence model, including the idea that
the evolutionary process of technological change is not something we do; rather, it
happens to us.
... Currently, empirical support for this scenario remains limited (McPeek 2008;Rabosky 2013;Stroud and Losos 2016;Machac et al. 2018) and, contrary to its diagnostic predictions, species-rich regions are typically expected to show fast, not slow, diversification (Ricklefs 2006;Rolland et al. 2014). Moreover, other scenarios have also been theorized (e.g., diversity begets further diversification) (Benton and Emerson 2007;Erwin 2008;Machac and Graham 2017;Souto-Vilarós et al. 2019). As a result, how the mechanisms hypothesized under the different explanations interact with each other remains unresolved, and we have limited knowledge as to how such interactions, should they occur, might be uniform across taxa and richness gradients. ...
Three prominent explanations have been proposed to explain the dramatic differences in species richness across regions and elevations, (1) time for speciation, (2) diversification rates, and (3) ecological limits. But the relative importance of these explanations and, especially, their interplay and possible synthesis remain largely elusive. Integrating diversification analyses, null models, and GIS, I study avian richness across regions and elevations of the New World. My results reveal that even though the three explanations are differentially important (with ecological limits playing the dominant role), each contributes uniquely to the formation of richness gradients. Further, my results reveal the likely interplay between the explanations. They indicate that ecological limits hinder the diversification process, such that the accumulation of species within a region gradually slows down over time. Yet, it does not seem to converge toward a hard ceiling on regional richness. Instead, species-rich regions show suppressed, but continued, diversification, coupled with signatures of possible competition (esp. Neotropical lowlands). Conversely, species-poor, newly-colonized regions show fast diversification and weak to no signs of competition (esp. Nearctic highlands). These results held across five families of birds, across grid cells, biomes, and elevations. Together, my findings begin to illuminate the rich, yet highly consistent, interplay of the mechanisms that together shape richness gradients in the New World, including the most species-rich biodiversity hotspots on the planet, the Andes and the Amazon.
... It provides a theoretical framework to understand and tackle modern challenges such as antibiotic resistance in medicine and pesticide resistance in farming. It is the basis for animal and plant conservation (Antonovics et al. 2007;Benton and Emerson 2007;Ffrench-Constant et al. 2000). ...
Lack of acceptance of biological evolution, despite the overwhelming evidence that supports it, can be very problematic in higher education courses that have a strong biological basis. We investigated acceptance of biological evolution in 344 first-year Life Sciences undergraduate students across five programmes at the University of Roehampton, UK. In line with previous findings in British universities, we found that 9% of the students did not accept evolution by natural selection, with an increase to 16% for human evolution. Both religiosity and programme of study were significantly related to acceptance levels in our students (p < 0.001). In particular, lower acceptance was associated with Muslim or Christian beliefs, and with Biomedical Sciences and Nutrition and Health programmes (compared with Anthropology, Zoology and Biological Sciences). We suggest embedding an evolutionary perspective in the teaching of biomedical and health programmes and creating space for explicit discussion of perceived conflicts with religious beliefs.
... The value of fossil data for evolutionary studies depends on the quality and precision of taxonomic identifications (and descriptions) of new collections (Patterson, 1981;Hedges et al., 1996;Blair and Hedges, 2005). New fossil data can help calibrate molecular clocks by providing firm minimum age of diversification events and therefore assist in estimating diversification rates (Alfaro et al., 2007;Benton and Emerson, 2007;Donoghue and Benton, 2007;Simpson et al., 2011). Understanding paleontological longevity and distribution of taxa supplements our knowledge of present-day distributions in our attempt to predict future diversities and distributions (Keith et al., 2013). ...
A new fossil coral collection enhances our understanding of scleractinian coral diversity during the origination of the Indo-Pacific biodiversity hotspot (Oligocene - earliest Miocene). The fossil corals were collected from Sarawak (Malaysia), Negros and Cebu (the Philippines). The oldest fossil specimens are from Cebu, found in the Calagasan Formation (late Oligocene - middle Chattian) and Butong Limestone (late Oligocene - late Chattian). The specimens from the Trankalan/Binaguiohan (Negros), Melinau and Subis Limestone (Sarawak) are all of the early Miocene (Aquitanian) age. Forty-four morphospecies belonging to 30 genera were identified, and detailed taxonomic descriptions are provided. These data extend the temporal ranges of six coral genera (Acanthastrea, Astrea, Blastomussa, Coelastrea, Lobophyllia, Paramontastraea). By expanding our knowledge of scleractinian coral diversity and morphological variation in the Central Indo-Pacific, this new fossil collection provides important background for future studies of coral taxonomy, diversity, and biogeography in the region.
... This is exemplified by the large discordance between the curves describing temporal variation of marine fossil diversity (measured using the number of genera or families) during the Phanerozoic (e.g., Alroy et al., 2008;Sepkoski, Bambach, Raup, & Valentine, 1981). Some of these curves reveal relative stability during the Palaeozoic, followed by near-exponential increases in the number of genera after the end-Permian extinction (Benton & Emerson, 2007). However, there are methodological problems associated with the "Pull of the Recent" (Foote, 2000), and the curves that avoid this problem do not indicate a continuous increase of species richness but instead relatively wide fluctuations in diversity levels during the whole Phanaerozoic (Alroy, 2010;Alroy et al., 2008). ...
The idea that the number of species within an area is limited by a specific capacity of that area to host species is old yet controversial. Here, we show that the concept of carrying capacity for species richness can be as useful as the analogous concept in population biology. Many lines of empirical evidence indicate the existence of limits of species richness, at least at large spatial and phylogenetic scales. However, available evidence does not support the idea of diversity limits based on limited niche space; instead, carrying capacity should be understood as a stable equilibrium of biodiversity dynamics driven by diversity‐dependent processes of extinction, speciation and/or colonization. We argue that such stable equilibria exist even if not all resources are used and if increasing species richness increases the ability of a community to use resources. Evaluating the various theoretical approaches to modelling diversity dynamics, we conclude that a fruitful approach for macroecology and biodiversity science is to develop theory that assumes that the key mechanism leading to stable diversity equilibria is the negative diversity dependence of per‐species extinction rates, driven by the fact that population sizes of species must decrease with an increasing number of species owing to limited energy availability. The recently proposed equilibrium theory of biodiversity dynamics is an example of such a theory, which predicts that equilibrium species richness (i.e., carrying capacity) is determined by the interplay of the total amount of available resources, the ability of communities to use those resources, environmental stability that affects extinction rates, and the factors that affect speciation and colonization rates. We argue that the diversity equilibria resulting from these biodiversity dynamics are first‐order drivers of large‐scale biodiversity patterns, such as the latitudinal diversity gradient.
The evolutionary histories of major clades, including mammals, often comprise changes in their diversification dynamics, but how these changes occur remains debated. We combined comprehensive phylogenetic and fossil information in a new “birth-death diffusion” model that provides a detailed characterization of variation in diversification rates in mammals. We found an early rising and sustained diversification scenario, wherein speciation rates increased before and during the Cretaceous-Paleogene (K-Pg) boundary. The K-Pg mass extinction event filtered out more slowly speciating lineages and was followed by a subsequent slowing in speciation rates rather than rebounds. These dynamics arose from an imbalanced speciation process, with separate lineages giving rise to many, less speciation-prone descendants. Diversity seems to have been brought about by these isolated, fast-speciating lineages, rather than by a few punctuated innovations.
