Speciation in ants: Unlocking ant diversity to study speciation (Hymenoptera: Formicidae)

Ants are among the most abundant terrestrial animals and play key roles in ecosystems across the globe. Their taxonomic and ecological diversity makes them a prime taxon for contributing to our understanding of the patterns and processes of speciation.However, studies often do not explicitly link their results to the broader framework of speciation and reproductive isolation. Here we combine macroevolutionary work on ant diversification with microevolutionary studies on reproductive isolation and hybridization to review what is known about ant speciation. We also discuss how two key features, sociality and haplodiploidy, could impact speciation and hybridization in ants. We find that, although key innovations as drivers of ant diversification have been studied, several gaps exist in our understanding of reproductive isolating mechanisms in ants. However, general population features or traits such as co-evolution within mutualistic or parasitic relationships suggest that reproductive isolating mechanisms are generalizable across the tree of life. We suggest that ants provide a sound system to study general aspects of speciation, especially hybridization, the genomic basis of intrinsic postzygotic isolation, and species interactions as drivers of reproductive isolation between species.