Search

The modular organization of tetrapod paired limbs and girdles, influenced by the expression of Hox genes is one of the primary driving forces of the evolution of animal locomotion. The increased morphological diversification of the paired limbs is correlated with reduced between‐limb covariation, while correlation within the elements is usually higher than between the elements. The tailed amphibians, such as Lissotriton newts, have a biphasic lifestyle with aquatic and terrestrial environments imposing different constraints on limb skeleton. By employing the methods of computerized microtomography and 3D geometric morphometrics, we explored the pattern of morphological variation, disparity, modularity and morphological integration in the proximal parts of the anterior limbs of six species of Eurasian small bodied newts. Although the species significantly differ in limb shape, there is a great overlap in morphology of scapula and humerus, and there are no differences in morphological disparity. For the scapula, the shape differences related to the duration of the aquatic period are in length, depth and curvature. The shape of the humerus is not affected by the length of aquatic period, and shape differences between the species are related to robustness of the body. The length of aquatic period has statistically supported phylogenetic signal. The scapula and humerus are structures of varying modularity. For the humerus, the strongest support on the phylogenetic level was for the capitulum/shaft hypothesis, which can also be interpreted as functional modularity. For the scapula, the greatest support was for the antero‐posterior hypothesis of modularity in case of Lissotriton vulgaris, which can be explained by different functional roles and muscle insertion patterns, while there was no phylogenetic modularity. The modularity patterns seem to correspond with the general tetrapod pattern, with modularity being more pronounced in the distal structure. The future research should include more salamandrid taxa with different habitat preferences and both adult and larval stages, in order to explore how size, phylogeny and ecology affect the morphology and covariation patterns of limbs. [ABSTRACT FROM AUTHOR]

Summary: Ontogenetic shape change has long been recognized to be important in generating patterns of morphological diversity and may be especially important in plant reproductive structures. We explore how seed cone disparity in Cupressaceae changes over ontogeny by comparing pollination‐stage and mature cones.We sampled cones at pollen and seed release and measured cone scales using basic morphometric shape variables. We used multivariate statistical methods, particularly hypervolume overlap calculations, to measure morphospace occupation and disparity.Cone scales at both pollination and maturity exhibit substantial variability, although the disparity is greater at maturity. Mature cone scales are also more clustered in trait space, showing less overlap with other taxa than at pollination. These patterns reflect two growth strategies that generate closed cones over maturation, either through thin laminar scales or relatively thick, peltate scales, resulting in two distinct regions of morphospace occupation.Disparity patterns in Cupressaceae seed cones change over ontogeny, reflecting shifting functional demands that require specific patterns of cone scale growth. The evolution of Cupressaceae reproductive disparity therefore represents selection for trajectories of ontogenetic shape change, a phenomenon that should be widespread across seed plants. See also the Commentary on this article by Olson, 242: 1856–1859. [ABSTRACT FROM AUTHOR]

Abstract Non-avialan theropod dinosaurs had diverse ecologies and varied skull morphologies. Previous studies of theropod cranial morphology mostly focused on higher-level taxa or characteristics associated with herbivory. To better understand morphological disparity and function within carnivorous theropod families, here we focus on the Dromaeosauridae, ‘raptors’ traditionally seen as agile carnivorous hunters. We applied 2D geometric morphometrics to quantify skull shape, performed mechanical advantage analysis to assess the efficiency of bite force transfer, and performed finite element analysis to examine strain distribution in the skull during biting. We find that dromaeosaurid skull morphology was less disparate than most non-avialan theropod groups. Their skulls show a continuum of form between those that are tall and short and those that are flat and long. We hypothesise that this narrower morphological disparity indicates developmental constraint on skull shape, as observed in some mammalian families. Mechanical advantage indicates that Dromaeosaurus albertensis and Deinonychus antirrhopus were adapted for relatively high bite forces, while Halszkaraptor escuilliei was adapted for high bite speed, and other dromaeosaurids for intermediate bite forces and speeds. Finite element analysis indicates regions of high strain are consistent within dromaeosaurid families but differ between them. Average strain levels do not follow any phylogenetic pattern, possibly due to ecological convergence between distantly-related taxa. Combining our new morphofunctional data with a re-evaluation of previous evidence, we find piscivorous reconstructions of Halszkaraptor escuilliei to be unlikely, and instead suggest an invertivorous diet and possible adaptations for feeding in murky water or other low-visibility conditions. We support Deinonychus antirrhopus as being adapted for taking large vertebrate prey, but we find that its skull is relatively less resistant to bite forces than other dromaeosaurids. Given the recovery of high bite force resistance for Velociraptor mongoliensis, which is believed to have regularly engaged in scavenging behaviour, we suggest that higher bite force resistance in a dromaeosaurid taxon may reflect a greater reliance on scavenging rather than fresh kills. Comparisons to the troodontid Gobivenator mongoliensis suggest that a gracile rostrum like that of Velociraptor mongoliensis is ancestral to their closest common ancestor (Deinonychosauria) and the robust rostra of Dromaeosaurus albertensis and Deinonychus antirrhopus are a derived condition. Gobivenator mongoliensis also displays a higher jaw mechanical advantage and lower resistance to bite force than the examined dromaeosaurids, but given the hypothesised ecological divergence of troodontids from dromaeosaurids it is unclear which group, if either, represents the ancestral condition. Future work extending sampling to troodontids would therefore be invaluable and provide much needed context to the origin of skull form and function in early birds. This study illustrates how skull shape and functional metrics can discern non-avialan theropod ecology at lower taxonomic levels and identify variants of carnivorous feeding.

Morphological disparity and taxonomic richness are two major aspects of evolution used to understand biodiversity changes. These metrics are often decoupled in time, particularly during the early history of clades. To assess the pervasiveness of this pattern during the post-acme of a clade, both morphological disparity and taxonomic diversity of the well-documented Devonian trilobites from North Africa were analysed. Morphospace occupancy and body size were estimated and compared to genus richness through time. This study highlights that, during the Early Devonian, morphological disparity of the pygidium and the cephalon strongly increased, whereas cranidium disparity remained low. Interestingly, the pygidium and cephalon morphological dynamics were decoupled. Taxonomic diversity also increased. Then, the Middle Devonian anoxic events affected the trilobite communities with simultaneous drastic loss of both morphologies and taxonomic richness. This coupling between diversity and disparity dynamics could be explained by either the intensity of extinctions or strong internal constraints. Finally, the weak Famennian recovery of both disparity and diversity did not reach the Early Devonian levels, thus making trilobites a 'dead clade walking' during their late evolutionary history. Devonian trilobite families are thus identified as 'Bottom-Heavy Clades', characterised by a diversity peak at the end of their history. [ABSTRACT FROM AUTHOR]

