Molecular phylogenetic evidence for ancient divergence of lizard taxa on either side of Wallace's Line

Wallace's Line, separating the terrestrial faunas of South East Asia from the Australia-New Guinea region, is the most prominent and well-studied biogeographical division in the world. Phylogenetically distinct subgroups of major animal and plant groups have been documented on either side of Wallace's Line since it was first proposed in 1859. Despite its importance, the temporal history of fragmentation across this line is virtually unknown and the geological foundation has rarely been discussed. Using molecular phylogenetics and dating techniques, we show that the split between taxa in the South East Asian and the Australian-New Guinean geological regions occurred during the Late Jurassic to Early Cretaceous in two independent lizard clades. This estimate is compatible with the hypothesis of rifting Gondwanan continental fragments during the Mesozoic and strongly rejects the hypothetical origin of various members of the Australian-New Guinean herpetofauna as relatively recent invasions from South East Asia. Our finding suggests an ancient fragmentation of lizard taxa on either side of Wallace's Line and provides further evidence that the composition of modern global communities has been significantly affected by rifting and accretion of Gondwanan continental plates during the Middle to Late Mesozoic

The Eurasian invasion: phylogenomic data reveal multiple Southeast Asian origins for Indian Dragon Lizards

A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Background: The Indian Tectonic Plate split from Gondwanaland approximately 120 MYA and set the Indian subcontinent on a ~ 100 million year collision course with Eurasia. Many phylogenetic studies have demonstrated the Indian subcontinent brought with it an array of endemic faunas that evolved in situ during its journey, suggesting this isolated subcontinent served as a source of biodiversity subsequent to its collision with Eurasia. However, recent molecular studies suggest that Eurasia may have served as the faunal source for some of India’s biodiversity, colonizing the subcontinent through land bridges between India and Eurasia during the early to middle Eocene (~35–40 MYA). In this study we investigate whether the Draconinae subfamily of the lizard family Agamidae is of Eurasian or Indian origin, using a multi locus Sanger dataset and a novel dataset of 4536 ultraconserved nuclear element loci. Results: Results from our phylogenetic and biogeographic analyses revealed support for two independent colonizations of India from Eurasian ancestors during the early to late Eocene prior to the subcontinent’s hard collision with Eurasia. Conclusion: These results are consistent with other faunal groups and new geologic models that suggest ephemeral Eocene land bridges may have allowed for dispersal and exchange of floras and faunas between India and Eurasia during the Eocene

Data from: Patterns of sexual size dimorphism in Chelonia

Macroevolutionary patterns of sexual size dimorphism (SSD) indicate how sexual selection, natural selection, and genetic and developmental constraints mold sex differences in body size. One putative pattern, known as Rensch’s Rule, posits that among species with female-larger SSD, the relative degree of SSD declines with species’ body size, whereas among male-larger SSD species, relative SSD increases with size. Using a dataset of 196 chelonian species from all fourteen families, we investigated the correlation in body size evolution between male and female Chelonia and the validity of Rensch’s Rule for the taxon and within its major clades. We conclude that male-female correlations in body size evolution are high, but these correlations differ among chelonian families. Overall, SSD scales isometrically with body size; Rensch’s Rule is valid for only one family, Testudinidae (tortoises). Since macroevolutionary patterns of SSD can vary markedly among clades, even in a taxon as morphologically conservative as Testudines, one must guard against inappropriately pooling clades in comparative studies of SSD. Our results also indicate that regression models that assume the x - variable (e.g. male body size) is measured without statistical error, although frequently reported, will result in erroneous conclusions about phylogenetic trends in sexual size dimorphism

Evolution of extreme body size disparity in monitor lizards (Varanus)

Many features of species’ biology, including life history, physiology, morphology, and ecology are tightly linked to body size. Investigation into the causes of size divergence is therefore critical to understanding the factors shaping phenotypic diversity within clades. In this study, we examined size evolution in monitor lizards (Varanus), a clade that includes the largest extant lizard species, the Komodo dragon (V. komodoensis), as well as diminutive species that are nearly four orders of magnitude smaller in adult body mass. We demonstrate that the remarkable body size disparity of this clade is a consequence of different selective demands imposed by three major habitat use patterns— arboreality, terrestriality, and rock-dwelling. We reconstructed phylogenetic relationships and ancestral habitat use and applied model selection to determine that the best-fitting evolutionary models for species’ adult size are those that infer oppositely directed adaptive evolution associated with terrestriality and rock-dwelling, with terrestrial lineages evolving extremely large size and rock-dwellers becoming very small. We also show that habitat use affects the evolution of several ecologically important morphological traits independently of body size divergence. These results suggest that habitat use exerts a strong, multidimensional influence on the evolution of morphological size and shape disparity in monitor lizards.Organismic and Evolutionary Biolog

