SEX-RATIO CONFLICTS, MATING FREQUENCY, AND QUEEN FITNESS IN THE ANT FORMICA-TRUNCORUM

We examined the effect of facultative sex allocation by workers on que en fitness in a Finnish population of the ant Formica truncorum. Worke rs rear female-biased broods in colonies headed by a singly mated quee n and male-biased broods in colonies headed by a multiply mated queen. As a result, multiply mated queens have a 37% fitness advantage over singly mated queens. Neither reproductive output nor worker population of colonies varied with queen mating frequency. We suggest that singl y mated queens persist in the population because fitness benefits to m ultiply mated queens via sex allocation are balanced by costs of addit ional matings. Alternatively, singly mated queens may persist simply b ecause some queens lack opportunities to mate multiply or because male control sometimes prevents additional matings by queens.