A grant has been awarded to Dr. Paul Chippindale and Mr. Brice Noonan of the University of Texas at Arlington to study relationships, genetic and morphological variation, and population fragmentation in the poison-dart frog Dendrobates tinctorius. This species occurs only in the northeastern corner of South America (Guyana, Suriname, French Guiana, and Brazil). It is the largest species of poison-dart frog, and its biology is poorly understood. Dendrobates tinctorius exhibits a tremendous amount of variation in size and color pattern among populations. Although all of the morphologically diverse populations are currently considered a single species, the remarkable degree of variation among them may indicate major barriers to gene flow, and perhaps even the existence of multiple species. The investigators will use microsatellite and mitochondrial DNA to analyze geographic genetic structure of D. tinctorius from throughout its range. Dendrobates tinctorius is restricted to the Guianan Shield of South America. This region encompasses the largest undisturbed tract of tropical rainforest in the world. The distribution of D. tinctorius represents an extreme with respect to natural fragmentation; understanding how this pattern of isolation affects population dynamics and genetic diversity will help biologists predict effects of human-induced fragmentation on other, more continuously distributed species. Additionally, D. tinctorius may be in the early stages of speciation, and this study will provide insight into the degree of gene flow that is necessary for genetic cohesion within species. This work will involve collaboration with researchers in the countries in which D. tinctorius occurs, and will contribute to efforts to conserve biodiversity in the Guianan Shield in the face of increasing human pressure. The current decline of amphibians throughout the world makes an understanding of their biology, diversity, and distributional constraints vital to their continued survival, and this research will provide key insights in these respects.
