Tracing the origins and evolution of nymphalid butterflies (Lepidoptera) in the Atlantic Forest

Understanding the relative roles of diversification and dispersal is key to explaining large‐scale biogeographical patterns. Although both processes are known to shape biodiversity, their relative contributions remain understudied for many organisms. Here, we examine how these processes have jointly contributed to the exceptional diversity and endemism of Nymphalidae butterflies in South America's Atlantic Forest, a global biodiversity hotspot. We obtained DNA sequences for 65 Nymphalidae species and integrated them into published time‐calibrated phylogenies. We used dispersal–xtinction–ladogenesis models and biogeographical stochastic mapping to infer historical biogeographical patterns over time, and the cladogenetic diversification rate shift (ClaDS) model to estimate region‐specific diversification patterns. We further evaluated whether regional patterns of diversification are associated with occurrence in montane environments or across the north–south biogeographical break within the Atlantic Forest. Our results show that nymphalid butterfly diversity in the region was driven primarily by recurrent dispersal from Amazonia and the Andes, rather than by elevated in situ diversification rates, which remained low and stable through time. Although dispersal increased progressively during the Cenozoic, we found no evidence that the diagonal of open formations acted as a major barrier, indicating that forest corridors probably allowed extensive dispersal between the Atlantic Forest and other Neotropical regions. Southern Atlantic Forest lineages exhibited slightly higher diversification rates than northern ones, especially among montane generalist species. However, overall diversification contributed little to the current species diversity patterns compared to the sustained input of dispersing lineages from other Neotropical biomes. Together, these findings highlight the central role of biome connectivity and dispersal in shaping Atlantic Forest Nymphalidae diversity, while underscoring the importance of jointly considering diversification and dispersal processes to better understand the macroevolutionary dynamics underlying current biodiversity patterns.