The genetic basis of variation in bovine tuberculosis infection, progression and diagnosis in a wild animal host

Parasites are ubiquitous in wild animal populations and have wide ranging effects on the health, fitness and eco-evolutionary dynamics of their host populations. To counter parasites, hosts have evolved a myriad of defence strategies, but individuals vary considerably in the efficacy of these strategies, and so, in their susceptibility to infection. While variation can generally be viewed as stemming from genetic and environmental effects, we currently have little knowledge of their relative importance in wild and unmanaged host populations. In this thesis, I use long-term mark-recapture data on a population of European badgers (Meles meles) to examine the genetic basis of variation in bovine tuberculosis infection and its progression. I first estimate a genetic pedigree and characterise variation in extra-group paternity in the population (Chapter 2). Then, adopting a pedigree-based quantitative genetic approach, I investigate the relative importance of genetic and social environmental sources of variation in bTB infection status (Chapter 3). Thirdly, I characterise associations between body weight and bTB infection and test for variation in host tolerance (Chapter 4). And finally, I examine the genetic basis of (co)variation in and among four diagnostic test responses, representing different aspects of host immune function (Chapter 5). Taken together, this work provides novel insight into the genetic architecture of bovine tuberculosis infection in a wild host species, and the evolutionary potential of immune traits in the wild