Embryonic experience to predation risk affects tadpoles of the common frog (Rana temporaria)

Abstract

Amphibians are known to exhibit phenotypic plasticity in response to variations in predation pressure. Data also indicate that developmental changes can be induced by embryonic exposures to predator non-contact cues. However, the possible consequences of such exposures on larval behavioural activity and sensitivity to chemical cues from predators have remained unexplored. These laboratory experiments examine the effects of predation cues experienced during embryonic development on some morphological and behavioural traits in hatchlings and tadpoles of the common frog (Rana temporaria). Eggs were raised until hatching in the nonlethal presence of either a sympatric predator (larval spotted salamander, Salamandra salamandra), or an allopatric predator (juvenile Turkish crayfish, Astacus leptodactylus), or crushed conspecific tadpoles. Predators were kept either starved, or fed with R. temporaria tadpoles. Embryonic treatments had significant consequences on weight and total length of hatchlings, as well as on the general activity of tadpoles. Olfactometric tests showed that the behavioural responses of tadpoles to chemical cues from the two predators tested were not significantly affected by embryonic treatments. In contrast, embryonic experience showed a significant influence on the behavioural response of tadpoles to chemical cues from crushed conspecifics. These results indicate that the morphology of hatchlings depends on the species and diet of the predators present during embryonic development and demonstrate for the first time that the subsequent activity and chemically mediated antipredator behaviour of tadpoles can be influenced by embryonic experience of the predation risk.