Closely related species are often predicted to compete for the same resources, yet many communities contain closely related species.
Two processes that can promote the coexistence of closely related species are ecological sorting and character displacement. Ecological sorting occurs when strong competition during community assembly excludes inferior competitors from a community, while character displacement occurs when species experience selection in sympatry to evolve trait differences that reduce competition.
While both of these processes were first articulated as being driven by resource competition, shared interactions with predators, mutualists, or facilitators can also generate ecological sorting and character displacement.
Because pollinators are often shared among co-occurring plants and can be essential for reproduction, the indirect interactions among co-occurring plants that share pollinators can lead to ecological sorting and character displacement.