A Phylogenetic Analysis And Molecular Classification Of The Hainan Scleractinian Coral Genus Montipora (Scleractinia,Acroporidae)

Montipora is the second most species-rich genus of scleractinian coral,which is found with many morphotypes and a wide variation,and widely distributed in the Indian and Pacific oceans.It is well known that traditional taxonomy of scleractinian corals is based solely on skeletal morphology.However skeletal morphology has been plagued by phenotypical plasticity,morphological convergence,and reticulate evolution,which renders the definition of taxa boundaris and the reconstruction of phylogenetic relationships very challenging.In this study,variable molecular markers were developed and analyzed to determine the boundaries of species and the phylogenetic relationship.A series of genetic markers(nuclear:Pax-C intron,ITS;mitochondrial:CR,COI)and morphological traits were examined to assess the DNA barcoding for Hainan Montipora(Montipora digitata,fragili,sp.,truncata,gaimardi,foveolata,solanderi,foliosa and efflorescens).Sequence analyses suggested that Pax-C was suitable for distinguishing interspecific genetic relationship with high values of sequence variation,genetic diversity and interspecific p-distance compared with the intraspecific.Although ITS was known with high values of sequence variation,the nearly genetic distance between interspecies and intraspecies made it determine partial genetic relationship of intespecies.And the mitochondrial markers with extremely slow rates of evolution were also different to distinguish the interspecific genetic relationship,which were fit for phylogenetic analyses at or above the genus level.Phylogenetic analyses revealed that each marker showed different levels of correspondence to morphological classification.For Hainan Montipora,the nuclear single-copy marker Pax-C intron showed a high level of resolution at the species level,followed by the ITS region and then by mitochondrial markers with little correspondence to morphological groups.And the molecular markers showed variable levels of adaptation among different geographic Montipora,Pax-C intron presented high levels of geographic adaptation among Hainan Montipora,but low levels of adaptation among Great Barrier Reef and Indonesian Montipora.And the mitochondrial markers showed little geographic adaptation among Hainan Montipora.On the contrary,mitochondrial markers were suitable for Hawaii Montipora with high levels of geographic adaptation.In addition,molecular classification showed a strong ability to resolve the confusion associated with traditional classification systems such as the evident examples of heterozygous individuals(M.sp.),morphological sister taxa(M.truncata,M.gaimardi),and plastic phenotypes(M.truncata).In general,the results indicated that Pax-C intron was reliable and adaptive for Montipora taxonomy at the species level.And no matter for Montipora or other corals,the selection of genetic markers suitable for identifying the species would better take the geographic adaptation into count.