Similar Survival Rates of Territorial and Sneaker Males in a Polymorphic Damselfly: A Multi-Year Study

Male alternative reproductive tactics (ARTs) have been documented across diverse taxa and typically involve a male morph that defends resources to attract females and an alternate morph that exploits this behavior to obtain matings by stealth (territorial-sneaker tactics). One might expect that territorial morphs would live shorter lives than sneaker morphs due to their higher vulnerability to predators, their propensity to get injured and higher energetic costs. To date, there have been few direct field tests of this prediction. A mark-release-resighting (MRR) study conducted in 1992 found that orange-winged territorial morphs of the damselfly Mnais costalis had on average a shorter minimum reproductive lifespan than clear-winged sneaker morphs, if one assumed that they all emerged on a single day, but not if they were assumed to be of age 0 at the time of capture. We fitted Cormack-Jolly-Seber models to these 1992 data, as well as MRR studies conducted on Mnais costalis in four subsequent years. These models allowed us to jointly estimate the daily survival and resighting rates of the morphs and identify consistent predictors of their survival and detectability. There was no evidence of a significant difference in survival between male morphs or between males and females, although daily survival did consistently rise then fall with time since capture (age) and consistently declined with temperature above 17°C. By contrast, there was strong evidence that the resighting rates of individuals differed among morphs, with orange-winged males being more detectable. While there is no compelling evidence that the territorial and sneaker morphs have different daily survival rates, this does not preclude the possibility that orange-winged territorial males have high reproductive success on the days they are able to maintain a territory while the reproductive success of clear-winged sneaker males has reproductive success that is more broadly distributed across their lives.