Integrative taxonomy and evolutionary ecology of the anthophilous Drosophila lutzii species complex (Diptera, Drosophilidae) provide evidence for range expansion of Drosophila alei

Cryptic species represent a substantial fraction of the diversity of Drosophilidae, hampering studies on species ecologies and their evolution. Anthophilous species within the Drosophila lutzii group encompass some of the most widely distributed Neotropical lineages. Nevertheless, their ranges, ecologies, divergence times, and phylogenetic relationships are largely unknown. In this study, we analyzed the cryptic diversity of the lutzii species complex occurring in Southern Brazil and shed light on the ecological and evolutionary processes underlying their current patterns of coexistence. We used an integrative approach, evaluating molecular, ecological, and morphological traits under an evolutionary ecology framework. We documented the unexpected occurrence of D. alei in Southern Brazil, whose range was only known for the Andean region. Our phylogenetic analysis indicated that despite morphological similarities, D. alei is more closely related to D. denieri than to D. lutzii, and that divergence among these three species dates back to the Neogene (7.3 Mya). Niche modeling suggests that D. denieri and D. lutzii populations expanded their ranges and were established in Southern Brazil during the Quaternary (150 kya), being affected by similar paleoclimatic events. On the other hand, D. alei shows distinct abiotic requirements than D. denieri and D. lutzii, and environmental distribution models suggested a significant reduction in its suitable areas during the Quaternary, especially in Southern Brazil. This suggests that the current sympatry observed in this region likely reflects a secondary contact between the three species resulting from niche divergence processes. Altogether, these results advance the understanding of the distribution and phylogenetic relationships of Neotropical anthophilous Drosophila, revealing the interplay between ecological and historical factors in their speciation.