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Contrast in floral characterisitics between D. wrightii, A. palmeri and A. chrysantha plants. The three plants are visited by nocturnal hawkmoths, but the floral traits in each plant differ from one another. (A) D. wrightii flowers. Note the bright floral reflectance of the corollas that produces a contrast with the dark foliage background. (B) A. palmeri umbel. Each umbel contains 8–20 flowers. Hyles lineata (Sphingidae), and Cotinus mutabilis (Scarabaeidae), are feeding from the umbel. (C) A. chrysantha umbel. The morphology of A. chrysantha closely resembles that of A. palmeri, but note the bright yellow corollas. (D) Principal-components analysis of the floral odor from these three plants. The D. wrightii flowers (blue circles) group together. In contrast, the agaves appear more variable. The odor of A. palmeri flowers (green squares) appears to more closely resemble that of D. wrightii due to the presence of monoterpenes and benzenoids in its headspace, but some A. palmeri flowers are also grouped in the same PCA space of A. chrysantha (yellow diamonds) due to their aliphatic esters. Scale bar = 5 cm. Picture images courtesy of Charles Hedgecock RBP, FBCA (ARL Division of Neurobiology, University of Arizona) and T. Beth Kinsey.
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Variation in floral traits including odor, color and morphology, demonstrate the selective pressures imposed by specific pollinator taxa, such as insects and birds. In southern Arizona, Manduca sexta (Sphingidae) hawkmoths are associated with Datura wrightii (Solanaceae) at both the larval (herbivore) and adult (nectar feeding) stages. However duri...
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... wrightii, Solanaceae), which exhibit bat and hawkmoth- adapted floral characters, respectively. D. wrightii floral traits include a sweet smelling odor composed of terpenoids (mono-and sesquit- erpenoids) (79%) and benzenoids (18%), a sucrose-rich nectar, and highly reflective corollas (reflectance > 50%) that appear white to the human eye (Fig. 1A). In contrast, A. palmeri traits consist of a foul floral scent dominated by esters (30%), sulfur compounds (<1%), and monoterpenoids (59%), abundant hexose-rich nectar, and a pale dull coloration (reflectance < 25%) (Fig. 1B). The hawk- moth, Manduca sexta (Sphingidae), is an important pollinator for D. wrightii and has an innate ...
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... (18%), a sucrose-rich nectar, and highly reflective corollas (reflectance > 50%) that appear white to the human eye (Fig. 1A). In contrast, A. palmeri traits consist of a foul floral scent dominated by esters (30%), sulfur compounds (<1%), and monoterpenoids (59%), abundant hexose-rich nectar, and a pale dull coloration (reflectance < 25%) (Fig. 1B). The hawk- moth, Manduca sexta (Sphingidae), is an important pollinator for D. wrightii and has an innate attraction to D. wrightii's floral odor. M. sexta hawkmoths also visit A. palmeri flowers, but only when D. wrightii is not locally abundant. Moths learn to utilize A. palmeri's abundant nectar resources through olfactory-mediated ...
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... of monoterpenes and aliphatic compounds known to attract diverse insect species, and have floral morphologies that permit nectar access by insects, bats and birds. However, their flowers' differ from one another in several ways. For instance, corollas of A. chrysantha are bright yellow- orange rather than the pale cream color of A. palmeri (Fig. 1C), which suggests that the former are visually more adapted to diurnal pollinators, and the latter to nocturnal pollinators. 16 A. chrysantha flowers produce nectar that has more than 63-times the sucrose content of A. palmeri (7.56 mg/flower versus 0.12 mg/flower, respec- tively), which suggest that A. chrysantha's nectar is under ...
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... differing in their visual display and nectar chemistry, exami- nation of their scent profiles by principal components analysis (PCA) revealed substantial overlap in the two agave species (Fig. 1D). For instance, A. palmeri and A. chrysantha share similar percentages of chemical odorant classes, including low levels of sulfur compounds (<1%)-a common marker of bat-adapted flowers-esters (ca. 53% and 77%, respectively), and terpenoids (ca. 38% and 15%, respec- tively). The contrast in floral color and nectar chemistry suggest ...
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... Recent studies comparing ecological networks along elevational gradients have yielded key insights into the effects of climate change on species interactions Pellissier et al. 2018). Variation in network structure across space and time reflects the shifting influences of ecological and evolutionary processes, such as environmental filtering and competition, that together shape community stability and ecosystem function (Thompson 2005(Thompson , 2006Schleuning et al. 2012;González et al. 2015 Riffell et al. 2008), there is no community-level moth pollen-transport study from the Southwestern US. We generally expected to find a high proportion of moths transporting pollen, consistent with recent findings from other regions with seasonally hot and dry climates (Banza et al. 2015(Banza et al. , 2019Ribas-Marquès et al. 2022). ...
