The effects of age at mating on female life-history traits in a seed beetle

Age at first reproduction is an important component of life history across taxa and can ultimately affect fitness. Because genetic interests of males and females over reproductive decisions commonly differ, theory predicts that conflict may arise over the temporal distribution of matings. To determine the potential for such sexual conflict, we studied the direct costs and benefits associated with mating at different times for females, using seed beetles (Acanthoscelides obtectus) as a model system. Virgin females were resistant to male mating attempts at a very early age but subsequently reduced their resistance. Although we found no difference in life span or mortality rates between females mated early in life and those mated later, females that mated early in life suffered a 12% reduction in lifetime fecundity. Thus, there are direct costs associated with mating early in life for females. Yet, males mate even with newly hatched females. We suggest that these data indicate a potential for sexual conflict over the timing of first mating and that female resistance to mating, at least in part, may represent a female strategy aimed at delaying mating to a later time in life.