Phylogeography of ants from the Brazilian Atlantic Forest

Known for its remarkable biodiversity and high levels of endemism, the Brazilian Atlantic Rainforest has been characterized as one of the most threatened biomes on the planet. Despite strong interest in recent years, we still lack a comprehensive scenario to explain the origin and maintenance of diversity in this region, partially given the relatively low power of analyses involving few independent genetic loci. In this study, we examine a phylogenomic dataset of five ant species to investigate phylogeographical patterns across the Brazilian Atlantic Forest. We sequenced ultraconserved elements to generate hundreds of loci using a bait set developed specifically for hymenopterans. We analyzed the data using Bayesian and maximum likelihood approaches of phylogenetic inference. Results were then integrated with environmental niche modeling of current and past climates, including the Last Glacial Maximum and the last interglacial period. The studied species showed differentiation patterns that were consistent with the north/south division of the Atlantic Rainforest indicated in previous studies for other taxa. However, there were differences among species, both in the location of phylogeographic breaks and in the pattern of genetic variation within these areas. Samples from southern localities tended to show recent genetic structure, although a site in Tapiraí (state of São Paulo) repeatedly showed an intriguing older history of differentiation. All species experienced shifts in areas of suitability through the time. Our study suggests that distinct groups may have responded idiosyncratically to the climatic changes that took place in the Brazilian Atlantic Forest. The amount of intraspecific genetic structure was related to the inferred geographical distribution of habitat suitability according to current and past times. Also, a parallel between the amount of Quaternary climatic suitability and the level of interspecific differentiation was detected for four species. Finally, despite strong contractions at the northeastern region of the forest, the remaining areas appear to have been able to act as refugia.