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Morphospace (principal components) plot of morphological diversity in tenrec and golden mole skulls. Principal components plots of the morphospaces occupied by tenrecs (triangles, n = 31 species) and golden moles (circles, n = 12 species) for skulls in dorsal (A), ventral (B) and lateral (C) views. Each point represents the average skull shape of an individual species. Axes are principal component 1 (PC1) and principal component 2 (PC2) of the average scores from principal components analyses of mean Procrustes shape coordinates for each species.
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It is important to quantify patterns of morphological diversity to enhance our understanding of variation in ecological and evolutionary traits. Here, we present a quantitative analysis of morphological diversity in a family of small mammals, the tenrecs (Afrosoricida, Tenrecidae). Tenrecs are often cited as an example of an exceptionally morpholog...
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Context 1
... and code for all of our analyses are available on GitHub (Finlay & Cooper, 2015). Figure 4 depicts the morphospaces defined by the first two principal component (PC) axes from our principal components analyses (PCAs) of skull and mandible morphologies. The PCAs are based on the average Procrustes-superimposed shape coordinates for skulls in three views (dorsal, ventral and lateral). ...
Context 2
... occupy significantly different positions in the dorsal (npMANOVA: F 1,42 = 68.13, R 2 = 0.62, p = 0.001), ventral (npMANOVA: F 1,42 = 103.33, R 2 = 0.72, p = 0.001) and lateral (npMANOVA: F 1,42 = 76.7, R 2 = 0.65, p = 0.001) skull morphospaces, indicating that the families have very different, non-overlapping cranial and mandible morphologies (Fig. 4). For each analysis, PC1 summarises a morphological change from the foreshortened, "squat" shape of golden mole skulls at one extreme to the rostrally elongated shape of tenrecs (particularly the Microgale) at the other ...
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... Since their arrival on the island of Madagascar between 50-20 Ma (Ali and Huber 2010;Samonds et al. 2012;Everson et al. 2016), these insectivores have since evolved into a dazzling array of distinct ecological niches. However, the degree to which these adaptations are reflected in tenrecomorph anatomy remains controversial: previous studies on skull morphology (e.g., Finlay and Cooper 2015) have documented surprisingly little disparity within the clade (in large part due to similarities encountered in the most speciose genus, Microgale), while those focusing on the postcranial skeleton (Salton and Szalay 2004;Sargis 2008a, b, 2009) found that cladistic and ecomorphotype signals varied, depending on the specific skeletal components investigated. ...
... Not all subfamilies display an equal amount of variation. Indeed, in keeping with previous morphometric analyses (Finlay and Cooper 2015), the genus Microgale is found to be relatively constrained morphologically, with the notable exception of M. mergulus. The tenrecines are responsible for driving an unexpectedly large amount of the variation observed across the entire tenrecid morphospace, even after accounting for allometry. ...
... Since their arrival on the island of Madagascar between 50-20 Ma (Ali and Huber 2010;Samonds et al. 2012;Everson et al. 2016), these insectivores have since evolved into a dazzling array of distinct ecological niches. However, the degree to which these adaptations are reflected in tenrecomorph anatomy remains controversial: previous studies on skull morphology (e.g., Finlay and Cooper 2015) have documented surprisingly little disparity within the clade (in large part due to similarities encountered in the most speciose genus, Microgale), while those focusing on the postcranial skeleton (Salton and Szalay 2004;Sargis 2008a, b, 2009) found that cladistic and ecomorphotype signals varied, depending on the specific skeletal components investigated. ...
... Not all subfamilies display an equal amount of variation. Indeed, in keeping with previous morphometric analyses (Finlay and Cooper 2015), the genus Microgale is found to be relatively constrained morphologically, with the notable exception of M. mergulus. The tenrecines are responsible for driving an unexpectedly large amount of the variation observed across the entire tenrecid morphospace, even after accounting for allometry. ...
It has long been recognized that, among extant mammals, the afrotherian clade Tenrecomorpha contains an exceptional range of sensory specialists in which arboreal, fossorial, semiaquatic and possibly even echolocating species occur within a single clade. Despite their obvious interest in this regard, the sensory apparatus of these animals has not been investigated with modern techniques. Presented here is a geometric morphometric analysis of virtual endocasts of 24 tenrecomorph species (~ 69% of extant diversity) reconstructed via high-resolution uCT techniques. Utilizing linear regression and PCA analyses we identify a model including allometry, habitat, and evolutionary history as the main factors underlying shape variability. Distinct clusters in the tenrecomorph morphospace correspond to shifts within the olfactory and cortical regions of the brain, which covary with independent evolution of aquatic and fossorial behaviors. These results showcase remarkable instances of sensory convergence within the clade and provide a template for inter- and intra-clade analyses of this distinctive branch of the mammal tree.
... does group A occupy as much space as group B?), indices related to the spread of the group in the morphospace are most appropriate (e.g. volume [47]; distance from the centroid [30,48]; variance and range [11]). Furthermore, aspects other than variation (sensu disparity) can be of interest: if we wish to describe the 'position' of a group in a morphospace (e.g. ...
