Explorando processos que geram variação de cor em Adelphobates galactonotus, uma espécie de sapo colorido e venenoso endémico da Amazônia Oriental

Abstract

ABSTRACT An aposematic coloration could serve like a defense against visually oriented predators because conspicuous signals are easy to detect, memorize and associate with unpalatabilty. However, the evolutionary processes driving aposematic coloration are enigmatic, because to be effective, an aposematic signal needs to be consistent and common, and also, should be selected at initial low frequencies. In this thesis we sampled Adelphobates galactonotus, a dendrobatid anuran distributed at the east of the Brazilian Amazon, south Amazonas River, and with a dorsal coloration varying geographically, as a model to explain the processes generating color variation in dendrobatids. In Chapter I we assess if there is local upon coloration of A. galactonotus selection mediated by predators in two close localities containing exclusively blue or orange morfotypes. We show that there was no difference in the attack frequency by visually oriented predators (birds) among models with native coloration, an introduced coloration or a brown control coloration, not supporting the hypothesis that local selection mediated by visually oriented predators is the cause of geographic variation and independent evolutionary origin of different aposematic colors in A. galactonotus. In Chapter II we investigate whether color morphs have evolved independently several times and if selection patterns are associated with these, using sequences of two mitochondrial genes (mtDNA) and thousands of single nucleotide polimorphisms (SNPs). We found a strong genetic partitioning associated with Xingu River. Using mtDNA, the estimated divergence time between frogs from opposite riverbanks, was 4.8 million years ago (m.y.a.) and genetic linages conduced to different color divergences along the Pleistocene, suggesting that the same color evolved independently several times, east and west of the Xingu River. 16 SNPs were highly associated to color, suggesting a role in color determination. We propose that rapid evolution of color diversity probably began on populations geographically isolated during habitat fragmentation periods associated to Pleistocene.