Anthropogenic global climate change can disrupt plant-pollinator interactions by altering the traits, phenologies, and distributions of interacting species, exacerbating insect declines and compromising ecosystem function. However, most research has focused on diurnal pollinators, and little is known about the prevalence, importance, and vulnerability of nocturnal moth pollination. This knowledge gap limits our ability to predict and mitigate the effects of climate change and other stressors on moths and their pollination services. In this dissertation, I investigate the ecology of moth pollination interactions, how moths and their host and nectar plants will be impacted by climate change, and how to apply this knowledge in conservation strategies. I focus on native plants and moths in California, a biodiversity hotspot that is particularly impacted by climate change. I employ techniques ranging from greenhouse experiments to DNA metabarcoding to explore impacts spanning the levels of functional traits to ecological networks. In Chapter 1, I document hundreds of previously undescribed moth pollen-transport interactions along an elevational gradient spanning desert to conifer forest. I also find that moths are smaller, less diverse, and more sensitive to the simulated loss of their nectar plants in hotter and drier conditions. In Chapter 2, I reveal that experimental warming and drought alter diel patterns of floral nectar quantity and quality in a generalist plant. This may differentially affect interactions with diurnal and nocturnal pollinators, scaling up to alter the structure and stability of plant-pollinator interaction networks. In Chapter 3, I analyze and compare Lepidoptera-host and -nectar plant interaction networks across California, revealing structural differences and spatial patterns that inform management priorities. I also analyze species roles in networks to identify spatially-explicit keystone plant species to be used in butterfly and moth conservation efforts. Together, my results reveal that moth pollination interactions are diverse, complex, and vulnerable to climate change, and that data-driven conservation strategies can help protect them. Ultimately, this dissertation highlights the importance of considering the nocturnal components of plant-pollinator networks in research and management.
... Datura wrightii (Solanales: Solanaceae) has begun to serve as a model system for research into the ecology and evolution of various plant traits, including both physical and chemical defenses [1,2], tolerance to herbivory [3], floral phenotypes [4,5], life histories [6,7], and ontogenetic changes in defense production throughout an individual plant's lifetime [8,9]. This is due to the wealth of ecological knowledge already gathered regarding this common plant and the specialist insects with which it interacts [10,11]. ...
The sacred datura plant (Solanales: Solanaceae: Datura wrightii) has been used to study plant–herbivore interactions for decades. The wealth of information that has resulted leads it to have potential as a model system for studying the ecological and evolutionary genomics of these interactions. We present a de novo Datura wrightii genome assembled using PacBio HiFi long-reads. Our assembly is highly complete and contiguous (N50 = 179Mb, BUSCO Complete = 97.6%). We successfully detected a previously documented ancient whole genome duplication using our assembly and have classified the gene duplication history that generated its coding sequence content. We use it as the basis for a genome-guided differential expression analysis to identify the induced responses of this plant to one of its specialized herbivores (Coleoptera: Chrysomelidae: Lema daturaphila). We find over 3000 differentially expressed genes associated with herbivory and that elevated expression levels of over 200 genes last for several days. We also combined our analyses to determine the role that different gene duplication categories have played in the evolution of Datura-herbivore interactions. We find that tandem duplications have expanded multiple functional groups of herbivore responsive genes with defensive functions, including UGT-glycosyltranserases, oxidoreductase enzymes, and peptidase inhibitors. Overall, our results expand our knowledge of herbivore-induced plant transcriptional responses and the evolutionary history of the underlying herbivore-response genes.
... In light of the evolutionary lability of pollination systems, we might expect intraspecific polymorphisms in the pollination biology of extant species. Indeed, plant-pollinator interactions often vary within species (Kunin, 1997;Lay et al., 2011;Namah et al., 2019;Newman et al., 2021;Riffell et al., 2008;Silva-Montellano & Eguiarte, 2003). Selection for floral traits has also been shown to differ across species' ranges (Armbruster, 1985) and altered pollinator environments over time or space drive divergent selection on floral traits (Anderson et al., 2010(Anderson et al., , 2014Johnson, 1997;Robertson & Wyatt, 1990), which could ultimately result in switches in pollination systems (Van der Niet et al., 2014). ...
