Diet and chemical defenses of the Sonoran Desert toad

Summary & key facts

Researchers studied wild Sonoran Desert toads and nearby frogs around Tucson, Arizona. They checked what the animals ate and what chemicals the toads secreted from their skin glands. They found that the Sonoran Desert toads all had high levels of the psychedelic chemical 5-MeO-DMT, while other nearby frogs did not. The toads did not eat a special or unusual diet compared with the other frogs, so the study suggests the toads do not get 5-MeO-DMT from their food. This makes it more likely that the toads either make the chemical themselves or get it from microbes that live with them, but the study did not prove which of those is true.

Key facts:

• The Sonoran Desert toad was the only species observed to have high amounts of the psychedelic chemical 5-MeO-DMT in its skin secretions.
• Researchers compared skin gland secretions and stomach contents from Sonoran Desert toads and other frogs living in the same areas around Tucson, Arizona.
• The toads’ diets were very similar to the diets of the other frogs nearby, so the toads do not appear to eat a special set of prey that would explain the 5-MeO-DMT.
• There were small differences in what the toads ate in natural versus urban places, but those differences did not explain why only the Sonoran Desert toads had 5-MeO-DMT.
• Because diet did not explain the presence of 5-MeO-DMT, the study supports two other ideas: the toads may make 5-MeO-DMT inside their own bodies, or microbes that live with the toads may make it for them.
• The study did not directly show how 5-MeO-DMT is produced, so the exact source of the chemical remains unknown and needs more research.

Abstract

The 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 in I. alvarius remains unknown. Some amphibians produce chemical defenses endogenously or through symbiotic interactions, while others acquire them from specialized diets. In this study we analyzed toxin gland secretions and diet profiles from wild I. alvarius and sympatric anurans from native and urban habitats around Tucson, Arizona to explore possible links between diet and 5-MeO-DMT production. All I. alvarius secreted high concentrations of 5-MeO-DMT, whereas other sympatric toads did not. The diet of I. alvarius was similar to that of sympatric anurans, indicating that I. alvarius does not exhibit relative dietary specialization. We found slight dietary differences between I. alvarius in native and urbanized habitats. Taken together, these lines of evidence suggest that diet is not directly linked to 5-MeO-DMT production and support the alternative hypotheses that I. alvarius synthesizes 5-MeO-DMT endogenously or via a microbial symbiont.

Topics

Amphibian and Reptile Biology Primate Behavior and Ecology Psychedelics and Drug Studies

Categories

Environmental Science Global and Planetary Change Physical Sciences

Tags

Biology Chemical defense Chemical toxicity Desert (philosophy) Ecology Feeding behavior Habitat Herbivore Interspecific competition Introduced species Sauria Secretion Sympatric speciation Sympatry Toad Zoology

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