Hyolitha represent one of the major constituents of the Cambrian Evolutionary Fauna, first appearing in the Terreneuvian and rapidly diversifying soon after. Recent work has both enriched the hyolith fossil record and expanded our understanding of their biology, but studies documenting the evolutionary trajectory of Cambrian hyoliths remain scarce. Here we present the first study of changes in morphological disparity in Cambrian hyoliths over time with the aim of characterizing the evolutionary trajectory of hyoliths throughout their primary period of diversification. Our results show that hyoliths occupied distinct regions of morphospace at different times during the Cambrian, with an expansion in morphospace occupation associated with the increase in hyolith diversity in the early Cambrian. Both the Sinsk Event and multiple abiotic factors led to a decline in hyolith diversity in the Miaolingian, and morphological disparity also contracts in association with this reduction in diversity. [ABSTRACT FROM AUTHOR]

Abstract Indices of morphological disparity seek to summarise the highly multivariate morphological variation across groups of species within clades, time bins or other groups. Morphological variation can be quantified using geometric morphometric, outline or surface‐based methods. These are most effective when morphological differences are relatively modest and there are numerous ubiquitous landmarks and phase aligned features of shape variation. The most disparate samples, such as those across classes and phyla, typically necessitate the use of discrete characters. Unfortunately, such characters are often compiled subjectively in a manner reflecting the level of morphological and taxonomic focus and the intensity of taxon sampling. Sampling intensity is often highly variable within a single data set, especially in repurposed and amalgamated cladistic matrices. Here, we propose indices of molecular disparity analogous to those of morphological disparity. Despite numerous shortcomings discussed here, molecular sequence data can be obtained in a more objective, automated and scalable manner than morphological data. Comparisons of the morphological and molecular disparity of subclades in 16 large data sets suggest that molecular disparity is less susceptible to sampling biases than morphological disparity. Moreover, distance matrices inferred from individual genes tend to correlate strongly with each other and with distances from all concatenated genes. By contrast, morphological and molecular disparity are typically not significantly correlated across subclades, such that comparisons for groups can help to give a fuller picture of their evolution. For example, within mammals, Afrotheria have conspicuously high morphological disparity but modest molecular disparity, suggesting unusually high morphological plasticity. Even more strikingly, the molecular disparity of rodents is over five times that for Artiodactyla, despite having only half of their morphological disparity. These contrasts suggest the differential operation of geometric, biomechanical, ontogenetic and environmental constraints on form. Given the increasing abundance of total evidence datasets in the literature and the widespread and sometimes uncritical repurposing of discrete morphological matrices, we propose the comparison of morphological and molecular disparity as a useful tool to understand subclade evolution more fully.

Variation of anteroconid morphotypes was studied using traditional and GM methods in five vole species: Stenocraniusgregalis, Alexandromysmiddendorffii, A. mongolicus, A. mujanensis, and A. oeconomus. The morphotypical space is three-dimensional within the framework of the traditional approach, with the axes being formed by (1) the complexity of the curve of the lingual and (2) labial sides of the AUL, and (3) the overall number of closed triangles. The total number of morphotypes for four species of Alexandromys is 56, with 30 of them being actualized (the degree of completeness of the morphospace is 53.6%). The thin-plate spline and Procrustes distance analyses were used in the quantitative approach. The distribution of morphotypes in the space of the first two relative warps (RWs), both for individual species and for their combination, displays an arcuate configuration. The first RW is associated mainly with the complication/simplification of the buccal side of the anteroconid, while the second RW with the bilateral complication/simplification and simultaneous extension/compression of the anteroconid. The part of the potential morphospace that corresponds to a moderately complicated and maximally elongated anteroconid remains unfilled. The distribution of morphotypes for all species in the space of the first two axes of multidimensional scaling forms a single and roughly homogeneous cloud that almost evenly fills the total morphospace. The correlation coefficients between the matrices of morphogenetic and Procrustes distances between morphotypes calculated for each of the species vary from 0.56 to 0.73. [ABSTRACT FROM AUTHOR]

Fossils of Devonian ammonoids are abundant and well-preserved in the Anti-Atlas of Morocco; as such they provide an invaluable record of regional morphological disparity changes (diversity of shapes) that characterise the first steps of ammonoid evolution. However, they were rarely analysed quantitatively with respect to their morphological spectrum. Here, we investigated the morphological disparity of the Early–Middle Devonian ammonoids of the Moroccan Anti- Atlas by analysing the shape of their whorl profile. A geometric morphometric approach based on the acquisition of outline semilandmark coordinates was used to analyse the whorl profiles. For comparison, morphometric ratios based on classical conch measurements were also analysed to investigate the overall conch geometry. Several standard disparity estimators were computed to measure different aspects of morphological disparity fluctuations through time. It appears that a major increase in disparity occurred throughout the Early Devonian, followed by fluctuating disparity during the Middle Devonian constituting a general decreasing trend. Only the end-Eifelian Kačák Event shows a significant decrease in disparity. Thus, the ammonoids explored the range of possible shapes fairly quickly during their initial radiation; however, we found no evidence for an early burst of shape diversity (i.e., the rise does not exceed the expectations given diversity). Nevertheless, correlation tests between diversity and disparity time series support that they are partially decoupled. The highly resolved biozone record highlights that the increase in disparity began earlier than the increase in diversity that characterises the late Emsian.

The morphological disparity of the marine benthos, through the Phanerozoic, is shaped by multiple abiotic and biotic factors, among which substrate and ecology are key contributors. However, the relationship among substrate, ecology, and morphology is not straightforward—a substrate can be occupied by phylogenetically unrelated families with different life habits, influencing morphological convergence. In contrast, related taxa may differ in substrate and life habits, indicating morphological divergence. Here we evaluate the effect of substrate and ecology on the community-level morphological disparity of 398 Recent marine bivalve species from coastal India, using geometric morphometrics. We further evaluate whether the observed patterns are decoupled from taxonomic identities, i.e. phylogenetic (in)dependence. We find that the Recent marine bivalve assemblages show significant morphological differences while living in different substrates or having different life habit traits. However, while sharing a specific substrate or life habit trait (tiering/motility), different families do not show shape convergence, i.e. families maintain their mean shape, except for families living in soft sediments, for which they show strong substrate-driven morphological convergence. These instances of morphological divergence and convergence suggest that the association among sediment preference, ecology, and shape can be rather complex, and can often transgress phylogenetic boundaries in bivalves. [ABSTRACT FROM AUTHOR]

