Biogeography of Mouse Opossums Genus Gracilinanus (didelphimorphia: Didelphidae) and Population Dynamics of G. Agilis and G. Microtarsus

Non-flying small mammals are interesting models to study biogeographic patterns due to their low vagility and diverse distribution patterns. Gracilinanus is a genus of mouse opossums widely distributed in different South American biomes, consisting of seven species. G. agilis and G. microtarsus, show distinct habitat preferences. The former is distributed over dry open forests and the latter is restricted to the Brazilian Atlantic Forest. In this study, we utilize molecular data to reconstruct the biogeographic history of Gracilinanus and the demographic history of G. agilis and G. microtarsus through probabilistic models: DEC and ABC models. We estimated the origin of the genus in the Middle Miocene and our analyses support that the uplift of the Andes could have been one of the major drivers of diversification. Looking at the past demographic history of two widely distributed species we found evidence of recent population expansion for G. agilis but not for G. microtarsus. These results suggest that G. microtarsus was ecologically resilient to maintain its effective population sizes throughout the glacial cycles during the Pleistocene. In contrast, ecological instability was higher for G. agilis, especially in the Caatinga biome.