Chapter 21 A Review of Chemical Defense in Poison Frogs (Dendrobatidae): Ecology, Pharmacokinetics, and Autoresistance Juan C. Santos , Rebecca D. Tarvin , and Lauren A. O’Connell 21.1 Introduction Chemical defense has evolved multiple times in nearly every major group of life, from snakes and insects to bacteria and plants (Mebs 2002 ). However, among land vertebrates, chemical defenses are restricted to a few monophyletic groups (i.e., clades). Most of these are amphibians and snakes, but a few rare origins (e.g., Pitohui birds) have stimulated research on acquired chemical defenses (Dumbacher et al. 1992 ). Selective pressures that lead to defense are usually associated with an organ- ism’s limited ability to escape predation or conspicuous behaviors and phenotypes that increase detectability by predators (e.g., diurnality or mating calls) (Speed and Ruxton 2005 ). Defended organisms frequently evolve warning signals to advertise their defense, a phenomenon known as aposematism (Mappes et al. 2005 ). Warning signals such as conspicuous coloration unambiguously inform predators that there will be a substantial cost if they proceed with attack or consumption of the defended prey (Mappes et al. 2005 ). However, aposematism is likely more complex than the simple pairing of signal and defense, encompassing a series of traits (i.e., the apose- matic syndrome) that alter morphology, physiology, and behavior (Mappes and J. C. Santos (*) Department of Zoology, Biodiversity Research Centre , University of British Columbia , #4200-6270 University Blvd , Vancouver , BC , Canada , V6T 1Z4 e-mail:
[email protected] R. D. Tarvin University of Texas at Austin , 2415 Speedway Stop C0990 , Austin , TX 78712 , USA e-mail:
[email protected] L.