The limits of polymorphism in Liolaemus rothi: molecular and phenotypic evidence for a new species of the Liolaemus boulengeri clade (Iguanidae, Liolaemini) from boreal Patagonia of Chile

Studies conducted over the last few years in Andean boreal Patagonia along the border of Argentina and Chile (36°50'S-37°53'S) have shown that its reptile diversity is comprised of several endemic lizards. Increasing research has led to recognize a number of cryptic iguanian species from previously named taxa. In this area is common the only known Chilean population of the Patagonian Liolaemus rothi, considered as a polymorphic species with wide geographical distribution. In this paper, we provide evidence to support the hypothesis that such population represents a new taxon, herein described as Liolaemus hermannunezi- This new species occurs in the southeastern areas of Laguna del Laja, in the Los Barros and Rio de Los Pinos basins of Antuco Volcano (1428-1521 m) in the Bio Bio Region. Liolaemus hermannunezi is closely related to L. rothi, from which is significantly differentiated by molecular variables. In addition, this new species appears to be related to L. loboi and L. sagei, from which differs in having a smaller body size, a distinctive colour pattern and an isolated geographical distribution. Liolaemus hermannunezi is known from the boreal Patagonia of Chile, whereas L. loboi, L. rothi, and L. sagei are endemic to Argentinean Patagonia. The new species is a member of the boulengeri clade, diagnosed by the presence of a patch of abruptly enlarged scales on the posterior medial surface of the thigh, a character that is more conspicuous in adult males. Finally, a phylogenetic hypothesis for 67 Liolaemini taxa based on DNA sequences is presented. Copyright © 2007 Magnolia Press

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Data_Chelonia_201

Rostral horn evolution among agamid lizards of the genus ceratophora endemic to Sri Lanka

The first phylogenetic hypothesis for the Sri Lankan agamid lizard genus Ceratophora is presented based on 1670 aligned base positions (472 parsimony informative) of mitochondrial DNA sequences, representing coding regions for eight tRNAs, ND2, and portions of ND1 and COI. Phylogenetic analysis reveals multiple origins and possibly losses of rostral horns in the evolutionary history of Ceratophora. Our data suggest a middle Miocene origin of Ceratophora with the most recent branching of recognized species occurring at the Pliocene/Pleistocene boundary. Haplotype divergence suggests that an outgroup species, Lyriocephalus scutatus, dates at least to the Pliocene. These phylogenetic results provide a framework for comparative studies of the behavioral ecological importance of horn evolution in this group

A Phylogenetic Test for Adaptive Convergence in Rock-dwelling Lizards

Phenotypic similarity of species occupying similar habitats has long been taken as strong evidence of adaptation, but this approach implicitly assumes that similarity is evolutionarily derived. However, even derived similarities may not represent convergent adaptation if the similarities did not evolve as a result of the same selection pressures; an alternative possibility is that the similar features evolved for different reasons, but subsequently allowed the species to occupy the same habitat, in which case the convergent evolution of the same feature by species occupying similar habitats would be the result of exaptation. Many lizard lineages have evolved to occupy vertical rock surfaces, a habitat that places strong functional and ecological demands on lizards. We examined four clades in which species that use vertical rock surfaces exhibit long hindlimbs and flattened bodies. Morphological change on the phylogenetic branches leading to the rock-dwelling species in the four clades differed from change on other branches of the phylogeny; evolutionary transitions to rock-dwelling generally were associated with increases in limb length and decreases in head depth. Examination of particular characters revealed several different patterns of evolutionary change. Rock-dwelling lizards exhibited similarities in head depth as a result of both adaptation and exaptation. Moreover, even though rock-dwelling species generally had longer limbs than their close relatives, clade-level differences in limb length led to an overall lack of difference between rock- and non-rock-dwelling lizards. These results indicate that evolutionary change in the same direction in independent lineages does not necessarily produce convergence, and that the existence of similar advantageous structures among species independently occupying the same environment may not indicate adaptation.Organismic and Evolutionary Biolog