Complex colony structure in social insects. II. Reproduction, queen-worker conflict, and levels of selection

Differences in colony structure between two populations of the forest ant, Myrmica punctiventris, have had dramatic consequences on allocation to growth and reproduction. A population in Vermont, in which colonies have a single, once-mated queen, shows no evidence of inbreeding or population subdivision and has allocated 25% of sexual reproduction to males in two consecutive years. In contrast, for a population in New York that is facultatively polygynous, we have evidence of microgeographic genetic structure and inbreeding, and the populationwide allocation ratio was extremely male-biased. Additionally, the Vermont population allocated much more energy to sexual reproduction than did the New York population. Detailed analysis of data from the Vermont population, within which colonies undergo a seasonal cycle of expansion to multiple nesting sites (polydomy), gave strong evidence of queenworker conflict over male allocation and indicated that workers are winning that conflict. Finally, we used contextual analysis to find that fertility selection operates almost exclusively at the level of the individual nest rather than at the higher level of the multinest colony.