Widespread introgression across a phylogeny of 155 Drosophila genomes

Genome-scale sequence data has invigorated the study of admixture and introgression, particularly in animals. However, outside of a few notable cases, we lack systematic tests for introgression at the macroevolutionary scale across entire clades. Here we leverage 155 genome assemblies, from 149 species, to generate a fossil-calibrated phylogeny and conduct multilocus tests for introgression across 9 monophyletic radiations within the genus Drosophila. Using complementary phylogenomic approaches, we identify widespread introgression across the evolutionary history of Drosophila. Mapping gene-tree discordance onto the phylogeny revealed that both ancient and recent introgression has occurred, with introgression at the base of species radiations being a particularly common feature. Our results provide the first evidence of introgression occurring across the evolutionary history of Drosophila and highlight the need to continue to study the evolutionary consequences of hybridization and introgression in this genus and across the Tree of Life.