Genetic differentiation in the winter pine processionary moth (Thaumetopoea pityocampa - wilkinsoni complex), inferred by AFLP and mitochondrial DNA markers.
The winter pine processionary moth has become an important pine pest in the last century, as a consequence of the spread of pine cultivation in the Mediterranean region. The pattern of genetic differentiation of this group, that includes two sibling species (T. pityocampa and T. wilkinsoni), has been studied in nine populations using amplified fragment length polymorphism (AFLP) and single strand conformation polymorphism-sequence analysis (SSCP) of the mitochondrial cytochrome oxidase [cytochrome-c oxidase] 1 (COI) and cytochrome oxidase 2 (COII). Results indicate the existence of strong genetic differentiation between the two species that became separated before the Quaternary ice ages. Moreover, data indicate that T. pityocampa has a strong geographical structure, particularly evident at the nuclear level, where all pairwise φST were highly significant and individuals from the same population were strongly clustered when an individual tree was reconstructed. The estimates of the absolute number of migrants between populations (Nm), obtained from mitochondrial and nuclear DNA markers suggest that gene flow is low and that a gender-related dispersal could occur in this species. The males appear to disperse more than females, contributing to the genetic diversity of populations on a relatively wide range, reducing the risks of inbreeding and the genetic loss associated with bottlenecks occurring in isolated populations.