Phacopidae were a successful family of the Silurian–Devonian period. Although their diversity trends are well identified, their shape evolution is unknown; their morphology often considered to be conservative. We have quantified these morphologies using geometric morphometrics (landmarks) and investigated their evolution using morphological disparity indices. Results identified morphological variations between the genera, and through time. Phacopids differ from each other by the position of the facial suture linked to the size of the visual complex, the shape of the genal angle and the elongation of both cephalon and pygidium. The morphological disparity of cephala was high from the Silurian, contrary to that of pygidia. Subsequently, the morphological disparity increased in the Early Devonian with the development of narrow cephala and triangular pygidia. Morphological disparity was greater in the Emsian for both cephala and pygidia, more than 50 myr after the origination of phacopids. It constituted a perfect example illustrating that a peak of biodiversity does not necessarily happen in the early history of a clade. Subsequently, a strong decrease of morphological disparity occurred in the Middle Devonian, in conjunction with sea‐level changes and anoxic events. Taxonomic richness and morphological disparity declined strongly in the Givetian, in a non‐random extinction affecting particularly blind genera. The morphological disparity remained low in the Frasnian despite progressive eye reduction influenced by environmental changes. An extensive recovery occurred in the Famennian with an important increase of both taxonomic and morphological diversity. The Hangenberg event caused the final extinction of phacopids. [ABSTRACT FROM AUTHOR]

Indices of morphological disparity seek to summarise the highly multivariate morphological variation across groups of species within clades, time bins or other groups. Morphological variation can be quantified using geometric morphometric, outline or surface‐based methods. These are most effective when morphological differences are relatively modest and there are numerous ubiquitous landmarks and phase aligned features of shape variation. The most disparate samples, such as those across classes and phyla, typically necessitate the use of discrete characters. Unfortunately, such characters are often compiled subjectively in a manner reflecting the level of morphological and taxonomic focus and the intensity of taxon sampling.Sampling intensity is often highly variable within a single data set, especially in repurposed and amalgamated cladistic matrices. Here, we propose indices of molecular disparity analogous to those of morphological disparity. Despite numerous shortcomings discussed here, molecular sequence data can be obtained in a more objective, automated and scalable manner than morphological data.Comparisons of the morphological and molecular disparity of subclades in 16 large data sets suggest that molecular disparity is less susceptible to sampling biases than morphological disparity. Moreover, distance matrices inferred from individual genes tend to correlate strongly with each other and with distances from all concatenated genes. By contrast, morphological and molecular disparity are typically not significantly correlated across subclades, such that comparisons for groups can help to give a fuller picture of their evolution. For example, within mammals, Afrotheria have conspicuously high morphological disparity but modest molecular disparity, suggesting unusually high morphological plasticity. Even more strikingly, the molecular disparity of rodents is over five times that for Artiodactyla, despite having only half of their morphological disparity. These contrasts suggest the differential operation of geometric, biomechanical, ontogenetic and environmental constraints on form.Given the increasing abundance of total evidence datasets in the literature and the widespread and sometimes uncritical repurposing of discrete morphological matrices, we propose the comparison of morphological and molecular disparity as a useful tool to understand subclade evolution more fully. [ABSTRACT FROM AUTHOR]

Fossils of Devonian ammonoids are abundant and well-preserved in the Anti-Atlas of Morocco; as such they provide an invaluable record of regional morphological disparity changes (diversity of shapes) that characterise the first steps of ammonoid evolution. However, they were rarely analysed quantitatively with respect to their morphological spectrum. Here, we investigated the morphological disparity of the Early-Middle Devonian ammonoids of the Moroccan Anti-Atlas by analysing the shape of their whorl profile. A geometric morphometric approach based on the acquisition of outline semilandmark coordinates was used to analyse the whorl profiles. For comparison, morphometric ratios based on classical conch measurements were also analysed to investigate the overall conch geometry. Several standard disparity estimators were computed to measure different aspects of morphological disparity fluctuations through time. It appears that a major increase in disparity occurred throughout the Early Devonian, followed by fluctuating disparity during the Middle Devonian constituting a general decreasing trend. Only the end-Eifelian Kačák Event shows a significant decrease in disparity. Thus, the ammonoids explored the range of possible shapes fairly quickly during their initial radiation; however, we found no evidence for an early burst of shape diversity (i.e., the rise does not exceed the expectations given diversity). Nevertheless, correlation tests between diversity and disparity time series support that they are partially decoupled. The highly resolved biozone record highlights that the increase in disparity began earlier than the increase in diversity that characterises the late Emsian. [ABSTRACT FROM AUTHOR]

High disparity among avian forelimb and hind limb segments in crown birds relative to non-avialan theropod dinosaurs, potentially driven by the origin of separate forelimb and hind limb locomotor modules, has been linked to the evolution of diverse avian locomotor behaviors. However, this hypothesized relationship has rarely been quantitatively investigated in a phylogenetic framework. We assessed the relationship between the evolution of limb morphology and locomotor behavior by comparing a numerical proxy for locomotor disparity to morphospace sizes derived from a dataset of 1,241 extant species. We then estimated how limb disparity accumulated during the crown avian radiation. Lastly, we tested whether limb segments evolved independently between each limb module using phylogenetically informed regressions. Hind limb disparity increased significantly with locomotor disparity after accounting for clade age and species richness. We found that forelimb disparity accumulated rapidly early in avian evolution, whereas hind limb disparity accumulated later, in more recent divergences. We recovered little support for strong correlations between forelimb and hind limb morphology. We posit that these findings support independent evolution of locomotor modules that enabled the striking morphological and behavioral disparity of extant birds. [ABSTRACT FROM AUTHOR]

The variability of the body shape in invasive fish species—Amur sleeper (Perccottus glenii)—from natural and anthropogenic water bodies of the Middle Urals, with different completeness of the species composition, was studied by the use of geometric morphometric methods. We compared samples of Amur sleepers from adjacent water bodies—Lake Shitovskoye and two peat quarries filled with water. Samples of different seasons and years of collection were taken in the lake, which allowed us to correlate the influence of climate and season on the morphogenesis of the Amur sleeper. According to the control catches, the fish community of the lake is represented by ten species; i.e., it is a species-rich community: six native species (roach, river perch, ruff, tench, crucian carp, and pike) and four alien species (bream, belica, Amur sleeper, carp). The share of Amur sleepers in the control catches in the lake was no more than 3–5%. In the water bodies of peat quarries, species-poor communities of two species were formed (Amur sleeper and crucian carp). Discriminant analysis of the body shape of fish from the lake and peat quarries allowed us to reveal the origin of 93–98% of specimens. Comparing the samples of the younger (2+–3+ years) and older (4+–7+ years) age groups of fish divided by sex and biotope, different directions of changes in the shape of the Amur sleeper's body in ontogenesis were revealed between the biotopic groups. The range of age variability was almost 5 times lower than the intergroup biotopic differences of fish from ecologically contrasting water bodies. The seasonal and interannual intrapopulation variability of body shape in Amur sleepers in the lake is significantly less pronounced than the intergroup differences between samples from the lake and peat quarries. Sex differences accounted for only 6% of the intergroup variance (3 times lower than the level of age differences), and in the species-rich lake community, sex differences decrease with age, and in the water bodies of quarries, on the contrary, they increase. Intragroup morphological disparity (MNND) was significantly higher in samples from peat quarries. The data obtained are of a key character, since they characterize a high degree of phenotypic plasticity of the Amur sleeper and a rapid adaptive restructuring of its morphogenesis to different conditions of natural and anthropogenic water bodies of the Middle Urals. [ABSTRACT FROM AUTHOR]

