Brazilian scientists have discovered that the strong odor released by some amphibian species is produced by bacteria and that attracting a mate is one of its purposes. The bacteria in question are a noteworthy example of symbiosis as they assist in the animal's mating process. A paper recounting the discovery of this role of microorganisms isolated from the skin of frogs has been published in the journal Proceedings of the National Academy of Sciences (PNAS).
"Frogs emit a pungent odor. Sometimes a particular species can be recognized by its scent, but until now, the function of this odor was unknown. It was typically assumed to be an aposematic smell, meaning a chemical warning sign that served to repel predators, as in the case of skunks [Mephitis mephitis] among mammals, for example," said Célio Haddad, a professor at São Paulo State University's Rio Claro Bioscience Institute (IBRC-UNESP) in Brazil and a coauthor of the article.
According to Haddad, who is also affiliated with the university's Aquaculture Center (CAUNESP) in Jaboticabal, this hypothesis was considered plausible because many amphibian species, especially when poisonous, are brightly colored, and this serves as a visual alert to frighten predators. "We thought odor might play a similar role among anurans [frogs and toads]," he said.
The new study resulted from the postdoctoral research of Argentinean biologist Andrés Eduardo Brunetti, supervised by Professor Norberto Peporine Lopes. Conducted at the University of São Paulo's Ribeirão Preto School of Pharmaceutical Sciences (FCFRP-USP), the research was supported by FAPESP.