My research focuses on the mechanisms of speciation and adaptation, fundamental evolutionary and biological processes responsible for the generation and the maintenance of biodiversity. My objective is to gain insights into the mechanisms of speciation and more specifically to understand the role of selection (ecological and sexual selection, reinforcement) in the formation of new species. I combine phenotypic, transcriptomic and genomic analyses of traits involved in reproductive isolation in various biological systems (house mice, pea aphids, other taxa). I focus mostly on the mechanisms of divergence-with-gene-flow (in sympatry or secondary contact zones) to understand how reproductive isolation (in particular non-random mating) and genetic differentiation build up in the face of homogenising gene flow. In this context, I pay particular attention to the evolution of chemosensory traits involved in premating isolation and of the associated large olfactory and gustatory receptor gene families.