The genetic basis of prezygotic isolation between species

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The formation of new species gives rise to the wide array of biodiversity we see today, yet very little is known about the underlying genetic basis of species isolation. In particular, no genes have been identified for behavioural isolation, which is thought to be the first species barrier to arise. My research program has identified the first three genes for behavioural isolation. The proposed research will characterize genes for species-specific female preference behaviour in four ways: (1) We will use the powerful Gal4-UAS system in Drosophila to identify the subset(s) of cells within the brain that are affected by these three genes, giving rise to female preference and isolation behaviours. (2) We will use transgenics to identify the precise nucleotides within each of these three genes that underlie behavioural isolation and whether these genes act via coding sequence (protein differences) or regulatory sequence (expression level differences). (3) We will evaluate these genes in multiple populations within each species in order to identify the evolutionary context of how these three loci contribute to behaviour within and between species. (4) We will continue mapping and performing tests of individual candidate genes order to identify additional behavioural isolation loci. This work will significantly add to our understanding of the genetic and neural basis of the complex trait of mating behaviour and allow us to identify the mechanism by which behaviour becomes a discriminating mechanism between species. By performing these studies in the context of species isolation, we can also begin to address fundamental questions regarding its underpinnings: the number and cytological location of the genes involved, their rate of evolution, their relative effect on isolation, and whether particular genetic or neurological pathways are more often involved, to name a few.