DISSERTATION RESEARCH: Why poison frogs don't poison themselves: phylogenetic origins and consequences of autoresistance

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Poison frogs (family Dendrobatidae) are well known for their bright colors and for the toxins (alkaloids) contained in their skin. In fact, some of the most powerful natural toxins known are found in dendrobatid frogs. Because these toxins interfere with the function of ion channels (proteins in cell membranes that control muscle contraction and sensory systems), predators exposed to poison frog alkaloids may experience numbness, slowed muscle response, or even respiratory failure at high doses. Predators of poison frogs learn to associate the frog's bright color with distastefulness and toxicity, and then avoid them as prey items. How is that poison frogs are not poisoned by their own toxins, and how could such a complex system evolve? One hypothesis is that genetic changes in ion channels within poison frogs prevent the adverse effects of alkaloids and thus prevent self-toxicity, and that this pre-adaptation enabled the evolution of the overall predatory defense system. This project will utilize new methods of DNA analysis and physiological tests of ion channel function in toxic and non-toxic poison frogs to reveal the evolutionary basis of toxin resistance in this group. In a broader context, this research will contribute to understanding the general effects of toxins and how resistance to these toxins can evolve. It will also strengthen international collaborations between scientists in Ecuador and the United States, and train several students in field and laboratory work.