Speaker
Description
Food choice is an important driver of speciation and exploration of novel ecological niches. However, we know little about the mechanisms leading to shifts in food preference at the cellular and molecular level. To study this phenomenon, we use the three closely related Drosophila species, D. sechellia, D. simulans and D. melanogaster, which dramatically differ in their feeding habits. D. sechellia, a host specialist, spends its whole life cycle on a single fruit (Morinda citrifolia, noni) - the latter two are generalists living on various substrates. Using several quantitative feeding assays, we can recapitulate the preference for noni in D. sechellia. Using neurogenetics, we identify sweet and bitter sensing neurons as the main drivers for this shift in behaviour and compare their physiology between species. We establish a causal link between genetic changes in one single gustatory receptor, peripheral neuron responses in bitter-sensing cells of the labellum and behavioural divergence between species. Through volumetric Calcium imaging in the ventral brain, we detect that, in addition to peripheral physiology, species-specific processing of noni and sugars detection in sensorimotor circuits alters feeding preference. Our data support a model where multiple species-specific modifications lead to altered food consumption across closely related species.
