Comparative landscape genetics in two amphibians demonstrates the influence of habitat specialization in a mountain range in Northeastern Brazil

Abstract Context Within the same geographical area, geographical distance is the most important landscape feature limiting dispersal in some species, whereas for others environmental variation, such as climate and vegetation patterns, may curtail dispersal. Such landscape effects are usually determined by the ecological traits of the species. Although very intuitive, landscape hypotheses remain poorly investigated in tropical regions. Objectives We developed a comparative landscape genetic study evaluating the association and importance of geographic and environmental landscape features on the genetic differentiation in two ecologically differing anurans, the treefrog Dendropsophus oliveirai (a reproductive habitat specialist) and the chorus frog Physalaemus cuvieri (a reproductive habitat generalist), in highland forests inserted in a dry vegetation matrix in Northeastern Brazil. Methods We applied Mantel tests and Structural Equation Modeling to assess associations between geographic distance and environmental factors on mitochondrial genetic variation of the two study species. Results We found lower genetic differentiation in P. cuvieiri, mainly associated with geographic distance along a latitudinal gradient and weakly influenced by environmental variation among highland forests. Conversely, the higher genetic differentiation in D. oliveirai was associated with a combination of geographic distance along a longitudinal gradient, environmental variation, and past climatic variation. Conclusions Idiosyncrasies in the genetic structure and associations with landscape features in the two species may have resulted from different abilities to cross the dry lowland among the mesic highland forests. Our findings also suggest selective and neutral evolutionary mechanisms conducive to intraspecific genetic variation in the study area.