Contrasting patterns of genetic and morphological diversity in the bumblebee Bombus lucorum (Hymenoptera: Apidae: Bombus) along a European gradient

The Iberian Peninsula is known to have acted as a glacial refugium for many species during the Pleistocene in Europe. Several phylogeographical studies have been carried out within the genus Bombus which indicate a genetic differentiation of some of its species in the southern European peninsulas. Bombus lucorum (Linnaeus, 1761) is one of the three cryptic species belonging to the B. lucorum complex. In recent years, this complex has been widely studied; however, there is a lack of information about the genetic diversity of this species and its possible postglacial recolonization events. To overcome this knowledge gap, in this study several populations from the centre of the Iberian Peninsula to Belgium have been characterized using mitochondrial and nuclear markers (cox1 barcoding and 11 microsatellite loci) and the geometric morphometrics of the wings. Results from cox1 indicate a genetic differentiation of the population of Sierra de Guadarrama at the centre of the Iberian Peninsula, while microsatellite loci and geometric morphometrics analyses do not show any population structure. These results point to a past event of genetic differentiation of B. lucorum in the Iberian Peninsula although they also suggest a current gene flow with populations from mainland Europe.