Convergent Evolution of Poison Frogs and Ants
Proceedings of the National Academy of Sciences release
August 10, 2005
A steady diet of ants may have driven the convergent evolution of
poisonous frogs in Madagascar and the Americas, researchers report.
 Painted mantella (Mantella madagascariensis) in Madagascar. |
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Some frog species in both Madagascar and the Neotropics secrete a
variety of toxic skin chemicals, called alkaloids, for protection
against predation. These “poison frogs” do not produce the alkaloids,
however, but instead attain them from their insect-rich diet. While
Neotropic frogs are well-studied, the alkaloid sources for Malagasy
frogs are unknown. Valerie Clark and colleagues extracted alkaloid
samples from both Malagasy frogs and their food sources, which were
determined by examining the frogs’ stomach contents. The authors found
that Malagasy frogs, like their New World counterparts, acquire their
alkaloids from a diet rich in ants. Thirteen of the 16 Malagasy
alkaloids detected are also known to exist in insects and frogs in the
Americas. Neither the frogs nor the ants in these two regions are
closely related,
which suggests that the evolution of acquisition
mechanisms for protective alkaloids in these ant species was likely
responsible for the subsequent convergent evolution of the frogs that
preyed on them. Additionally, the researchers found the well-known plant
alkaloid nicotine in one Malagasy frog species, suggesting a possible
plant-insect-frog toxin food chain.
Article #03502: “Convergent evolution of chemical defense in poison
frogs and arthropod prey between Madagascar and the Neotropics” by
Valerie C. Clark, Christopher J. Raxworthy, Valérie Rakotomalala, Petra
Sierwald, and Brian L. Fisher
MEDIA CONTACT: Valerie C. Clark, Cornell University, Ithaca, NY; tel:
212-864-1123; fax: 607-255-1227; e-mail:
The above text is copyright Proceedings of the National Academy of Sciences