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

Susana C. Martins Ferreira

Currently little is known about the factors determining individual heterogeneity in parasite infections in unmanaged wild mammal populations, including the gastrointestinal community of most wildlife species. In particular, the eukaryotic proportion of the biome, the eukaryome, remains largely unknown, and little is known about the fitness consequences which parasite infections impose on their hosts. In my research I primarily focus on individually known spotted hyenas in three large clans in the Serengeti NP. I aim to investigate determinants of gastrointestinal parasite infections of this wild social mammal and to assess the fitness consequences of infection. I hypothesise that individual variation of parasite infections is determined by 1) life-history traits; 2) social, ecological and abiotic environmental factors; 3) host immune-competence and 3) gastrointestinal community.

Stipend by the Research Training Group GRK2046 – Parasite infections: From experimental models to natural systems.

Fitness consequences and determinants of parasite infections in a wild social carnivore, the spotted hyena

Assessing both infection and the associated immune responses in free-ranging wildlife is challenging, as is the assessment of the consequences of infection on components of Darwinian fitness throughout the life-span of an individual. Our research aims to investigate the effect of the infection load of energetically costly intestinal parasites on host immune function and assess whether they have an effect on components of Darwinian fitness. We will combine results from longitudinal measures of parasite load, faecal hormone concentrations and measures of immunological responses in faeces from individually known spotted hyenas with information on their social rank and components of Darwinian fitness (age of first reproduction, longevity and life-time reproductive reproductive success) in our study population in the Serengeti National Park. This project is funded by the Research Training Group 2046 “Parasite Infections: from experimental models to natural systems”, Freie Universität Berlin”.

Early-life conditions and their long-term consequences in spotted hyenas

Morgane Gicquel

The developmental period is a particularly sensitive window during which the phenotypic effects of the environment are particularly marked. This means that the conditions experienced during development can have both immediate and  delayed effects on life history traits and fitness. Very little is known about these effects in free-ranging populations. My research will use long-term detailed data from individually known free-ranging spotted hyenas (Crocuta crocuta) in the Serengeti National Park, Tanzania.

Epigenetic stability and plasticity of social environmental effects

Sarah Benhaiem

Social status significantly affects Darwinian fitness by altering health, life history, and physiological trade-offs. Because social status is usually stable throughout life and is a behaviourally transmitted trait, social inequalities persist within and across generations. Even so, the molecular mechanisms underlying these social effects are poorly understood. We hypothesize that DNA-methylation is a main epigenetic pathway through which an individual’s social environment regulates gene expression and hence physiological responses and life-history trade-offs. We predict that methylation patterns in individuals experiencing social stability will promote status-specific trade-offs. We further predict that when the social environment results in status changes  as when high (low) born offspring are reared by a low (high) status surrogate mother, plasticity in methylation patterns should match the gene regulatory pathways, life-history trade-offs and fitness to the new social conditions. We test our hypothesis using long-term data obtained from spotted hyenas in the Serengeti National Park. To assess the impact of status-specific methylation patterns on health, we will measure faecal immunoglobulin, cytokine levels and eukaryome diversity, and will control for the possible confounding effect of gut microbiomes. By linking for the first time in a wild social mammal changes in social status to DNA-methylation, fitness and health, this project will shed light on gene pathways underpinning social inequalities, their plasticity, health consequences and potential implications for humans.