Mating structure and nestmate relatedness in primitively social hymenoptera as revealed by microsatellites

Abstract: Mating structure and nestmate relatedness have been estimated in social Hymenoptera with different levels of sociality. Microsatellite markers have been developed for both communal bees (Andrena scottica) and for primetively eusocial wasps (Vespula rufa).In the communal bee, Andrena scottica, females of the same colony are not related to each other suggesting that the lack of inclusive fitness payoffs may effectively constrain their social evolution. There was a positive inbreeding coefficient for both examined populations of Andrena scottica as a result of a high degree of intranidal mating. This inbreeding did not lead to extensive production of diploid males as would be expected on the basis of the CSD (complementary sex determination) system of the honey bee, and thus Andrena scottica either avoids "matched matings", (i.e. either or both sexes refrain from mating with an individual carrying the same sex allele) or the sex determination departs from the honey bee model.The primitively eusocial wasp Dolichovespula saxonica is highly polyandrous.Queens (n=7) mated 4-11 times (mean 6.0) and the effective promiscuity, ke was 3.30-9.14 (mean 4.81). This resulted in low average relatedness among workers (gww=30-0.40; mean 0.37). On the contrary Dolichovespula media queens from three colonies mated with one male only. All males (n=80) originating from four D. saxonica colonies were produced by the queen, in agreement with the genetical interests of both the queen and the collective worker force ("worker policing"). One D. saxonica colony includedboth workers and male sexuals of two matrilines.Bombus hypnorum is a primitively eusocial bumble bee. Queens from 14 colonies had mated 1-5 times (mean 2.43) with an effective promiscuity of 1-2.8 (mean 1.40). Half of the colonies examined, inhabited alien workers. These workers could originate from an earlier nest usurpation event, and the colonies with such alien workers had on average a larger size. Alien workers together with polyandry results in high variation among colonies in sociogenetic organisation. Genetical data were consistent with the view that all males (n = 233 examined) were produced by a colony's queen, in conflictwith the collective worker interest.