Phylogenetic Classification And Genetic Differentiation Of Spiny Seahorses Along The Coast Of China

Seahorses were small marine bony fishes,which were belongs to genus Hippocampus,family Syngnathidae.Seahorses were found worldwide in tropical and temperate shallow coastal habitats including seagrass beds,coral reefs,mangroves and estuaries.Dried seahorses are used extensively in traditional medicine with high commercial value,particularly traditional Chinese medicine(TCM).Seahorses are flagship species for many issues in marine conservation including overexploitation,incidental bycatch and habitat loss.In this condition,many countries(England,Australia,New Zealand,America and Spain et al)have built resource banks for various of seahorse species.Species resource of seahorses in China is abundant in reserves,but patterns of distribution and population structure of seahorses are relatively poorly known.According to the situation,it's necessary to investigate the phylogenetic classification and genetic structure of seahorse populations along the coast of China.Seahorses are highly unusual marine fishes that have been attracting increasing attentions from many marine biologists.Their unique body morphology,with horse shaped head,large eyes,curvaceous trunk and prehensile tail,has made them different from other teleosts.Among various of seahorses,one class of seahorses with spikes that stick out on their body surface was really special when compared with other seahorses.Species identification of these seahorses was difficult to be carried out on the basis of morphology since that they have similar body size and rings.5 species of spiny seahorses were reported internationally to the present,and among which there were 3 species were found in China.However,distribution and population structure of spiny seahorses are poorly known at present.The studies were focused on the phylogenetic classification and genetic differentiation of spiny seahorses along the coast of China.On the one hand,we were trying to figure out the taxonomy issues of these spiny seahorse species by morphologic characters and mitochondrial DNA markers.On the other hand,the phylogenetic relationship between different seahorses based on mitochondrial genomes and COI gene sequences was investigated.Additionally,the population structure of 4 seahorse populations has been evaluated,and the data obtained from the study will contribute to seahorse conservation efforts.The main results of the study are included as follows:1.Three species of spiny seahorse along the coast of China by large-scale resourceinvestigation were found including Barbour's seahorse(H.barbouri),thorny seahorse(H.histrix)and hedgehog seahorse(H.spinosissimus).2.Many seahorse specimens from various coastal areas of China were collected,and then a meticulous measurement to the morphological characteristics of these specimen were made.Then PCA(principal component analysis)of these morphological data to find main variables distinguish these species from each other was carried out.3.The mitochondrial genome of H.spinosissimus was first determined in this study.The mitogenome was compared with other seahorse and teleosts,no differences were found in genome organization as well as composition.In addition,SSRs were detected from the mitogenome sequence of seahorses,and evidences of adaptive evolution in seahorses were found in this study.4.The population structure of 4 seahorse populations were evaluated in this study,and the result that obtained from the study will contribute to the conservation of seahorses.