The search for drivers of hominin speciation and extinction has tended to focus on the impact of climate change. Far less attention has been paid to the role of interspecific competition. However, research across vertebrates more broadly has shown that both processes are often correlated with species diversity, suggesting an important role for interspecific competition. Here we ask whether hominin speciation and extinction conform to the expected patterns of negative and positive diversity dependence, respectively. We estimate speciation and extinction rates from fossil occurrence data with preservation variability priors in a validated Bayesian framework and test whether these rates are correlated with species diversity. We supplement these analyses with calculations of speciation rate across a phylogeny, again testing whether these are correlated with diversity. Our results are consistent with clade-wide diversity limits that governed speciation in hominins overall but that were not quite reached by the Australopithecus and Paranthropus subclade before its extinction. Extinction was not correlated with species diversity within the Australopithecus and Paranthropus subclade or within hominins overall; this is concordant with climate playing a greater part in hominin extinction than speciation. By contrast, Homo is characterized by positively diversity-dependent speciation and negatively diversity-dependent extinction—both exceedingly rare patterns across all forms of life. The genus Homo expands the set of reported associations between diversity and macroevolution in vertebrates, underscoring that the relationship between diversity and macroevolution is complex. These results indicate an important, previously underappreciated and comparatively unusual role of biotic interactions in Homo macroevolution, and speciation in particular. The unusual and unexpected patterns of diversity dependence in Homo speciation and extinction may be a consequence of repeated Homo range expansions driven by interspecific competition and made possible by recurrent innovations in ecological strategies. Exploring how hominin macroevolution fits into the general vertebrate macroevolutionary landscape has the potential to offer new perspectives on longstanding questions in vertebrate evolution and shed new light on evolutionary processes within our own lineage.
Of all species on Earth, only one – Homo sapiens – has developed a technological civilization. As a consequence, estimates of the number of similar civilizations beyond Earth often treat the emergence of human-like intelligence or ‘sophonce’ as an evolutionary unicum: a contingent event unlikely to repeat itself even in biospheres harbouring complex brains, tool use, socially transmitted behaviours and high general intelligence. Here, attention is drawn to the unexpected recency and temporal clustering of these evolutionary preconditions to sophonce, which are shown to be confined to the last ≤10 ² million years. I argue that this pattern can be explained by the exponential biotic diversification dynamics suggested by the fossil record, which translated into a nonlinearly expanding range of cognitive and behavioural outcomes over the course of Earth's history. As a result, the probability of sophonce arising out of a buildup of its enabling preconditions has been escalating throughout the Phanerozoic. The implications for the Silurian hypothesis and the search for extraterrestrial intelligence (SETI) are discussed. I conclude that the transition from animal-grade multicellularity to sophonce is likely not a rate-limiting step in the evolution of extraterrestrial technological intelligences, and that while H. sapiens is probably the first sophont to evolve on Earth, on macroevolutionary grounds it is unlikely to be the last.
Research into freshwater fungi has generated a wealth of information over the past decades with various published articles, i.e., reviews, books, and monographs. With the advancement of
methodologies used in freshwater fungal research, and numerous mycologists working on this ecological group, our knowledge progress and understanding of freshwater fungi, including novel
discoveries and new insights in the ecology of freshwater fungi, has advanced. With this enormous progress, it is timely that an updated account of freshwater fungi be compiled in one volume. Thus, this account is published to give a comprehensive overview of the different facets of freshwater fungal biology. It includes an updated classification scheme based on the latest taxonomic and phylogenetic analysis of freshwater fungal taxa, including their evolutionary history. The biology, diversity, and geographical distribution of higher and basal freshwater fungi are also discussed in the entries. A section on dispersal and adaptation of filamentous freshwater fungi is included in the present work. The ecological importance and role of fungi in the breakdown of wood in freshwater habitats, including their physiology, are discussed in detail. The biotechnological potential of freshwater fungi as producers of bioactive metabolites are reviewed, with methodologies in antimicrobial drug discovery. The present volume also provides an overview of different high throughput sequencing (HTS) platforms for freshwater fungal research highlighting their advantages and challenges, including recent studies of HTS in identification and quantification of fungal communities in freshwater habitats. The present volume also identifies the knowledge gaps and direction of future research in freshwater fungi.
Complexity, defined as the number of parts and their degree of differentiation, is a poorly explored aspect of macroevolutionary dynamics. The maximum anatomical complexity of organisms has undoubtedly increased through evolutionary time. However, it is unclear whether this increase is a purely diffusive process or whether it is at least partly driven, occurring in parallel in most or many lineages and with increases in the minima as well as the means. Highly differentiated and serially repeated structures, such as vertebrae, are useful systems with which to investigate these patterns. We focus on the serial differentiation of the vertebral column in 1,136 extant mammal species, using two indices that quantify complexity as the numerical richness and proportional distribution of vertebrae across presacral regions and a third expressing the ratio between thoracic and lumbar vertebrae. We address three questions. First, we ask whether the distribution of complexity values in major mammal groups is similar or whether clades have specific signatures associated with their ecology. Second, we ask whether changes in complexity throughout the phylogeny are biased towards increases and whether there is evidence of driven trends. Third, we ask whether evolutionary shifts in complexity depart from a uniform Brownian motion model. Vertebral counts, but not complexity indices, differ significantly between major groups and exhibit greater within-group variation than recognized hitherto. We find strong evidence of a trend towards increasing complexity, where higher values propagate further increases in descendant lineages. Several increases are inferred to have coincided with major ecological or environmental shifts. We find support for multiple-rate models of evolution for all complexity metrics, suggesting that increases in complexity occurred in stepwise shifts, with evidence for widespread episodes of recent rapid divergence. Different subclades evolve more complex vertebral columns in different configurations and probably under different selective pressures and constraints, with widespread convergence on the same formulae. Further work should therefore focus on the ecological relevance of differences in complexity and a more detailed understanding of historical patterns.
By comparing detrended estimates of diversity (taxonomic richness) and rates of origination, extinction, and net diversification, I show that at the global scale over the course of the Phanerozoic eon, rates of diversification and origination are negatively correlated with diversity. By contrast, extinction rates are only weakly correlated with diversity for the most part. These results hold for both genus- and species-level data and for many alternative analytical protocols. The asymmetry between extinction on the one hand and origination and net diversification on the other hand supports a model whereby extinction is largely driven by abiotic perturbations, with subsequent origination filling the void left by depleted diversity. Diversity dependence is somewhat weaker, but still evident, if the initial Ordovician radiation or rebounds from major mass extinctions are omitted from analysis; thus, diversity dependence is influenced, but not dominated, by these special intervals of Earth history. In the transition from Paleozoic to post-Paleozoic time, diversity dependence of origination weakens while that of extinction strengthens; however, diversity dependence of net diversification barely changes in strength. Despite nuances, individual clades largely yield results consistent with those for the aggregate data on all animals. On the whole, diversity-dependent diversification appears to be a pervasive factor in the macroevolution of marine animal life.
