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Freie Universität Berlin (2019)

Intrinsic and extrinsic determinants of parasite infections in spotted hyenas in the Serengeti National Park

Martins Ferreira, Susana

Titre : Intrinsic and extrinsic determinants of parasite infections in spotted hyenas in the Serengeti National Park

Intrinsische und extrinsische Determinaten der Infektion mit Parasiten in Tüpfelhyänen des Serengeti Nationalparks

Auteur : Martins Ferreira, Susana

Université de soutenance : Freie Universität Berlin

Grade : PhD of Biomedical Sciences 2019

Résumé
Parasite infections have been examined in a limited number of wild mammalian species. These studies have revealed substantial heterogeneity between individuals within a population. Currently little is known about the Darwinian fitness consequences of parasite infections and the factors determining the observed heterogeneity. Key determinants expected to affect individual differences in the infection load of different parasite taxa are host environmental factors, including the social environment, that influence exposure to parasites, and phenotypic characteristics and life-history stages of individual hosts that may be linked to susceptibility to parasite infections. The biotic environment of gastrointestinal parasites, i.e., the assemblage of organisms found in the gastrointestinal tract of the host, collectively called intestinal biome, is also expected to be a key determinant of infection load. Knowledge is limited on the composition, diversity and richness of the intestinal biomes of wild mammals. In this thesis I aimed to investigate determinants of gastrointestinal parasite infections and their fitness consequences in a free-ranging population of a highly social large mammal, the spotted hyena (Crocuta crocuta), in three social groups termed clans in the Serengeti National Park, Tanzania. I hypothesised that individual variation in parasite infections is determined by 1) life-history traits ; 2) social, ecological and abiotic environmental factors ; 3) host immuno-competence and 4) the gastrointestinal biome community. In chapter 2, I conducted the first metabarcoding (amplicon sequencing) study of the intestinal biome of female spotted hyenas, including both the eukaryome and bacterial microbiome. Consistent with my predictions, juveniles differed in the composition of their bacterial microbiomes from adults, and overall showed a low richness and diversity. The composition, richness and diversity of the eukaryome of females varied with their social status, with high-ranking individuals having a higher richness and diversity than low-ranking individuals. In chapter 3, I investigated the ubiquitous intracellular parasite of warm blooded animals Toxoplasma gondii. I analysed sera from spotted hyenas and sympatric carnivores, including mostly adult lions (Pathera leo), the most abundant large felid in the Serengeti, and also a striped hyena (Hyaena hyaena) and four bat-eared foxes (Otocyon megalotis), an insectivore. This study revealed high seropositivity of adult spotted hyenas and lions

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