The North American seed-harvester ant Pogonomyrmex (Ephebomyrmex) pima (subfamily Myrmicinae) displays a dimorphism that consists of winged (alate) and wingless (intermorph) queens.  The two queen morphs are both fully reproductive, but do not typically co-occur within polygynous colonies.  We tested for genetic differentiation between dealate and intermorph queens in one population using microsatellite allele frequency distributions and mtDNA sequences.  We found no distinction between the nuclear gene pools of the two queen morphs.  A mitochondrial haplotype network will be constructed to determine whether dealate and intermorph queens form separate clades.

Pogonomyrmex is one of the few groups of eusocial hymenopterans in which queens mate with multiple males, and it has been proposed that the resulting increase in within-colony genetic variation is adaptive.  An array of genetic variation hypotheses invoke different mechanisms, but collectively predict that polyandry should be less common among polygynous than among monogynous species, assuming multiple mating has costs.  All Pogonomyrmex species analyzed thus far belong to the subgenus Pogonomyrmex sensu stricto, are strictly monogynous, and have multiply-mated queens.  In contrast, P. pima is a member of the subgenus Ephebomyrmex and exhibits functional polygyny.  Therefore, P. pima is expected to have a lower queen mating frequency than the Pogonomyrmex sensu stricto species.  We reared laboratory colonies and used microsatellite genotyping of brood to determine the average number of matings by P. pima queens.  Both dealate and intermorph queens have an effective mating frequency < 2, which is lower than all other Pogonomyrmex species studied thus far.  Our results provide insight into the evolution of polyandry in Pogonomyrmex and other social insects.