Consequences of mating and predation risk for longevity in a freshwater snail: Abstinence makes the heart beat longer

Senescence is not a static property of an individual or population, but rather it is a dynamic process that may be influenced by environmental conditions. This can occur in at least two ways: in the long-term across multiple generations, and in the short-term via phenotypic plasticity. The former has attracted a lot of attention, both theoretically and empirically; the latter has lagged behind. To determine whether two important environmental variables (predation risk and mate availability) affect the pattern of actuarial senescence (i.e., the increase in mortality with age), we reared 30 full-sib families of the simultaneously hermaphroditic freshwater snail Physa acuta under four different environmental conditions and tracked individuals until death. Individuals were reared in a 2x2 factorial experiment that manipulated the non-lethal presence of chemical cues from predatory crayfish (presence/absence) and the opportunity to mate with an unrelated partner (mated/not mated). Snails tha...