Drosophila at the "Evolution Canyon" Microsite, MT. Carmel, Israel: Selection Overrules Migration

Abstract

Extensive slope-specific adaptive and non-adaptive characteristics were observed and described in the summer-dry "Evolution Canyon", Israel, in many organisms, including fruit flies. By means of the capture-mark-release-recapture method, we tested if this phenomenon could be displayed by fruit flies (Drosophila melanogaster-simulans) with selection against interslope migrants, as proposed earlier. In contrast to our expectations, our results showed an extensive interslope migration that, together with accumulated evidence on interslope differentiation for adaptive and non-adaptive traits, indicates that the interslope gene flow is not disrupted by migration. Unfortunately, the relationship between migration rate and gene flow is not known. If the bimodal distribution of resources, combined with assortative mating and frequency-dependent selection is present, then a certain level of gene flow might not be able to prevent the observed interslope incipient sympatric populations' differentiation at "EC"

Keywords:

• migration
• selection
• Drosophila
• "Evolution Canyon"
• sympatric speciation
• gene flow