ASIH Stoye Award, Herpetology I (Genetics and General Herpetology) and Reptile Genetics2021-07-21 13:45 - 15:15 |
| Moderator: Robert Espinoza |
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1. 13:45 IN-PERSON Batrachochytrium dendrobatidis at 5400masl: Amphibian Disease in Range-shifting Andean Anurans. Emma Steigerwald*, University of California, Berkeley; Cassandra Gendron, University of California, Berkeley; Allison Byrne, Smithsonian National Zoo; Juan C. Chaparro, Museo de Biodiversidad del Perú; Rosemary Gillespie, University of California, Berkeley; Rasmus Nielsen, University of California, Berkeley; Erica Bree Rosenblum, University of California, Berkeley emma_steigerwald@berkeley.edu
To persist, species today must successfully respond to multiple interacting stressors. Climate-driven range shifts and emerging infectious diseases are examples of stressors, faced in common across much of contemporary biodiversity, that we expect to interact with one another. We studied the genetics and dynamics of the devastating fungal pathogen of amphibians, Batrachochytrium dendrobatidis (Bd), along an elevational gradient recently colonized by three anurans: the Marbled four-eyed frog (Pleurodema marmoratum), the Marbled water frog (Telmatobius marmoratus), and the Warty toad (Rhinella spinulosa). These species have expanded their elevational ranges in the wake of glacial retreat in the Cordillera Vilcanota, a chain in the Peruvian Andes, to become the highest living amphibians in the world. Although frog population density declined along the expansion front, and decreasing frog density was associated with a decreased probability that sampling sites were Bd-, elevation was a sufficiently important predictor of site infection status that sites were still increasingly likely to be Bd+ with increasing elevation. According to current data, site mean infection intensity is not affected by elevation, site infection prevalence declines with elevation, and we do not have evidence that frogs stressed by life at extreme high elevations are more vulnerable to Bd infection. Bd from the Cordillera Vilcanota is of the Global Panzootic Lineage, does not with our amplicon sequencing panel show signatures of high elevation adaptation, and does not exhibit spatial genetic structure, having evidently undergone extensive and frequent dispersal across the study landscape. However, the Cordillera Vilcanota provides an excellent system to further investigate how Bd adapts to elevational extremes in future, and to continue exploring whether the stress of recently colonized, marginal habitat exacerbates range shifting species' vulnerability to coincident stressors. |
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2. 14:00 IN-PERSON Phylogenetic Regionalization of Middle American Herpetofauna. Dillon Jones*, San Diego State University dilljone96@gmail.com
Biogeography aims to uncover the underlying causes of why and how biodiversity is distributed around the planet. An often-used biogeographic method involves inferring regions within a larger geographic area using some form of biologically relevant criteria. Phylogenetically explicit bioregions (phyloregions) extend this methodology by incorporating evolutionary history directly into the regionalization methodology. This study aims to infer phyloregions using the amphibians and squamate reptiles of Middle America as a focal group. Phylogenetic information for amphibians and squamates were obtained from published phylogenies and occurrence data were obtained as range maps from IUCN and point occurrence information from GBIF. Preliminary results utilizing these data for 1255 species (560 amphibian species; 695 squamate species) inferred 12 phyloregions through Middle America. These phyloregions differ considerably in terms of area (50.4 – 1529 km^2), phylogenetic diversity (22.15 - 59.14), and taxonomic richness (118 – 485 sp). Further, several of these regions contain a large amount of endemism, with up 40% of species found exclusively within a single phyloregion. While still in preliminary stages, this study aims to showcase patterns of biodiversity not previously seen at this resolution or scale. Future analyses include correlating environmental variables to phyloregions, assessing patterns of neo- and paleo-endemism, as well identifying phyloregions of particular conservation concern. |
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3. 14:15 IN-PERSON Multilocus Phylogeny of Indo-Burman Hemidactylus Geckos Reveals Major Endemic Radiation in Myanmar with Insights into Asian Biogeographic Patterns. Matthew Murdoch*, Villanova University; Lee Grismer, La Sierra University; Todd Jackman, Villanova University; Aaron Bauer, Villanova University mmurdoch@villanova.edu
The gecko genus Hemidactylus is one of the most speciose and widely distributed reptile genera known. India has proved to be an epicenter for Hemidactylus diversity with a significant drop off in species numbers believed to occur to the east. Recent fieldwork in the country of Myanmar has produced numerous new species from the gecko genera Cyrtodactylus, Hemiphyllodactylus, and Cnemaspiswith Hemidactylushistorically receiving far less attention. Utilizing phylogenetic and morphological analyses I will demonstrate that Myanmar is the epicenter of an ancient, morphologically diverse, and endemic Southeast Asian Hemidactylusradiation occurring east of the Ganges drainage. This monophyletic group, once referred to as the Hemidactylus bowringii clade, contains hitherto unknown diversity with Hemidactylus karenorum proving to be a complex consisting of seven species all of which are endemic to the Irrawaddy basin and neighboring Shan Plateau. Hemidactylus platyurus also yields at least three deeply divergent new species from the Arakan Hills and Assam valley in India. Multi-locus time calibrated analyses demonstrate that this monophyletic lineage is unrelated to the vast majority of Indian species and saw rapid radiation events in Southeast Asia corresponding with an intensification in the uplift of the Himalayan mountains 23 mya and subsequent late Miocene aridification 10 mya. This work has implications not only for understanding the history of the genus but also for the interpretation of biogeographic trends and the geologic interplay between South and Southeast Asia and how these processes shaped current herpetofaunal diversity in Asia. |