... The fact that their analysis methods were suited to detection of this compound and that they did detect (E)β-caryophyllene in other sampled species suggests that this compound is absent from A. digitata in West Africa. This sweet, woody-smelling terpenoid occurs in some moth-pollinated flowers (Knudsen & Tollsten, 1993), whereas closely related batpollinated species lack β-caryophyllene, as has been found in Agave (Riffell et al., 2008). ...
Chiropterophily, or bat pollination, is typically considered a highly specialized pollination system that has evolved independently numerous times across the angiosperm phylogeny, with distinct lineages often converging on a similar suite of floral traits. The African baobab, Adansonia digitata, occurs widespread across continental Africa and introduced throughout much of the tropics, possesses floral traits classically associated with bat pollination, namely nocturnal anthesis, pendulous white flowers, and a “musky” fragrance. Despite this, our observations and pollination exclusion experiments in South African baobab populations suggested little if any role for bats, but instead showed that hawkmoths are the main pollinators. Hand pollination indicated strong self‐incompatibility and crossing experiments suggest minimal diurnal receptivity. Furthermore, our analyses of floral volatiles revealed not only sulfur‐containing compounds, commonly associated with bat pollination, but also a high concentration of the sesquiterpene β‐caryophyllene, a compound generally more typical of hawkmoth pollination. Comparing previous pollination studies and published floral scent profiles from West Africa suggests that the classic bat pollination system in baobabs may be more labile than previously thought. This study provides an empirical example of a species that most likely evolved due to bat pollination yet has some degree of generality and possible geographic variation in floral traits and pollinator visitation patterns across its range. Baobabs have long been recognized as being bat‐pollinated. However, in the absence of bats, hawkmoths are the primary pollinators in some populations, suggesting geographic variation in pollinator visitation rates across Africa, possibly driven by differences in floral scent.
... These phalaenophilous attributes include: (i) the time of anthesis, which could to limit visitation to a specific guild of pollinators (nocturnal); (ii) the presence of odour, an important trait for guiding the pollinators to the flowers in the dark; and (iii) concentrated nectar, which restricts even more the guild of pollinators associated with the flowers. Many authors have suggested phalaenophily for plant species that demonstrate such floral characteristics (Faegri & van der Pijl 1979;Haber & Frankie 1989;Manning & Snijman 2002;Riffell et al. 2008;Avila & Freitas 2011). Those characteristics, in combination with receptive stigmas and viable pollen grains when moths are foraging (the first floral visitors, ca 04:00) and touching the reproductive structures of the flowers, constitute evidence of legitimate visitation, which allows classifying them as potential pollinators. ...
Background and aims – Copaifera coriacea, a species in the resin-producing clade Detarioideae (Leguminosae), is an endemic and abundant species found in sand dunes in Brazilian Caatinga domain vegetation – a Quaternary paleodesert. We investigated floral traits and aspects of pollination biology, focusing on the pollination system of C. coriacea. Material and methods – Anthesis duration, stigma receptivity, pollen viability, nectar concentration, and the presence of osmophores and pigments reflecting UV light were assessed. Floral visitors were classified as potential pollinators, occasional pollinators or thieves, based on the time and foraging behaviour and resource collected. Pollination effectiveness were assessed for potential pollinators by the detection of pollen tubes on the stigma or stylar canal by epifluorescence microscopy.Key results – The species has white and small flowers, with anthesis beginning in the dark (ca 00:30) and the flowers are completely opened approximately 3 h later, when a sweet odour is perceptible. The onset of stigma receptivity and pollen grain viability occurs only after the completion of flower opening, and a concentrated nectar is available during the day. The presence of pollen tubes confirmed the efficiency of the main insects in the transfer of pollen. Conclusion – Our result demonstrates that C. coriacea has a generalist pollination system mediated mainly by two distinct guilds of insect pollinators: moths (nocturnal, searching for nectar) and bees (diurnal, pollen collectors). This finding can provide more information about diversification in the genus Copaifera.
... The aims of this study were to characterize the diversity and distributions of microbes associated with nectar of two iconic plants of the Sonoran Desert region, where previous studies of nectar microbiomes have been limited in scope. Specifically, we quantified the frequency, abundance, diversity, and composition of bacterial and fungal communities in floral nectar of two species of night-blooming plants: Datura wrightii (Solanaceae), which is pollinated by hawkmoths [15], and Agave palmeri (Agavaceae), which is pollinated by bats but visited by hawkmoths that forage for nectar [15][16][17]. These two species differ in their nectar composition, concentration, floral display, flower longevity, and flowering phenology [15], yet are both a major source of nectar for the hawkmoth community of the southwest [16,17]. ...
