Sexual cooperation: Mating increases longevity in ant queens

The phenomenon of sexual conflict is a powerful driving force in the evolution of reproductive biology for many animal species. Males often try to manipulate their female mates during copulation--for example, by traumatic inseminations (as in the case of bed bugs) or by the transfer of toxic seminal fluids (as in the case of the fruitfly Drosophila). These manipulations are beneficial to males because, for example, they reduce female re-mating probability or boost their fecundity directly after mating, but they can be very harmful to females, whose lifespan and future reproductive output can be drastically reduced. New findings suggest that in some social insects--in which both sexes ultimately benefit from long, successful reproductive lives of females--sexual cooperation, rather than sexual conflict, may be favored.

The findings, reported in the February 8 issue of Current Biology by researchers from the Universities of Regensburg, Germany, and Copenhagen, Denmark, show that queens of the social ant Cardiocondyla obscurior actually benefit from mating by gaining increased lifespan and reproductive success, living longer irrespective of whether males could transfer viable sperm or had been sterilized prior to mating. It remains unknown how mating increases the longevity of the females.

Sexual cooperation, rather than sexual conflict, is promoted by the life history of social insects; whereas most insect females undergo repeated phases of mating and reproduction throughout their lifetime, ant queens in social species mate only during a short period early in life and store and use the sperm of their mate for the rest of their lives. Sexual offspring are only produced after several months or years of colony growth, during which a sterile worker force is built up in the population. The fact that mates bond so early reduces the conflict between mating partners because both sexes benefit from the queen experiencing a long reproductive phase after the colony reaches sexual maturity.

Source : Cell Press