The Devonian was a time of drastic environmental change that shaped the morphology of trilobites. This study aims to investigate their morphological evolution and to show the influence of some abiotic and biotic factors (bathymetry, feeding habits and visual abilities) on their shape. A dataset was compiled to investigate the shape of three structures (cephalon as a whole, central part of the cephalon, and pygidium) of Devonian trilobites from North Africa, using a geometric morphometric approach. Based on empirical morphospaces, the morphological changes were quantified through the Devonian stages. The results reveal important variations in the morphological disparity of the glabella shape, the facial suture location, the pygidial length and the presence of spines. In the Lochkovian, morphological disparity was low, subsequently increased in the Pragian with numerous innovations, and reached a maximum in the Emsian. If the morphospace occupancy remained until the Eifelian, a severe loss of disparity occurred in the Givetian, a time known for important environmental changes. Disparity then remained low in the Late Devonian. The shapes inherited from the Silurian persisted throughout the Devonian whereas Pragian novelties were most affected by losses. These persistent shapes were more versatile for environmental adaptation, helping those trilobites to survive the environmental events. Similarly, the trilobite orders that survived Devonian events had a wide morphological spectrum and were better adapted to withstand environmental change. [ABSTRACT FROM AUTHOR]

Abstract The neural crest hypothesis posits that selection for tameness resulted in mild alterations to neural crest cells during embryonic development, which directly or indirectly caused the appearance of traits associated with the “domestication syndrome” (DS). Although representing an appealing unitary explanation for the generation of domestic phenotypes, support for this hypothesis from morphological data and for the validity of the DS remains a topic of debate. This study used the frameworks of morphological integration and modularity to assess patterns that concern the embryonic origin of the skull and issues around the neural crest hypothesis. Geometric morphometric landmarks were used to quantify cranial trait interactions between six pairs of wild and domestic mammals, comprising representatives that express between five and 17 of the traits included in the DS, and examples from each of the pathways by which animals entered into relationships with humans. We predicted the presence of neural crest vs mesoderm modular structure to the cranium, and that elements in the neural crest module would show lower magnitudes of integration and higher disparity in domestic forms compared to wild forms. Our findings support modular structuring based on tissue origin (neural crest, mesoderm) modules, along with low module integration magnitudes for neural crest cell derived cranial elements, suggesting differential capacity for evolutionary response among those elements. Covariation between the neural crest and mesoderm modules accounted for major components of shape variation for most domestic/wild pairs. Contra to our predictions, however, we find domesticates share similar integration magnitudes to their wild progenitors, indicating that higher disparity in domesticates is not associated with magnitude changes to integration among either neural crest or mesoderm derived elements. Differences in integration magnitude among neural crest and mesoderm elements across species suggest that developmental evolution preserves a framework that promotes flexibility under the selection regimes of domestication.

Investigation of the ecological and evolutionary mechanisms governing the origin and diversification of species requires integrative approaches that often have to accommodate strong discordance among datasets. A common source of conflict is the combination of morphological and molecular characters with different evolutionary rates. Resolution of these discordances is crucial to assess the relative roles of different processes in generating and maintaining biodiversity. Anuran amphibians provide many examples of morphologically similar, genetically divergent lineages, posing questions about the relative roles of phylogeny and ecological factors in phenotypic evolution. We focused on three circum-Mediterranean anuran genera (Hyla , Alytes and Discoglossus), characterizing morphological and environmental disparity and comparing diversity patterns across biological levels of organization. Using a comparative phylogenetic framework, we tested how shared ancestry and climatic factors come together to shape phenotypic diversity. We found higher morphological differentiation within Hyla and Alytes than in Discoglossus. Body size and limb morphology contributed most to inter- and intraspecific morphological variation in Hyla and Alytes , but there was no strong phylogenetic signal, indicating that shared ancestry does not predict patterns of phenotypic divergence. In contrast, we uncovered a significant association between morphology and climatic descriptors, supporting the hypothesis that morphological disparity between species results from adaptive evolution. [ABSTRACT FROM AUTHOR]

Marsupial neonates are born at an earlier developmental stage than placental mammals, but the rapid development of their forelimbs and cranial skeleton allows them to climb to the pouch, begin suckling and complete their development ex utero. The mechanical environment in which marsupial neonates develop is vastly different from that of placental neonates, which exhibit a more protracted development of oral muscles and bones. This difference in reproductive strategy has been theorized to constrain morphological evolution in the oral region of marsupials. Here, we use 3D morphometrics to characterize one of these oral bones, the lower jaw (dentary), and assess modularity (pattern of covariation among traits), morphological disparity and rates of morphological evolution in two clades of carnivorous mammals: the marsupial Dasyuromorphia and placental fissiped Carnivora. We find that dasyuromorph dentaries have fewer modules than carnivorans and exhibit tight covariation between the angular and coronoid processes, the primary attachment sites for jaw‐closing muscles. This pattern of modularity may result from the uniform action of muscles on the developing mandible during suckling. Carnivorans are free from this constraint and exhibit a pattern of modularity that more strongly reflects genetic and developmental signals of trait covariation. Alongside differences in modularity, carnivorans exhibit greater disparity and faster rates of morphological evolution compared with dasyuromorphs. Taken together, this suggests dasyuromorphs have retained a signal of trait covariation that reflects the outsized influence of muscular force during early development, a feature that may have impacted the ability of marsupial carnivores to explore specialized regions of morphospace. [ABSTRACT FROM AUTHOR]

Divergence of ecological niches in phylogenetically closely related species indicates the importance of ecology in speciation, especially for sympatric species are considered. Such ecological diversification provides an advantage of alleviating interspecies competition and promotes more efficient exploitation of environmental resources, thus being a basis for ecological speciation. We analyzed a group of closely related species from the subgenus Neritrema (genus Littorina, Caenogastropoda) from the gravel‐bouldery shores. In two distant sites at the Barents and Norwegian Sea, we examined the patterns of snail distribution during low tide (quantitative sampling stratified by intertidal level, presence of macrophytes, macrophyte species, and position on them), shell shape and its variability (geometric morphometrics), and metabolic characteristics (metabolomic profiling). The studied species diversified microbiotopes, which imply an important role of ecological specification in the recent evolution of this group. The only exception to this trend was the species pair L. arcana / L. saxatilis, which is specifically discussed. The ecological divergence was accompanied by differences in shell shape and metabolomic characteristics. Significant differences were found between L. obtusata versus L. fabalis and L. saxatilis / L. arcana versus L. compressa both in shell morphology and in metabolomes. L. saxatilis demonstrated a clear variability depending on intertidal level which corresponds to a shift in conditions within the occupied microhabitat. Interestingly, the differences between L. arcana (inhabiting the upper intertidal level) and L. compressa (inhabiting the lower one) were analogous to those between the upper and lower fractions of L. saxatilis. No significant level‐dependent changes were found between the upper and lower fractions of L. obtusata, most probably due to habitat amelioration by fucoid macroalgae. All these results are discussed in the contexts of the role of ecology in speciation, ecological niche dynamics and conservatism, and evolutionary history of the Neritrema species. [ABSTRACT FROM AUTHOR]

