Acoustic and morphological dataset of seven anuran populations of two species from highland forests in Northeastern Brazil

Highlands are of paramount importance to the study of evolution as they
are frequently implicated in historical and ecological processes that
generate and maintain biological diversity. In northeastern Brazil, sparse
rainforest remnants are located in highlands north of the São Francisco
River, generally surrounded by the dry and open landscape of the Caatinga
biome. Earlier studies suggest that these forests acted as historical
refuges to the rainforest fauna and flora, especially during the climatic
cycles of the Pleistocene. However, it is still unclear whether
populations distributed in distinct highlands experienced phenotypic
differentiation as a result of adaptation to the environmental conditions
of each forest remnant. In this study, we used two frog species with wide
geographic distributions, Dendropsophus oliveirai, a habitat
specialist which breeds in permanent ponds, and Physalaemus cuvieri, a
habitat generalist which breeds in temporary and permanent lentic
environments, as models to investigate the relationships between
environmental variation, geographic, genetic, and body size distance with
advertisement call variation among populations inhabiting different
highlands. We hypothesized that call variation would be strongly
influenced by local environmental conditions, as sound signals are
frequently adapted to the transmission environment. Our results indicate
that acoustic variation among P. cuvieri populations is strongly
influenced by environmental variation and moderate by geographic distance.
In D. oliveirai, the environment is also the most influential factor in
acoustic variation, followed by genetic and morphological variation.
Besides that, the association between environmental and geographic factors
suggests an indirect effect of geographic distance on acoustic variation
in both species through an environmental gradient and also in genetic
traits of the habitat specialist species. We believe that selective
processes and isolation possibly act together in driving interpopulational
acoustic variation with habitat-specific species being more affected by
the isolation in suitable habitats.