A dinâmica filogeográfica explica o isolamento entre Pithecopus ayeaye e Pithecopus megachephalus, duas pererecas endêmicas de ilhas de altitude no domínio dos campos rupestres?

Abstract

The Serra do Espinhaço (SE) and the Quadrilátero Ferrífero (QF) are two large physiographic units that extend lengthways the eastern portion of Brazil along the states of Bahia and Minas Gerais. Although the history of these formations is different, both have in common the ecosystem of the campos rupestres, that are generally restricted to altitudes above 900m. Despite occupying less than one percent of the national territory, this ecosystem has a high rate of endemism. Among the endemic species of this phytophysiognomy are two monkey-frogs, Pithecopus ayeaye Lutz, 1966 and P. megacephalus (Miranda-Ribeiro, 1926) (Hylidae: Phyllomedusinae), that show several similarities, such the reticulated pattern on flanks, the territorial behaviour of males and the use of first order crystalline water bodies, permanent or temporary, for reproduction even though they are not sister lineages. Although they have an allopatric distribution, with a distribution limit between the QF and the Southern Espinhaço (SdEM), an area of high climatic suitability between these physiographic units was evidenced in a previous study. In this sense, we aimed to test the following hypotheses: (1) the climatic oscillations of Pleistocene propitiated the contact between P. ayeaye and P. megacephalus, which would be evidenced by historical signatures of interspecific gene flow and the increase of diffusion rates in moments of expansion of suitable climatic areas (i.e., glacial periods), if they occurred. Alternatively, (2) those species remaining isolated throughout their evolutionary history, which would imply in strong genetic isolation resulting from barriers to gene flow and lack of correlation between diffusion acceleration and glacial periods. In addition, we do not expect to find a relation between phylogeographic diffusion rates and past changes in suitable areas for the species. To test these hypotheses, we applied models on gene flow, ecological niche, and phylogeographic diffusion in a statistical phylogeographic way.