Carryover effects of phenotypic plasticity: embryonic environment and larval response to predation risk in Wood Frogs (Lithobates sylvaticus) and Northern Leopard Frogs (Lithobates pipiens)

Limitations of phenotypic plasticity affect the success of individuals and populations in changing environments. We assessed the plasticity-history limitation on predator-induced defenses in anurans (Wood Frogs, Lithobates sylvaticus (LeConte, 1825), and Northern Leopard Frogs, Lithobates pipiens (Schreber, 1782)), predicting that plastic responses to predation risk by dragonfly larvae (family Aeshnidae) in the embryonic environment would limit the defensive response to predators in the larval environment. Predator-conditioned Wood Frog embryos increased relative tail depth in response to those same cues as larvae, whereas predator-naive tadpoles did not. However, no carryover effect was noted in the behavioural response of Wood Frog tadpoles to predation risk. Predator-naive Northern Leopard Frog tadpoles increased relative tail depth in response to predation risk in the larval environment. Predator-conditioned Northern Leopard Frog embryos hatched with, and maintained, a marginal increase in tail depth as larvae in the absence of predation risk. Predator-conditioned Northern Leopard Frog embryos exposed to predation risk as larvae showed no morphological response. While we find no strong support for the plasticity-history limitation per se, carryover effects across embryonic and larval life-history stages were noted in both Wood Frog and Northern Leopard Frog, suggesting that predation risk early in ontogeny can influence the outcome of future interactions with predators.