An efficient statistical method of detecting introgressive events from big genomic data

Introgressive hybridization, also called introgression, is the gene flow from one species to another due to mating between species. The genetic signals of introgression are not always obviously observed. Current methods of detecting introgressive events rely on the analysis of orthologous markers, and therefore do not consider gene duplication and gene loss. Since introgression leaves a phylogenetic signal similar to horizontal gene transfer, introgression events can be detected under a gene tree-species tree reconciliation framework, which simultaneously accounts for evolutionary mechanisms including gene duplication, gene loss, and gene transfer. In this work, the reconciliation-based method has been applied to a large dataset of Anopheles mosquito genomes. We recover extensive introgression that occurs in gambiae complex, a group of African mosquitoes, although with some variations compared to previous reports. Our analysis results also imply a possible ancient introgression between the Asian and African mosquitoes.