Simulating progressive, multiple species extinctions in ecological networks while keeping track of the network’s response to subsequent species loss can be an informative exercise. However, the nature of the information emerging from such exercise strongly depends on the identity of nodes (species) removed from the network and the order in which we remove them. For example by replicating the experiment of removing nodes one after another in random order in different ecological networks, one can get an idea of how the networks compare in robustness against a generic form of perturbation. Yet, informative criteria can be used instead of random node removal. For example one could remove species in decreasing order of their current vulnerability
to extinction as assessed by IUCN. Similarly, one could combine ecological niche and global circulation models to estimate relative species vulnerability to future climate change and then use those predictions to identify extinction sequences. Although these “informed” approaches can provide a more realistic picture of the potential paths diversity loss might take in the near future compared to random simulations, identifying boundaries (i.e. a best and a worst-case scenarios) for the many potential trajectories of collapse in a given network is essential to put specific predicted patterns into perspective. Knowledge developed in the physics context offers sophisticated and efficient techniques to identify either the most or the least detrimental
sequences of species extinction, that is sequences either maximizing or minimizing the speed at which a given network approaches collapse following progressive species removal. In doing that, those techniques also offer novel, largely overlooked tools for conservation. Determining which nodes are crucial for network persistence (at any stage of network dismantling) appears as a straightforward criterion for identifying conservation targets which has received very little consideration to date.
This book provides, for the first time, a comprehensive overview of the fundamental roles that ecological interactions play in extinction processes, bringing to light an underground of hidden pathways leading to the same dark place: biodiversity loss.
We are in the midst of the sixth mass extinction. We see species declining and vanishing one after another. Poached rhinos, dolphins and whales slaughtered, pandas surviving only in captivity are strong emotional testimonials of what is happening. Yet, the main threat to natural communities may be overshadowed by the disappearance of large species, with most extinctions happening unnoticed and involving less eye-catching organisms, such as parasites and pollinators. Ecosystems hide countless, invisible wires connecting organisms in dense networks of ecological interactions. Through these networks, perturbations can propagate from one species to another, producing unpredictable effects. In worst case scenarios, the loss of one species might doom many others to extinction. Ecologists now consider such mechanisms as a fundamental – and still poorly understood - driver of the ongoing biodiversity crisis. Hidden Pathways to Extinction makes the invisible links connecting the fates of species and organisms evident, exploring why complexity can enhance ecosystem stability and yet accelerate species loss. Page after page, Strona provides convincing evidence that we are primarily responsible for the fall in biodiversity, that we are falling too, and that we need to redouble our conservation efforts now, or it won't be long before we hit the ground.
RESUMO-A erosão nas pedras ocorre 10000 trilhões de vezes a mais que clivagem, portanto , se tivéssemos um tempo gigante de milhões de anos para acontecimentos geológicos catastróficos e globais, quase todas as pedras da terra deveriam estar sem arestas, dada esta proporção de frequência. Portanto podemos atestar que houve um acidente imenso global recente pela onipresença de pedras pontiagudas com suas arestas ainda preservadas em proporção maior que pedras arredondadas (Lembrando que muitas pedras arredondadas também advieram de processos catastróficos) . Quintilhões e inumeráveis pedras rachadas encontradas em todo planeta terra, com pouco desgaste de tempo, ou com pouco tempo de sedimentação acima das mesmas, revelam um imenso acidente recente na terra, bem como aspectos catastrofistas que implicam em aceleradores de elétrons capazes de perturbar o núcleo arrancando nêutrons e prótons, e consequentemente ter criado proporção de elementos químicos que passaram a ser instáveis, e inclusive rochas com aparência de bilhões de anos, em segundos. O conjunto de evidências evolutivas, genéticas, paleontológicas, geológicas, astronômicas, dos estudos em física de plasma e colisão de íons pesados, demonstram claramente que temos uma outra cronologia e história do universo, da terra e das espécies. Neste trabalho apresentamos evidências de que impactos de asteroides possam ter participado deste evento recente, na forma de chuva de asteroides, pois possuem poder de gerar aceleração de partículas perturbadoras do núcleo atômico para não somente acelerar decaimento radioativo "envelhecendo rochas" como também criar elementos instáveis a partir de estáveis, explicando pequenas proporções deles na terra e milhares de meteoros que nos rodeiam. Esta quebra de paradigma datacional , tão esperada na academia que passa tanta vergonha e descrédito ao ver fósseis contendo tecidos orgânicos serem datados em milhões de anos, nos abre espaço para conjugar acontecimentos consequentes ocorridos imediatamente um depois do outro (temporalidade), que estavam separados por uma espécie de absolutismo datacional na geologia e paleontologia convencional atual, que restringiam o saber científico livre, e impediam sobretudo de harmonizar arqueologias (274 fontes incluindo bíblica) , aspectos genéticos (entropia e meia vida curta do DNA), evolutivos-paleontológicos (falta de mudança morfológica fóssil e repetição de formas de vida em 71% nas amostragens fósseis o que expressa sepultamento em larga escala de todas as espécies da terra em um tempo único e não separado) .
A Desonestidade das Datações Classificadas Pseudocientificamente como "Inerrantes" e "Absolutas"
A fragilidade genética, a entropia genética acompanhada até em tempo real, combina com uma recente reavaliação crítica geocronológica do tempo assumido, que tem sido feita principalmente depois de centenas de publicações relatando achados de tecidos moles não petrificados e ainda orgânicos (preservados) em fósseis, que se acreditava possuir milhões de anos, porém tal preservação desbancou totalmente e falseou a geocronologia atual, tornando totalmente falsa as datações chamadas de "absolutas" que já era um termo epistemicamente errado no hall da ciência, como pretensioso demais e anticientifico já que ciência deve se pautar por principio de invcerteza e verdades provisórias; se não bastasse, ainda temos c14 original presente em materiais de origem orgânica em diversos fósseis e diamentes incrustados em rochas datadas entre 300 a 2,5 bilhão de anos.
Estas revelações ecoam com reclamações de professores de geologia de que datas fora do paradigma são consideradas erradas , por algum motivo (acusam a metodologia por exemplo) e datas dentro do paradigma aceito são consideradas certas. Recebi a contribuição de João Paulo Reis Braga citando que "Richard Milton, que mesmo não sendo defensor do movimento científico criacionismo da terra jovem, aponta, no entanto, que a prontidão em rejeitar datas radiométricas, exceto aquelas que fornecem "valores esperados", é o motivo pelo qual vários métodos radiométricos podem ser considerados convergentes nas "eras" que "medem" (Milton, 1997, p. 49): “Assim, as datas publicadas sempre obedecem a datas preconcebidas e nunca as contradizem. Se todas as datas rejeitadas fossem recuperadas da cesta de lixo e adicionadas às datas publicadas, os resultados combinados mostrariam que as datas produzidas são a dispersão que se esperaria apenas pelo acaso” (Milton, 1997, p. 51) Milton, Richard. 1997. Shattering the myths of darwinism. Park Street Press, Rochester, VT.
Em geral, as datas no 'parque correto' são consideradas corretas e são publicadas, mas aquelas em desacordo com outros dados raramente são publicadas... (Mauger, 1977, p. 37). In general, dates in the `correct ball park' are assumed to be correct and are published, but those in disagreement with other data are seldom published…(Mauger, 1977, p. 37) MAUGER, Richard L. K-Ar ages of biotites from tuffs in Eocene rocks of the Green River, Washakiw and Uinta Basins. Contributions to Geology, Wyoming University. 15(1):17, 1977.
“A aparente convergência de resultados de datação radiométrica é mais uma quimera do que realidade porque "muitas determinações de idade que não concordam com as escalas de tempo atualmente aceitas são simplesmente rejeitadas como erradas..." (Paul, 1980, p. 184) PAUL, Christopher RC. The natural history of fossils. Holmes and Meier, New York, 1980.
