Meeting Abstract
Exclusive male parental care, a form of sex role-reversal, may evolve when males invest more heavily in reproduction than females. Here, competition for mates should intensify sexual selection among females, while males must mitigate fitness loss from polyandry. Yet true sex role-reversal, which involves increased selection on competitive females, is rare in nature, even in species with male parental care. In giant water bugs Abedus herberti Hidalgo (Hemiptera: Belostomatidae), females glue their eggs to males’ backs to be tended until hatching, while males attempt to ensure paternity by inseminating females between ovipositions. We investigated the genetic mating system of A. herberti in southern Arizona to determine whether paternal care evolved in the context of selection on polyandrous females. Using microsatellite DNA, we conducted parentage assignment and measured rates of polygynandry, ecological correlates, and strength of sexual selection in 1,341 individuals (123 adults and 36 broods). Results showed that both polyandry and genetic cuckoldry are common, with an average 36% of brooding males carrying offspring sired by another male, an effect that is enhanced by ecological density. Strength of sexual selection was significantly higher on females than males, where paternal care and reciprocal cuckoldry ensured less benefit from remating. We conclude that selection on polyandrous females has helped to drive the evolution of paternity assurance and male parental care in the giant water bug Abedus herberti.