The neural crest hypothesis posits that selection for tameness resulted in mild alterations to neural crest cells during embryonic development, which directly or indirectly caused the appearance of traits associated with the "domestication syndrome" (DS). Although representing an appealing unitary explanation for the generation of domestic phenotypes, support for this hypothesis from morphological data and for the validity of the DS remains a topic of debate. This study used the frameworks of morphological integration and modularity to assess patterns that concern the embryonic origin of the skull and issues around the neural crest hypothesis. Geometric morphometric landmarks were used to quantify cranial trait interactions between six pairs of wild and domestic mammals, comprising representatives that express between five and 17 of the traits included in the DS, and examples from each of the pathways by which animals entered into relationships with humans. We predicted the presence of neural crest vs mesoderm modular structure to the cranium, and that elements in the neural crest module would show lower magnitudes of integration and higher disparity in domestic forms compared to wild forms. Our findings support modular structuring based on tissue origin (neural crest, mesoderm) modules, along with low module integration magnitudes for neural crest cell derived cranial elements, suggesting differential capacity for evolutionary response among those elements. Covariation between the neural crest and mesoderm modules accounted for major components of shape variation for most domestic/wild pairs. Contra to our predictions, however, we find domesticates share similar integration magnitudes to their wild progenitors, indicating that higher disparity in domesticates is not associated with magnitude changes to integration among either neural crest or mesoderm derived elements. Differences in integration magnitude among neural crest and mesoderm elements across species suggest that developmental evolution preserves a framework that promotes flexibility under the selection regimes of domestication. [ABSTRACT FROM AUTHOR]

The order Characiformes is one of the most diverse and widely distributed groups of fishes in cis-Andean basins. That diversity is reflected in the São Francisco River (Brazil), where approximately 1/3 of all described species belong to that order, with many being endemic and/or considered endangered. The great morphological diversity observed in this group has been the focus of several systematic, ecomorphological, and evolutionary studies. Here, we evaluated the morphological patterns of 39 species of Characiformes from the São Francisco River using geometric morphometric and comparative phylogenetic techniques to better understand how ecological factors can modulate morphological diversity. Our data produced a highly supported topology revealing two promoters that drive the diversity of the analyzed forms, one is associated with phylogenetic inheritance, while the other is modulated by habitat, generating similarities between phylogenetically distant species. The absence of any observed relationship between body shape and trophic niche may reflect phylogenetic inertia of food preferences and morphological characteristics. Our data highlights the importance of combined analysis of all available evidences for understanding the evolutionary routes of diverse groups, as is the case of the Characiformes of the São Francisco River. [ABSTRACT FROM AUTHOR]

Kateretidae is a beetle family with 15 reported fossil species, four of them with specialized antennal scape. Specialized scape represents a rare form of sexual dimorphism in Kateretidae. Here we report two new species with a special scape in males of Protokateretes Zhao, Huang and Cai, 2023, and one female individual of an unnamed species of Protokateretes. The discovery of new species provides a supplementary diagnosis of Protokateretes , and increases the biodiversity of the fossil genus. The high diversity of species in Protokateretes provides new insights into sexual dimorphism of Kateretidae in mid-Cretaceous, enriching the knowledge of potential courtship strategy of kateretid beetles in the late Mesozoic. [ABSTRACT FROM AUTHOR]

Understanding the underlying reasons for phenotypic plasticity and resulting morphological disparity is one of the key topics of evolutionary research. The phenotypic plasticity of extant and fossil melanopsids has been widely documented. Yet millennial-resolution, well-dated records from small aquatic habitats harboring endemics are scarce. The thermal spring-fed Lake Pețea is an ice age refugia harboring a unique endemic warm-water fauna. Subfossil melanopsids display incredible morphological variability from smooth to keeled, elongated to ribbed, shouldered forms. Numerous morphotypes have been considered as individual taxa with a fluent succession from the smooth elongated to the ribbed, shouldered types. This study presents an extensive morphometric analysis of subfossil melanopsids (ca. 3500 specimens) derived from stratified samples with an independent chronology. The aim was to separate morphotypes for investigations of temporal morphological disparity. Our results challenge the widely accepted hypothesis that proposes the evolution of shouldered, compressed, ribbed shells through a two-step process from smooth elongated spindle-shaped shells. Instead, it suggests that the subfossil shells belong to two distinct taxa present throughout the available stratigraphic data. The main components of shape variation, shape globularity, and shell coiling seem allometry-related. Ribs, striation, and keels appear randomly. High-spired spindle-shaped forms were considered to represent specimens of Microcolpia daudebartii hazayi. Bulkier low-spired and shouldered specimens represent phenotypes of Mi. parreyssii parreyssii. The collective and random distribution of morphotypes from the early stages of the lake's history also refutes the idea of a continuous transformation of the elongated forms into compressed, shouldered ones. Rather points to multiple events and environmental stimuli triggering development. Melanopsids appear in Late Glacial horizons, with Theodoxus prevostianus preferring temperatures above 23°C which may indicate the subordinate presence of hot water microhabitats in cooler waters., (© 2024 Wiley Periodicals LLC.)

The carditid genus Cyclocardia is currently the most diverse genus of the family, including nearly 180 nominal species encompassing wide stratigraphical (Cretaceous–Recent) and geographical (Antarctica, South and North America, Europe, Africa, Alaska, Russia, Japan and New Zealand) ranges. Due to the lack of autapomorphies in the diagnosis of the genus and its large account of species, we re‐evaluate the systematic and phylogenetic status of Cyclocardia. We applied three approaches: bibliographic revision, phylogenetic analysis and an exploration of morphological disparity. We used a shell–character matrix comprising 65 taxa (2 outgroups, 29 non‐Cyclocardia carditids and 28 species of Cyclocardia) for phylogenetic and disparity analyses. Maximum Observable Rescaled Distances was used to construct a distance matrix to compare Cyclocardia species and other carditid groups. According to our results, Cyclocardia represents a non‐monophyletic taxon and is thus a 'wastebasket taxon', chiefly because its diagnosis was based mainly on plesiomorphic characters. The European species C. kickxi and C. chameformis are placed within Scalaricardita, and the previously proposed genus Crassicardia is monophyletic (including C. crassidens, C. crebricostata, C. isaotakii and C. rjabininae). Three new genera are proposed for new groups identified by the phylogenetic analysis: South American Oesterheldia gen. nov. (including O. cannada and O. dalek), western North American Coanicardita gen. nov. (including C. ventricosa and C. occidentalis), and North Pacific Hippocampocardia gen. nov. (including H. barbarensis, H. hamiltonensis and H. yakatagensis). The newly defined monophyletic Cyclocardia is restricted to the Atlantic Ocean species C. borealis, C. novangliae and C. compressa. [ABSTRACT FROM AUTHOR]

