Local mate competition and parental investment in social insects

Abstract

Efforts to develop formulas for contrasting genetic interests of workers and queens in social Hymenoptera are complicated by many factors, including multiple matings by queens, oviposition by unmated females, and mating rivalry among genetic relatives (Hamilton's "local mate competition"). Because of haplodiploid sex determination in Hymenoptera, when such influences are absent, queens benefit from 1:1 sex ratios of investment (male: female) in reproductive offspring, workers from 1:3 ratios among reproductive siblings. Reports of variable ratios, including many well above 1:3, and female biases in nonsocial Hymenoptera and diplodiploid termites, implicate local mate competition and raises questions about previous interpretations that workers have their way.