Mitochondrial DNA variability and Wolbachia infection in two sibling woodlice species

Several morphological races and subspecies have been described and later in cluded within the terrestrial isopod species Porcellionides pruinosus. Duri ng our study of this species, we have worked on specimens from France, Gree ce, Tunisia and Reunion island. Laboratory crosses have revealed two separa te groups of populations: French populations (four localities) in one group , and those from Tunisia, Reunion island and Greece in the other. French in dividuals were reproductively isolated from those of the other populations. We have undertaken a survey of mitochondrial DNA (mtDNA) polymorphism in t hese seven populations. We observed two groups of mitotypes corresponding t o the two groups of populations. Interfertility experiments between populat ions and the mitochondrial genetic distances between mitotypes both suggest the presence of two different species, one in France and one in Greece, Tu nisia and Reunion island. The two species harbour, respectively, two differ ent Wolbachia lines. Another feature of the molecular genetic analysis was the apparent mitochondrial monomorphism in the French populations and the l ow variability in the other three populations. The result can be related to the possibility of Wolbachia-induced genetic hitchhiking in these populati ons.