The evolution of mating systems in tropical reef corals

The life histories of tropical reef corals (Scleractinia) include two traits that can strongly bias mating systems towards inbreeding: (1) most species express both sexes simultaneously, creating the potential for self-fertilization; and (2) there is philopatric dispersal of planktonic or demersal larvae. Recent studies have confirmed that all hermaphrodite species with broad dispersal potential are either completely, or almost completely, self-incompatible. By contrast, species with limited dispersal potential have high, but variable, rates of self-fertilization. This interspecific variation in coral mating systems is similar to that found in terrestrial plants. Understanding the selective forces that drive mating-system variation in marine environments will undoubtedly broaden our understanding of the evolution of inbreeding and outbreeding in sessile plants and animals.