Esse artigo em particular tem excelentes tabelas e referências bibliográficas mostrando discrepâncias nas datações e a própria técnica radiométrica desbanca estas datações como podemos ver em:
Resumo : O paradoxo da estase morfológica na literatura paleontológica, SPM ( stasis paradox morphological ) representa uma grande incógnita que segundo Ernest Mayr, é o maior problema da teoria histórica da Evolução. A SPM é uma anomalia porque esperaríamos encontrar muita diversidade morfológica e taxonômica nas amostras fósseis e nunca repetição de mesmas formas. Se não bastasse este problema , descobrimos outro maior : Fósseis vivos que não mudaram morfologicamente durante centenas de milhões de anos (ficaram em estase) , ao serem submetidos a mudanças ambientais, apresentam mudanças morfológicas hoje e ainda com tendência a não voltar a forma anterior. Ou seja, mesmo se centenas de artigos científicos tentem de várias maneiras justificar a anomalia da PMS e tentar salvar a teoria da evolução histórica, calculamos ser impossível justificarem como fósseis vivos permaneceram sem mudanças em suas várias amostras fósseis e mudarem hoje. Segundo meta-análise de 58 trabalhos de Simpson , existe 71% de repetição de formas nos fósseis, e questionamos este fato com o contraste de podermos assistir em tempo real, mudanças morfológicas geradas facilmente por pressões ambientais.
Podemos até fabricar em tempo real mudanças também no nível de sub especiações, gerando inumeráveis variações morfológicas e taxonômicas que são testemunhadas apenas na biodiversidade de hoje, mas não nos trilhões de fósseis e bilhões de amostras . Estimamos haver trilhões de fósseis no mundo, e as bilhões de amostras já coletadas são consideradas como sendo amostras de 570 milhões de anos e até 3,5 bilhão de anos se considerarmos bactérias e fósseis anteriores a explosão cambriana e Ediacara, contando uma historia evolutiva da vida que sai das formas de vida mais simples e acidentalmente vai formando seres mais complexos, porém além de encontrarmos complexidades maiores que as atuais em amostras fósseis antigas, podemos perceber uma tendência maior de simplificação, perda de tamanho, perda de inteligencia, perda de características na historia dos seres vivos e não de ganho, como considerado quando se observa alguma sobrevivência adaptativa. Será que o fato de haver 71% de repetição de formas nos fósseis, indica um catastrofismo global que foi capaz de sepultar as diversas populações de ancestrais tipo básicos defendidos pelo movimento dos biólogos da baraminologia (que defendem os antigos tipos básicos originais da cladística muito citados e “refutados” por Darwin)? Será que o fato da extinção total das famílias e esquemas corporais das primeiras camadas sedimentares contendo fósseis do Ediacara e Cambriano, representam apenas o fato delas estarem mais ao fundo e por receberam maior aporte sedimentar geradas por uma catástrofe global se extinguiram totalmente? Mais estudos são necessários para defender esta mudança de paradigma, porém apresentamos alguns pontos aqui que nos fazem refletir esta possibilidade.
A repetição morfológica dos fósseis nunca ocorreria se eles estivessem intercalados por milhões de anos, mas facilmente ocorreria se diversas populações da terra estivessem sendo sepultados.
Resumo : O paradoxo da estase morfológica na literatura paleontológica, SPM ( stasis paradox morphological ) representa uma grande incógnita que segundo Ernest Mayr, é o maior problema da teoria histórica da Evolução. A SPM é uma anomalia porque esperaríamos encontrar muita diversidade morfológica e taxonômica nas amostras fósseis e nunca repetição de mesmas formas. Se não bastasse este problema , descobrimos outro maior : Fósseis vivos que não mudaram morfologicamente durante centenas de milhões de anos (ficaram em estase) , ao serem submetidos a mudanças ambientais, apresentam mudanças morfológicas hoje e ainda com tendência a não voltar a forma anterior. Ou seja, mesmo se centenas de artigos científicos tentem de várias maneiras justificar a anomalia da PMS e tentar salvar a teoria da evolução histórica, calculamos ser impossível justificarem como fósseis vivos permaneceram sem mudanças em suas várias amostras fósseis e mudarem hoje. Segundo meta-análise de 58 trabalhos de Simpson , existe 71% de repetição de formas nos fósseis, e questionamos este fato com o contraste de podermos assistir em tempo real, mudanças morfológicas geradas facilmente por pressões ambientais.
Podemos até fabricar em tempo real mudanças também no nível de sub especiações, gerando inumeráveis variações morfológicas e taxonômicas que são testemunhadas apenas na biodiversidade de hoje, mas não nos trilhões de fósseis e bilhões de amostras . Estimamos haver trilhões de fósseis no mundo, e as bilhões de amostras já coletadas são consideradas como sendo amostras de 570 milhões de anos e até 3,5 bilhão de anos se considerarmos bactérias e fósseis anteriores a explosão cambriana e Ediacara, contando uma historia evolutiva da vida que sai das formas de vida mais simples e acidentalmente vai formando seres mais complexos, porém além de encontrarmos complexidades maiores que as atuais em amostras fósseis antigas, podemos perceber uma tendência maior de simplificação, perda de tamanho, perda de inteligencia, perda de características na historia dos seres vivos e não de ganho, como considerado quando se observa alguma sobrevivência adaptativa. Será que o fato de haver 71% de repetição de formas nos fósseis, indica um catastrofismo global que foi capaz de sepultar as diversas populações de ancestrais tipo básicos defendidos pelo movimento dos biólogos da baraminologia (que defendem os antigos tipos básicos originais da cladística muito citados e “refutados” por Darwin)? Será que o fato da extinção total das famílias e esquemas corporais das primeiras camadas sedimentares contendo fósseis do Ediacara e Cambriano, representam apenas o fato delas estarem mais ao fundo e por receberam maior aporte sedimentar geradas por uma catástrofe global se extinguiram totalmente? Mais estudos são necessários para defender esta mudança de paradigma, porém apresentamos alguns pontos aqui que nos fazem refletir esta possibilidade.
Are we now entering a mass extinction event? What can mass extinctions in Earth's history tell us about the Anthropocene? What do mass extinction events look like and how does life on Earth recover from them? The fossil record reveals periods when biodiversity exploded, and short intervals when much of life was wiped out in mass extinction events. In comparison with these ancient events, today's biotic crisis hasn't (yet) reached the level of extinction to be called a mass extinction. But we are certainly in crisis, and current parallels with ancient mass extinction events are profound and deeply worrying. Humanity's actions are applying the same sorts of pressures - on similar scales - that in the past pushed the Earth system out of equilibrium and triggered mass extinction events. Analysis of the fossil record suggests that we still have some time to avert this disaster: but we must act now.
Are we now entering a mass extinction event? What can mass extinctions in Earth's history tell us about the Anthropocene? What do mass extinction events look like and how does life on Earth recover from them? The fossil record reveals periods when biodiversity exploded, and short intervals when much of life was wiped out in mass extinction events. In comparison with these ancient events, today's biotic crisis hasn't (yet) reached the level of extinction to be called a mass extinction. But we are certainly in crisis, and current parallels with ancient mass extinction events are profound and deeply worrying. Humanity's actions are applying the same sorts of pressures - on similar scales - that in the past pushed the Earth system out of equilibrium and triggered mass extinction events. Analysis of the fossil record suggests that we still have some time to avert this disaster: but we must act now.
