Study discovers why poison dart frogs are toxic
Rhett Butler, mongabay.com
August 9, 2005
Poison poison dart frogs are small, colorful frogs found in the tropical forests of Central and South America. The brilliant coloration of these amphibians warns predators of their extraordinary toxicity -- the golden poison frog (Phyllobates terribilis) of Colombia is said to be lethal if held in one's hand.
The conclusion that poison frogs' toxic alkaloids are derived from ants explains why frogs reared in captivity lack the toxic defense of their counterparts in the wild. It also supports the observation that when poison frogs are introduced to non-native places like Hawaii their toxic alkaloids are different. Evidently, introduced frogs are feeding on different species of ants which have their own set of alkaloids.
|Golden mantella (Mantella aurantiaca) on the Indian ocean island of Madagascar. Like poison arrow frogs of the New World, Mantella frogs of Madagascar are capable of storing ant poisons in glands along their back. Their bright coloration wards of predators who have learned to avoid these conspicuous amphibians. Madagascar is home to an estimated 300 species of frogs.|
The creation of ABT-594 almost didn't happen. The area of Ecuadorian rainforest from which the frog was originally collected in 1974 was cleared shortly thereafter for banana plantations. Luckily, a second collection site still housed the frogs and scientists were able to collect a sample of the poison which would later serve as the template for the painkiller.
This near miss with ABT-594 illustrates the importance of conserving biodiversity, especially in the tropics. Frog conservation is of particularly concern given the recent worldwide decline in amphibians species. The Global Amphibian Assessment, a survey of the planet's amphibian species, found that nearly a third (32%) of the world's amphibian species are threatened. No one has yet pinpointed the ultimate cause for the demise of amphibians -- global climate change and the emergence of deadly chytrid fungal disease are often cited as prime culprits -- but it is evident that we may be losing a lot more than just some colorful frog species.
Mites are the primary source of poison arrow frog toxins
Release from the Proceedings of the National Academy of Sciences: Convergent Evolution of Poison Frogs and Ants
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.|
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:
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7 new species of frog discovered in Ecuador
(10/22/2008) Seven previously unknown species of frog discovered over the past two years by Ecuadorian researchers are already under threat from habitat loss, reports a newsletter from the IUCN Amphibian Specialist Group.
Mass amphibian die-offs affect ecosystems
(10/19/2008) Large-scale die-offs of amphibians due to the outbreak of a killer fungal disease is impacting the forest ecosystem in which they live, reports a new study published in the journal Ecosystems.