Mayer, M., P. Böning, A. P. Lima, H. Krehenwinkel, Y. O. C. Bitar, P. S. Bernarde, M. Veith, M. B. de Souza & S. Lötters

Disentangling the biogeographic history of a truly pan-Amazonian amphibian – the case of the three-striped poison frog, Ameerega trivittata (Dendrobatidae: Colostethinae). pp. 63-77 plus Supplementary document Fig S1, Supplementary document Fig S2, Supplementary document Fig S3, Supplementary document Table S1, Supplementary document Table S2. 

Abstract. Anuran amphibians have intensively been studied to understand Amazonian biodiversity. Improved methods and sampling has revealed that many widespread nominal species in fact are complexes of species with smaller allopatric ranges. Pan-Amazonian anuran species are rather an exception. In a case study using the three-striped poison frog (Anura: Dendrobatidae: Ameerega trivittata), we ask how the pan-Amazonian distribution of this taxon can be explained and hypothesize that dispersal has played a major role. Species delimitation and intraspecific relationships of the study species were examined from novel and existing (GenBank) sequences of the mitochondrial 16S rRNA gene from 108 specimens of 38 localities using maximum likelihood and Bayesian methods. We performed BioGeoBEARS models using a time-calibrated population tree to reconstruct the biogeographic history. Our results support that A. trivittata is a pan-Amazonian species scattered over its geographic range. Being of Late Miocene origin, the species rapidly spread into newly available space and repeatedly dispersed for-and backward, while vicariance played a major role only in the Early Pliocene. We suggest that intrinsic morphological and life history characteristics (adult size, relative reproductive success) make A. trivitta­ta a more successful disperser than other species, so that riverine barriers are more permeable and hamper allopatric speciation. We conclude that there is no universal causality explaining Amazonia biodiversity, because species-specific biological characteristics are key determents of biogeographical histories. Comparatively better dispersal advantages foster larger geographic ranges and can explain pan-Amazonian distributions.

Key words. Amphibia, Anura, BioGeoBEARS, dispersal, genetic diversity, mitochondrial DNA, Neotropics, riverine barrier, vicariance, widespread species.