Department of Organismic and Evolutionary Biology
16 Divinity Street
Abstracts (first author)
Genetic changes underlying host plant resistance in Drosophila sechellia
The genetic basis of adaptation is a major question in evolutionary biology. In particular, ecological specialization can result from rapid host shifts and strong selective forces. Although most Drosophila species are generalists, D. sechellia a species endemic to the Seychelles archipelago is one such specialist species. D. sechellia feeds and breed almost exclusively on Morinda citrifolia, and its fruit commonly known as noni. M. citrifolia produces several volatile compounds which are toxic for most arthropod species and all closely related Drosophila species. Nonetheless, D. sechellia has evolved resistance and host preferences that include stimulation of egg production, oviposition site preference and chemotaxis. To understand how this suite of host specialization traits evolved, it is important to dissect the underlying genetic basis of these phenotypes. QTL mapping is an important tool for the study of such complex traits. In order to detect and localize loci that influence resistance to M. Citrifolia, we use bulk segregant mapping approaches, based on backcrosses between D. sechellia and its sister species D. simulans (which is sensitive to Noni) and use by deep sequencing to identify QTL regions. We combine this approach with genome scans, based on light coverage sequencing of over 250 isofemale lines of D. Sechellia and D. Simulans derived from recent field collections in the Seychelles. This approach allows us to unravel the genetic characteristics that allow D. sechellia to contend with the toxic compounds that are otherwise lethal to close relatives.