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Landscape Genetics, Demographic Models and Conservation of the Eastern Massasauga Rattlesnake (Sistrurus catenatus)

Martin, Scott Anthony
http://orcid.org/0000-0003-3311-6352
http://rave.ohiolink.edu/etdc/view?acc_num=osu1640167751497387

Abstract Details

2022, Doctor of Philosophy, Ohio State University, Evolution, Ecology and Organismal Biology.
Successful conservation actions require a detailed understanding of how individuals interact with their environment. For many threatened and endangered species, anthropogenic changes to their landscape have created barriers separating formerly connected populations. This isolation can have profound impacts on the long-term viability of these populations and ultimately the conservation status of the species. For example, as populations become more isolated, they may enter the “extinction vortex” where small populations experience high levels of inbreeding and genetic drift depressing demographic rates, driving the population into a positive feedback loop that can lead to a decline in numbers and eventual extinction. However, if barriers to movement are not complete, even infrequent dispersal between populations can counter potential vortex effects by bolstering local population sizes and introducing new genetic material. Determining if populations are connected via dispersal or if they are isolated is a difficult question with no single best approach. For the Federally threatened Eastern Massasauga Rattlesnakes, Sistrurus catenatus, their reclusive, sedentary lifestyle make many field-based methods for generating this information difficult and unreliable without unrealistic investments of time and resources. In my thesis, I used information from DNA single nucleotide polymorphisms (SNPs) from neutral genetic markers to address the following three fundamental questions regarding how S. catenatus move through their landscape in Ohio and how this information can be used to evaluate proposed activities for their conservation: (1) Do snakes in scattered habitat patches across Northeastern Ohio belong to a single connected population, a metapopulation with infrequent dispersal, or isolated populations? I used 1000s of DNA SNPs to reconstruct a pedigree across 86 individuals and showed that no individuals have moved between habitat patches separated by more than a few meters in the last three generations. This is despite known movements of over 2 km by individual snakes in other populations of this species found in more continuous habitat. From these results, I concluded that S. catenatus in NE Ohio is split into five genetically distinct populations in an area smaller than 15 km2 with no recent connectivity. (2) What landscape features drive the observed lack of connectivity? I next used the same SNP dataset with a second SNP dataset collected from 103 S. catenatus from a large population in Central Ohio to model landcover features that potentially impact resistance to movement between local habitat patches. I found that an inherent landscape feature, elevation, and contemporary landcover, specifically roads, were the main barriers to connectivity. I then used the resistance maps and pedigrees for S. catenatus populations in NE Ohio and Central Ohio to estimate the resistance values between all pairs of closely related individuals and used those to estimate dispersal kernels around each population. The kernels results reinforced our previous finding of no contemporary connectivity between S. catenatus populations in this region. (3) How would proposed management actions impact the demographic viability of S. catenatus in NE Ohio? The habitat occupied by populations of S. catenatus in NE Ohio has been targets of active management to prevent vegetation succession, and there has been increased interest in additional habitat management. Suggested management actions for individual S. catenatus populations have focused on increasing habitat sizes, increasing the frequency of woody vegetation removal, creating habitat between populations, and translocating snakes between populations. I built forward-in-time simulations of population trends under current management and five alternative management activities using resistance maps that I previously developed in Population Viability Analysis (PVA) models. I found that connectivity improvements via the formation of new habitats (and ideally new populations) between the current populations or a hybrid connectivity/translocation strategy offered the greatest improvement towards both overall population size and the number of occupied patches. These connectivity models were superior to the base scenario representing no changes to management. Overall, my research has generated novel tools and approaches based on landscape genetics and demographic modeling for conservation of endangered and threatened species in fragmented landscapes. When applied to S. catenatus population is in NE Ohio, these approaches have provided new and significant insights on contemporary population structure in S. catenatus in NE Ohio, how the landscape created the observed patterns, and how this information can be used to generate management recommendations to promote the long-term persistence of this threatened reptile.
H. Lisle Gibbs (Advisor)
Andreas Chavez (Committee Member)
Bill Peterman (Committee Member)
135 p.
Conservation; Ecology; Wildlife Conservation
Eastern Massasauga Rattlesnake; Conservation; Landscape Genetics; Sistrurus catenatus; Population Genetics

Recommended Citations

Citations

  • Martin, S. A. (2022). Landscape Genetics, Demographic Models and Conservation of the Eastern Massasauga Rattlesnake (Sistrurus catenatus) [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1640167751497387

    APA Style (7th edition)

  • Martin, Scott. Landscape Genetics, Demographic Models and Conservation of the Eastern Massasauga Rattlesnake (Sistrurus catenatus). 2022. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1640167751497387.

    MLA Style (8th edition)

  • Martin, Scott. "Landscape Genetics, Demographic Models and Conservation of the Eastern Massasauga Rattlesnake (Sistrurus catenatus)." Doctoral dissertation, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1640167751497387

    Chicago Manual of Style (17th edition)

osu1640167751497387
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