Diet and chemical defenses of the Sonoran Desert toads

Abstract

AbstractThe Sonoran Desert Toad (Incilius alvarius) is the only animal known to secrete the psychedelic compound 5-MeO-DMT as a chemical defense, but the source of 5-MeO-DMT inI. alvariusremains unknown. Some amphibians endogenously produce chemical defenses while others acquire them from specialized diets. In this study we analyzed toxin gland secretions and diet profiles from wildI. alvariusand sympatric anurans from native and urban habitats around Tucson, Arizona to explore possible links between diet and 5-MeO-DMT production. AllI. alvariussecreted high concentrations of 5-MeO-DMT, whereas other sympatric toads did not. The diet ofI. alvariuswas similar to that of sympatric anurans, indicating thatI. alvariusdoes not exhibit relative dietary specialization. Slight dietary differences betweenI. alvariusin native and urbanized habitats were observed. Taken together, these lines of evidence suggest that diet is not directly linked to 5-MeO-DMT production, and support the alternative hypotheses that Sonoran Desert toads synthesize 5-MeO-DMT endogenously or via a microbial symbiont.