A key to understanding life's great diversity is discerning how competing organisms divide limiting resources to coexist in diverse communities. While temporal resource partitioning has long been hypothesized to reduce the negative effects of interspecific competition, empirical evidence suggests that time may not often be an axis along which animal species routinely subdivide resources. Here, we present evidence to the contrary in the world's most biodiverse group of animals: insect parasites (parasitoids). Specifically, we conducted a meta‐analysis of 64 studies from 41 publications to determine if temporal resource partitioning via variation in the timing of a key life‐history trait, egg deposition (oviposition), mitigates interspecific competition between species pairs sharing the same insect host. When competing species were manipulated to oviposit at (or near) the same time in or on a single host in the laboratory, competition was common, and one species was typically inherently superior (i.e. survived to adulthood a greater proportion of the time). In most cases, however, the inferior competitor could gain a survivorship advantage by ovipositing earlier (or in a smaller number of cases later) into shared hosts. Moreover, this positive (or in a few cases negative) priority advantage gained by the inferior competitor increased as the interval between oviposition times became greater. The results from manipulative experiments were also correlated with patterns of life‐history timing and demography in nature: the more inherently competitively inferior a species was in the laboratory, the greater the interval between oviposition times of taxa in co‐occurring populations. Additionally, the larger the interval between oviposition times of competing taxa, the more abundant the inferior species was in populations where competitors were known to coexist. Overall, our findings suggest that temporal resource partitioning via variation in oviposition timing may help to facilitate species coexistence and structures diverse insect communities by altering demographic measures of species success. We argue that the lack of evidence for a more prominent role of temporal resource partitioning in promoting species coexistence may reflect taxonomic differences, with a bias towards larger‐sized animals. For smaller species like parasitic insects that are specialized to attack one or a group of closely related hosts, have short adult lifespans and discrete generation times, compete directly for limited resources in small, closed arenas and have life histories constrained by host phenology, temporal resource subdivision via variation in life history may play a critical role in allowing species to coexist by alleviating the negative effects of interspecific competition.
A review of biodiversity curves of marine organisms indicates that, despite fluctuations in amplitude (some large), a large-scale, long-term radiation of life took place during the early Palaeozoic Era; it was aggregated by a succession of more discrete and regionalized radiations across geographies and within phylogenies. This major biodiversification within the marine biosphere started during late Precambrian time and was only finally interrupted in the Devonian Period. It includes both the Cambrian Explosion and the Great Ordovician Biodiversification Event. The establishment of modern marine ecosystems took place during a continuous chronology of the successive establishment of organisms and their ecological communities, developed during the ‘Cambrian substrate revolution’, the ‘Ordovician plankton revolution’, the ‘Ordovician substrate revolution’, the ‘Ordovician bioerosion revolution’ and the ‘Devonian nekton revolution’. At smaller scales, different regional but important radiations can be recognized geographically and some of them have been identified and named (e.g. those associated with the ‘Richmondian Invasion’ during Late Ordovician time in Laurentia and the contemporaneous ‘Boda event’ in parts of Europe and North Africa), in particular from areas that were in or moved towards lower latitudes, allowing high levels of speciation on epicontintental seas during these intervals. The datasets remain incomplete for many other geographical areas, but also for particular time intervals (e.g. during the late Cambrian ‘Furongian Gap’). The early Palaeozoic biodiversification therefore appears to be a long-term process, modulated by bursts in significant diversity and intervals of inadequate data, where its progressive character will become increasingly clearer with the availability of more complete datasets, with better global coverage and more advanced analytical techniques.
Does the fossil record present a true picture of the history of
life or should it be viewed with caution? Raup argued that
plots of the diversification of life were an illustration of bias: the
older the rocks, the less we know. The debate was partially
resolved by the observation that different data sets gave similar
patterns of rising diversity through time. Here we show that new
assessment methods, in which the order of fossils in the rocks
(stratigraphy) is compared with the order inherent in evolutionary trees (phylogeny), provide a more convincing analytical tool:
stratigraphy and phylogeny offer independent data on history.
Assessments of congruence between stratigraphy and phylogeny
for a sample of 1,000 published phylogenies show no evidence of
diminution of quality backwards in time. Ancient rocks clearly
preserve less information, on average, than more recent rocks.
However, if scaled to the stratigraphic level of the stage and the
taxonomic level of the family, the past 540 million years of the
fossil record provide uniformly good documentation of the life of
the past.
The environmental and biotic history of the late Quaternary represents a critical junction between ecology, global change studies, and pre-Quaternary paleobiology. Late Quaternary records indicate the modes and mechanisms of environmental variation and biotic responses at time-scales of 101-104 years. Climatic changes of the late Quaternary have occurred continuously across a wide range of temporal scales, with the magnitude of change generally increasing with time span. Responses of terrestrial plant populations have ranged from tolerance in situ to moderate shifts in habitat to migration and/or extinction, depending on magnitudes and rates of environmental change. Species assemblages have been disaggregated and recombined, forming a changing array of vegetation patterns on the landscape. These patterns of change are characteristic of terrestrial plants and animals but may not be representative of all other life-forms or habitats. Complexity of response, particularly extent of species recombination, depends in part on the nature of the underlying environmental gradients and how they change through time. Environmental gradients in certain habitats may change in relatively simple fashion, allowing long-term persistence of species associations and spatial patterns. Consideration of late Quaternary climatic changes indicates that both the rate and magnitude of climatic changes anticipated for the coming century are unprecedented, presenting unique challenges to the biota of the planet.
Organization in natural assemblages of desert lizards and tropical fishes
Mass extinctions are often followed by intervals in which taxa disappear from the fossil record only to reappear again later. This 'Lazarus effect' is often attributed to a poor-quality fossil record or migration to refuges. Testing these alternatives, with examples from the end Permian and late Triassic extinctions, reveals that there is no link with the abundance of fossiliferous sites and the proportion of Lazarus taxa nor are missing taxa encountered in potential refuges. Therefore, the abundance of Lazarus taxa in the aftermath of these extinctions is probably a reflection of the extreme rarity of organisms at this time.
This paper begins with a survey of the patterns in discovering and recording species of animals and plants, from Linnaeus' time to the present. It then outlines various approaches to estimating what the total number of species on Earth might be: these approaches include extrapolation of past trends; direct assessments based on the overall fraction previously recorded among newly studied groups of tropical insects; indirect assessment derived from recent studies of arthropods in the canopies of tropical trees (giving special attention to the question of what fraction of the species found on a given host-tree are likely to be `effectively specialized' on it); and estimates inferred from theoretical and empirical patterns in speciessizes relations or in food web structure. I conclude with some remarks on the broader implications of our ignorance about how many species there are.
The study of fossil beetles has played an important role in the reconstruction of Beringian paleoenvironments. More than 25 fossil localities have yielded Late Pleistocene beetle assemblages, comprising more than 300 species, of which about 147 are predators and scavengers, groups which are suitable for paleoclimatic reconstruction. The author has developed climate envelopes (climatic parameters characterizing the modern localities in which species are found) for these species, in order to perform mutual climatic range paleotemperature studies. This paper describes the thermal requirements of these beetles, and their zoogeographic history since the interval just prior to the last interglacial period. The fossil assemblages include 14 arctic and alpine species, 66 boreo-arctic species, and 68 boreal and temperate species. The greatest percentage of species with restricted thermal requirements occurs in the arctic and alpine group. The majority of boreo-arctic and boreal and temperate species have very broad thermal requirements. Based on modern distribution and the North American fossil record, it appears that some species resided exclusively in Beringia during the Late Pleistocene. These Beringian species comprise 64 % of the arctic and alpine species found in the fossil assemblages, 34 % of the boreo-arctic species, and only 1 % of the boreal and temperate species.