... The aims of this study were to characterize the diversity and distributions of microbes associated with nectar of two iconic plants of the Sonoran Desert region, where previous studies of nectar microbiomes have been limited in scope. Specifically, we quantified the frequency, abundance, diversity, and composition of bacterial and fungal communities in floral nectar of two species of night-blooming plants: Datura wrightii (Solanaceae), which is pollinated by hawkmoths [15], and Agave palmeri (Agavaceae), which is pollinated by bats but visited by hawkmoths that forage for nectar [15][16][17]. These two species differ in their nectar composition, concentration, floral display, flower longevity, and flowering phenology [15], yet are both a major source of nectar for the hawkmoth community of the southwest [16,17]. ...
... Specifically, we quantified the frequency, abundance, diversity, and composition of bacterial and fungal communities in floral nectar of two species of night-blooming plants: Datura wrightii (Solanaceae), which is pollinated by hawkmoths [15], and Agave palmeri (Agavaceae), which is pollinated by bats but visited by hawkmoths that forage for nectar [15][16][17]. These two species differ in their nectar composition, concentration, floral display, flower longevity, and flowering phenology [15], yet are both a major source of nectar for the hawkmoth community of the southwest [16,17]. Here we describe the relevance of growing environment (greenhouse vs. field), time (before and after anthesis), season (from early to late in the flowering season), and flower visitors (excluded via mesh sleeves or allowed to visit flowers naturally) in shaping microbial communities in nectar. ...
Nectar-inhabiting microbes are increasingly appreciated as important components of plant-pollinator interactions. We quantified the incidence, abundance, diversity, and composition of bacterial and fungal communities in floral nectar of two night-blooming plants of the Sonoran Desert over the course of a flowering season: Datura wrightii (Solanaceae), which is pollinated by hawkmoths, and Agave palmeri (Agavaceae), which is pollinated by bats but visited by hawkmoths that forage for nectar. We examined the relevance of growing environment (greenhouse vs. field), time (before and after anthesis), season (from early to late in the flowering season), and flower visitors (excluded via mesh sleeves or allowed to visit flowers naturally) in shaping microbial assemblages in nectar. We isolated and identified bacteria and fungi from >300 nectar samples to estimate richness and taxonomic composition. Our results show that microbes were common in D. wrightii and A. palmeri nectar in the greenhouse but more so in field environments, both before and especially after anthesis. Bacteria were isolated more frequently than fungi. The abundance of microbes in nectar of D. wrightii peaked near the middle of the flowering season. Microbes generally were more abundant as time for floral visitation increased. The composition of bacterial and especially fungal communities differed significantly between nectars of D. wrightii and A. palmeri, opening the door to future studies examining their functional roles in shaping nectar chemistry, attractiveness, and pollinator specialization.
... Other research on mutualistic plant-pollinator interactions has focused on large flowers or large, high-energy pollinators. Such are the cases of the pioneer work by Gregory (1963Gregory ( , 1964 on the pollination of Oenothera, and other, more recent work with hawk moths (e.g., Willmott and Búrquez 1996;Raguso andWillis 2003, 2005;Riffell et al. 2008). Below we discuss the best-known pollination systems from the Sonoran Desert and their implications in the specialization/generalization paradigm of pollination. ...
... This content downloaded from 178.198.030.103 on March 10, 2016 06:57:06 AM ful in uncovering the danger of simplifying interactions, through the use of pollination syndromes, and the evolutionary significance of reliance on several agents of pollen transport (e.g., Riffell et al. 2008). Also evident is the widespread generalization within pollination systems, largely driven by spatiotemporal variation in the abundance of resources, pollinator assemblages, and visitation rates (Herrera 1996;Ollerton 1996;Waser et al. 1996;Waser 1998;Thompson 2005). ...
Premise of research. Biotic interactions have long been considered to be of less importance in structuring desert systems than other ecosystem types, but biotic interactions often play a critical role in meeting the challenges posed by the extreme conditions of desert environments. The Sonoran Desert, in particular, is home to several textbook examples of mutualisms, such as the interactions between the iconic saguaro cactus and its bat pollinators. But what do we know about the diversity, ecology, and evolution of plant-animal, plant-plant, and plant-microbe interactions and their impacts on individual plants and plant species in the Sonoran Desert?
