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

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Abstract
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 5 spp of Phyllobates [P. terribilis, P. bicolor, P. aurotaenia, P. vittatus, and P. lugubris], 12 ssp. of Dendrobates [D. auratus, D. tinctorius, D. steyermarki, D. pumilio, D. bombetes, D. arboreus, D. viridis, D. histrionicus, D. speciosus, D. espinosai, D. trivittatus, and an unnamed new species] and 2 spp. of Colostetbus [C. inguinalis and an unnamed new species] 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 Choco 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 5 million years; 2 ssp. 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 3 million years ago. The species of Dendrobates (s. l.) 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.