Do males that experience weapon damage have greater reproductive potential than intact males in polygynous scenarios?

Abstract

Males with damaged weapons often lose intraspecific contests; however, recent research suggests these males may use post-copulatory means to mitigate reduced reproduction. When intraspecific competition is absent, can weapon-damaged males produce more offspring in multi-mating scenarios relative to intact males? We examined the reproductive potential of weapon-damaged males in Narnia femorata (Hemiptera: Coreidae), a species that exhibits resource defense polygyny and is known to increase testes size when developmental weapon damage occurs. We induced weapon damage during development. Upon sexual maturation, we provided intact and weapon-damaged males with access to four unmated females successively and without any competitors. The mating partners of weapon-damaged males were more likely to have their eggs hatch. Furthermore, weapon-damaged males produced more offspring, though only with larger females. These results suggest that weapon-damaged males have enhanced fertilization outcomes, potentially minimizing reproductive costs of weapon damage. Weapon damage is common in nature and can reduce pre-copulatory success. However, few studies have examined the reproductive consequences of weapon damage. We tested the hypothesis that weapon-damaged males can compensate for a pre-copulatory disadvantage through increased investment in traits that improve post-copulatory fertilization success. To examine the reproductive potential of weapon-damaged males, we provided males with four females in succession, then measured reproductive outcomes. We found that mating partners of weapon-damaged males were more likely to have their eggs hatch relative to the mating partners of intact males. Furthermore, we found that weapon-damaged males produced a larger number of offspring than intact males. This evidence reveals that weapon damage allows males to boost reproductive outcomes in non-competitive contexts.