Divergence in emergence time of host races due to differential gene flow

Abstract

Differential gene flow between adjacent plant populations, induced by environmental influences on reproductive characters such as flowering time, may increase isolation between them (Stam, 1983). With the aid of a simulation model, an analogous process is demonstrated for populations of phytophagous insects. Allochronic isolation due to differences in host plant phenology can be accentuated in sympatry. Interpretations of divergence between host-associated insect populations should take account of the potential effects of differential gene flow before invoking explanations involving selection.