Genetic divergence and speciation in lowland and montane peruvian poison frogs.

Amazonia is famous for high biodiversity, and the highlands of the transition zone between the Andes and the lowlands of the Amazon basin show particularly high species diversity. Hypotheses proposed to explain the high levels of diversity in the highlands include repeated parapatric speciation across ecological gradients spanning the transition zone, repeated allopatric speciation across geographic barriers between the highlands and lowlands, divergence across geographic barriers within the transition zone, and simple lineage accumulation over long periods of time. In this study, we investigated patterns of divergence in frogs of the genus Epipedobates (family Dendrobatidae) using phylogenetic and biogeographic analyses of divergence in mitochondrial DNA (1778 aligned positions from genes encoding cyt b, 12S and 16S rRNA for 60 Epipedobates and 11 outgroup specimens) and coloration (measured for 18 specimens representing nine species in Epipedobates). The majority of phenotypic and species diversity in the poison frog genus Epipedobates occurs in the transition zone, although two morphologically conserved members of the genus are distributed across the lowlands of the Amazon basin. Phylogenetic analysis reveals that there is a single highland clade derived from an ancestral colonization event in northern Peru by a population of lowland ancestry. Epipedobates trivittatus, a widespread Amazonian species, is a member of the highland clade that reinvaded the lowlands. Comparative analyses of divergence in coloration and mtDNA reveals that divergence in coloration among populations and species in the highlands has been accelerated relative to the lowlands. This suggests a role for selection in the divergence of coloration among populations and species.