Prior selfing can mitigate the negative effects of mutual reproductive interference between coexisting congeners

When more than one closely related plant species share the same pollination niche, reproductive interference (RI) via interspecific pollen transfer should limit their coexistence. However, some studies have reported the sympatric coexistence of two native close-relatives pollinated by the same pollinators under RI without niche partitioning. To clarify the mechanisms promoting the coexistence of species sharing pollinators, we examined the frequency dependency of RI in natural conditions and the potential roles of autonomous selfing in mitigating the negative RI effects between congeneric species. We investigated sympatrically growing Commelina communis (Cc) and C. c. f. ciliata (Ccfc) populations. These species exhibit very large overlaps in habitat preference and pollination niche, but seldom produce hybrids. First, we conducted a hand-pollination experiment to examine the negative effects of heterospecific pollen deposition (HPD) on seed production and the potential of self-pollinati...