Session 51: Herpetology Systematics & Biogeography IIRoom: Room 206D2022-07-31 15:30 - 16:45 |
| Moderator: Todd Jackman |
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1. 15:30 The West Indian Boas: Seventeen Years of Research. R. Graham Reynolds*, University of North Carolina Asheville greynold@unca.edu
Fourteen species of West Indian boid snakes are recognized in the genus Chilabothrus. They occupy habitats ranging from xeric scrub to montane rainforest and have maximum adult body sizes spanning a range from<1 m to nearly 4 m. As recently as 2013, only nine species were recognized, though substantial work in the last few years has increased the number of known species by 36%. This includes the recognition of cryptic species such as the Virgin Islands Boa, the re-discovery of the Crooked-Acklins Boa, and the dramatic discoveries of the Silver Boa and the Vineboa. The last decade has also seen a substantial amount of progress in our understanding of the biology West Indian Boas. Two morphotypes have been recognized based on ecological, morphometric, and meristic analyses: large-bodied generalists and small-bodied specialists. Both large and small species are distributed across the West Indies, though no single island has more than one large species, and small species frequently co-occur with large species (with the exception of the Bahamas banks). Further, this determinism in body size and ecological evolution has been arrived at via different evolutionary pathways, notably, via accelerated rates of head shape (trophic morphology) evolution as small-bodied species evolved from larger ancestors. I will discuss my nearly 2 decades of work with this group, as well as our current understanding of the ecology and evolution of these boas, including the application of multivariate morphological analysis, statistical historical biogeography, molecular phylogenomics, and phylogenetic comparative methods. |
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2. 15:45 A Gondwanan Origin in the Early Jurassic and Subsequent Importance of Africa in Biogeography of Extant Squamata. Ian Wilenzik*, George Washington University; Benjamin Barger, George Washington University; R. Alexander Pyron, George Washington University ivwilenzik@gwu.edu
Squamata (lizards, snakes, and amphisbaenians) is an ancient lineage with an extensive and complex evolutionary and geographic history. The fossil record shows a Pangaean distribution of early lineages by the Middle Jurassic, though many of these (e.g., Paramacellodidae, Mosasauria) subsequently went extinct. Thus, the ancestral range of lineages leading to most extant radiations is unclear and may have been regionalized within Pangaea to Laurasia (North America and Eurasia) or Gondwana (South America, Africa, Australia, Antarctica). We used recent tectonic models to reconstruct nine discrete plates and utilized polygon range shape files to assign taxa more objectively to the different areas. Using a suite of biogeographic models accommodating different evolutionary processes, we modeled ancestral range for crown Squamata from an extant-only molecular phylogeny. Under the model with the highest support value (DEC+J), we find strong support for Gondwanan localization of the ancestors of extant squamates. Furthermore, Africa has high support as the region of origin for multiple lineages of squamates including Scincoidae, Gekkota, Iguania, and Lacertoidea. These results represent a starting point to promote future research on the complex biogeographic history of an ancient order. |
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3. 16:00 Phylogenetic Systematics, Biogeography, and Diversity of Hemisotidae: An Endemic African Radiation. João Tonini*, University of Richmond; Rafael de Sá, University of Richmond rdesa@richmond.edu
The family Hemisotidae comprise a single genus, Hemisus, currently consisting of nine described species – referred as shovel-nose frogs. Hemisus species are distributed in tropical and subtropical Africa, south of the Sahara. These frogs have an overall rounded body shape, small eyes, a pointed snout, and the arms and fingers are muscular and strong, facilitating head-first for burrowing. Hemisus species have similar external morphology but vary in body and limb size, as well as coloration patterns. Although some species of Hemisus have been included in molecular phylogenies, a comprehensive phylogenetic hypothesis including all known Hemisus is still lacking. In addition, Hemisus represent a radiation endemic to Africa and phylogenetic information would allow to test biogeographic scenarios of diversification unique to the continent. Moreover, given the fossorial habit, low dispersal potential, similar external morphology, and wide range of some species, we hypothesize the existence of cryptic undescribed new lineages. Herein we sample 202 representing all described Hemisus species, and several previously synonymized subspecies. We sequence four genetic markers, two mitochondrial and two nuclear, and use probabilistic phylogenetic methods to estimate the phylogeny of Hemisotidae. We time-calibrate the phylogeny using fossils and secondary calibrations to test biogeographic scenarios. Furthermore, we use the phylogenies to identify potential cryptic, undescribed lineages using coalescent methods. Our preliminary results show Hemisus as a monophyletic genus and that several previously synonymized species and sub-species could be elevated to species. Furthermore, we identify new, cryptic lineages related to H. marmoratus, H. guineensis, H. barotseensis, and H. brachydactylus. |