The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate
outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation ofAnolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists,
termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin
of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently
on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly
similar evolutionary outcomes.
The fossil record of non-marine tetrapods (amphibians, reptiles, birds and mammals) has been described by numerous authors1–3, and major ecological replacements, mass extinctions and adaptive radiations have been identified. However, most of these features of the large-scale evolution of tetrapods have been noted without numerical data of the kind assembled for marine invertebrates4–10, marine vertebrates7–10 and vascular land plants11. Much has been learnt from the record of marine invertebrates, particularly about the overall patterns of diversification with time, the performance of different major taxonomic groups at different times, and the magnitude and timing of mass extinctions. The present study tests some of the general conclusions on the basis of a new compilation of data on the fossil record of terrestrial tetrapods. I show that family diversity rose with time, and in particular from the Cretaceous to the present day. There were several mass extinction events, but none of these was associated with a statistically high extinction rate. The extinction events, including the famous terminal Cretaceous extinction, were the result of a slightly elevated extinction rate combined with a depressed origination rate, and the present evidence does not support the view that mass extinctions are statistically distinguishable from background extinctions. Further, the record of non-marine tetrapods shows an increasing total extinction rate and an only marginally decreasing probability of extinction (per-taxon rate) from the late Devonian to the present, the opposite of the findings from the record of marine animals.
Tentative preliminaire de developpement d'une theorie (basee sur l'hypothese de la «Red Queen», sur la theorie de la biogeographie des iles et sur d'autres concepts) sur le comportement a long terme des ecosystemes, comprenant des changements dans le nombre d'especes, leur constitution genetique et leur abondance relative
A simple equilibrial model for the growth and maintenance of Phanerozoic global marine taxonomie diversity can be constructed from considerations of the behavior of origination and extinction rates with respect to diversity. An initial postulate that total rate of diversification is proportional to number of taxa extant leads to an exponential model for early phases of diversification. This model appears to describe adequately the “explosive” diversification of known metazoan orders across the Precambrian-Cambrian Boundary, suggesting that no special event, other than the initial appearance of Metazoa, is necessary to explain this phenomenon. As numbers of taxa increase, the rate of diversification should become “diversity dependent.” Ecological factors should cause the per taxon rate of origination to decline and the per taxon rate of extinction to increase. If these relationships are modeled as simple linear functions, a logistic description of the behavior of taxonomie diversity through time results. This model appears remarkably consistent with the known pattern of Phanerozoic marine ordinal diversity as a whole. Analysis of observed rates of ordinal origination also indicates these are to a large extent diversity dependent; however, diversity dependence is not immediately evident in rates of ordinal extinction. Possible explanations for this pattern are derived from considerations of the size of higher taxa and from simulations of their diversification. These suggest that both the standing diversity and the pattern of origination of orders may adequately reflect the behavior of species diversity through time; however, correspondence between rates of ordinal and species extinction may deteriorate with progressive loss of information resulting from incomplete sampling of the fossil record.
A general model of taxonomic diversity, incorporating diversity-dependent rates of origination and extinction, is constructed to examine the dynamic responses of diversity to perturbation. The model predicts that the trajectories of diversification increase and decrease are substantially different. The trajectories of diversity during disequilibrium conditions are displayed in phase diagrams to permit a simple graphical analysis of stability. A positive displacement of diversity from equilibrium results in a rapid decline in diversity and may involve an initial overshoot of the equilibrium condition. A negative displacement of equal magnitude results in a gradual increase in diversity. The model is expressed as a nonlinear difference equation to incorporate intrinsically a delay time due to the characteristic noninstantaneous response of origination and extinction. The model initially assumes a parabolic curve expressing total taxon origination rate as a function of diversity. A second model, constructed assuming a sigmoidal total taxon origination rate derived from considerations of allopatric speciation, enhances the asymmetry of the diversity response. The delayed recovery of the Triassic fauna is shown to be characteristic of return to equilibrium from an undersaturated condition, whereas the more rapid “catastrophic” decline in the Late Permian fauna is shown to be characteristic of return to equilibrium from the oversaturated condition. It is proposed, although not assumed, that perturbation may include a degree of selectivity related to the dispersal abilities of organisms, thereby enhancing the observed asymmetry.
Data on numbers of marine families within 91 metazoan classes known from the Phanerozoic fossil record are analyzed. The distribution of the 2800 fossil families among the classes is very uneven, with most belonging to a small minority of classes. Similarly, the stratigraphic distribution of the classes is very uneven, with most first appearing early in the Paleozoic and with many of the smaller classes becoming extinct before the end of that era. However, despite this unevenness, a Q -mode factor analysis indicates that the structure of these data is rather simple. Only three factors are needed to account for more than 90% of the data. These factors are interpreted as reflecting the three great “evolutionary faunas” of the Phanerozoic marine record: a trilobite-dominated Cambrian fauna, a brachiopod-dominated later Paleozoic fauna, and a mollusc-dominated Mesozoic-Cenozoic, or “modern,” fauna. Lesser factors relate to slow taxonomic turnover within the major faunas through time and to unique aspects of particular taxa and times. Each of the three major faunas seems to have its own characteristic diversity so that its expansion or contraction appears as being intimately associated with a particular phase in the history of total marine diversity. The Cambrian fauna expands rapidly during the Early Cambrian radiations and maintains dominance during the Middle to Late Cambrian “equilibrium.” The Paleozoic fauna then ascends to dominance during the Ordovician radiations, which increase diversity dramatically; this new fauna then maintains dominance throughout the long interval of apparent equilibrium that lasts until the end of the Paleozoic Era. The modern fauna, which slowly increases in importance during the Paleozoic Era, quickly rises to dominance with the Late Permian extinctions and maintains that status during the general rise in diversity to the apparent maximum in the Neogene. The increase in diversity associated with the expansion of each new fauna appears to coincide with an approximately exponential decline of the previously dominant fauna, suggesting possible displacement of each evolutionary fauna by its successor.
The kinetic model of taxonomic diversity predicts that the long-term diversification of taxa within any large and essentially closed ecological system should approximate a logistic process controlled by changes in origination and extinction rates with changing numbers of taxa. This model is tested with a new compilation of numbers of metazoan families known from Paleozoic stages (including stage-level subdivisions of the Cambrian). These data indicate the occurrence of two intervals of logistic diversification within the Paleozoic. The first interval, spanning the Vendian and Cambrian, includes an approximately exponential increase in families across the Precambrian-Cambrian Boundary and a “pseudo-equilibrium” through the Middle and Late Cambrian, caused by diversity-dependent decrease in origination rate and increase in extinction rate. The second interval begins with a rapid re-diversification in the Ordovician, which leads to a tripling of familial diversity during a span of 50 Myr; by the end of the Ordovician diversity attains a new dynamic equilibrium that is maintained, except for several extinction events, for nearly 200 Myr until near the end of the Paleozoic. A “two-phase” kinetic model is constructed to describe this heterogeneous pattern of early Phanerozoic diversification. The model adequately describes the “multiple equilibria,” the asymmetrical history of the “Cambrian fauna,” the extremely slow initial diversification of the later “Paleozoic fauna,” and the combined patterns of origination and extinction in both faunas. It is suggested that this entire pattern of diversification reflects the early success of ecologically generalized taxa and their later replacement by more specialized taxa.
