Effects of embryonic exposure to conspecific chemical cues on hatching and larval traits in the common frog (Rana temporaria)

Abstract

Recent studies indicate that amphibian eggs are capable of hatching plasticity in response to chemical cues released by predators feeding on conspecific eggs or larvae. However, information is scarce on the relative importance of predator and conspecific cues in such a process. In particular, no attempt has been made to compare the effects of embryonic exposures to chemical cues indicative of a predation risk for eggs and larvae, although both life stages can co-occur in natural habitats. In this context, common frog embryos (Rana temporaria) were raised until hatching in the presence of crushed conspecific extracts from eggs and tadpoles to assess their respective influences on some hatching and larval traits. While a significant delay in hatching time was observed in embryos exposed to chemical cues from tadpole extract, this life-history shift appeared unaffected by embryonic exposure to egg extract. Hatchlings derived from eggs incubated in the presence of both conspecific extracts showed a significantly greater weight than unexposed controls. However, such an effect was no longer apparent 15, 30 and 50 days after hatching, suggesting that embryonic exposure to chemical cues from damaged conspecific eggs and tadpoles has no influence on larval growth. Lastly, morphological measurements performed on hatchlings and older tadpoles (15, 30 and 50 days old) revealed no significant effect of embryonic treatments on the shape of body and tail.

Phylogenetic patterns of trait and trait plasticity evolution: Insights from amphibian embryos

“…We also observed that embryos exposed to crushed eggs induced earlier time to hatching in two experiments, a later time to hatching in two experiments, and no change in 19 experiments. We only found two studies that have examined amphibian embryo responses to damaged eggs; one study observed the induction of earlier hatching ( Chiromantis hansenae ; Poo & Bickford ), whereas the other study observed no effect ( L. temporaria ; Mandrillon & Saglio ). Collectively, these results suggest that amphibian embryos often respond to cues from crayfish eating conspecific eggs and occasionally respond to cues from damaged conspecific eggs.…”

Effects of potential predator and competitor cues and sibship on wood frog (Rana sylvatica) embryos

“…Four species of Triturus newts hatched smaller and at a less developed stage than embryos not exposed to the predator cues (Orizaola and Braña, 2004). Rana temporaria exposed to cues from crushed conspecifics were larger, and had longer tails compared to controls (Mandrillon and Saglio, 2007).…”

“…Some embryos can also accelerate hatching in response to fungal pathogens Touchon et al, 2006) or delay hatching in the presence of cues from crushed conspecifics (Mandrillon and Saglio, 2008). In addition some amphibian species show changes in morphology (e.g., body size or shape) or developmental stage at hatching depending on the presence of predator cues (e.g., Orizaola and Braña, 2004;Mandrillon and Saglio, 2007). The cues that affect embryos can be quite specific and attuned to actual risk (e.g., Warkentin et al, 2006).…”

Semiochemicals in Anurans: Testing Different Categories with One Poison Frog Species

“…However, the defi nitions of releaser and primer pheromones are not mutually exclusive, since physiological changes also ( 1981 ) trigger behavior. In anurans physiological effects are typically of morphological nature (e.g., Mandrillon and Saglio 2008 ;Hagman et al 2009 ), but they can also infl uence time until hatching or metamorphosis (e.g., Kiesecker et al 2002 ;Touchon et al 2006 ;Mandrillon and Saglio 2007 ). Based on an extensive literature review, primer pheromones infl uencing the adult stage have not been described thus far in anurans.…”