Adaptive radiations are bursts in biodiversity that generate new evolutionary lineages and phenotypes. However, because they typically occur over millions of years, it is unclear how their macroevolutionary dynamics vary through time and among groups of organisms. Phyllostomid bats radiated extensively for diverse diets—from insects to vertebrates, fruit, nectar, and blood—and we use their molars as a model system to examine the dynamics of adaptive radiations. Three-dimensional shape analyses of lower molars of Noctilionoidea (Phyllostomidae and close relatives) indicate that different diet groups exhibit distinct morphotypes. Comparative analyses further reveal that phyllostomids are a striking example of a hierarchical radiation; phyllostomids' initial, higher-level diversification involved an "early burst" in molar morphological disparity as lineages invaded new diet-affiliated adaptive zones, followed by subsequent lower-level diversifications within adaptive zones involving less dramatic morphological changes. We posit that strong selective pressures related to initial shifts to derived diets may have freed molars from morpho-functional constraints associated with the ancestral molar morphotype. Then, lineages with derived diets (frugivores and nectarivores) diversified within broad adaptive zones, likely reflecting finer-scale niche partitioning. Importantly, the observed early burst pattern is only evident when examining molar traits that are strongly linked to diet, highlighting the value of ecomorphological traits in comparative studies. Our results support the hypothesis that adaptive radiations are commonly hierarchical and involve different tempos and modes at different phylogenetic levels, with early bursts being more common at higher levels. [Display omitted] • Phyllostomids radiated via an "early burst" only apparent in traits linked to diet • Within-diet-group diversifications do not demonstrate early burst patterns • The hierarchical radiation pattern seen here may be common among radiations • Results highlight the value of using ecomorphological traits in comparative studies To assess macroevolutionary patterns of the phyllostomid bat radiation, Grossnickle et al. use molar traits that are strongly linked to diet. The radiation is hierarchical: the initial, higher-level diversification involves a diet-driven "early burst" in morphology, and subsequent, lower-level diversifications lack an early burst pattern. [ABSTRACT FROM AUTHOR]

The tectonic evolution of landscape topography is an important driver of biotic evolution throughout Earth's history. Studies of extant diversity have shown a higher diversity of mammals in topographically complex regions, suggesting that landscape complexity plays a role in generating taxonomic diversity. However, this relationship is poorly understood, especially over geologic time scales. Previous work has posited that heterogeneous topography should lead to increased species diversity as a result of new niche spaces into which lineages may speciate. This is in comparison to homogeneous landscape topography, which offers fewer and less varied niche spaces and thus less ecological opportunities for diversification. It is also thought that barriers to species and individual movement created by mountainous landscapes may divide populations, leading to speciation by restricting gene flow. These two models can be distinguished by their effects on morphological disparity. If niche differentiation is important to the process, we would expect increased morphological disparity in association with heterogeneous landscape topography, whereas the allopatry model predicts no greater morphological disparity over the complex landscape, only taxonomic diversification. We explore these models in the tectonically active and passive regions of North America in rodents from 25 to 0 Ma. We investigate diversity and disparity trends and examine the effects of climate, landscape heterogeneity, and environmental shifts on these patterns. We find that morphological and taxonomic evolution are not impacted by topography in a predictable way, and find that homogeneous landscapes host taxonomic and morphological diversity surpassing that of heterogeneous landscapes for much of the last 19 million years in North America. Furthermore, diversity and disparity trends are both coupled and decoupled during this period, signifiying that taxonomic and morphologic increase and decrease are discordant through time. Our results support the finding that the relationship between landscape heterogeneity and species diversity has not remained constant through geologic time. • Diversity and disparity patterns correspond to a degree with environmental trends. • Homogeneous landscapes can exhibit higher biodiversity than complex landscapes. • Morphological disparity in rodents was elevated during the Pliocene-Pleistocene. [ABSTRACT FROM AUTHOR]

The development of an improved hearing sense in teleosts as expressed in fossil otoliths may have been one important element in the success of their evolution. Hence, fossil otoliths add valuable information to paleoichthyology. Teleost otolith morphology, however, has initially diversified very slowly during the Jurassic and Early Cretaceous and accelerated only during major phases of teleost radiation in Late Cretaceous and Paleogene times.

Abstract Background Fishes are extremely speciose and also highly disparate in their fin configurations, more specifically in the number of fins present as well as their structure, shape, and size. How they achieved this remarkable disparity is difficult to explain in the absence of any comprehensive overview of the evolutionary history of fish appendages. Fin modularity could provide an explanation for both the observed disparity in fin configurations and the sequential appearance of new fins. Modularity is considered as an important prerequisite for the evolvability of living systems, enabling individual modules to be optimized without interfering with others. Similarities in developmental patterns between some of the fins already suggest that they form developmental modules during ontogeny. At a macroevolutionary scale, these developmental modules could act as evolutionary units of change and contribute to the disparity in fin configurations. This study addresses fin disparity in a phylogenetic perspective, while focusing on the presence/absence and number of each of the median and paired fins. Results Patterns of fin morphological disparity were assessed by mapping fin characters on a new phylogenetic supertree of fish orders. Among agnathans, disparity in fin configurations results from the sequential appearance of novel fins forming various combinations. Both median and paired fins would have appeared first as elongated ribbon-like structures, which were the precursors for more constricted appendages. Among chondrichthyans, disparity in fin configurations relates mostly to median fin losses. Among actinopterygians, fin disparity involves fin losses, the addition of novel fins (e.g., the adipose fin), and coordinated duplications of the dorsal and anal fins. Furthermore, some pairs of fins, notably the dorsal/anal and pectoral/pelvic fins, show non-independence in their character distribution, supporting expectations based on developmental and morphological evidence that these fin pairs form evolutionary modules. Conclusions Our results suggest that the pectoral/pelvic fins and the dorsal/anal fins form two distinct evolutionary modules, and that the latter is nested within a more inclusive median fins module. Because the modularity hypotheses that we are testing are also supported by developmental and variational data, this constitutes a striking example linking developmental, variational, and evolutionary modules.

Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages. [ABSTRACT FROM AUTHOR]

The Generalized Euclidean Distance (GED) measure has been extensively used to conduct morphological disparity analyses based on palaeontological matrices of discrete characters. This is in part because some implementations allow the use of morphological matrices with high percentages of missing data without needing to prune taxa for a subsequent ordination of the data set. Previous studies have suggested that this way of using the GED may generate a bias in the resulting morphospace, but a detailed study of this possible effect has been lacking. Here, we test whether the percentage of missing data for a taxon artificially influences its position in the morphospace, and if missing data affects pre‐ and post‐ordination disparity measures. We find that this use of the GED creates a systematic bias, whereby taxa with higher percentages of missing data are placed closer to the centre of the morphospace than those with more complete scorings. This bias extends into pre‐ and post‐ordination calculations of disparity measures and can lead to erroneous interpretations of disparity patterns, especially if specimens present in a particular time interval or clade have distinct proportions of missing information. We suggest that this implementation of the GED should be used with caution, especially in cases with high percentages of missing data. Results recovered using an alternative distance measure, Maximum Observed Rescaled Distance (MORD), are more robust to missing data. As a consequence, we suggest that MORD is a more appropriate distance measure than GED when analysing data sets with high amounts of missing data. [ABSTRACT FROM AUTHOR]

Like many fossil insect groups, the systematic framework of extinct 'Homoptera' is mainly based on venational traits of isolated wings; most taxa of Mesozoic Sinoalidae, however, were erected with whole-bodied specimens. On the basis of new fossil data and phylogenetic analyses, this froghopper family is herein chosen as a case study to discuss the potential influence of the absence and/or neglect of body information in palaeoentomological studies. Mesodorus orientalis Chen et Wang, gen. et sp. nov., found in the mid-Cretaceous Burmese amber, bears a venational topology of fore- and hindwings similar to that of the genus Fangyuania from the same horizon and locality, but distinctly differs from the latter and other known sinoalids in possessing a series of unique body characters. Given the similar wing features, Jiania crebra and J. gracila were proposed to be synonyms in a recent study; these two congeners, however, are apparently discernable in their ovipositor and so the synonym should be rejected. Three main clades were recovered within the Sinoalidae in our cladistic analyses, including Clade I (Stictocercopis + Chengdecercopis), Clade II (Huabeicercopis + Luanpingia + Sinoala + Jiania + Shufania), and Clade III (Fangyuania + Mesodorus), and their relationship is as following: Clade I + (Clade II + Clade III). The Jurassic Clade I, as the basal lineage, is remarkably different from other sinoalids in bearing wings with complex venation, but similar to the Jurassic Clade II in body structures. The Cretaceous Clade III possesses a reduced wing topology similar to Clade II, but differs from the latter in possessing a series of novel body characteristics for each taxon (i.e., Fangyuania and Mesodorus). Unsurprisingly, our finds confirm that the information from body structures, vital to understanding the biodiversity and evolutionary history of extinct insects, should not be ignored in palaeoentomological studies. [ABSTRACT FROM AUTHOR]

Mammals and their closest fossil relatives are unique among tetrapods in expressing a high degree of pectoral girdle and forelimb functional diversity associated with fully pelagic, cursorial, subterranean, volant, and other lifestyles. However, the earliest members of the mammalian stem lineage, the “pelycosaur”-grade synapsids, present a far more limited range of morphologies and inferred functions. The more crownward nonmammaliaform therapsids display novel forelimb morphologies that have been linked to expanded functional diversity, suggesting that the roots of this quintessentially mammalian phenotype can be traced to the pelycosaur–therapsid transition in the Permian period. We quantified morphological disparity of the humerus in pelycosaur-grade synapsids and therapsids using geometric morphometrics. We found that disparity begins to increase concurrently with the emergence of Therapsida, and that it continues to rise until the Permo-Triassic mass extinction. Further, therapsid exploration of new regions of morphospace is correlated with the evolution of novel ecomorphologies, some of which are characterized by changes to overall limb morphology. This evolutionary pattern confirms that nonmammaliaform therapsid forelimbs underwent ecomorphological diversification throughout the Permian, with functional elaboration initially being more strongly expressed in the proximal end of the humerus than the distal end. The role of the forelimbs in the functional diversification of therapsids foreshadows the deployment of forelimb morphofunctional diversity in the evolutionary radiation of mammals. [ABSTRACT FROM AUTHOR]

Lake Malaŵi cichlids have evolved rapidly, extensively, and in some cases iteratively to fill an array of ecological niches; however, neither species richness nor trophic diversity is distributed equally across lineages. In the context of evolutionary theory, such differences offer predictions about the magnitudes and patterns of morphological variation within lineages. In this paper, we use geometric morphometrics in three prevalent rock-dwelling genera to address questions related to morphological diversity, disparity, integration, and modularity. In particular, we focus on comparisons between the highly specialized and species-poor genus, Labeotropheus (Ahl in Sitzungsberichte der Berlinische Gesellschaft Naturforschender Freunde zu Berlin 1926:51-62, 1927), and the more ecologically diverse and species-rich genus, Tropheops (Trewavas in Revue Française d'Aquariologie Herpétologie 10:97-106, 1984), as well as between species with lake-wide versus more limited distributions. We find that Labeotropheus exhibits comparable levels of morphological disparity to Tropheops, which suggests that a specialized foraging mode has not constrained cranial variability in this genus. We also find that species with a lake-wide distribution exhibit levels of disparity three times greater than that in a species with a limited distribution. Finally, we show that magnitudes of integration and patterns of modularity are lineage specific, and do not directly correspond to ecology. In sum, these data provide insights into the complex relationship between ecology, morphological variability, and evolvability. [ABSTRACT FROM AUTHOR]

The ideas of the evolutionary ecology of the 20th century and its modern conceptual space are considered with regard to new knowledge of the contents of population and evolutionary synecology. The article proposes (1) a population cenotic approach to analyzing the covariation of cenopopulations of sympatric species and taxocenes in space and historical time; (2) an approach to assessing the intragroup morphological disparity in cenopopulations of sympatric species and taxocenes as a measure of morphogenetic stability. Consideration is given to experimental evolutionary ecology as a particular methodological area. Prospects for the formation of evolutionary ecology as an interdisciplinary applied science are discussed in view of the necessity of predicting regional biocenotic crises and rapid coevolutionary changes in biotic communities in a technogenic environment against the background of predicted unfavorable trends of climate changes. [ABSTRACT FROM AUTHOR]

The article addresses the interrelationship between different forms of group varia­bility of craniometrical features according to value of their contribution in the overall morphological disparity of individuals in the population Microtus socialis in southern Ukraine. It is shown that most of the variability of traits determined primarily the age animals and less sex, season, number and density of individuals in the population. Obtained results indicate that the age variability is the base for formation of all other forms of group variability. It is proved that the variability of craniometrical traits in young and subadult voles is determined primarily by size and density of individuals in population (cyclic variability). Second largest impact on the variability of craniometrical features includes season, third – sex whose influence on the variability of traits in young voles was statistically proven. In juvenile voles sex and season affect the variability of linear dimensions and proportions of the skull, while in subadult and adults – mostly in the proportions of the skull and almost no influence on the variability of its linear dimensions. Sexual variability of the craniometrical traits increases markedly with the age of voles.

