The ghost of competition past in the phylogeny of island endemic plants

1 Large endemic plant taxa found on oceanic archipelagos are frequently monophyletic, indicating that they originate from a single colonization event. 2 Colonization is a two-stage process requiring both dispersal and establishment to be successful. Accordingly, once-only colonization may be explained either by dispersal barriers limiting colonization, or by the first successful colonization of an island inhibiting the establishment of later arrivals through niche pre-emption and interspecific competition. 3 Using the endemic flora of the Canaries and Macaronesia as a test case, I argue that barriers to dispersal are low and that niche pre-emption is therefore the more likely explanation for the monophyly of large endemic groups in these islands.