Coexistence induced by pollen limitation in flowering-plant species

We report a novel mechanism for species coexistence that does not invoke a trade-off relationship in the case of outbreeding flowering plants. Competi tion for pollination services may lead to interspecific segregation of the timing of flowering among plants. This, in turn, sets limits on the pollina tion services, which restrain the population growth of a competitively supe rior species, thereby allowing an inferior species to sustain its populatio n in the habitat. This explains the often-observed tendency for interspecif ic differentiation in the timing of flowering between coexisting plants. It also predicts that the introduction of an efficient pollinator to a habita t may cause the extinction of competitively inferior plant species.