Delayed oviposition: a female strategy to counter infanticide by males?

Abstract

Conflicts of interest between males and females can lead to an evolutionary arms race in which adaptations of each sex coevolve. Intersexual conflict is extreme in the brood caring, semelparous spider Stegodyphus lineatus; males encountering females that have already produced their usually single egg sac attempt to remove and discard the egg sac and then remate with the female. Females that cannot defend their eggs lose valuable time and fecundity by having to replace the clutch. Selection should favor females that complete their suicidal maternal care as quickly as possible because of the high risk of predation. However, some females take up to four times longer to oviposit than others. I propose that females minimize the risk of male infanticide by postponing oviposition. Accordingly, early-maturing females, who suffer the highest risk of infanticide by males, should have a longer interval between maturation and oviposition than late-maturing females. The date of maturation significantly predicted the interval between maturation and oviposition and explained up to 35% of its variation in a data set from a natural population and longer term data from a seminatural, enclosed population. Body size was predicted to have a weak effect on the timing of oviposition and was consistently less important than maturation date. The observed facultative timing of oviposition may have evolved as a result of intersexual conflict over mating.