Reproductive barriers between three closely related socially parasitic ant species (Doronomyrmex sp, Hymenoptera, Formicidae, Myrmicinae)

Reproductive isolation is investigated in three inquiline species of the genus Doronomyrmex Kutter (D. kutteri (Buschinger), D. goesswaldi (Kutter) and D. pacis Kutter) which parasitize the holarctic formicoxenine ant Leptothorax acervorum (F.). Several factors contribute to the maintenance of genetic integrity of the three species, which are broadly sympatric in the Alps and Northern Europe and often live within the same host population. The observed barriers include premating (timing of sexual behaviour, mate recognition), postmating prezygotic (gametic isolation of yet unknown cause) and postzygotic (hybrid sterility) effects. Only in one out of six possible interspecific combinations of females and males, slight introgression could not be excluded.