Non-lethal contact with pathogenic agents affects disease transmission rates by yielding a positive selective pressure on avoidance of infectious agents. Oak toads, for example, learn to avoid the pathogenic fungus Batrachochytrium dendrobatidis (Bd) after one infection clearance event. Here, we investigated whether four taxonomically distinct species of amphibians, greenhouse frogs (Eleutherodactylus planirostris), pine woods treefrogs (Hyla femoralis), Cuban treefrogs (Osteopilus septentrionalis), and southern toads (Bufo terrestris), were also able to learn to avoid Bd and, if so, what cues they used to identify Bd.
Results/Conclusions
We found that Bd-naïve Cuban and pine woods treefrogs demonstrated an innate ability to avoid Bd, while Bd-naïve southern toads did not avoid Bd initially but learned to avoid Bd after only one exposure, and greenhouse frogs never avoided Bd even with previous Bd experience. The southern toads, which learned to avoid Bd after one exposure, avoided any treatment with Bd metabolites; and their avoidance response to dead and live Bd, as well as, treatments with and without zoospores did not differ significantly. The metabolites released by Bd, which includes enzymes that digest amphibian tissue, appear to be the cues that amphibians use to avoid Bd, consistent with a Classic or Pavlovian Conditioning response. We found that not all species respond the same way to Bd, which is important information when developing conservation and restoration plans.