Cues signaling predation risk strongly influence prey phenotypes both within and between generations. Parental and early-life exposure to predators can independently affect the response of prey to predation risk, but in many systems, parental and embryonic risk experiences may also act synergistically to impact offspring traits. In such cases, offspring may rely upon signals that they receive from their parents about their potential risk environment as well as those they experience while developing as embryos. This interaction may be especially influential in systems where developing embryos have limited dispersal. Despite the potential for parental and embryonic experiences with predation risk to synergistically influence offspring, their interactive effects are poorly understood. We conducted a series of laboratory experiments to examine the synergistic impacts of parental and embryonic experience with predator cues on offspring size at emergence in an ecologically important intermediate consumer (the snail, Nucella lapillus) on rocky intertidal shores. We also explored potential mechanisms driving differences in offspring size patterns.
Results/Conclusions
We found that offspring of risk-experienced parents emerged with longer shells and greater tissue mass than offspring of risk-free parents, but only if they were exposed to risk as embryos. These patterns likely occurred because both parental and embryonic exposure to risk promoted increased growth efficiency by reducing embryonic respiration rates under risk. Offspring size patterns were not driven by differences in development time, allocation of energy to induced defenses, tradeoffs between offspring size and number, parental provisioning, or egg capsule size. These results provide novel insight into how predators drive prey performance in natural systems, and suggest that organism phenotypes may be influenced by a complex history with environmental cues.