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    SSAR Seibert Award II

    2021-07-21   13:45 - 15:30

    Moderator: Travis Hagey

    1.  13:45  IN-PERSON    Muddy Systematics: The Diversity and Biogeography of Mud Snakes (Serpentes: Homalopsidae). Justin Bernstein*, Rutgers University-Newark; John Murphy, Field Museum of Natural History; Harold Voris, Field Museum of Natural History; Rafe Brown, University of Kansas; Sara Ruane, Rutgers University-Newark

    Mud snakes (Serpentes: Homalopsidae) are a family of54,mainly aquatic species primarily distributed throughout mainland Southeast Asia and the Indo-Australian Archipelago. Although they have been the focus of prior research, the basic relationships amongst genera and species remain poorly known. We used a combined mitochondrial and nuclear gene dataset to infer their phylogenetic relationships, using the highest levels of taxon and geographic sampling for any homalopsid phylogeny to date (64% generic and 63% species coverage; 140 individuals). Our results indicate two reciprocally monophyletic groups: the fangless genus Brachyorrhos and a sister clade comprised of all rear-fanged homalopsids. Most genera and interspecific relationships were recovered as monophyletic and were strongly supported, but intergeneric relationships and intraspecific populations lack support. We find evidence of both undescribeddiversityas well as cases of taxonomic inflation within several species. Tree-based species delimitation approaches (mPTP) support potential new species as distinct from their conspecifics and also suggest that many named taxa are not likely distinct species. Divergence date estimation and lineage-through-time analyses indicate lower levels of speciation in the Eocene, with a subsequent burst in diversification in the Miocene. Homalopsids may have diversified most rapidly during the Pliocene and Pleistocene due to tectonic shifts and sea-level fluctuations that took place in Sundaland and the Sahul Shelf. Our analyses provide new insights on homalopsid taxonomy, a baseline phylogeny for the family, andfurtherbiogeographic implications demonstrating that dynamic tectonics and Quaternary sea level changes may have shaped a widespread, diverse family of snakes.

    2.  14:00  IN-PERSON    The Influence of Phylogenetic History on Fossorial Specialization in the Skulls of African Burrowing Skinks. Natasha Stepanova*, University of Michigan; Aaron Bauer, Villanova University

    Burrowing squamates are characterized by limb reduction, body elongation, and modifications to streamline and reinforce the skull. As different substrates have variable physical properties, different skull shapes may offer selective advantages in particular substrates. Despite this, studies of variation within burrowers have been limited and are typically focused on a single origin of fossoriality. We investigated skull morphology in 7 genera of African skinks (Acontias, Typhlosaurus, Scelotes, Sepsina, Feylinia, Typhlacontias, and Mochlus; 39 sp.) from 3 subfamilies representing independent derivations of fossoriality. We used CT scans, 3D geometric morphometrics, and phylogenetic comparative methods to evaluate variation in skull morphology and test the influence of phylogeny, ecology, and size. We found a strong effect of phylogenetic history on skull shape, with size and substrate playing secondary roles. Although there was a general gradient in morphospace from less specialized to more specialized burrowers, only burrowers in sand consistently stood out as different from those in other substrates. Furthermore, convergence in shape and qualitative traits was largely the result of different anatomical changes between lineages, implying adaptation for a specialized ecology does not follow a single deterministic pathway.

    3.  14:15  IN-PERSON    Adaptive morphological variation among invasive populations of Mediterranean House Geckos in the USA. Nicole Bisente*, California State University, Northridge; Robert Espinoza, California State University, Northridge

    Introduced species offer unique opportunities to investigate how organisms respond and adapt to new environments. Invasive species, in particular, provide researchers the unusual opportunity to document rapid evolutionary adaptations to novel environmental conditions. Following their initial introduction onto Key West, Florida in 1910, Mediterranean House Geckos (Hemidactylus turcicus; MHGs) subsequently established populations in 24 states across the USA. Over this broad range, MHGs experience a diversity of climates, including some that are vastly different from their native range along the Mediterranean Coast of southern Europe and northern Africa. We hypothesized that invasive populations of MHGs have evolved differences in their morphology (scale and tubercle counts, body and limb proportions) that are adaptive for the divergent climates they now occupy. To date, we have measured more than 300 MHG specimens from seven states across the US representing subtropical, Mediterranean, and desert climates. Snout–vent length and head proportions varied among all climates types, as did axilla–groin distance and forelimb and hind limb proportions for geckos from subtropical and Mediterranean climates. Our preliminary analyses also suggest the rate of adaptive change in head and limb proportions may be faster for females than for males among gecko populations from subtropical and desert climates. Our study is the first to document sex-dependent differences in adaptive morphology across diverse climates for a continentally distributed invasive reptile.

    4.  14:30  IN-PERSON    Urbanization Affects the Skin Microbiome of Western Fence Lizards (Sceloporus occidentalis). Sarah Vasquez*, CSUSB; Breanna Putman, CSUSB

    This study provides a deeper insight on the skin microbiome of vertebrates, how it may be affected by present anthropogenic factors and how the surrounding environment plays a vital role in microbial composition. Since urban environments typically undergo biotic homogenization, this study was conducted with the assumption that the skin microbiomes of lizards would maintain greater diversity in a natural environment compared to an urban one. Wild Western Fence Lizards (Sceloporus occidentalis) were captured from both urban and natural areas to collect skin swabs of their underbellies, which were then sent to Zymo Research Lab for DNA analysis. We found that the skin microbiomes of lizards from the urban site contained significantly reduced taxonomic diversity than that of lizards from the natural area, and a shift in taxonomic composition for both bacterial and fungal groups. There appears to be a connection between the microbiome ofS. occidentalisand the type of land they inhabit. Further research could explore which exact anthropogenic factors have caused this difference and if this could be detrimental to the lizards’ or other organisms’ wellbeing in the future.

