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Albumin Evolution in Tropical Poison Frogs (Dendrobatidae): A Preliminary Report

1985; Wiley; Volume: 17; Issue: 1 Linguagem: Inglês

10.2307/2388378

1744-7429

Linda R. Maxson, Charles W. Myers,

Mosquito-borne diseases and control

The Dendrobatidae are a predominantly South American group with a minor center of diversity in southern Central America. A study of albumin evolution was initiated in order to help elucidate phylogenetic lineages within the family and to estimate their time of arrival in Central America. Using antisera to serum albumin from Phyllobates terribilis and Dendrobates auratus, the albumins of all five species of Phyllobates, 12 species of Dendrobates, and two species of Colostethus were compared by the quantitative immunological technique of micro-complement fixation. The results accord with the previous recognition of Phyllobates as a monophyletic group defined by the presence of batrachotoxins, unique skin alkaloids used by the Choc6 tribes of western Colombia as a potent dart poison. Speciation events leading to the living species of true dart-poison frogs (Phyllobates) appear to have occurred within the last five million years; two species in Costa Rica and western Panama were derived from a primitively striped ancestor that probably invaded Central America after uplift of the Isthmus of Panama about three million years ago. The species of Dendrobates (s. 1.) thus far studied are genetically much more variable than Phyllobates, which is consistent with accumulating evidence that Dendrobates is a polyphyletic assemblage. Several major lineages of dendrobatids seem to date back to the start of the Cenozoic, about 60 million years ago. NEOTROPICAL FROGS of the family Dendrobatidae have long attracted attention because of the brilliant coloration of many species and because of their unusual life-style, which includes diurnal habits, terrestrial eggs, and transport of tadpoles to water on the back of a nurse frog (reviewed by Myers and Daly 1983). It has been known since the early 19th century that Indians obtain a potent poison for blowgun darts from dendrobatid frogs in western Colombia. The few fragmentary investigations of this custom were among the reasons that led various writers to surmise that all brightly colored dendrobatids are and that such frogs are used as a source of arrow poison by a diversity of Indian tribes outside of western Colombia. Myers et al. (1978) presented new ethnographic data and reviewed the relevant literature. They pointed out that three unusually species of Phyllobates confined to western Colombia are the only frogs known with certainty to have been used for poisoning blowgun darts (not arrows), and that only the Embera Choco and Noanama Choco are positively known to have practiced this custom, which is now on the dedine. One still hears reports of frog poisons being used in other regions but these remain unconfirmed, and, in any case, the great majority of published statements are certainly fictional. The assumption that all brightly colored dendrobatids are toxic or at least noxious has proven to be essentially correct, although several relatively dull-colored species also secrete defensive