Populationsbiologie zweier gefährdeter sozialparasitischer Ameisenarten

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Socially parasitic ants exploit the workforce of societies of other ant species to rear their own offspring. The fascinating behavior during the usurpation of host societies, the elimination of the host queen, the replenishment of host workers during slave raids, and the coevolution between social parasites and their hosts has attracted researchers ever since Darwin. Because of the destructive effect on their hosts, most social parasites are extremely rare, and almost all are listed as threatened by IUCN and national red lists. Nevertheless, comparatively little effort has been made to determine the actual conservation status of these interesting, rare ants. We intend to investigate the population and colony structure of two closely related taxa with notably different life histories, the active slave-maker Myrmoxenus ravouxi and the degenerate slave-maker M. kraussei. Myrmoxenus ravouxi is one of the few slave-making ants found in Germany. It has been reported from a few scattered, dense populations of Temnothorax ants in several xerothermic areas in Germany (Seifert 1995, 2007) and is considered to be endangered or even close to extinction everywhere in Central Europe. Queens found new colonies after dispersing and mating during a nuptial flight and workers pillage pupae from neighboring host nests to increase the number of host workers in their colonies. M. kraussei is a similarly rare, degenerate slave-maker from Northern Italy and Southern France, i.e., its queens focus on the production of sexuals and produce too few workers for active slave-raiding. Female sexuals mate with their brothers in the maternal nest. From their different life histories we expect the two social parasites to have different population structures, different extinction risks, and different impact on the respective host populations. We therefore intend to analyze the genetic structure of several of the presently known populations of both species and their Temnothorax hosts by microsatellite genotyping and sequencing of mitochondria I and nuclear genes to obtain information on colony structure and population dynamics (local genetic variability, gene flow between populations, the extent and effect of inbreeding, and the pattern of host utilization). The data shall help to clarify whether populations of Myrmoxenus and other slave-making ants with similar life history are indeed highly threatened by extinction or more robust than previously thought.