This one-year award for US-France cooperative research in population biology involves David Rand of Brown University and Michel Veuille of the Universite Pierre et Marie Curie. Their collaboration is aimed at an extensive characterization of genetic variation within and among Old World and New World populations of the fruit fly, Drosophila melanogaster and Drosophila simulans. It is believed that this species originated in Africa, spread to European locations and more recently colonized the New World. The presence of geographically dispersed populations offers a unique opportunity to test genetic variations that may have evolved over centuries. In this one-year project, the investigators will direct their efforts towards collecting wild population samples from European and other old-world localities and prepare representative natural samples of Drosophila melanogaster for later analysis in each laboratory.