This study will document the geographic structure of genetic diversity in African populations of the fruit fly Drosophila melanogaster. Before expanding to a nearly worldwide distribution, this species is thought to have originated in tropical Africa. Yet, very little is known about the evolutionary history and genetic structure of African populations. This study will use DNA sequence and repeat length variation to: (1) evaluate genetic relationships among African populations, (2) identify which populations appear to be the most ancestral, and (3) infer the most likely geographic route for the expansion of D. melanogaster from sub-Saharan Africa into north Africa and Eurasia. This work will lead to an improved understanding of how evolutionary forces like population history and natural selection shape genetic variation, particularly in species colonizing new environments.
The history of D. melanogaster is similar to that of many invasive species and crop plants, so this project has the potential to guide future studies that examine genetic diversity in ecologically and economically important species. By improving our evolutionary understanding of a model organism in genetics, this study will facilitate connections between biological disciplines. This research will contribute to graduate and undergraduate training. Findings will be communicated at scientific meetings, in print, online, and in the high school classroom. New scientific contacts will be made with researchers in Africa, and new collections of D. melanogaster will be obtained and shared freely.