Abstract Analyses of ceramic vessel shape are neither new or novel; however, the relatively recent adoption of geometric morphometric (GM) methods by archaeologists provides a preview of the contribution of GM to the systematic and rigorous study of morphology as applied to material culture. This study is focused upon an analysis of Caddo bottle shapes for Belcher Engraved, Hickory Fine Engraved, Keno Trailed, Smithport Plain, and Taylor Engraved vessels from the Allen Plantation, Belcher Mound, Gahagan Mound, and Smithport Landing sites in the Clarence H. Webb collections from northwest Louisiana. Results indicate some significant relationships between bottle shape and size (allometry), bottle shape and type, and bottle shape and site. A test of morphological integration indicates that the bottles are significantly integrated, meaning that those discrete traits used to characterise their shape (rim, neck, body, and base) vary in a coordinated manner, highlighting significant integration between suites of attributes. The Smithport Plain and Hickory (Fine) Engraved bottles found at the Belcher Mound, Smithport Landing, and Gahagan Mound sites also provide evidence for two discrete (north–south) base and body shapes. [ABSTRACT FROM AUTHOR]

Abstract: In this article, I use geometric morphometrics in 2D from a sample of 366 elbow joints to quantify phenotypic disparity in domestic dog breeds, in wild canids, and across the order Carnivora. The elbow joint is a well‐established morphological indicator of forearm motion and, by extension, of functional adaptations toward locomotor or predatory behavior in living carnivores. The study of the elbow joint in domestic dogs allows the exploration of potential convergences between (i) pursuit predators and fast‐running dogs, and (ii) ambush predators and fighting breeds. The results indicate that elbow shape disparity among domestic dogs exceeds than in wolves; it is comparable to the disparity of wild Caninae, but is significantly lower than the one observed throughout Canidae and Carnivora. Moreover, fast‐running and fighting breeds are not convergent in elbow joint shape with extreme pursuit and ambush wild carnivores, respectively. The role of artificial selection and developmental constraints in shaping limb phenotypic disparity through the extremely fast evolution of the domestic dog is discussed in the light of this new evidence. [ABSTRACT FROM AUTHOR]

One of the key faunal transitions in Earth history occurred after the Permo- Triassic mass extinction (ca 252.2 Ma), when the previously obscure archosauromorphs (which include crocodylians, dinosaurs and birds) become the dominant terrestrial vertebrates. Here, we place all known middle Permian--early Late Triassic archosauromorph species into an explicit phylogenetic context, and quantify biodiversity change through this interval. Our results indicate the following sequence of diversification: a morphologically conservative and globally distributed post-extinction 'disaster fauna'; a major but cryptic and poorly sampled phylogenetic diversification with significantly elevated evolutionary rates; and a marked increase in species counts, abundance, and disparity contemporaneous with global ecosystem stabilization some 5 million years after the extinction. This multiphase event transformed global ecosystems, with far-reaching consequences for Mesozoic and modern faunas. [ABSTRACT FROM AUTHOR]

Biodiversity is unevenly distributed in space and time. One possible explanation for this is the influence of climate on the ecology, evolution, and morphology of taxa. Here we investigated the link between climatic variability and phenotypic integration, rates of morphological evolution, and disparity (morphological diversity) in three carnivoran clades (Canidae, Felidae, andMustelidae).Wegathered landmark data from the lower jaw and extracted current temperature and precipitation data from range maps. We found a significant negative relationship between climatic variability and integration for canids and felids. Among canids, variability in temperature was the key climatic variable, while in felids it was a combination of variability in temperature and precipitation. In both cases, relatively variable climates were associated with low phenotypic integration. We also found evidence for a negative association between climatic variability and both disparity and rates of morphological evolution in canids and mustelids. Selection can drive the evolution of jaw shape along lines of least resistance defined by patterns of integration, and this study suggests that climate may be a predictor of phenotypic integration. As a result, taxa in more variable regions (e.g., temperate, montane) may be more evolvable and more able to respond to fluctuating environmental conditions over a period of generations. [ABSTRACT FROM AUTHOR]

Genital morphology in animals with internal fertilization is considered to be among the fastest evolving traits. Sexual selection is often proposed as the main driver of genital diversification but the exact selection mechanisms involved are usually unclear. In addition, the mechanisms operating may differ even between pairs of sibling species. We investigated patterns of male genital variation within and between natural populations of the cactophilic fly Drosophila koepferae ranging its entire geographic distribution and compared them with those previously observed in its sibling species, D. buzzatii. Using both mtDNA and nDNA markers we found that genital shape variation in D. koepferae is more restricted than expected for neutral evolution, suggesting the predominance of stabilizing selection. We also detected dissimilar patterns of divergence between populations of D. koepferae that were allopatric and sympatric with D. buzzatii. The constrained evolution inferred for D. koepferae’s genitalia clearly contrasts with the rapid divergence and higher morphological disparity observed in the populations of D. buzzatii. Finally, different possible scenarios of male genital evolution in each species and within the radiation of D. buzzatii cluster are discussed. [ABSTRACT FROM AUTHOR]

The radiation of vascular plants during the mid to late Paleozoic has been considered one of the most important drivers of change in Earth's terrestrial environments. Non-marine deposits of the South China Block document plant diversification through the crucial Silurian and Devonian periods in a series of well-preserved fossil assemblages when this block occupied a paleoequatorial to low-latitude position and was isolated from the Laurussia paleocontinent. Significant plant fossils include the Pridoli and Early Devonian assemblages, from Yunnan and Sichuan provinces, southwestern China, and the Pragian Posongchong Flora from the Posongchong Formation of Wenshan, Yunnan. The Middle Devonian (Givetian) Haikou Formation and correlative strata supported diverse lycopsids and euphyllophytes, documenting landscapes with the first tree-like plants in South China. The Late Devonian Huangjiadeng, Xiejingsi and Wutong formations, particular the latter, preserve an abundance of lycopsids, fern-like plants, sphenopsids and seed plants, revealing complex plant communities. The taxonomic diversity in South China is characterized by a gradual increase from the Pridoli, with great diversification during the Pragian, a gap in the Emsian-Eifelian record, and a moderate increase in the Givetian and Frasnian, followed by a 2–3 times increase in the Famennian. Although the raw diversity pattern is somewhat obscured by different sampling intensity, the apparent increases during the Pragian and Famennian seem to be bona fide radiation events. Phytogeographically, the endemism of Early and Middle Devonian floras of South China has been supported by increasing paleobotanical data. The Late Devonian floras of South China began to share some, primarily arborescent species with other parts of the world. Axial diameter, leaf size, and multiple-character-based morphological disparity (mean pairwise dissimilarity) show stepwise evolutionary increase through the Devonian in parallel with the rise of taxonomic diversity. New integrative studies will further illuminate the terrestrialization process and the environmental impact of vascular plants. [ABSTRACT FROM AUTHOR]