The influence of predator threat on the timing of a life-history switch point: predator-induced hatching in the southern leopard frog (Rana sphenocephala)

Abstract

We tested the hypotheses that potential egg predators, crayfish Procambarus nigrocinctus and dytiscid Cybister sp. larvae, would accelerate the timing of hatching and that a larval predator, dragonfly naiad Anax junius, would delay hatching in the southern leopard frog (Rana sphenocephala). We also tested the hypothesis that differences in response would be proportional to predator lethality. Our results indicate that our hypotheses were partially supported. The presence of an efficient egg predator (crayfish) induces hatching faster than a less efficient predator (dytiscid larvae). However, the presence of a larval predator (naiads) did not delay hatching. Eggs that developed in the presence of egg predators produced hatchlings that were shorter (total length) than those reared in the presence of larval predators or those reared in the absence of predators. We suggest that earlier hatching times should decrease vulnerability to egg predators but result in shorter hatchlings.

How do embryos assess risk? Vibrational cues in predator-induced hatching of red-eyed treefrogs

“…Sih & Moore 1993;Warkentin 1995;Moore et al 1996;Vonesh 2000;Chivers et al 2001;Laurila 2002;Wedekind 2002;Johnson et al 2003). Such responses indicate that embryos are receiving and interpreting information about conditions in their environment.…”

“…None the less, in the last decade it has become increasingly clear that they are not completely defenceless, nor solely reliant on parentally provided defence. In several species of amphibians, embryos alter their hatching stage in response to risk of predation or pathogen infection (Sih & Moore 1993;Warkentin 1995;Vonesh 2000;Chivers et al 2001;Warkentin et al 2001;Laurila 2002;Johnson et al 2003). Pathogen-induced early hatching has also been demonstrated in fish (Wedekind 2002).…”

Flexible information sampling in vibrational assessment of predation risk by red-eyed treefrog embryos

“…Some embryos respond to chemical cues (e.g. Chivers et al, 2001;Johnson et al, 2003) and others to vibrational cues from predators (Warkentin, 2005). These responses provide a natural context in which to examine the sensory and information-processing capacity of embryos.…”

Herbicide exposure affects the chemical recognition of a non native predator in common toad tadpoles (Bufo bufo)

“…In the present work, the conditioning association leading to the learned chemical recognition of the predator resulted from exposure of freeswimming tadpoles. However, recent studies have shown that amphibian eggs and hatchlings can exhibit phenotypic plasticity in response to chemical cues indicating predation (Chivers et al 2001;Laurila et al 2001Laurila et al , 2002Johnson et al 2003;Orizaola & Braña 2004;Saglio & Mandrillon 2006). Consequently, it might be speculated that these early developmental stages have also the ability to develop the Pavlovian conditioning (Pavlov 1906) involved in the chemical recognition of novel predators.…”