Patterns of evolution in the scleractinian coral genus Montipora (Acroporidae)

One of the key issues in coral evolutionary biology is the significance of interspecific hybridisation in shaping modern reef corals. Despite this, few detailed studies of speciation and evolution exist for scleractinians. We examined molecular relationships among 25 species of the species-rich scleractinian genus Montipora sampled from Irian Jaya (Indonesia) and Magnetic Island (central Great Barrier Reef) using a nuclear and mitochondrial marker. Mitochondrial DNA (mtDNA) haplotypes are shared among several species and at least four species are not monophyletic based on the nuclear intron sequences. Moreover, although the mtDNA and nuclear trees have similar topologies, there are several important inconsistencies. These results, in combination with the observation of simultaneous spawning of and in vitro cross-fertility between some Montipora species, suggest that occasional gene exchange through interspecific hybridisation occurs between a small number of species in this coral genus. Little correlation was observed between morphological and molecular relationships.