Date of Award

Fall 12-17-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology and Environmental Sciences

Advisor

Pauline Kamath

Second Committee Member

Erik Blomberg

Third Committee Member

Anne Lichtenwalner

Additional Committee Members

Peter Milligan

Allison Gardner

Abstract

Widespread wild turkey reintroductions in the late 1900s have led to increases in population density and geographic distribution across North America. This rapid population expansion has put them into proximity with closely-related wild and domestic avian species, increasing the risks of pathogen transmission. Lymphoproliferative disease virus (LPDV) is an avian oncogenic retrovirus detected in wild turkeys in 2009, and previously known to infect domestic turkeys. Following its initial detection, surveys reported variable LPDV prevalence across eastern North America with most wild turkeys being asymptomatic, however diagnostic cases revealed 10% mortality of LPDV-infected individuals. Given its recent detection, little is known about LPDV ecology, transmission or evolution in wild turkeys. We sought to evaluate (1) an alternative detection method for surveillance, (2) individual risk factors, (3) fitness effects, and (4) the genetic diversity and evolutionary history of LPDV in Maine’s wild turkeys. From 2017–2020, we collected tissues and associated data from 72 hunter-harvested and 627 live-captured wild turkeys, and attached radiotransmitters to a subset of live-captured females to monitor survival and reproduction. We used PCR to estimate the infection prevalence of LPDV (59%) and reticuloendotheliosis virus (REV; 16%), another oncogenic retrovirus. In a sample subset, we used plate agglutination to determine the prevalence of exposure to the bacteria, Mycoplasma gallisepticum (74%) and Salmonella pullorum (3.4%). We found cloacal swabs are a reliable LPDV detection method for live-captured wild turkeys. Sex, age, and season were significant predictors of LPDV infection, with females, adults, and individuals sampled in spring having a higher infection risk. Furthermore, we found both LPDV and REV infection negatively affected individual fitness by reducing clutch size and weekly hen survival rate, respectively. Finally, LPDV in Maine is characterized by high diversity and weak spatial genetic structure, which we hypothesize may be driven by high mutation rates, intrahost pathogen dynamics, and/or the history of human-induced and natural wild turkey movement across the state. Overall, this study provides valuable insights into LPDV infection, transmission, and evolution in wild turkeys, data which will aid in future disease monitoring and risk assessments to evaluate effects of infection on wild turkey population dynamics.

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