Abstract:
Ageing is characterized by a progressive decline in physiological functioning. It is influenced by various biotic and abiotic factors, including the host’s microbiota. Ageing can induce compositional and metabolic changes in the microbiota, which, in turn, can modulate the host’s fitness, with effects that can potentially span across generations. In this thesis, I study how the fitness of the host and its offspring is affected when there is a mismatch between the age of the host and its corresponding microbiota. I found that the microbiome undergoes non-monotonic compositional changes with increasing host age. Moreover, at the single-generational level, host age is a dominant factor in determining the host’s fitness, whereas at the transgenerational level, both parental age and the age of the microbial community can have significant trait- and sex-specific effects on the offspring’s fitness. Although these results point to the importance of the microbiome in determining the outcomes of age-dependent decline in parental physiology on offspring fitness, I failed to find a generalized trend in these parental age and microbial community age-dependent effects and emphasize the importance of context and focal trait.
