Predation embryonic amphibians

Examination of life-history shifts in embryonic amphibians has been a recent development. We have identified 18 studies between 1995 and 2003 that have tested the responses of larval amphibians to cues that represent potential danger. Of these 18 studies, 3 studies have tested mechanical cues tom predators (Warkentin, 1995,2000), 2 studies examine responses to pathogens (Warkentin et al., 2001 Kiesecker et al., unpublished data) and the remaining 13 studies examining chemical cues from predators (see Table 1). Chemosensory assessment of predation risk is widespread in aquatic systems (Chivers and Smith, 1998 Kats and Dill, 1998). Studies completed primarily in the last decade suggest that the level of this assessment is probably much more sophisticated than was previously thought This review will show that this sophistication is also present in the embryonic stage. 

Table 1. Summary of experiments that have tested predator-mediated life-history shifts in embryonic amphibians.

Rowe, C. L., Sadinsld, W. J., and Dunson, W. A., 1994, Predation on larval and embryonic amphibians by acid-tolerant caddisfly larvae (Ptilostomispostica), J.Herp. 28 357-364. 

The majority of smdies that examine shifts in life-history traits in amphibians focus on the shift from the tadpole to the juvenile stage. One stage that is often overlooked is the embryonic stage. The embryonic stage is viewed as a simple developmental stage, however, there is evidence that shows that amphibian embryos can detect and respond to cues from predators in their environments. The aim of this paper is to provide a review of studies that have examined life-history shifts in amphibian embryos in response to chemical cues from predators. From the results of these studies, we will develop generalized hatching patterns that may be used to predict these shifts in other amphibian species. We will also discuss the complexity and specificity of the chemical cues involved and lastly we will examine those results which do not fit into our hypothesized patterns and address why there is variability in life-history responses. 

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