The small myrmicine ant tribe Formicoxenini is extraordinarily rich in social parasites, i.e. species that exploit already established societies of other social insects to rear their own offspring. More than 10% of all socially parasitic ants belong to the Formicoxenini and it was suggested that social parasitism convergently evolved more than ten times in this taxon. Our proposal aims at investigating the causes of different evolutionary patterns in five taxa of socially parasitic formicoxenine ants: Chalepoxenus spp., Epimyrma spp., Harpagoxenus spp., Leptothorax duloticus, and Protomognathus americanus. In particular, we want to determine the potential influence of the history of parasite-host associations, mating behavior, and imprinting and the formation of host races in speciation/radiation. We suggest to a) construct a phylogeny of formicoxenine parasites and their Leptothorax hosts from sequence data, b) study genetic variation within and between populations of social parasites, and c) investigate by gas chromatography and mass spectrometry the chemical basis of nest odor which might play a role in imprinting and the formation of host races. As studies on Epimyrma and Protomognathus are in part already funded by DFG in two separate projects (Or 107/1, Fo 298/2), the present proposal will focus on the three remaining taxa and, in the end, the comparison among all five lineages.
