Heterostyly

Gene

Character displacement

Reproductive isolation

Demography

Ecology

Biology

Sympatric speciation

Pollinator

Evolutionary biology

Genetics

Interspecific competition

Sympatry

Zoophily

Pollination

Genetic algorithm

Pollen

Introgression

Population

Sociology

Annual Review of Ecology Evolution and Systematics

Understanding how pollen moves between species is critical to understanding speciation, diversification, and evolution of flowering plants. For co-flowering species that share pollinators, competition through interspecific pollen transfer (IPT) can profoundly impact floral evolution, decreasing female fitness via heterospecific pollen deposition on stigmas and male fitness via pollen misplacement during visits to heterospecific flowers. The pollination literature demonstrates that such reproductive interference frequently selects for reproductive character displacement in floral traits linked to pollinator attraction, pollen placement, and mating systems and has also revealed that IPT between given pairs of species is typically asymmetric. More recent work is starting to elucidate its importance to the speciation process, clarifying the link between IPT and current and historical patterns of hybridization, the evolution of phenotypic novelty through adaptive introgression, and the rise of reproductive isolation. Our review aims to stimulate further research on IPT as a ubiquitous mechanism that plays a central role in angiosperm diversification.

Importance of Pollinator-Mediated Interspecific Pollen Transfer for Angiosperm Evolution