Multiple Queens versus Multiple Mates: A Test of the Polygyny/Polyandry Tradeoff Hypothesis in the Ant Veromessor pergandei

According to evolutionary theory, cooperation should evolve most easily in closely related groups. In colonies of ants, bees, and wasps, within-colony relatedness is maximized when all offspring are descended from a single queen mated with a single male. However, in many species colonies are not composed of strictly nuclear families, suggesting there may also be benefits to greater genetic diversity. To increase genetic diversity, a queen can mate with multiple males, termed polyandry, or join with other queens to cohabitate and raise offspring together, termed polygyny. Both options have associated costs, leading to an expected tradeoff in whether queens invest in polygyny or polyandry. In this project, I tested the polygyny/polyandry tradeoff hypothesis in the desert seed harvester ant Veromessor pergandei. This species forms three different types of colonies across its geographic range: single queen, polygynous, and a temporary form of polygyny where colonies begin with multiple queens but they aggressively compete until only one queen is left alive. If the polygyny/polyandry tradeoff hypothesis explains their mating behaviors, I predict that solofounding queens should mate with more males than polygynous queens, and polyandry would be higher in temporary groups than in permanent groups. Queens and their offspring from each geographic area were genotyped at six highly variable microsatellite loci to infer the number of males with which the queen had mated. Results showed tentative support for a tradeoff between polygyny and polyandry, but implicated a more complex array of factors then genetic variation only influencing mating frequency in V. pergandei.