Life on land today is as much as 25 times as diverse as life in the sea. Paradoxically, this extraordinarily high level of continental biodiversity has been achieved in a shorter time and it occupies a much smaller area of the Earth's surface than does marine biodiversity. Raw palaeontological data suggest very different models for the diversification of life on land and in the sea. The well-studied marine fossil record appears to show evidence for an equilibrium model of diversification, with phases of rapid radiation, followed by plateaux that may indicate times of equilibrium diversity. The continental fossil record shows exponential diversification from the Silurian to the present. These differences appear to be real: the continental fossil record is unlikely to be so poor that all evidence for a high initial equilibrial diversity has been lost. In addition, it is not clear that the apparently equilibrial marine model is correct, since it is founded on studies at familial level. At species level, a logistic family-level curve probably breaks down to an exponential. The rocketing diversification rates of flowering plants, insects, and other land life are evidently hugely different from the more sluggish rates of diversification of life in the sea, perhaps as a result of greater endemism and habitat complexity on land. Copyright (C) 2001 John Wiley & Sons, Ltd.
The study of fossil beetles has played an important role in the reconstruction of Beringian paleoenvironments. More than 25 fossil localities have yielded Late Pleistocene beetle assemblages, comprising more than 300 species, of which about 147 are predators and scavengers, groups which are suitable for paleoclimatic reconstruction. The author has developed climate envelopes (climatic parameters characterizing the modern localities in which species are found) for these species, in order to perform mutual climatic range paleotemperature studies. This paper describes the thermal requirements of these beetles, and their zoogeographic history since the interval just prior to the last interglacial period. The fossil assemblages include 14 arctic and alpine species, 66 boreo-arctic species, and 68 boreal and temperate species. The greatest percentage of species with restricted thermal requirements occurs in the arctic and alpine group. The majority of boreo-arctic and boreal and temperate species have very broad thermal requirements. Based on modern distribution and the North American fossil record, it appears that some species resided exclusively in Beringia during the Late Pleistocene. These Beringian species comprise 64 % of the arctic and alpine species found in the fossil assemblages, 34 % of the boreo-arctic species, and only 1 % of the boreal and temperate species.
J.M. Diamond's assembly rules model predicts that competitive interactions between species lead to nonrandom co-occurrence patterns. We conducted a meta-analysis of 96 published presence-absence matrices and used a realistic "null model" to generate patterns expected in the absence of species interactions. Published matrices were highly nonrandom and matched the predictions of Diamond's model: there were fewer species combinations, more checkerboard species pairs, and less co-occurrence in real matrices than expected by chance. Moreover, nonrandom structure was greater in homeotherm vs. poikilotherm matrices. Although these analyses do not confirm the mechanisms of Diamond's controversial assembly rules model, they do establish that observed co-occurrence in most natural communities is usually less than expected by chance. These results contrast with previous analyses of species co-occurrence patterns and bridge the apparent gap between experimental and correlative studies in community ecology.
Time series of global diversity and extinction intensity measured from data on stratigraphic ranges of marine animal genera show the impact of bio-events on the fauna of the world ocean. Measured extinction intensities vary greatly, from major mass extinctions that eradicated 39 to 82% of generic diversity to smaller events that had substantially less impact on the global fauna. Many of the smaller extinction events are clearly visible only after a series of filters are applied to the data. Still, most of these extinction events are also visible in a smaller set of data on marine families. Although many of the episodes of extinction seen in the global data are well known from detailed biostratigraphic investigations, some are unstudied and require focused attention for confirmation or refutation.
Develops a theory of the long-term behavior of ecosystems, including changes in the number of species, in their genetic constitutions, and in their relative abundances. The theory is based on the Red Queen hypothesis, on the theory of island biogeography, and on the concepts of species packing and limiting similarity. The main conclusion is that an ecosystem in a physically constant environment may be in one of 2 evolutionary modes: 1) Red Queen, or steady state of evolutionary change, or 2) evolutionary stasis. In the latter case, continued evolution necessarily depends on changes in the physical environment. A decision as to which mode has been prevalent in the past depends on a study of the fossil record, but such study of the past must be accompanied by the study of how organisms interact in current ecosystems.-from Authors
Ecological studies of the past 30 yr have presumed that interactions among populations within small areas are the fundamental forces regulating community structure, but this paradigm has failed to solve one of the central problems of biology - the origin and maintenance of global patterns of diversity. Disparities have often been found in the numbers of species present in similar environments in different parts of the world, hinting that larger-scale processes were also at work which might even dominate local ones. This book aims to provide a statement of current understanding of patterns of and the causes behind biodiversity. Contributions use recent theoretical developments, analyses and case studies to explore large-scale mechanisms that generate and maintain diversity. Part I, Local patterns and processes, looks at species richness on local and regional scales, examines the relation between species diversity and habitat productivity, and compares ecological processes in different locations. Part II, Coexistence at the mesoscale, considers the influence of regional processes on local communities, the effects of species interactions on biodiversity, regulation of species-area relations, and the relationship between distribution and abundance of species. Part II, Regional perspectives, offers case studies on various taxa and regions. Part IV, Historical and phylogenetic perspectives, considers approaches to studying the development of ecological communities using research from systematics, biogeography and palaeontology. Twenty-eight individual chapters are abstracted separately. -from Editors
Two hypotheses to explain potentially high forest biodiversity have different implications for the number and kinds of species that can coexist and the potential loss of biodiversity in the absence of speciation. The first hypothesis involves stabilizing mechanisms, which include tradeoffs between species in terms of their capacities to disperse to sites where competition is weak, to exploit abundant resources effectively and to compete for scarce resources. Stabilization results because competitors thrive at different times and places. An alternative, 'neutral model' suggests that stabilizing mechanisms may be superfluous. This explanation emphasizes 'equalizing' mechanisms, because competitive exclusion of similar species is slow. Lack of ecologically relevant differences means that abundances experience random 'neutral drift', with slow extinction. The relative importance of these two mechanisms is unknown, because assumptions and predictions involve broad temporal and spatial scales. Here we demonstrate that predictions of neutral drift are testable using palaeodata. The results demonstrate strong stabilizing forces. By contrast with the neutral prediction of increasing variance among sites over time, we show that variances in post-Glacial tree abundances among sites stabilize rapidly, and abundances remain coherent over broad geographical scales.
Quantified features of community structure and of breeding biology, behavior, and life history of bird species occupying several sites in semi-arid shrub deserts in the Great Basin of North America and the interior of Australia. Study sites on both continents were statistically indistinguishable in most measures of vegetation structure. Breeding-bird assemblages contained the same number of species per unit area, but densities of individuals in Australia averaged half those in North America. A cluster analysis based on a multivariate similarity matrix derived from 14 ecological and life-history characteristics of the species revealed little close matching of Australian species with a North American counterpart, although 2 such pairings suggest possible ecological convergence. The Australian species were characterized by longer breeding periods with more breeding attempts, greater social aggregation during breeding and feeding activities, greater use of domed nests, and sedentariness or nomadism rather than seasonal migration. The avifaunas did not differ in mean clutch sizes, incidence of polygyny, nesting height, territory size, or general dietary patterns. That differences between the species and communities are more striking than the similarities may be related to climatic differences. Although long-term mean precipitation in the 2 regions does not differ, the monthly and yearly variance in Australia is substantially greater. Droughts may be prolonged and widespread, and this factor, together with soil-nutrient limitations, may result in generally lower and more erratic primary and secondary production in the Australian deserts. -from Author
The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.
