Male-biased dispersal promotes large scale gene flow in a subterranean army ant, Dorylus (Typhlopone) fulvus

Sex-biased dispersal is a widespread phenomenon in the animal kingdom, which strongly influences gene flow and population structure. Particularly army ants, important key-stone predators in tropical ecosystems, are prone to population fragmentation and isolation due to their extraordinary mating system: queens are permanently wingless, propagate via colony fission, and only the males disperse in mating flights. Here we report on sex-biased dispersal and the genetic population structure of an African subterranean army ant, Dorylus (Typhlopone) fulvus. Using maternally inherited mtDNA markers and bi-parentally inherited nuclear microsatellites we found strong geographical structuring of mtDNA haplotypes, whereas the nuclear genetic population structure was less pronounced. Strong mtDNA (Φ _ST = 0.85), but significantly lower nuclear (F _ST = 0.23) genetic differentiation translated into a more than an order of magnitude larger male migration rate compared to that of queens, reflecting the low motility of queens and strong, promiscuous dispersal by males. Thus, the well flying D. fulvus males appear to be the sex to promote large scale gene flow, and D. fulvus is indeed a species in which sex specific dispersal patterns and the mating system profoundly affect the population structure and phylogeography.