Analyses of morphological disparity have been used to characterize and investigate the evolution of variation in the anatomy, function and ecology of organisms since the 1980s. While a diversity of methods have been employed, it is unclear whether they provide equivalent insights. Here, we review the most commonly used approaches for characterizing and analysing morphological disparity, all of which have associated limitations that, if ignored, can lead to misinterpretation. We propose best practice guidelines for disparity analyses, while noting that there can be no 'one-size-fits-all' approach. The available tools should always be used in the context of a specific biological question that will determine data and method selection at every stage of the analysis.
... Other factors that may account for morphological variations are related to phylogenetic signal (Keogh et al. 2005), behavioral effects on gene expression (Raia et al. 2010), latitudinal distribution, community structure, and climate (Millien and Damuth 2004;Rychlik et al. 2006;Dawson and Milne 2012;van der Geer et al. 2018b). However, relatively few studies have examined changes in the shape of island mammals (Pergams and Ashley 2001;Renaud et al. 2013;Finlay and Cooper 2015;van der Geer et al. 2018b). ...
Adaptation and evolution of terrestrial vertebrates inhabiting islands have been the topic of many studies, particularly those seeking to identify trends or patterns in body size in mammals, albeit not necessarily in shape, in relation to mainland populations. The spiny pocket mouse, Chaetodipus spinatus, is distributed in the Baja California peninsula and its surrounding islands. Insular populations became isolated ~12,000 due to changes in sea level; these populations’ matrilinear (mitochondrial) DNA shows minor interpopulation variation. We tested the hypothesis that adaptation and evolution in these island populations involve variation in both skull size and skull shape (using geometric morphometrics) relative to mainland populations, rather than only in size as previously assumed. A total of 363 specimens from 15 insular and peninsular populations were used in analysis of the skull length and geometric morphometric analyses. Our findings revealed significant differences related to skull size among population. The skull shape analyses showed two significantly different morphotypes: one for all island specimens and one for all mainland samples. Our analyses support the hypothesis that insular populations may not only vary in size relative to mainland populations, but may also show variations in shape, regardless of differing conditions across islands.
... The study of the morphological variation of species is an interesting topic, given that this variability can be associated with the evolution of species and can promote future speciation events, as well as indicate phenotypic flexibility and the ability of a species or population to adapt to changes in their environment (Gerhart & Kirschner 2007;Asahara 2014). Moreover, morphological variability is associated with the ecological interactions and life history of the species (Finlay & Cooper 2015). ...
... The study of the morphological variability is an interesting topic, since it is related to ecological variables, and can act as a promoter of new species (Gerhart & Kirschner 2007;Asahara 2014;Finlay & Cooper 2015). In this context, having samples narrowed down in time and space gave us an opportunity to study intra-population variation, and by doing this, to have a starting point to study the variability of a species throughout its distribution range. ...
Marsupials of the genus Didelphis are an interesting model to study morphological variation, since they show constant growth throughout their life, and have a wide distribution. Having samples narrowed down in time and space gave us an opportunity to study intra-population variation, therefore having a starting point to study the variability of a species. Our aims are: to analyze the intra-population variation of Didelphis albiventris, Didelphis aurita, and Didelphis marsupialis using specimens collected in the same locality in a short period of time; to compare the variability found in the population of D. albiventris, with the variability of specimens collected in a wide geographic and temporal range (i.e., inter-population variability). We used 2D geometric morphometrics to analyze the skull and mandible of 123 specimens. We found a trend where the population of D. albiventris had the lowest Procrustes variance; however, since differences were not large enough to be statistically significant in most of the analyses, our results might be indicating that the three species are morphologically versatile, as suggested by their ability to adapt to different environments. The results obtained for the intra vs. inter population analyses in D. albiventris showed similar levels of morphological disparity in the population from Corrientes Province, including specimens collected throughout a year in the same locality, and in the sample from Uruguay grouping specimens collected throughout 60 years in an entire country. This trend was also observed when comparing the entire D. albiventris sample with both subsamples. These results were unexpected and could be indicating that the population analyzed is highly variable, or that the species as a whole has little morphological variation.
... Tenrec skulls are less morphologically diverse than those of golden moles. It is suggested that the similarities in skull morphology among the speciose genus Microgale masks morphological diversity among the rest of the family [111] Hyracoidea All four extant hyrax species have short skulls and deep dentary bones. The skull has a postorbital bar, which is sometime complete (Dendrohyrax) and sometime incomplete (Heterohyrax and Procavia) ...
Mammals (class Mammalia) have evolved diverse craniofacial morphology to adapt to a wide range of ecological niches. However, the genetic and developmental mechanisms underlying the diversification of mammalian craniofacial morphology remain largely unknown. In this paper, we focus on the facial length and orofacial clefts of mammals and deduce potential mechanisms that produced diversity in mammalian facial morphology. Small-scale changes in facial morphology from the common ancestor, such as slight changes in facial length and the evolution of the midline cleft in some lineages of bats, could be attributed to heterochrony in facial bone ossification. In contrast, large-scale changes of facial morphology from the common ancestor, such as a truncated, widened face as well as the evolution of the bilateral cleft possessed by some bat species, could be brought about by changes in growth and patterning of the facial primordium (the facial processes) at the early stages of embryogenesis.
