Insights into genome differentiation: Pheromone-binding protein variation and population history in the European corn borer (Ostrinia nubilalis)

Examination of sequence variation at nuclear loci can give insights into po pulation history and gene flow that cannot be derived from other commonly u sed molecular markers, such as allozymes. Here, we report on sequence varia tion at a single nuclear locus, the pheromone-binding protein (PBP) locus, in the European corn borer (Ostrinia nubilalis). The European corn borer ha s been divided into three races in New York State on the basis of differenc es in pheromone communication and life history. Previous allozyme data have suggested that there is a small but significant amount of genetic differen tiation between these races. The PBP does not appear to be involved in the pheromone differences between these races. Examination of variation at the PBP locus in the three races reveals no fixed differences between races des pite high levels of polymorphism. There also appears to have been considera ble recombination in the history of the pheromone-binding protein alleles. Observation of both recombination between alleles and lack of significant n ucleotide or insertion/deletion divergence between races leads us to sugges t that these populations are either recently diverged or have continued to exchange genetic material subsequent to divergence in pheromone communicati on and life history.