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

毒蛙(Dendrobatidae科)以其鲜艳的颜色和皮肤中含有的毒素(生物碱)而闻名。事实上，已知的一些最强的天然毒素是在树蛙身上发现的。由于这些毒素干扰离子通道(控制肌肉收缩和感觉系统的细胞膜蛋白质)的功能，暴露在毒蛙生物碱中的捕食者可能会在高剂量下出现麻木、肌肉反应减慢，甚至呼吸衰竭。毒蛙的捕食者学会了将青蛙的鲜艳颜色与厌恶和毒性联系起来，然后避免将它们作为猎物。为什么毒蛙不是被它们自己的毒素毒死的，这样一个复杂的系统是如何进化的？一种假设是，毒蛙体内离子通道的遗传变化防止了生物碱的不利影响，从而防止了自我毒性，这种预适应使整个捕食性防御系统得以进化。本项目将利用新的DNA分析方法和对有毒和无毒毒蛙离子通道功能的生理测试，来揭示这一群体毒素抗性的进化基础。在更广泛的背景下，这项研究将有助于了解毒素的一般影响以及对这些毒素的抵抗力是如何演变的。它还将加强厄瓜多尔和美国科学家之间的国际合作，并培训几名学生从事实地和实验室工作。

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.