Testing Population Structure of Agkistrodon Piscivorus in East Texas Populations Using Microsatellite Markers

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological and Environmental Sciences

Date of Award

5-22-2024

Abstract

Reptiles generally occupy smaller geographic ranges and specialized habitats causing them to be more vulnerable to anthropomorphic impacts. Habitat fragmentation creates patch fragmentation and in some cases patch isolation. The consequences of habitat fragmentation can decrease access to mating opportunities along with the distribution of new genes to local populations. Once a population size becomes lower than their minimum viable population, the probability of inbreeding increases and genetic diversity decreases. Microsatellites are molecular markers that are highly variable because of high rates of polymorphism. The use of theoretical models allows for the testing of genetic material to gain an understanding of the genetic health of studied populations through testing for inbreeding and population genetic structure. In this study, I collected genetic material from Agkistrodon piscivorus through tail clippings from 3 locations: TAMUC Wetlands, Sulphur River and Cooper WMA. From the cottonmouth tail clippings, DNA extracted and processed using the E.Z.N.A.® Tissue DNA Kit from Omega Bio-Tek according to their instructions. Cottonmouths are a common species found within wetland habitats and have been used for microsatellite research before by using microsatellite loci PCR primers from Agkistrodon contortrix. These microsatellite loci PCR primers were used for the PCR protocol and data analysis was completed using STRUCTURE, MIGRATE, and GENALEX. Major findings of this study show the populations to not be within HWE because of the high levels of inbreeding between sampled snakes. The highest levels of genetic differentiation came from the Cooper WMA while the lowest levels were found in the Sulphur River populations. shown with the data from STRUCTURE with the use of Puechemaille method found a K 3 result which suggests that each location is a separate population but with a larger split between the Cooper WMA and the TAMUC sites. DAPC analysis using the Adgent package in R, placed the individuals into clusters based on genotype similarity and found a similar pattern. Both the TAMUC Wetland and Sulphur River had significant overlap with minor separations between one another, while the Cooper population remains separate. A Wilcoxon rank-sum test on FIS levels per locus did not find a significant difference in inbreeding levels between the Commerce locations and the Cooper WMA.

Advisor

Bjorn Schmidt

Subject Categories

Biology | Life Sciences

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