Late Pliocene and Quaternary Palaeogeographical and Climatic Drivers of Diversification in the Neotropical Leishmaniasis Vector Sand Fly Group <i>Lutzomyia</i> s.l.

ABSTRACT Aim The aim of this study was to investigate the evolutionary and palaeogeographical drivers of diversification in the Neotropical sand fly group Lutzomyia s.l., a major vector of leishmaniasis, across the Americas. Location The study was focused on the Neotropical regions of the Americas. Time Period The diversification of Lutzomyia s.l. was examined over the past 9 million years, with emphasis on the Late Pliocene and Quaternary. Major Taxa Studied A total of 68 extant taxa of Lutzomyia s.l. were analysed. Methods A phylogenetic time tree was reconstructed to estimate divergence times. Kernel density estimation was applied to identify diversification peaks. Palaeoclimatic suitability models were developed for the mid‐Piacenzian, MIS19, the Last Interglacial and the Last Glacial Maximum to assess historical distributional shifts. Results It was revealed that all extant lineages of Lutzomyia s.l. originated within the last 9 million years, with a diversification peak between 3.25 and 0.6 million years ago, particularly around 1.625 million years ago. The emergence of key vector groups, including the Lutzomyia longipalpis complex, was shown to coincide with periods of increasing climatic instability and with major palaeogeographical events such as the final closure of the Isthmus of Panama. Kernel density analysis indicated that most divergence events occurred during the early Pleistocene, closely aligned with the onset of end‐Pliocene cooling. Climatic suitability models demonstrated expansions and contractions of habitats in response to climatic transitions, sea level fluctuations and biome shifts. Following the Last Glacial Maximum, a general poleward expansion and regional habitat recovery were observed, particularly in the Brazilian Highlands and Central America. Main Conclusions It was demonstrated that past climatic and palaeogeographical changes strongly shaped the diversification and distribution of Lutzomyia s.l. These findings provide insights into the historical biogeography of this vector group and contribute to understanding the potential future spread of leishmaniasis.