Multiple male partners enable insect colonies to respond to changing environments

Mating with more than one male (polyandry) is a high-risk activity as it is an energy-expensive and time-consuming process and puts the females at a greater risk of accident or predation. It is actively discouraged in many social animals, but in highly successful social insects it is relatively common. Several hypotheses exist to explain the evolution of polyandry in the face of such costs, but little evidence exists to support the idea that it contributes to a better division of labor in social colonies, and it has generally been accepted that physically polymorphic worker classes arise from purely external cues—such as pheromones—unrelated to genetics. In the July 21 PNAS, William Hughes and colleagues at the University of Copenhagen Department of Population Ecology report that genetics play a significant role in worker caste determination, revealing an interplay between nature and nurture that accounts for the ability of colonies to balance levels ...