D3420: Investigating the impact of seasonality on the gut microbiome in Drosophila melanogaster

The interaction between the gut microbiome and its host has been studied in many species. Particularly, in the context of human health, a wide variety of host conditions and diseases have been linked to changes in microbiome composition. The microbiome is impacted by environmental factors such as diet, antibiotic intake, and air pollution. It is known that humans experience a seasonal shift in diet which in turn can alter the microbiome composition of the gut. Seasonal changes mean changes in day length (photoperiod) and temperature. Abrupt changes in photoperiods can have detrimental effects on human health, such as the development of certain mood disorders and reproduction. However, the effects of photoperiodic changes on the gut microbiome of the host remain poorly understood. To address this gap, I use Drosophila melanogaster, which has proven to be a powerful model for studying the gut microbiome due to its simple composition and ease of manipulation in the lab. First, I assessed the impact of changes in photoperiod and temperature on the fly gut microbiome. Winter-like shifts in photoperiod and temperature alter adult fly microbiome abundance. These temperature and light changes also alter female reproduction, leading to a reduction in ovary size and quality, inducing a diapause-like state. Next, I aim to determine whether these shifts alter fly susceptibility to pathogens and how the microbiome might mediate such changes. This study allows for a better understanding of how the microbiome responds to seasonal changes and its impacts on host physiology.