Session 47: Herpetology Phylogeography & BiogeographyRoom: Room 206D2022-07-31 10:15 - 11:30 |
| Moderator: R. Graham Reynolds |
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1. 10:15 Incipient or Ephemeral? Lineage Formation and Fusion in a Widespread Terrestrial Salamander (Plethodon cinereus). Brian Waldron*, Ohio University; Emily Watts, Ohio University; Donald Morgan, Ohio University; Maggie Hantak, University of Florida; Emily Lemmon, Florida State University; Alan Lemmon, Florida State University; Shawn Kuchta, Ohio University bwaldron18@jcu.edu
At the tips of the tree of life, the mechanisms of evolutionary change grade into the formation and diversification of lineages. Widespread species harboring divergent, geographically distinct lineages offer a window into what may be a common mode of species formation, whereby a species spreads across the landscape, then fragments into multiple lineages. However, incipient lineages often lack reproductive barriers that prevent their fusion upon secondary contact. Here, we explore this model of species formation in the Eastern Red-backed Salamander (Plethodon cinereus), a widespread terrestrial vertebrate with at least six mitochondrial clades throughout its range. Using Anchored Hybrid Enrichment, we apply phylogenomic and population genomic approaches to investigate patterns of divergences, gene flow, and lineage fusion. Genomic data agree with most mitochondrial groups, but reveal mitochondrial introgression and admixture at several contact zones. We examine the nature of a divergent, narrow-ranging mitochondrial clade in the central Appalachian region, which exploratory analyses of genomic data suggested was instead the site of a four-clade contact zone. Using approximate Bayesian computation (ABC), we explicitly compare scenarios in which these populations are either a divergent population undergoing lineage fusion, or they strictly represent a region of secondary contact between the surrounding populations. Finally, we analyze morphological data to test if divergence and range expansion correspond to diversification in traits related to dispersal propensity or fossoriality. Plethodon cinereus exemplifies an early stage of the phylogeographic–phylogenetic continuum, a single species in which future range dynamics will largely determine if divergent populations will maintain their independence. |
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2. 10:30 Genetic Diversity Among Bornean Populations of Peat Swamp Dweller Pulchrana baramica BOETTGER 1900. Ramlah Zainudin*, Universiti Malaysia Sarawak; Elvy Quatrin Deka, Universiti Malaysia Sarawak; Nurhidayah Zulkeifli, Universiti Malaysia Sarawak ramlahzainudin29@gmail.com
Sufficient genetic diversity need to be retained in order to maintain short-term fitness and long-term sustainability as well as ensuring local adaptations are not being lost due to intermixing of previously distinct populations. Hence, genetic diversity measurement can provide insights into the consequences of environmental changes especially in a hotspot biodiversity area. The Brown Kerangas Frog Pulchrana baramica inhabits the remaining of 1.47% peat swamp forest in Sarawak and although the species is listed as Least Concern, its population is decreasing over the years. Rapid development at swampy areas up to coastal areas forces exploitation of the frogs’ natural habitats. Thus, the study aims to infer genetic structure of P. baramica from different localities in Sarawak via mitochondrial cytochrome oxidase 1. The study revealed low population subdivision of P baramica with high levels of gene flow especially between distantly populations of Bako and Maludam. Continuous swampy areas connecting both localities might contribute to the high connectivity. In contrast, despite being closely located, Bako and Bau has the low level of gene flow, partly due to the disruption of connectivity by the rapid infrastructure development between these two areas. This may reduce the potential of species dispersal. Habitat connectivity revealed by species gene flow reflects the fitness of individuals to the changing environment. These outcomes will be useful in sustainable management of species and natural (biodiversity) heritage in Borneo. |
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3. 10:45 How the Roles of Demographic History and Gene Flow Inform Contrasting Patterns of Phylogenomic Diversity in Neotropical Toads (Rhinella). Danielle Rivera*, North Carolina State University; Ivan Prates, University of Michigan; Thomas J Firneno, Jr., University of Denver; Janalee Caldwell, University of Oklahoma; Miguel T Rodrigues, Universidade de São Paulo; Matthew K Fujita, University of Texas at Arlington drivera2288@gmail.com