    5.  14:45  IN-PERSON    Thermal Ecology and Activity Patterns of Adult and Juvenile Bolson Tortoises (G. flavomarginatus). Julia Joos*, Ohio University; Christiane Wiese, Turner Endangered Species Fund; Scott Hillard, Turner Endangered Species Fund; Donald B. Miles, Ohio University

    Desert-adapted tortoises face challenges due to climate change as arid environments are expected to continuously become drier and warmer. To better predict and mitigate the impact of rising temperatures on tortoises, an understanding of the influence of variations in the thermal environment on tortoise activity patterns and physiological processes is needed. In this study we evaluated whether thermoregulatory strategies differed between male and female Bolson tortoises as well as adults and juveniles. We obtained data on temporal patterns in body temperatures by affixing temperature loggers onto the shell of Bolson tortoises. Temperature loggers were attached on either the anterior or posterior part of the carapace for juveniles and in both locations for adults to capture temperature variation within individuals. Temperatures were recorded every 30 minutes for 6 weeks during the summer of 2019. Preliminary results showed a similar unimodal distribution of carapace temperatures for all tortoises over a 24-hour period. Mean temperature ranges, while similar during the day, showed significant differences between adults and juveniles and between males and females at night. Adult males exhibited larger temperature ranges at night than either of the other groups which could indicate that adult males spend more time outside the burrow at night than adult females or juvenile males/females. We compared the frequency and duration of emergences per day among adults and juveniles of both sexes and investigated the association between body size and heating and cooling rates. These results indicate that adults and juveniles may use different strategies to thermoregulate.

    6.  15:00  IN-PERSON    Lessons Learned from a Conservation Translocation of a Microendemic Habitat Specialist. Mickey Parker*, Texas A&M University; Toby Hibbitts, Texas A&M University; Wade Ryberg, Texas A&M University; Lee Fitzgerald, Texas A&M University

    Reintroductions and other conservation translocations are becoming an increasingly important tool to combat biodiversity loss in the Anthropocene. Though success rates of translocations have improved in recent years, failures are still commonplace. To improve outcomes and meet conservation objectives, it is crucial that lessons learned from unsuccessful translocations be implemented in the design and implementation of future translocations. We conducted a 4-year study (2016-2019) designed to reintroduce a microendemic habitat specialist, the Dunes Sagebrush Lizard (Sceloporus arenicolus), to a site near a historical locality where the species disappeared. In 2016 and 2017, we conducted two translocations of 76 individual lizards from nearby populations to a site with suitable habitat that is contiguous with the historical locality. We implemented a delayed release, acclimating translocated individuals in temporary enclosures. We then removed the enclosures and monitored the translocated population using a grid of 597 pitfall traps covering 15 ha. In 2018 and 2019, we monitored the incipient population using trapping and visual surveys. Dunes sagebrush lizards lived and reproduced at the site in small numbers, but by the fourth year, after 112,451 trap-days and 415 person-hours of visual surveys the species could no longer be detected at the site. Despite this outcome, we learned important lessons in habitat, behavior, reproduction, land tenure, and monitoring of lizards in the translocated population that are immediately applicable to future translocation efforts.

    7.  15:15  IN-PERSON    Using climatically weighted models to determine current and future drivers of habitat suitability for the Mojave Desert Tortoise, Gopherus agassizii. Anjana Parandhaman*, University of Nevada Reno; Nathan Byer, University of Nevada Reno; Thomas Dilts, University of Nevada Reno; Scott Wright, University of Nevada Reno; Derek Friend, University of Nevada Reno; Marjorie Matocq, University of Nevada Reno; Douglas Boyle, University of Nevada Reno; Scott Bassett, University of Nevada Reno; Amy Vandergast, United States Geological Survey; Todd Esque, United States Geological Survey

    Climate change and urban development in the southwestern United States are projected to rapidly impact the region, due to projected warmer and drier conditions as well as increased habitat fragmentation. The federally-listed Mojave Desert Tortoise (Gopherus agassizii) is a long-lived species that has suffered population declines, yet continues to persist in this dynamic and increasingly fragmented landscape. To adequately protect tortoise populations, improved knowledge of the future effects of stressors on habitat suitability is necessary.We first conducted fieldwork across the Mojave and Colorado Deserts and used the data collected to build a rangewide habitat suitability model for the tortoise with a wide array of environmental predictor variables and ensemble modeling methods. We identified abiotic factors that drive regional habitat differences in the tortoise’s range under current and future forecasted climate scenarios and identified clusters of regional climate conditions. We built regional habitat models based on climatic clusters to compare to our rangewide global model and projected these regional models to multiple future climate scenarios using a climatically-weighted approach, which allows separate modelled relationships with climate per cluster. Our preliminary results show that regional models differ in fine-scale predictions of suitable habitat as well as climatic variables that influence each region, for example tortoises in northern regions experience lower winter minimum temperatures than those in central regions. We also found that, under future climate scenarios, suitable habitat begins to shift northward. Our work suggests that regional, climatically-weighted models hold promise for predictions of anthropogenic impacts on the tortoise and beyond.

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