ARTHROPOD ALKALOIDS IN POISON FROGS: A REVIEW OF THE 'DIETARY HYPOTHESIS'

Poison frogs are chemically defended from predators and/or microorganisms by the presence of alkaloids in dermal skin glands. Over the past 40 years, more than 800 alkaloids, which are generally organized into 28 structural classes, have been identified in several lineages of poison frogs worldwide. Originally, the presence of alkaloids in frogs was thought to be the result of biosynthesis, however research led largely by John W. Daly resulted in the discovery that most of these alkaloids are sequestered unchanged from dietary arthropods. In the present paper, we review the most significant findings and studies that led to the proposal of the 'dietary hypothesis'.