Mito-nuclear discordance, often identified through multi-locus sequencing of selected markers, presents difficulties in identifying historical processes which drive species diversity and boundaries. Mechanisms causing discordance, such as incomplete lineage sorting or introgression due to interspecific hybridization, are better identified based on population-level genomic datasets. Toads are known to exhibit complex genetic patterns, including introgression and hybridization, across populations. The Rhinella marina and granulosa species groups are widely distributed across the Neotropics, and have complex taxonomic histories, which make them useful systems to investigate how prevalent these phenomena are in widespread natural toad populations across a large geographic region spanning heterogeneous climates and landscapes. We assessed the extent of genetic introgression across species thought to hybridize based on natural history observations and multi-locus analyses by characterizing patterns of variation across thousands of genomic loci. We used phylogeographic methods, incorporating both mitochondrial and ddRADseq data, to find contrasting patterns of mito-nuclear discordance across populations, and incorporated D-statistics and demographic model testing to explore possible processes and mechanisms which may explain the genomic diversity observed. These results both confirm and challenge previous assertions that the evolutionary history of Rhinella was characterized by varying levels of hybridization across environmentally heterogeneous regions. They also pose exciting questions about what factors prevent complete fusion of diverging yet highly interdependent evolutionary lineages, and which factors strongly influence the maintenance of species boundaries among very closely-related populations. |
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4. 11:00 Lizards in paradise: How the brown anole made its way to Hawai`i and Southern California. Valentina Alvarez*, University of Hawai`i Manoa; Robert Thomson, University of Hawai`i Manoa val64@hawaii.edu
The brown anole (Anolis sagrei), native to the Greater Antilles, has demonstrated its invasiveness in several regions of the world. In part through its tolerance to extreme temperatures and high reproductive success, Anolis sagrei rapidly forms dense populations in invaded regions. The species was introduced to Florida in the late 1960s and subsequently expanded to other states in the southeastern United States, displacing the native green anole (Anolis carolinensis). In 1992, Anolis sagrei was first collected on the island of O`ahu, Hawai`i. The species was then observed on Kaua`i in 2001, Maui in 2005, and Hawai`i Island in 2010, gaining a strong foothold on every major Hawaiian Island. Subsequently, several populations have also become established in Southern California and observations show the species is spreading. It is believed these lizards were introduced as passengers on ornamental tropical plants from Hawai`i. Here, we report on the source of the Hawaiian and southern California brown anole populations. By pairing genome-wide SNP data, population genetics, and approximate Bayesian computation (ABC) methods, we reconstruct the invasion history of the brown anole from its native range to its invasive ranges. We demonstrate the likely source of each population and provide insights into pathways which may be applicable for managing the spread of this species, especially in a region as rich with native reptiles as Southern California. |
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5. 11:15 Landscape genomics of the Sandstone and Granite Night Lizards in the Anza Borrego State Park. Matthew Murdoch*, La Sierra University; Jesse Grismer, La Sierra University; L. Lee Grismer, La Sierra University; Peter Scott, West Texas A&M; Robert Fisher, U.S. Geological Survey’s Western Ecological Research Center hewmurdoch@gmail.com
The Night Lizard genus Xantusia spans Southwestern North America and northern Mexico and is comprised of nocturnal, highly secretive species. Remarkably, Xantusia gracilis, the Sandstone Night Lizard, is currently a locally endemic species found only in the sandstone habitats of the Truckhaven Rocks of the Anza Borrego Park. Its preferred habitat consists of crumbling sandstone canyons bearing complex series of boulders, crevices, and exfoliations. These microhabitats have a disjunct and fragmented distribution throughout the park and recent field surveys have yielded newly discovered populations of sandstone adapted Xantusia. The Granite Night Lizard, Xantusia henshawi, is the closest relative to X.gracilis and can be found in granite ecosystems throughout Southern California including the higher elevation regions of the Anza Borrego. Preliminary genetic analyses seeks to shed light on the evolutionary relationships of these disjunct populations and whether or not they are true X.gracilis, suggesting a broader range, hitherto unknown species level lineages within the same clade, or populations of X.hanshawi which have invaded these sandstone ecosystems. It has been well established that species with small, fragmented distributions are at the highest risk of local extinction and that genetic data is the cornerstone for helping conserve these types of species and their populations. As X.gracilis is Anza Borrego’s only endemic vertebrate, the genetic data gathered from this project will be instrumental in helping preserve it into the future given the projections of climate change and rising temperatures in one of America’s most hostile environments. |