MOLECULAR AND REPRODUCTIVE CHARACTERIZATION OF SIBLING SPECIES IN THE EUROPEAN EARWIG (FORFICULA AURICULARIA)

The European earwig (Forficula auricularia) was formerly thought to present a mosaic of populations differing in their reproductive biology. We show that it is comprised of two as yet unrecognized sibling species. The molecular divergence between the two species, for a 627-bp amplified fragment overlapping the COI and COII mitochondrial loci, is six times larger than intraspecific variation. A species with two clutches a year lives predominantly in lowland and oceanic European habitats. A species with one clutch a year—except in the Mediterranean area where it has two clutches—lives predominantly in highland and continental European habitats. They both invaded North America during the 20th century, respectively, from the west and the east coasts, with no apparent mixing of their populations. The two species can occur in sympatry in Europe and are reproductively isolated by nearly complete failure to produce F₁ hybrids.