Methodology. To address this question, we review the published research on seven common kinds of plant biotic interactions by revisiting the respective literature, identifying gaps in our knowledge, and outlining future research directions.
Pivotal results. Numerous gaps in our knowledge of plant biotic interactions in the Sonoran Desert were identified. Studies of insect herbivory, bee pollination, and plant-microbe interactions are poorly represented in the Sonoran Desert literature. Across all categories of interaction, few have examined the impacts of interactions on plant fitness or context-dependent variation in the outcomes and strengths of interactions. For the most part, interactions have been studied at single locations and over short periods of time, resulting in an incomplete understanding of their diversity, ecology, and evolution.
Conclusions. Plant biotic interactions shape the habitats in which they occur and play an important role in the maintenance of species diversity. Therefore, we call for increased efforts to fill the gaps in our understanding of plant biotic interactions in the Sonoran Desert, with an emphasis on studies linking interactions to plant fitness and the context-dependent nature of interactions. Without this knowledge we have limited capacity to predict the outcomes of global change on species interactions and to develop measures to conserve the biodiversity of the Sonoran Desert region.
... For pollinators that rely on olfactive learning, such as generalist social bees (D€ otterl & Vereecken, 2010), changes in the ratios of floral emissions may thus not involve serious problems of identification, because these pollinators continuously learn the scents of the flowering species in the community and establish associations between their scents and the resources they offer. In contrast, specialist pollinators such as hawkmoths that visit nocturnally blooming flowers (Raguso et al., 2003;Riffell et al., 2008), or specialist bees visiting only one or a few host plant species (Filella et al., 2011), tend to rely to various degrees on innate preferences for the species-specific floral scents of the plants they visit, and these innate preferences may have a genetic basis that is much less dynamic than the acquired knowledge obtained by learning. ...
We addressed the potential effects of changes in ambient temperature on the profiles of volatile emissions from flowers and tested whether warming could induce significant quantitative and qualitative changes in floral emissions, which would potentially interfere with plant-pollinator chemical communication. We measured the temperature responses of floral emissions of various common species of Mediterranean plants using dynamic headspace sampling and used GC-MS to identify and quantify the emitted terpenes. Floral emissions increased with temperature to an optimum and thereafter decreased. The responses to temperature modeled here predicted increases in the rates of floral terpene emission of 0.03-1.4-fold, depending on the species, in response to an increase of 1 °C in the mean global ambient temperature. Under the warmest projections that predict a maximum increase of 5 °C in the mean temperature of Mediterranean climates in the Northern Hemisphere by the end of the century, our models predicted increases in the rates of floral terpene emissions of 0.34-9.1-fold,depending on the species. The species with the lowest emission rates had the highest relative increases in floral terpene emissions with temperature increases of 1-5 °C. The response of floral emissions to temperature differed among species and among different compounds within the species. Warming not only increased the rates of total emissions, but also changed the ratios among compounds that constituted the floral scents, i.e. increased the signal for pollinators, but also importantly altered the signal fidelity and probability of identification by pollinators, especially for specialists with a strong reliance on species-specific floral blends.This article is protected by copyright. All rights reserved.
... In fact, A. palmeri produces hexose-rich nectar (.50 ml/h), emits a floral scent composed of monoterpenes and aliphatic compounds which are known to be attractive to diverse insects, and has brush-like flowers that permit nectar access by many animal taxa [20,37,60,61]. As such, A. palmeri functions as an important nectar resource in southern Arizona for hawkmoths as well as the larger pollinator community, particularly prior to the onset of the summer monsoon rains when D. wrightii and other herbaceous plants are still dormant [37,62]. ...
Combinations of floral traits - which operate as attractive signals to pollinators - act on multiple sensory modalities. For Manduca sexta hawkmoths, how learning modifies foraging decisions in response to those traits remains untested, and the contribution of visual and olfactory floral displays on behavior remains unclear.
