Examining The Disease Ecology of Gopher Tortoises (Gopherus Polyphemus) in Southwest Alabama

Date of Award

8-2022

Document Type

Thesis

Degree Name

M.S.

Department

Biological Sciences

Committee Chair

Dr. Jason L. Strickland, Ph.D.

Abstract

The factors responsible for controlling pathogen prevalence are complex, but it is hypothesized that diversity within the major histocompatibility complex (MHC) region of the genome that partially codes for adaptive immunity, regulates pathogen resistance within and among populations. Gopher Tortoises were my model species to test this hypothesis as they are a conservation priority partially due to high rates of Upper Respiratory Tract Disease, which is caused by five separate pathogens. To determine infection status and assess MHC diversity, I collected blood from 76 tortoises and extracted DNA to 1) determine presence/absence and prevalence of five pathogens and 2) amplify and sequence two regions of the MHC. I did not find Mycoplasma agassizii or Testudinid Herpesvirus 3 in any samples, Ranavirus (10.5%) and M. testudineum (1.3%) had low prevalence, and Testudinid Herpesvirus 2 was found in all individuals. MHC classes I and II displayed low allelic richness, but 53% of the individuals that sequenced for class II were heterozygotes. Despite low MHC diversity, I found low pathogen prevalence, which is a good indicator for Gopher Tortoise conservation. Additionally, this is the first study to specifically test for TeHV-2 and TeHV-3 independently. These data will serve as a baseline for SW Alabama and improve Gopher Tortoise conservation efforts.

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