The Brazilian Atlantic Forest (BAF) is one of the most impacted biomes in the world, and in this region, there are several examples of the effects of Pleistocene climate changes among the species found there. Athenaea fasciculata (Solanaceae) is a forest component distributed mainly throughout the BAF extension. Here, we investigated the genetic diversity and population structure of A. fasciculata based on plastid and nuclear markers, aiming to better understand the impact of Pleistocene climate changes on BAF vegetation. We used population genetics, demographic methods and ecological niche modelling coupled to an evolutionary approach to describe the species distribution across time. The phylogeographic analysis of A. fasciculata indicated that Pleistocene climate changes played an important role in its evolution. The species is structured in two groups of populations that emerged from different refugia and were under different climate influences, supporting previously proposed connections between the Atlantic and Amazon Forests, the two most important Neotropical rainforests. [ABSTRACT FROM AUTHOR]