Ultraconserved elements-based phylogenomic systematics of the snake superfamily Elapoidea, with the description of a new Afro-Asian family.

The highly diverse snake superfamily Elapoidea is considered to be a classic example of ancient, rapid radiation. Such radiations are challenging to fully resolve phylogenetically, with the highly diverse Elapoidea a case in point. Previous attempts at inferring a phylogeny of elapoids produced highly incongruent estimates of their evolutionary relationships, often with very low statistical support. We sought to resolve this situation by sequencing over 4,500 ultraconserved element loci from multiple representatives of every elapoid family/subfamily level taxon and inferring their phylogenetic relationships with multiple methods. Concatenation and multispecies coalescent based species trees yielded largely congruent and well-supported topologies. Hypotheses of a hard polytomy were not retained for any deep branches. Our phylogenies recovered Cyclocoridae and Elapidae as diverging early within Elapoidea. The Afro-Malagasy radiation of elapoid snakes, classified as multiple subfamilies of an inclusive Lamprophiidae by some earlier authors, was found to be monophyletic in all analyses. The genus Micrelaps was consistently recovered as sister to Lamprophiidae. We establish a new family, Micrelapidae fam. nov., for Micrelaps and assign Brachyophis to this family based on cranial osteological synapomorphy. We estimate that Elapoidea originated in the early Eocene and rapidly diversified into all the major lineages during this epoch. Ecological opportunities presented by the post-Cretaceous-Paleogene mass extinction event may have promoted the explosive radiation of elapoid snakes.

Colour scales with climate in North American ratsnakes: a test of the thermal melanism hypothesis using community science images.

Animal colour is a complex trait shaped by multiple selection pressures that can vary across geography. The thermal melanism hypothesis predicts that darker coloration is beneficial to animals in colder regions because it allows for more rapid solar absorption. Here, we use community science images of three closely related species of North American ratsnakes (genus Pantherophis) to examine if climate predicts colour variation across range-wide scales. We predicted that darker individuals are found in colder regions and higher elevations, in accordance with the thermal melanism hypothesis. Using an unprecedented dataset of over 8000 images, we found strong support for temperature as a key predictor of darker colour, supporting thermal melanism. We also found that elevation and precipitation are predictive of colour, but the direction and magnitude of these effects were more variable across species. Our study is the first to quantify colour variation in Pantherophis ratsnakes, highlighting the value of community science images for studying range-wide colour variation.

A new Liopeltis Fitzinger, 1843 (Squamata: Colubridae) from Pulau Tioman, Peninsular Malaysia.

Liopeltis is a genus of poorly known, infrequently sampled species of colubrid snakes in tropical Asia. We collected a specimen of Liopeltis from Pulau Tioman, Peninsular Malaysia, that superficially resembled L. philippina, a rare species that is endemic to the Palawan Pleistocene Aggregate Island Complex, western Philippines. We analyzed morphological and mitochondrial DNA sequence data from the Pulau Tioman specimen and found distinct differences to L. philippina and all other congeners. On the basis of these corroborated lines of evidence, the Pulau Tioman specimen is described as a new species, L. tiomanica sp. nov. The new species occurs in sympatry with L. tricolor on Pulau Tioman, and our description of L. tiomanica sp. nov. brings the number of endemic amphibians and reptiles on Pulau Tioman to 12.

A species-level phylogeny of Trachylepis (Scincidae: Mabuyinae) provides insight into their reproductive mode evolution.

Trachylepis (Mabuyinae) includes ∼80 species of fully-limbed skinks found primarily in Africa and Madagascar, but a robust species-level phylogeny for this genus is lacking and this impedes studies on a wide-range of topics from biogeography to character evolution. Trachylepis and its close relatives (which together form the Mabuya group or Mabuyinae) are notable in that they have undergone multiple transitions and remarkable specializations in their reproductive modes. A Trachylepis phylogeny will be particularly useful for investigating reproductive evolution, because it includes species that exhibit oviparity, viviparity, and bimodal parity (species with both oviparous and viviparous populations). We sequenced DNA at four mitochondrial and five nuclear loci for 67 (∼84% of) Trachylepis species to infer a phylogeny for this genus. We performed stochastic character mapping of parity mode under a variety of parity mode transition models to infer ancestral parity mode states and the number and type of parity mode transitions. We recovered a strongly supported phylogeny of Trachylepis that is generally consistent with earlier phylogenetic studies. The best-fit model of reproductive mode evolution supports an oviparous ancestor for Trachylepis, and supports at least three viviparity to oviparity transitions. We compared parity mode evolution under the overall best-fit model (no constraints on parity mode transitions) to the best-fit model among the subset of models that assume viviparity to oviparity transitions are impossible. Our results support a model of reproductive evolution that allows for reversibility from viviparity to oviparity, a process that is not generally accepted. Alternatively, the best-fit model of evolution among the set of models that eliminate reversals from viviparity to oviparity suggests that bimodal reproduction may have persisted for millions of years within multiple lineages.

Systematics and phylogeography of the widely distributed African skink Trachylepis varia species complex.

