title: Understanding drivers of parasite infections in baboons: insights across multiple levels, from populations to genetics
Creators: name: Raby, Cassandra
Publisher: name: University of Liverpool Repository
Year: 2020

description: Parasites play an important role in evolutionary processes and regulating host populations. Furthermore, parasites have the ability to result in economically and physically disruptive diseases which are becoming increasingly common as anthropogenic change disrupts the ecology of host-parasite systems. Exploring the drivers that influence parasite transmission and infection can further our understanding of host-parasite relationships and how these might change in the future. Such drivers occur across multiple scales, with different factors influencing host exposure and susceptibility to infection across species, across populations, and across individuals and groups within populations. In this thesis, I investigate these drivers across multiple scales. I begin by analysing the patterns of gastrointestinal parasite communities across species of the genus Papio (baboons), and then focus my observations on a population of wild chacma baboons (Papio ursinus) in Namibia. I focus on primates due to their zoonotic potential and the fragility of some primate populations to extinction; I focus on baboons because in Africa it is this primate taxon that may be of greatest significance for human health: their wide distribution and coexistence with people living in rural and urban populations make them a likely source of zoonotic pathogen transmission. To explore the drivers of gastrointestinal parasite communities and richness across Papio species, I conducted a meta-analysis assessing the importance of species differences and environmental conditions. I found that the parasite communities were widely shared across baboon species in Africa, and that the environment was more important than the host species in determining where specific parasite species occurred. I then went on to explore patterns of gastrointestinal parasite transmission and infection across individuals in the chacma baboon population in Namibia. First, I explored how spatial heterogeneity in the environment shapes the risk of parasite transmission and whether the baboons practice avoidance behaviours at the troop level. I identified those habitats that might be better suited for parasite cyst and egg survival, and found that the baboon troops avoided revisiting these areas when they had already been exposed to parasite infection. In the next two chapters, I assessed whether two components of individual variation, sociality and genetic diversity, shaped exposure and susceptibility to parasites. In the first, I found no evidence that social network position influenced parasite infection. However, in the second, I found that inbreeding and Mhc-DRB allelic richness were associated with infection by some parasite species. Overall, the findings of my thesis highlight the myriad ways in which the environment, host behaviour, and host heterozygosity can influence host-parasite interactions – at the multiple scales of the individual, social group, population, and species.