V: Reptile Conservation and Management II2021-07-26 09:00 - 11:30 |
| Moderator: Allyson Fenwick |
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1. 09:00 VIRTUAL A dry future for the Everglades favors invasive herpetofauna. Hunter Howell*, University of Miami; Giacomo Delgado, University of Miami; Alyssa Wood, University of Miami; Leila Thompson, University of Miami; Eric Cline, South Florida Water Management Distric hunterhowell04@gmail.com
The Greater Everglades Ecosystem is a globally important ecoregion, home to 68 threatened or endangered species and the largest designated wilderness area in the Eastern United States. Anthropogenic manipulations of natural hydrology have led to widespread degradation of this ecosystem and monitored population declines across multiple taxa. Simultaneous introductions of hundreds of non-native species into South Florida and their subsequent invasion into the Everglades has further impacted native Everglades communities. Predictions for future climate change suggest that the Everglades is headed towards a drier future, making it crucial to understand how changes in hydrological regimes will impact both native and non-native fauna. Our study combines the results of a landscape-scale experimental manipulation conducted to assess the impact of differing hydrological regimes at the Loxahatchee Impoundment Landscape Assessment between 2018 and 2020 with a community composition analysis of data collected across multiple habitat types throughout Everglades National Park between 2000 and 2002. Both datasets used a variety of survey methods to extensively characterize the amphibian and reptile assemblage across habitat types and hydrological regimes. An NMDS analysis indicated that variation in hydrology is the primary axis structuring herpetofauna habitat usage across the Everglades, with non-native species more likely to be indicators of drier habitat types. This result concurred with those from the landscape-scale manipulation, in which non-native species were significantly favored by drier hydrological conditions. Taken together, these results suggest that a drier future within the Greater Everglades Ecosystem may facilitate further spread of South Florida’s diverse herpetofauna assemblage. |
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2. 09:15 VIRTUAL Monstrous Reptile Narratives and Conservation Ethics. Nick Clark*, Fordham University nclark16@fordham.edu
The social construction of herpetofauna has been known to affect conservation efforts. This is especially true for larger species, which are often construed as monsters in popular discourse. With this in mind, the present study attempts to bring together conservation science, ethnoherpetology, and narratology (the study of narrative form and structure) to investigate how two films (Anaconda [1997] and Godzilla [2014]) narratively, linguistically, and visually construe reptiles as monsters by using the tools of narrative analysis. Central to narrative analysis is separating narratives into their constituent parts and analyzing how those parts are arranged in a given text to construct meaning. This study, then, focuses on the monster narrative and how its parts (specifically events and character-schemas) are arranged to construct the monstrous reptile and guide audience interpretation. Anaconda and Godzilla were chosen as the main texts for analysis because they are exemplum monster narratives that deviate in how they interpret the monstrous reptile. Anaconda is a traditional monster narrative in which the monstrous reptile must be destroyed; Godzilla, on the other hand, is a nontraditional monster narrative that values the monstrous reptile. Using the latter film as a guide, I propose a conservation ethic that embraces the monster's cultural value, arguing that monsters may be a useful concept for conservation in some situations. Similarly, I argue that because narrative often helps to structure and interpret the world around us, it is also an important tool for conservation. |
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3. 09:30 VIRTUAL Where Will It End?: Range Mapping and Population Genetics of Mediterranean Geckos (Hemidactylus turcicus) at the University of Central Oklahoma. Allyson Fenwick*, University of Central Oklahoma; Briant Nguyen, University of Central Oklahoma; Maria Nguyen, University of Central Oklahoma afenwick@uco.edu
When invasive species enter an area, they often quickly spread and obscure any geographic signals of the pattern of colonization. In contrast, the exotic Mediterranean gecko establishes easily through human activity, but spreads slowly through a local area. Restricted to building walls, geckos are easily surveyed and sampled. At the University of Central Oklahoma, geckos were introduced in 1963–1965 and 1985–1997, then the spread from a single building was documented from 2003 through the present. The current project expands sampling to nearby buildings off-campus; we have not yet identified the edges of the local range. However, in comparison to the nearby colonization at the University of Oklahoma which began earlier and spread to most of Norman, OK, this colonization should be limited to a few blocks near campus. Using 16 previously published microsatellites, we find low genetic diversity and moderate but significant genetic differentiation. This is a project that should be replicated across independent colonizations in order to compare dispersal patterns in core gecko range such as the Gulf coast to isolated range edge populations like central Oklahoma. Understanding the colonization pattern of a small-bodied invasive ectotherm can help establish this species and other herpetofauna as model systems in invasion biology. |
