Prior exposure to conspecific chemical cues affects predator recognition in larval common toad (Bufo bufo)

Abstract

In a laboratory experiment, we investigated the role played by conspecific chemical cues in the acquisition of chemical recognition of an unfamiliar predator by common toad tadpoles, Bufo bufo. During a ten-day period, we assigned one group of tadpoles to a control (unexposed) and five other groups to different conditioning treatments involving exposure to either an allopatric predatory crayfish (Astacus leptodactylus), or a sympatric harmless gastropod (Lymnaea stagnalis). We kept the caged crayfish under three conditions: i) starved, ii) starved in combination with cues from crushed tadpoles, or iii) fed with toad tadpoles. In the same way, we kept the caged pond snails either alone or paired with cues from crushed tadpoles. After exposure, we carried out behaviour measurements to assess the effects of conditioning treatments on the behavioural responses to chemical cues from starved crayfish, pond snails and crushed conspecifics. Test solutions from starved crayfish and snails produced a significant decrease in the percentage of moving tadpoles, a known antipredator response, but only in the two groups of tadpoles previously exposed to these organisms in combination with cues from crushed conspecifics. These results indicate that Bufo bufo tadpoles can learn to recognize an organism as representing a predation risk based on a prior association between the chemical stimuli from that organism and the chemical cues from damaged conspecifics. © 2005 E. Schweizerbart'sche Verlagsbuchhandlung.