Disease ecology and virus evolution in wild cougars (Puma concolor): From infection patterns to population processes

The dynamics of wildlife pathogens and their potential use as fast-evolving host population markers represent a largely unexplored research area. I studied the ecology and evolution of a retrovirus, feline immunodeficiency virus (FIV), and the interactions with its natural feline host, the cougar (Puma concolor), in wild cougar populations in the central Rocky Mountains in North America.; Based on data from a single cougar population, I established that virus prevalence can be high locally (58%) and increases with host age. Samples temporally spaced over several years allowed to estimate the evolutionary rate of the virus, which was found to measurably diversify in a matter of years leading to appreciable genetic diversity.; More widespread sampling of 207 cougars from four populations confirmed that FIV was ubiquitous but also provided evidence for locally different virus dynamics within host populations. Infection with other feline pathogens, some of which were also endemic in cougars, was not correlated with FIV status of individuals, thus indicating no elevated risk of infection due to FIV.; Demographic data collected for 160 monitored cougars from two populations revealed no effect of chronic FIV infection on cougar survival but suggested a possible reduction in reproductive parameters for infected females.; Genetic sampling of 352 cougars from several northwestern states and provinces was used to describe the spatial distribution of genetic variation in the virus and compare this to genetic population structure of the host, which was assessed using eleven microsatellite loci. Evidence for genetic population structure in cougars was weak but fit an isolation by distance pattern. Spatial structure in the virus was more pronounced, as evidenced by limited spatial overlap in the distribution eight viral strains that could be distinguished based on phylogenetic relationships. Based on a molecular clock based analysis I found that all strains had common ancestors within the twentieth century and that they had undergone a rapid population expansion in the last two decades. The recent demographic history of the virus correlates well with that of the cougar host, which has recovered only recently from low population numbers due to human persecution.