Data from: Evidence for low-level hybridization between two allochronic populations of the pine processionary moth, Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

Divergence between populations sharing the same habitat can be initiated
by different reproductive times, leading to allochronic differentiation. A
spatially localized allochronic summer population (SP) of the pine
processionary moth Thaumetopoea pityocampa, recently discovered in
Portugal, occurs in sympatry with the local winter population (WP). We
examined the level of genetic differentiation between the two populations
and estimated the current gene flow within the spatial framework of their
co-occurrence. Mitochondrial data indicated that the two sympatric
populations were genetically closer than other WP populations. Conversely,
microsatellite genotyping uncovered greater differentiation between the
two sympatric populations than between allopatric ones. While male
trapping confirmed that reproduction of SP and WP occurred at distinct
times, clustering approaches demonstrated the presence of a few LateSP
individuals emerging within the WP flight period, although genetically
identified as SP. We also identified rare recent hybridization events
apparently occurring mainly in the margins of the current SP range. The
ongoing gene flow detected between the ancestral and the emerging
allochronic populations revealed an incomplete reproductive isolation,
which must therefore be taken into account and integrated with studies
focussed on ecological drivers, so that a complete understanding of the
ongoing speciation process might be achieved.