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4. 10:15 VIRTUAL Limited Gene Flow and Pronounced Population Genetic Structure of Eastern Massasauga (Sistrurus catenatus) in a Midwestern Prairie Remnant. Whitney Anthonysamy*, University of Health Sciences and Pharmacy in St. Louis; Michael Dreslik, Illinois Natural History Survey; Sarah Baker, McNeese State University; Mark Davis, Illinois Natural History Survey; Marlis Douglas, University of Arkansas; Michael Douglas, University of Arkansas; Christopher Phillips, Illinois Natural History Survey whitney.anthonysamy@gmail.com
As anthropogenic changes continue to put ecological pressure on wildlife, obtaining measures of gene flow and genetic diversity are crucial for evaluating population trends and considering recovery strategies for small, isolated, and imperiled populations. We conducted a molecular assessment to expand on previous work to determine patterns of diversity and connectivity in the remaining disjunct Eastern Massasauga rattlesnake (Sistrurus catenatus) hibernacula in Illinois. We assayed 327 samples across 21 microsatellite loci for data collected from 1999-2015 in the Carlyle Lake region. We found hibernacula formed distinct genetic clusters corresponding to the three major study areas. Genetic structuring and low estimates of dispersal indicated connectivity among the major study areas is limited, and that each is demographically independent. Hibernacula exhibited moderate levels of heterozygosity (0.60-0.73), but estimates of effective population size (5.2-41.0) were low and comparable with long-term mark-recapture population size estimates. Our work suggests that recovery efforts should focus on managing the three major study areas as three separate conservation units to preserve and maintain the long-term adaptive potential of these populations. Specific management goals should include 1) maintaining or restoring connectivity among hibernacula, 2) protecting critical habitats such as crayfish burrows, and 3) minimizing all anthropogenic sources of mortality. Our molecular study provides additional details about demographic parameters and connectivity at Carlyle Lake to guide the recovery of Eastern Massasauga in Illinois and throughout its range. |
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5. 10:30 VIRTUAL Application and Ecological Effects of Hormone Manipulation as Invasive Species Control Tool in Greater Everglades Ecosystem. Andrea Currylow*, U.S. Geological Survey; Bryan Falk, U.S. Geological Survey; M. Rockwell Parker, James Madison University; Jillian Josimovich, U.S. Geological Survey; Austin Fitzgerald, U.S. Geological Survey; Amy Yackel Adams, U.S. Geological Survey; Frank Ridgley, Zoo Miami; Robert Reed, U.S. Geological Survey; Melia Nafus, U.S. Geological Survey acurrylow@usgs.gov
Reptiles detect chemical signals in their environments to inform crucial behavioral processes such as resource use and mate seeking. Reproductive chemical signals (pheromones) facilitate mate tracking and female courtship, even amid large breeding aggregations comprising hundreds of individuals. For some snake species, this chemical signaling is so ingrained that males pheromonally feminized via hormone implants become chemically attractive to other males. We assessed how effective estrogen was in activating female-like pheromone production in Burmese pythons (Python bivittatus), an invasive species that poses ongoing management challenges and ecological threats to the Greater Everglades Ecosystem in southern Florida. To determine if hormone manipulation could enhance existing management tools for invasive snakes, we implanted wild and radio-transmittered males with silastic estradiol implants or empty controls to monitor aggregation activity, movement, and habitat use during two breeding seasons (December – March). We found the number of conspecifics associated with study pythons did not differ between the treatments. However, estradiol-implanted males exhibited lower body condition, moved shorter total distances, and used smaller total habitat area compared to control males. Contrary to prior studies in other snake species, our results indicate that estradiol hormone treatment does not effectively feminize male Burmese pythons to attract conspecifics during the breeding season, but that hormone manipulation may reduce vagility, thereby reducing filed labor needs to track them. Our findings highlight the poor understanding of seasonal and reproductive hormone cycles in pythons and continues to pose a barrier to the development of chemical control tools and techniques. |
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6. 10:45 VIRTUAL Small nature preserves do not adequately contain large-ranging snakes: movement ecology and site fidelity in a fragmented rural landscape. Eric Nordberg*, University of New England; John Ashley, Middle Tennessee State University; Alyssa Hoekstra, Middle Tennessee State University; Sarah Kirkpatrick, Middle Tennessee State University; Vince Cobb, Middle Tennessee State University ericjnordberg@gmail.com
