Angiosperm sexual systems-Concepts, evolution, ecology, and future directions

Aims: The angiosperm sexual system is a critical trait closely related to mutation accumulation and genetic diversity resulting from sexual reproduction, which could further significantly affect the evolution of extant angiosperm diversity and ecosystem stability. There is growing recognition that the sexual system plays an important role at various levels including population, community, and ecosystem and can also reflect the response of vegetation to environmental change. Progresses: We reviewed key research progress over the last three decades addressing important ecological issues based on the angiosperm sexual system, including evolution of sexual system diversity, the relationship between sexual system and phylogeny, ecological correlation of dioecy in angiosperms, mechanisms of community assembly and dynamics regarding sexual systems, variation of sexual system distribution along environmental gradients, and the effect and response of functional traits to ecosystem functions and disturbance. In addition, we also provided future recommendations, including research directions, methods and applications based on functional traits in plant science. Prospect: Sexual systems are not only a genetically determined trait but may also be an environmentally adaptive strategy to enhance plant fitness. We thus propose that sexual systems can also be used as an indicator or reference for biodiversity conservation and management of ecosystems under global climate change.