This paper begins with a survey of the patterns in discovering and
recording species of animals and plants, from Linnaeus' time to the
present. It then outlines various approaches to estimating what the
total number of species on Earth might be: these approaches include
extrapolation of past trends; direct assessments based on the overall
fraction previously recorded among newly studied groups of tropical
insects; indirect assessment derived from recent studies of arthropods
in the canopies of tropical trees (giving special attention to the
question of what fraction of the species found on a given host-tree are
likely to be `effectively specialized' on it); and estimates inferred
from theoretical and empirical patterns in speciessizes relations or in
food web structure. I conclude with some remarks on the broader
implications of our ignorance about how many species there are.
To quantify the 'emptiness' of adaptive space a mathematical model of diversification is derived which makes explicit the relationship between maximum species capacity and realized diversity. The proportion of niches empty at equilibrium is a function only of the intrinsic rates of species origination and extinction. Estimates of these rates for 8 marine invertebrate groups suggest that the mean proportion of empty niches is somewhere in the range of 12-54%. Evolution in such an open adaptive space should be characterized by unremitting taxonomic turnover and continuous faunal change (but only occasional adaptive improvements), and should permit the rapid establishment of new morphospecies. These expectations are qualitatively borne out by the fossil record. -from Authors
The concept of global taxonomic diversity tending to an equilibrium state is central to many macroevolutionary hypotheses. It is widely accepted and considered to be corroborated by quantitative models of biotic diversification in the Phanerozoic. These models assume diversity dependence of the rates of extinction and origination of taxa. This basic assumption, however, is contradicted by the empirical data. The process of diversification may depend on historical contingencies rather than on general macroevolutionary laws.-Author
Natural archives of Earth's past climate take several forms — sea and lake sediments, tree rings, peat bogs and glacier ice — all of which are used in reconstructing climate history. But the records locked up in the large polar ice sheets are especially valuable. Cores of this ice not only allow reconstruction of changes in local temperature and precipitation, but also provide information about volcanic activity, storminess, solar activity and atmospheric composition.
One of the great unsolved mysteries of evolutionary biology concerns the genetic mechanisms underlying the origin of genomic incompatibilities between species. Two prevailing thoughts are that such incompatibilities often result from epistatically interacting genes that act as loss-of-function alleles in hybrid backgrounds or from chromosomal rearrangements that result in mis-segregation during meiosis in hybrids. However, it is unclear how genes that cause a radical breakdown in hybrids arise without reducing fitness within species, and numerous cases of speciation appear to be unassociated with obvious chromosomal rearrangements. Here we suggest that duplicate genes, and more generally any kind of genomic redundancies, provide a powerful substrate for the origin of genomic incompatibilities in isolated populations. The divergent resolution of genomic redundancies, such that one population loses function from one copy while the second population loses function from a second copy at a different chromosomal location, leads to chromosomal repatterning such that gametes produced by hybrid individuals can be completely lacking in functional genes for a duplicate pair. Under this model, incompatibility factors accumulate with essentially no loss of fitness within populations as postulated under the Bateson-Dobzhansky-Muller (BDM) model of speciation and despite the fact that they arise from degenerative mutations. However, unlike the situation often envisioned under the BDM model, no change in the mode of gene action in hybrid backgrounds need be invoked. The plausibility of this model derives from a number of recent observations, including the fact that most genomes harbor substantial numbers of gene duplicates whose turnover is common and ongoing process and the fact that many genes have complex regulatory regions that facilitate their divergent resolution in sister taxa.
Several recent studies have proposed the use of higher taxa as a proxy for species-level biodiversity patterns. Here this premise is evaluated by using a large database of benthic marine molluscs from the eastern Pacific. In this assemblage, diversity patterns at the genus and family level are significantly correlated with those at the species level. However, the choice of taxonomic rank depends on the resolution required to address a given problem. Although familial data are very robust to sampling and adequately reflect the general species-level patterns (for example, the presence and sign of diversity gradients), they cannot adequately resolve regional variations such as stepped diversity trends. Genera are useful even at regional scales, but species-frequency distributions within higher taxa vary with diversity (and biogeography). Hence, for regional studies, calibration based on a few well-sampled local assemblages is recommended to increase the effectiveness of genera as proxies for species-level patterns. Information contained within the taxonomic hierarchy can also provide insights into other macroecological patterns that are not evident from a simple tabulation of species, such as estimates of the latitudinal deployment of biodisparity.
A new Markov chain is introduced which can be used to describe the family relationships among n individuals drawn from a particular generation of a large haploid population. The properties of this process can be studied, simultaneously for all n, by coupling techniques. Recent results in neutral mutation theory are seen as consequences of the genealogy described by the chain.
Temporal patterns of origination and extinction are essential components of many paleontological studies, but it has been difficult to obtain accurate rate estimates because the observed record of first and last appearances is distorted by the incompleteness of the fossil record. Here I analyze observed first and last appearances of marine animal and microfossil genera in a way that explicitly takes incompleteness and its variation into consideration. This approach allows estimates of true rates of origination and extinction throughout the Phanerozoic. Substantial support is provided for the proposition that most rate peaks in the raw data are real in the sense that they do not arise as a consequence of temporal variability in the overall quality of the fossil record. Even though the existence of rate anomalies is supported, their timing is nevertheless open to question in many cases. If one assumes that rates of origination and extinction are constant through a given stratigraphic interval, then peaks in revised origination rates tend to be displaced backward and extinction peaks forward relative to the peaks in the raw data. If, however, one assumes a model of pulsed turnover, with true originations concentrated at lower interval boundaries and true extinctions concentrated at upper interval boundaries, the apparent timing of extinction peaks is largely reliable at face value. Thus, whereas rate anomalies may well be real, precisely when they occurred is a question that cannot be answered definitively without independent support for a model of smooth versus pulsed rate variation. The pattern of extinction, particularly the major events, is more faithfully represented in the fossil record than that of origination. There is a tendency for the major extinction events to occur during stages in which the quality of the record is relatively high and for recoveries from extinctions to occur when the record is less complete. These results imply that interpretations of origination and extinction history that depend only on the existence of rate anomalies are fairly robust, whereas interpretations of the timing of events and the temporal covariation between origination and extinction may require substantial revision.
▪ Abstract The Siluro-Devonian primary radiation of land biotas is the terrestrial equivalent of the much-debated Cambrian “explosion” of marine faunas. Both show the hallmarks of novelty radiations (phenotypic diversity increases much more rapidly than species diversity across an ecologically undersaturated and thus low-competition landscape), and both ended with the formation of evolutionary and ecological frameworks analogous to those of modern ecosystems. Profound improvements in understanding early land plant evolution reflect recent liberations from several research constraints: Cladistic techniques plus DNA sequence data from extant relatives have prompted revolutionary reinterpretations of land plant phylogeny, and thus of systematics and character-state acquisition patterns. Biomechanical and physiological experimental techniques developed for extant plants have been extrapolated to fossil species, with interpretations both aided and complicated by the recent knowledge that global landmass positi...
Strong correlations between various local and global estimates of Phanerozoic marine diversity for taxa below the ordinal level indicate a single pattern of change underlying all data on fossil density. Geological time alone seems insufficient to explain all of the significant covariation among the data sets, and it is proposed that the common pattern in diversity reflects the signal from a real evolutionary phenomenon strong enough to overcome the biases inherent in the fossil record.