Interspecies reproductive interactions and the evolution of plant and animal mating systems. A commentary on Clo et al. (2025).

The selective forces that influence mating-system evolution are most often considered using a within-species context. Reproductive interactions, however, also can involve related species and can influence the evolutionary trajectories of diverse mating-related traits and the genetic composition of interacting species. The ecological conditions associated with selection for reproductive assurance in plants and animals also are conditions that are likely to result in interspecies reproductive interactions. In this commentary, I explore a variety of factors that link mating-system evolution and interspecies reproductive interactions, including genetic introgression by hybridization, extinction-by-fusion ("genetic swamping"), evolutionary rescue, pre-zygotic reproductive interference between species, and persistent incomplete assortative mating between species and in hybrid zones. A particular focus aims to make the case that reproductive interference holds the potential to foster the evolution of selfing syndrome traits as a form of reproductive character displacement rather than purely as adaptations for reproductive assurance per se. Although interactions among individuals within-species remain central to understanding mating-system evolution, a variety of interspecific factors are also likely to contribute to realized patterns of mating in both plant and animal taxa, especially under conditions of conspecific mate limitation that impose selection for reproductive assurance.