Habitat fragmentation is a leading causes of species declines world-wide. To mitigate these effects, land managers have engaged two major pathways to conserve biodiversity: land-sparing, by which land is set aside for wildlife and conservation values; and land-sharing, by which land is managed to provide benefits for multiple land uses. Here, we examine the movement ecology of a large-ranging snake in a fragmented landscape as a case study to examine the efficacy of small nature preserves to protect threatened biodiversity. We monitored the movement patterns and habitat use of 25 timber rattlesnakes (Crotalus horridus) over four years in a small nature preserve (252 ha) and fragmented agricultural landscape in central Tennessee, USA. Rattlesnakes showed a positive association with rocky cedar barrens and glades, habitat edges, and sites with dense ground cover and relatively open canopy. In addition, 49% of all rattlesnake locations fell outside the boundary perimeter of the nature preserve. Most rattlesnakes travelled through the nature preserve and into patchy agricultural areas and rural housing properties while foraging for and searching for mates. The conservation of species with large movement patterns or migratory behaviors, are difficult to protect in a land-sparing or protected area scenario. We highlight that while the nature preserve does not adequately contain timber rattlesnakes throughout the year, it does provide the conservation of key habitat for overwintering, which is essential for the survival of this species. A combination of land-sparing and land-sharing are required for the protection and management of this and many other species. |
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7. 11:00 VIRTUAL Recruitment and Indirect Assessment of Natal Homing in Northern Recovery Unit Loggerhead Turtles Via Genetic Tagging. Brian Shamblin*, University of Georgia; Mark Dodd, Georgia Department of Natural Resources; Michelle Pate, South Carolina Department of Natural Resources; Matthew Godfrey, North Carolina Wildlife Resources Commission; Sarah Dawsey, Cape Romain National Wildlife Refuge; Breanna Ondich, Georgia Sea Turtle Center; James Richardson, University of Georgia; Rebecca Bell, Little Cumberland Island Turtle Project; Michael Arendt, South Carolina Department of Natural Resources; Ruth Boettcher, Virginia Department of Wildlife Resources brian.shamblin@gmail.com
Recruitment into marine turtle nesting populations is typically inferred from tagging data, but weak nest site fidelity can confound identification of neophytes. Genetic capture-recapture via clutch sampling permits characterization of recruitment patterns at the subpopulation scale through female identification and relatedness analysis. From 2010 through 2019, we assigned approximately 77,000 loggerhead turtle (Caretta caretta) clutches laid from Georgia through Maryland to 11,500 unique females using 16 to 18 microsatellite loci. Among approximately 6,000 females genetically tagged from 2008-2012, 893 could not be excluded as potential mothers of 1,538 females that nested through 2019. Among 136 candidate mothers with three or more assigned daughters, 57 nested at Cape Romain, 36 nested elsewhere in South Carolina, 26 in Georgia, 16 in North Carolina, and one in Virginia. Comparisons of relative nesting locations within maternal families suggest regional natal homing spanning 10s of km. Most daughters nested in close proximity to their mothers (on the same or adjacent barrier islands), but a minority nested as far as 200 km away from their mother’s last known nesting site. Of 47 females tagged on southern Georgia barrier islands from 1980 - 1999 that nested long enough to be DNA sampled, 13 were assigned as candidate mothers of 21 nesting females. Among these was a female with a 36-year nesting history, a record for loggerheads globally, with three daughters assigned thus far. The potential for reproductive longevity spanning nearly four decades underscores the need for long-term monitoring to better resolve population dynamics in marine turtle populations. |
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8. 11:15 VIRTUAL Determinants of Community Structures in the Spiny-tailed Iguana, Ctenosaura similis. Ann-Elizabeth Nash*, Colorado Reptile Humane Society aenash@gmail.com
Research on animal social groups, including non-cooperative Squamates, has demonstrated that most association patterns are non-random. When sub-groups of individuals associate more strongly with each other than to the rest of the network, so-called community structures within animal aggregations are present. As with non-random interaction preferences among individuals, community structure is also a widespread feature of animal groups, and may emerge from a combination of social behavior, ecological, and anthropogenic factors. However, social structures of reptile species are poorly known, and testing for community structure lags behind work in other animal taxa. Using a stable aggregation of Spiny-tailed Iguanas, Ctenosaura similis, in Costa Rica, community structure, size, and determinants were investigated. Previous work with these lizards determined genetic relatedness, personalities, and preferential association patterns. Analysis revealed community structures in the overall network, suggesting potentially biologically relevant differences among smaller sets of connected animals. In Spiny-tailed Iguanas, these community structures were stable within but variable between seasons (two breeding, two non-breeding). Statistical models revealed season and individual network attributes as significantly explanatory for group size. This work demonstrates observed community structures may develop from an active choice of individual sociality and not from attributes and resources such as body size, retreat co-location, or spatial distribution. Individual preferences and adaptation to local conditions may explain the social variability of sub-structures. Detecting community structure in a network has practical applications in conservation and invasive species management as group size and structure may be receptive to manipulation to increase fitness or undermine network cohesion. |