Session 1: SSAR Seibert EcologyRoom: Ballroom 111A2022-07-28 13:30 - 14:30 |
| Moderator: Rob Lovich |
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1. 13:30 Venomous Snakes Reveal Ecological and Phylogenetic Factors Influencing Variation in Gut and Oral Microbiomes. Sierra Smith*, Sam Noble Oklahoma Museum of Natural History; Timothy Colston, University of Puerto Rico Mayagüez; Cameron Siler, Sam Noble Oklahoma Museum of Natural History sierrasmith@ou.edu
The gastrointestinal tract (GIT) of vertebrates contains a series of organs beginning with the mouth and ending with the anus or cloacal opening. Each organ represents a unique environment for resident microorganisms. Due to their simple digestive anatomy, snakes are good models for studying microbiome variation along the GIT. Cloacal sampling captures the majority of the microbial diversity found in the GIT of snakes—yet little is known about the oral microbiota of snakes. Most research on the snake mouth and gut microbiota are limited to studies of a single species or captive-bred individuals. It therefore remains unclear how a host’s life history, diet, or evolutionary history correlate with differences in the microbial composition within the mouths and guts of wild snakes. We sampled the mouth and gut microbial communities of three species of Philippine venomous snakes and utilized 16S rRNA microbial inventories to test if host phylogenetic and ecological differences correlate with distinct microbial compositions within the two body sites. These species occupy three disparate habitat types: marine, semi-arboreal, and arboreal, and our results suggest that the diversity of snake mouth and gut microbial communities correlate with differences in both host ecology and phylogeny. |
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2. 13:45 Changes in Central Texas lizard diversity from the late Pleistocene to the Holocene. David Ledesma*, The University of Texas at Austin; Melissa Kemp, The University of Texas at Austin ledesma-david@utexas.edu
Herpetofauna play important roles in modern ecosystems; unfortunately, living amphibians and reptiles are experiencing declines in biodiversity worldwide. The study of Quaternary fossils has the potential to guide and aid conservation strategies by granting insight into how past biota responded to environmental changes over long timescales. We use fossils from Hall’s Cave, located in Kerr County, Texas, to reveal changes in lizard diversity in Central Texas over the last 20,000 years. We employed an apomorphy-based identification framework, using evolutionary derived features to provide strong evidence for fossil identifications at the genus or family level. We cataloged and described over 1,400 fossil lizard specimens and in doing so added several new taxa not previously known from the site. We examined lizard community composition through time and found that at the family level there have been substantial changes in the lizard community over time. Specifically, we recover relatively low Shannon diversity index values between four and five thousand years ago, between nine and ten thousand years ago, and prior to fourteen thousand years ago. The change in lizard diversity at the family level appears to be temporally correlated with changes in vegetation in the area surrounding Hall’s Cave including the transition from woodland dominated vegetation to increasingly open grassland habitat based on previously published pollen records. Our results demonstrate that by extending our temporal study interval, the fossil record can serve as a superb system for furthering our understanding of organisms’ ecological and evolutionary responses to environmental changes. |
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3. 14:00 Injuries in Herpetofauna and its Possible Relations to Lateralization and Ecology. Caroline Honan*, Southeastern Louisiana University caroline.honan@selu.edu
Research involving injuries generally focuses on the cause and effect without noting injury location, especially if there is a bias in distribution. Asymmetrical injury distributions have been used as a proxy for cerebral lateralization, turning behavior biases, and intraspecific conflict versus predation rates. If these are valid proxies, there should be species and order level trends reflected in injury placement. To investigate trends in distributions in herpetofauna, we examined injuries in museum specimens of twenty-eight species of squamates and three species of testudines. We split injuries into three separate distributions for testing: right versus left, anterior versus posterior, and dorsal versus ventral. Distribution values consisted of injury proportion on one side. Factors used in modeling included organismal traits such as life stage and length, as well as variables surrounding capture like year or location of capture. Phylogenetic relationships were also considered. Variables were tested using general linear modeling with Poisson adjustments. Findings support the notion that injuries accumulate in specific areas dorsally/ventrally and anterior/posteriorly based on environmental and organismal factors, not randomly. This potentially opens a method of estimating ecological interactions that occurred during an organism’s lifetime using injury placement. |
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4. 14:15 A Review of Chemical Defense in Harlequin Toads (Bufonidae: Atelopus). Kannon Pearson*, University of California, Berkeley; Rebecca Tarvin, University of California, Berkeley kannonpearson@berkeley.edu
> Toads of the genus Atelopus are chemically defended by a unique combination of endogenously synthesized cardiotoxins (bufadienolides) and neurotoxins which may be sequestered (guanidinium alkaloids). Investigation into Atelopus small-molecule chemical defenses has been primarily concerned with identifying and characterizing various forms of these toxins while largely overlooking their ecological roles and evolutionary implications. In addition to describing the extent of knowledge about Atelopus toxin structures, pharmacology, and biological sources, we review the detection, identification, and quantification methods used in studies of Atelopus toxins to date and conclude that many known toxin profiles are unlikely to be comprehensive because of methodological and sampling limitations. Patterns in existing data suggest that both environmental (toxin availability) and genetic (capacity to synthesize or sequester toxins) factors influence toxin profiles. From an ecological and evolutionary perspective, we summarize the possible selective pressures acting on Atelopus toxicity and toxin profiles, including predation, intraspecies communication, disease, and reproductive status. Ultimately, we intend to provide a basis for future ecological, evolutionary, and biochemical research on Atelopus. |