Using M. sexta and the floral traits of two important nectar resources in southwestern USA, Datura wrightii and Agave palmeri, we examined the relative importance of olfactory and visual signals. Natural visual and olfactory cues from D. wrightii and A. palmeri flowers permits testing the cues at their native intensities and composition - a contrast to many studies that have used artificial stimuli (essential oils, single odorants) that are less ecologically relevant. Results from a series of two-choice assays where the olfactory and visual floral displays were manipulated showed that naïve hawkmoths preferred flowers displaying both olfactory and visual cues. Furthermore, experiments using A. palmeri flowers - a species that is not very attractive to hawkmoths - showed that the visual and olfactory displays did not have synergistic effects. The combination of olfactory and visual display of D. wrightii, however - a flower that is highly attractive to naïve hawkmoths - did influence the time moths spent feeding from the flowers. The importance of the olfactory and visual signals were further demonstrated in learning experiments in which experienced moths, when exposed to uncoupled floral displays, ultimately chose flowers based on the previously experienced olfactory, and not visual, signals. These moths, however, had significantly longer decision times than moths exposed to coupled floral displays.
These results highlight the importance of specific sensory modalities for foraging hawkmoths while also suggesting that they learn the floral displays as combinatorial signals and use the integrated floral traits from their memory traces to mediate future foraging decisions.
... The time course of these NO-mediated memory traces is strikingly similar to the nocturnal habits of flowering and feeding between Datura (Solanaecea) and hawkmoths (Sphingidae). In Southern Arizona, M. sexta feed from trumpet-shaped D. wrightii flowers in a relationship that has co-evolved over time (Riffell et al., 2008a;Riffell et al., 2008b;Raguso et al., 2003). Datura wrightii flowers open at dusk and wilt during the morning hours of the next day (Grant, 1983;Raguso and Willis, 2005). ...
... Moreover, when D. wrightii are not locally abundant, it becomes necessary for M. sexta to learn to feed from other species such as Agave spp. (Riffell et al., 2008a;Riffell et al., 2008b), thus demonstrating that learning and memory is important at this time of day. ...
Nitric oxide (NO) is thought to play an important neuromodulatory role in olfaction. We are using the hawkmoth Manduca sexta to investigate the function of NO signaling in the antennal lobe (AL; primary olfactory network in invertebrates). We have found previously that NO is present at baseline levels, dramatically increases in response to odor stimulation, and alters the electrophysiology of AL neurons. It is unclear, however, how these effects contribute to common features of olfactory systems such as olfactory learning and memory, odor detection, and odor discrimination. In this study, we have used chemical detection and a behavioral approach to further examine the function of NO in the AL. We have found that basal levels of NO fluctuate with the daily light cycle being higher during the nocturnal active period. NO also appears necessary for short-term olfactory memory. NO does not appear to affect odor detection, odor discrimination between dissimilar odorants, or learning acquisition. These findings may suggest a modulatory role for NO in the timing of olfactory-guided behaviors.
... Nectar and pollen constitute the most frequent rewards offered by plants to hawkmoths and hummingbirds (Scobell and Scott, 2002), and bumblebees and honeybees, respectively (Robertson et al., 1999). Thus, an adaptive role of the nectary tube, in this regard, has been proposed (Rowley, 1980;Wolf and Stiles, 1989;Aigner, 2005), similar to anther length (Grant, 1983;Robertson et al., 1999), especially in species with tubular flowers (Hodges, 1995;Scobell and Scott, 2002;Riffell et al., 2008). Although we did not conduct natural selection experiments, D. inoxia is commonly pollinated by hawkmoths (Grant, 1983). ...
Question: Is differentiation in single and correlated floral traits among populations of Datura inoxia the result of contrasting natural selection?
Hypothesis: The pattern and structure of phenotypic variance–covariance matrices of putative adaptive traits differ from those produced by random processes. Population differ-entiation in quantitative floral traits (Q ST) of D. inoxia exceeds the magnitude of population differentiation in neutral characters (F ST), supporting a selection-driven differentiation scenario.
Organism: Datura inoxia Mill. (Solanaceae).
Field sites: Six natural populations in Mexico (latitudinal range: 1848N to 2641N).
Methods: Using different methods (Mantel and modified Mantel tests, jackknife MANOVA, Flury's method, and Q ST –F ST of Whitlock and Guillaume), we contrasted the pattern of phenotypic variance–covariance matrices as well as the magnitude of population differentiation in seven quantitative floral traits, against population structure of D. inoxia in neutral loci (molecular markers). We also contrasted floral characters measures and integration indices with local inbreeding values (F IS) for each population to contrast selection mediated by pollinators and selection of selfing.
Conclusions: Datura inoxia populations are genetically structured in both quantitative traits and neutral loci but population differentiation in four of seven floral traits is greater than expected by random differentiation. The strong correlations in characters related to attraction of pollinators and pollen deposition/removal are in agreement with a pattern expected for the adaptive evolution of funnel-shaped corollas in outcrossing species.