A systematic study of the Trachylepis varia complex was conducted using mitochondrial and nuclear DNA markers for individuals sampled across the species range. The taxonomic history of T. varia has been complicated and its broad geographic distribution and considerable phenotypic variation has made taxonomic revision difficult, leading earlier taxonomists to suggest that T. varia is a species complex. We used maximum likelihood and Bayesian inference to estimate gene trees and a multilocus time-tree, respectively, and we used these trees to identify the major clades (putative species) within T. varia. Additionally, we used morphological and color pattern data to distinguish and revise the taxonomy of the southern African clades. The major clades recovered in the multilocus time-tree were recovered in each of gene trees, although the relationships among these major clades differed across gene trees. Genetic data support the existence of at least eight species within the T.varia complex, each of which originated during the mid to late Miocene or early Pliocene. We focus our systematic discussion on the southern African members of the T. varia complex, revive Trachylepis damarana (Peters, 1870) and T. laevigata (Peters, 1869), and designate lectotypes for T.damarana and T. varia.

Discovery of an old, archipelago-wide, endemic radiation of Philippine snakes.

The extraordinarily rich land vertebrate biodiversity of the Philippines includes at least 112 species of terrestrial snakes (74% of which are endemic to the archipelago) in 41 genera (12% endemic). Endemic Philippine snake genera include Cyclocorus (two species), Hemibungarus (three species), Hologerrhum (two species), Oxyrhabdium (two species), and Myersophis (monotypic). Although Hemibungarus and Oxyrhabdium have been included in previous species-level phylogenies, the affinities of the other three Philippine endemic genera are completely unknown. We generated novel DNA sequences for six species from four genera and analyzed these in conjunction with data from earlier studies to infer a phylogeny for the group containing Colubridae, Elapoidea (Elapidae + Lamprophiidae), and Homalopsidae. We present a novel phylogenetic result that strongly supports the existence of an entirely endemic Philippine radiation of elapoid snakes that originated 35-25 million years ago. We provide a revised, phylogeny-based classification to accommodate the new clade, transfer Cyclocorus, Hologerrhum, and Myersophis to Lamprophiidae, and provide the first estimate of the evolutionary relationships among these genera and the related Oxyrhabdium, setting the stage for future investigation of this entirely endemic, novel Philippine elapoid radiation.

A single origin of extreme matrotrophy in African mabuyine skinks.

Most mammals and approximately 20% of squamates (lizards and snakes) are viviparous, whereas all crocodilians, birds and turtles are oviparous. Viviparity evolved greater than 100 times in squamates, including multiple times in Mabuyinae (Reptilia: Scincidae), making this group ideal for studying the evolution of nutritional patterns associated with viviparity. Previous studies suggest that extreme matrotrophy, the support of virtually all of embryonic development by maternal nutrients, evolved as many as three times in Mabuyinae: in Neotropical Mabuyinae (63 species), Eumecia (2 species; Africa) and Trachylepis ivensii (Africa). However, no explicit phylogenetic hypotheses exist for understanding the evolution of extreme matrotrophy. Using multilocus DNA data, we inferred a species tree for Mabuyinae that implies that T. ivensii (here assigned to the resurrected genus Lubuya) is sister to Eumecia, suggesting that extreme matrotrophy evolved only once in African mabuyine skinks.

Resolving the higher-order phylogenetic relationships of the circumtropical Mabuya group (Squamata: Scincidae): An out-of-Asia diversification.

Despite an abundance of phylogenetic studies focused on intrageneric relationships of members of the Mabuya group, the intergeneric relationships have remained difficult to resolve. The most-persistent unresolved regions of the phylogeny of the group include: (1) the placement of the Middle-Eastern Trachylepis with respect to the Afro-Malagasy Trachylepis and its taxonomic status; (2) the phylogenetic position of the Cape Verdean Chioninia within the larger Mabuya group; (3) support for the placement of Dasia with respect to the entire group; and (4) the phylogenetic placement of Eutropis novemcarinata with respect to other Eutropis and Dasia. In this study, we include representatives of all these taxa as well as African Eumecia and Neotropical Mabuya. We seek to address these phylogenetic and systematic issues by generating a well-resolved and supported phylogeny for the Mabuya group as a whole that can be used to develop a stable taxonomy and reconstruct the geographic patterns of diversification within the group. To meet these goals, we built a large multi-locus dataset of 11 markers (nine nuclear and two mitochondrial), and performed concatenated and species tree analyses to generate a well-supported phylogeny for the group. Statistical topology tests reject the monophyly of Middle-Eastern Trachylepis with Afro-Malagasy Trachylepis, and to reflect monophyly we place the Middle-Eastern species into a previously described genus, Heremites. Cape-Verdean Chioninia are resolved as the strongly supported sister-group to Afro-Malagasy Trachylepis. Monophyly of the Southeast-Asian genera, Eutropis and Dasia, is not supported, with a clade composed of Dasia+Eutropis novemcarinata more closely related to the rest of the Mabuya group than to the remaining Eutropis. The phylogenetic position of E. novemcarinata renders Eutropis polyphyletic, and we therefore describe and place E. novemcarinata into a new monotypic genus, Toenayar, to preserve monophyly among the genera. In light of these novel findings, we review and discuss the historical biogeography of the entire Mabuya group.