... 4,13,16 Literature on appropriate clinical and husbandry parameters is lacking in tenrecs, because previously published studies have mainly related to tenrec anatomy, physiology, and evolution. 1,2,[5][6][7][8][9]11,[17][18][19][20]22,24,28 Our evaluation was carried out to provide essential and up-to-date information on common husbandry practices for lesser hedgehog tenrecs in zoological institutions, their morbidities, and causes of their mortalities. ...
Causes of morbidity and mortality for various species of tenrecs have not been widely published, aside from several reports of neoplasia, and these data are crucial for advancing objectives for preventive medicine, diagnosis, and treatment. A survey on husbandry, morbidity, and mortality of lesser hedgehog tenrecs (Echinops telfairi) in Association of Zoos and Aquariums (AZA) institutions was conducted. Out of 32 institutions, 20 responded with data for 98 living and 93 dead animals. The most common causes of mortality among the dead animals were neoplasia (24%), hepatic lipidosis (11%), septicemia (8.6%), pneumonia (8.6%), cardiomyopathy (7.5%), renal disease (6.5%), osteomyelitis (3.2%), and trauma (3.2%). There was no statistically significant correlation between sex and neoplasia. Data about educational usage were specifically provided by survey respondents for 50 of the tenrecs, with only 42% being excluded from educational programming. Tenrecs are common to many AZA institutions as both educational and exhibit animals, and this study provides a helpful reference for expected health problems and highlights the need for future investments into medical diagnosis and treatment for these animals.
... The outline-based approach is less widely applied than the landmark-based approach, having mainly been utilized in anthropological studies (Slice, 2007;Baab et al., 2012). However, three limitations of outline-based methods should be considered: (1) protrusions on one individual that do not appear on another can be poorly captured by the resulting semilandmark alignment; (2) it is often not clear how many semilandmarks should be used for any given outline; and (3) outline methods only define relative features (MacLeod, 1999;McCane, 2013;Finlay & Cooper, 2015). Regardless, their utility is highlighted in studies like ours, in which the clarity of results is considerably improved in the landmark configuration(s) that utilize both landmarks and outlines (Baab et al., 2012;Finlay & Cooper, 2015). ...
... However, three limitations of outline-based methods should be considered: (1) protrusions on one individual that do not appear on another can be poorly captured by the resulting semilandmark alignment; (2) it is often not clear how many semilandmarks should be used for any given outline; and (3) outline methods only define relative features (MacLeod, 1999;McCane, 2013;Finlay & Cooper, 2015). Regardless, their utility is highlighted in studies like ours, in which the clarity of results is considerably improved in the landmark configuration(s) that utilize both landmarks and outlines (Baab et al., 2012;Finlay & Cooper, 2015). By increasing the number of coordinates along a homologous contour or surface, it is ultimately possible to obtain more information on the shape of a structure. ...
... In conclusion, our study adds to a growing body of evidence suggesting multiple carefully designed 2D landmark configurations can provide fairly accurate descriptions of interspecific variation in complex structures like the vertebrate head (Cardini & Thorington, 2006;Perez et al., 2009;Alvarez & Perez, 2013;Cardini, 2014;Finlay & Cooper, 2015;Klingenberg, 2015). The key benefits of 3D techniques may instead be in the extensions to assessing morphological patterns in internal structures (e.g. ...
Geometric morphometrics is a powerful tool for the quantification, visualization and analysis of morphological variation and change. This approach is being applied more frequently in a phylogenetic comparative context to assess the relative influence of size, ecology, function, and developmental constraints on morphological evolution. Geometric morphometric methods rely on homologous landmarks as the source of shape data, and the level of detail and accuracy increases with the amount of information contained in a landmark configuration. It may be possible, however, to capture particular elements of shape variation by concentrating on different observation angles of a complex structure like the vertebrate cranium. Our study examines how observation view (dorsal, ventral and lateral) influences 2D geometric morphometric analysis of interspecific cranial shape variation in monitor lizards. We recover a strong phylogenetic signal in all three views and general concordance in patterns of size-corrected shape diversification within the genus. We also find subtle, but important differences, however, among views in analyses of evolutionary allometry and shape variation, which may reflect both landmark configuration design and adaptive functional trends of the study system. Our study shows that studies restricted to a 2D geometric morphometric analysis of a complex 3D biological structure can combine carefully designed 2D landmark configurations describing alternative planes to maximize shape coverage.
... When using this approach, form is approximated by actual continuous measurements collected from the organisms (e.g. Friedman, 2010;Hopkins, 2013;Finlay and Cooper, 2015). In our case, however, we instead used inter-taxon distances based on discrete morphological features to describe form (i.e. the cladistic disparity method; e.g. ...
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