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4. 16:15 Systematics of the kukri snake genus Oligodon Fitzinger, 1826 (Reptilia: Squamata: Colubridae) from Myanmar and adjacent regions. Justin L. Lee*, Department of Biology and Center for Biodiversity and Ecosystem Stewardship, Villanova University; Aaron M. Bauer, Department of Biology and Center for Biodiversity and Ecosystem Stewardship, Villanova University justinllee@verizon.net
Kukri snakes of the genus Oligodon Fitzinger, 1826 are small to moderately sized colubrid snakes with high species diversity and a wide geographic range stretching across the Asian continent. Despite being one of the most speciose of all snake groups, most members are poorly understood due to their secretive and semi-fossorial behaviors. Efforts are needed to properly assess the geographic variation and species boundaries of several taxa, particularly those that are known from only a few specimens. Myanmar (Burma) harbors 14 species of Oligodon, of which a majority are poorly known and five are considered endemic. Here, we present a taxonomic review of all Oligodon species found within the country based on external morphology, internal features acquired from x-ray computed tomography (CT) scans, and molecular data. Our results support the validity of all species inhabiting Myanmar, but we remove Oligodon taeniatus from the country’s snake fauna based on a misidentified specimen. We redescribe all poorly known Burmese Oligodon and discuss distributional patterns associated with endemic species. Integrating molecular and morphological data allow us to clarify the relationships of several previously defined classifications, specifically the Oligodon cinereus and Oligodon theobaldi species-groups. More generally, we discuss problems associated with taxonomic inflation and cryptic diversity found in species such as Oligodon albocinctus and O. cinereus. Finally, we report on variation observed in the cranial and dental features of Oligodon and discuss their potential utility in future taxonomic investigations. |
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5. 16:30 Delimitation, diagnosis, convergence: taxonomic implications of recurring morphological and phylogenetic discordance among cryptic, arboreal species in the Cyrtodactylus brevipalmatus group. L. Lee Grismer*, La Sierra University; Attapol Rujirawan, Kasetsart University; Siriporn Yodthong, Kasetsart University; Anchalee Aowphol, Kasetsart University lgrismer@lasierra.edu
A cornerstone of biodiversity conservation is a phylogenetic-based taxonomy where the names of the component species are consistent with the patterns and processes by which they evolved. Taxonomies constructed from non-monophyletic species misrepresent history, thus obscuring true diversity and potentially countermanding the effectiveness of conservation efforts. Before a newly discovered population is named, it should be properly delimited and diagnosed. Delimiting and diagnosing species are independent complementary operations used to construct taxonomies that reflect, and are consistent with evolutionary history. Unfortunately, these two operations are often conflated when analyses performed to diagnose species—which are rooted in phenetics and overall morphological similarity—are equated with species delimitation methodologies rooted in phylogenetic history. The unfortunate consequence of this, is that taxonomies may be constructed using non-monophyletic species, thus obscuring rather than revealing true biodiversity. This is especially true for taxonomies comprised of highly specialized, cryptic, closely related species where in the absence of a phylogeny, morphological similarity can be mistaken for common ancestry. A molecular phylogeny and a multiple factor analysis of 16 highly specialized cryptic arboreal populations/species within the Cyrtodactylus brevipalmatus group recovered clades of species and morphological groups of species with discordant memberships resulting from recurring morphological convergence throughout the phylogeny. Previous taxonomies using only traditional morphological analyses to delimit and diagnose species simultaneously, misrepresented history and obscured rather than revealed the group’s diversity. Uncovering the converging species via phylogenetic analysis, has important biological implications for taxonomy, conservation, and other downstream analyses. |