Patterns of paternity skew in Formica ants.

摘要

Reproductive skew among cooperatively breeding animals has recently attracted considerable interest. In social insects reproductive skew has been studied in females but not in males. However, cooperative breeding of males occurs when two males matewith the same queen and father offspring. The first analysis of comparative data on paternity skew in ants is presented. It is shown that, across seven species of Formica ants, the average skew in paternity among worker offspring of doubly mated queens is negatively correlated with the population-wide frequency of multiple (mostly double) mating. It is also demonstrated that this trend is relatively robust in additional analyses taking phylogenetic relationships between species into account. The observed trend is opposite to the one normally found in non-social insects with second-male precedence through sperm displacement, but agrees with predictions based on queen-male conflict over sperm allocation as a consequence of facultative, worker controlled,sex allocation - an interpretation which assumes first-male precedence. However, alternative (but not mutually exclusive) explanations are possible and further studies will be needed to discriminate between these alternatives.