Susceptibility of fire-bellied toad (B. bombina and B. variegata) tadpoles to predation

<p><em>B. bombina</em> and <em>B. variegata</em> are ecologically distinct taxa that nevertheless hybridise in nature wherever their distribution ranges adjoin. These data were collected to test the hypothesis that <em>B. variegata</em> tadpoles are more susceptible to predation than those of <em>B. bombina</em>. The former develop in ephemeral aquatic sites that can be predator-free, whereas the latter are found in predator-rich semi-permanent ponds. Tadpoles of both taxa were raised under under uniform laboratory conditions and their relative predation risk was assessed over a four-week period using dragonfly larvae as predators. The tadpoles were reared in the presence of chemical predation cues so that they could develop a predator-induced phenotype. The data confirm our hypothesis. These results suggest that <em>B. variegata</em> traits associated with higher predation risk produce barriers to gene flow across the hybrid zone.</p>