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4. 14:30 VIRTUAL Phylogenomics of an Ecologically DIverse Group of North American Snakes (Natricidae: Thamnophiini). Leroy Nuñez*, American Museum of Natural History; Frank Burbrink, American Museum of Natural History lnunez@amnh.org
North American Natricids (garter snakes, water snakes, and brown snakes) are among the most ecologically diverse groups of squamates in North America. This group exhibits a remarkable amount of ecological and phenotypic diversity, particularly for a temperate radiation. However, previous systematic studies of this group were limited by the amount of data available. As a result, several major lineages of the group remain phylogenetically unresolved with low statistical support. In this study, we estimate phylogenies based on over 3,700 ultraconserved elements (UCEs), which is the largest dataset so far for a systematic study on this group. From this dataset, we infer phylogenies using multispecies coalescent methods and time calibrate them based on the fossil record. We also test for the presence of deep time reticulation and hybrid nodes throughout the phylogeny using network estimation methods. This study provides valuable insight into the evolutionary history of this group that will be vital in understanding how ecological and phenotypic diversity arose in this group. |
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5. 14:45 VIRTUAL Bone conduction hearing in salamanders supports directional sensitivity to airborne sound. Grace Capshaw*, University of Maryland; Jakob Christensen-Dalsgaard, University of Southern Denmark; Daphne Soares, New Jersey Institute of Technology; Catherine E. Carr, University of Maryland gcapshaw@umd.edu
Sound and vibration are generated by mechanical disturbances within the environment, and the ability to detect these acoustic cues and associate them with their source enhances survival within complex environments. The tympanic middle ear emerged several times in vertebrate evolutionary history and acts as an impedance-matching device to enable the detection of airborne sound pressure; however many species, including “earless” frogs, snakes, and salamanders, have reduced tympanic middle ears and have long been considered functionally deaf on land. Recent study has shown that atympanate species are capable of hearing via extratympanic bone conduction pathways in which sound pressure induces vibrations in the animal’s skull that are detectable to the auditory endorgans of the inner ear. In this study, we used salamanders to investigate the ability of extratympanic bone conduction to confer auditory directionality to an atympanate vertebrate. We used laser Doppler vibrometry to measure the velocity of sound pressure-induced head vibrations and found that bone conduction generates vibrations in the animal that vary with the angle of the incident sound. We assessed directional hearing in salamanders using auditory brainstem response recordings and observed a figure-eight pattern of directional sensitivity to sound pressure, with maximum sensitivity along the interaural axis. We conclude that bone conduction of sound represents a key extratympanic mechanism for hearing in terrestrial atympanate vertebrates, and that this pathway is sufficient to generate directional cues at the peripheral level of the auditory system in the absence of a pressure-transducing tympanic ear. |
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6. 15:00 VIRTUAL XROMM Analysis of Feeding Mechanics in Anurans: Interactions of the Tongue, Hyoid Apparatus, and Pectoral Girdle. Rachel Keeffe*, University of Florida; Richard Blob, Clemson University; David Blackburn, University of Florida; Christopher Mayerl, Northeast Ohio Medical University rmkeeffe@gmail.com
While the feeding mechanics of the anuran tongue are well-studied, fewer studies have examined how the motions of the tongue relate to the movements of the skeleton. In many vertebrates, the tongue acts in concert with other elements such as the hyoid and pectoral girdle to feed effectively, and in frogs all three of these elements are interconnected by musculature. Although these structures are not externally visible in frogs, their motions can be tracked in X-ray video. Here, we use XROMM (X-ray Reconstruction of Moving Morphology) techniques to track the 3D movements of the tongue, hyoid apparatus, pectoral girdle, skull, and jaw during feeding strikes of Rhinella marina. We show how the movements of these elements are integrated during tongue protrusions and prey capture, as well as during swallowing. Our findings suggest that the hyoid apparatus is important both for tongue protrusion and swallowing. In addition, our data provide new perspective on the potential influence of the pectoral girdle, an element with a predominant locomotor function, during feeding events. This work raises new questions about the evolution of feeding in frogs, and how the diversity of pectoral and buccal anatomy may influence feeding kinematics across anuran species. |