MATING FREQUENCY OF ANT QUEENS WITH ALTERNATIVE DISPERSAL STRATEGIES,AS REVEALED BY MICROSATELLITE ANALYSIS OF SPERM

In social Hymenoptera (ants, bees, and wasps), the number of males tha t mate with the same queen affects social and genetic organization of the colony. However, the selective forces leading to single mating in certain conditions and multiple mating in others remain enigmatic. In this study, I investigated whether queens of the wood ant Formica para lugubris adopting different dispersal strategies varied in their matin g frequency (the number of males with whom they mated). The frequency of multiple mating was determined by using microsatellite markers to g enotype the sperm stored in the spermatheca of queens, and the validit y of this method was confirmed by analysing mother-offspring combinati ons obtained from experimental single-queen colonies. Dispersing queen s, which may found new colonies, did not mate with more males than que ens that stayed within polygynous colonies, where the presence of nume rous reproductive individuals ensured a high level of genetic diversit y. Hence, this study provides no support to the hypotheses that multip le mating is beneficial because it increases genetic variability withi n colonies. Most of the F. paralugubris queens mated with a single mal e, whatever their dispersal strategy and life history. Moreover, multi ple mating had little effect on colony genetic structure: the effectiv e mating frequency was 1.11 when calculated from within-brood relatedn ess, and 1.13 when calculated from the number of mates detected in the sperm. Hence, occasional multiple mating by F. paralugubris queens ma y have no adaptive significance.