Phylogenetic Analysis Of 28 Species Of Gobies In The East China Sea Based On Morphology, Barcode And Nuclear Genes.

Gobioidei called gobies is the biggest group of Perciformes.They are widely distributed in tropical,subtropical and temperate shallow sea area of complex terrain,most of them are small in shape.The phylogenetic relationship of 28 species of gobies from the East China Sea was reconstructed based on the morphological features,the mitochondrial COI gene and the nuclear gene Ptr and plagl2.The bar code sequence of 5 subfamilies,45 genera and 75 species of goby fish was downloaded from NCBI,which covered almost all the species of the family in the family of Chinese gobies.Then we studied the applicability of COI barcode to the Chinese gobies.All these will Provide a theoretical basis for the classification and species identification of gobies.1.Morphological characteristics and analysis 28 kinds of gobiesThe length,scales and fins of 28 species of the gobies were measured and the morphology were briefly described.26 main classification characteristics were found out.The characteristics were 1 and 0,forming a morphological matrix and using Bayes method to construct the phylogenetic tree.Near Amblyoinae,except for the Trypauchen vagina and the Ctenotrypauchen microcephalus,the other three species are all naked.The morphologic feature of Tridentiger bifasciatus and Tridentiger trigonocephalus are similar,but the difference is obvious in the form of the Tridentiger barbatus.The main difference is the small whiskers in the jaw and the edge of the rostral.In the past study,the Tridentiger barbatus was divided into the Triaenopogon,but the three species of the fish were parallel in the morphological cluster analysis,and the result was more inclined to support the three classification results in the same genus.The Amblychaeturichthys hexanema and Chaeturichthys stigmatias in the previous taxonomy are found in the same genus,and the genetic relationship between the two species is close to the previous taxonomy.The three species of the Amoya are similar to the Acentrogobius viridipunctatus which belong to genus Acentrogobius.They were once classified as a genus,but according to this study,the two species of fish are together with the Lophiogobius ocellicauda,so the two species may be only similar in shape and are insufficient to belong to one genus.The dorsal fin spines of the other Gobionellinae species in this study are VI,and the fins are about 10,but the number of dorsal fin spines of the Lophiogobius ocellicauda is VII,the fin is 16~18,far greater than 10,and the fins of the fins are far larger than those of the other Gobionellinae species.So,we indicated that the Lophiogobius ocellicauda may not belong to Gobionellinae.The Pseudogobius javanicus and Rhinogobius giurinus were classified in the subfamily Gobiinae in the previous study,but the fins of the dorsal fin dorsal fin are less than those of the other Gobiinae fish,and the scales are significantly less than those of other Gobiinae fish,especially the Pseudogobius javanicus which is close to the subfamily of the shrimp.From all above,the border of subfamily Gobionellinae and Gobiinae are not very obvious.It may need more morphological characteristics to do more in-depth study.2.Study on the COI barcode and its applicability in the systematic evolution of Chinese gobiesThe COI gene sequence of 28 species of gobies were amplified by PCR,and other species belonging to 5 subfamilies,45 genera and 75 species of gobies were downloaded from NCBI.The results showed that the effective length of the COI of all 194 individuals was 540 bp,the average base content A+T(51.4%)was significantly higher than that of G+C(48.6%),and the G+C content of the second codon sites(56%)was significantly higher than the first and third codon sites(40.2% and 42.3%),and the variation of third codon loci were the highest(168).The average genetic distance of the 103 species is 0.0059,the average interspecific genetic distance is 0.1828,the interspecific genetic distance is 30.98 times greater than that of intraspecies,indicating that the DNA bar code is suitable for 103 species of goby fish.The mean genetic distance between the genera is 1.32 times greater than interspecific genetic distance,and the difference is not obvious.The phylogenetic tree constructed by COI sequence is similar to that of previous studies.From the results,we can see that the clustering of COI is more obvious in the species,and 100% of the species can be correctly clustered,54.76% of them are correct and most of the species can separate subfamilies,but the intergenera relationship and interspecific relationship COI cannot be solved.This will provide some basis for phylogeny of Chinese gobies.Compared with mtDNA,some nuclear genes may evolve slowly.We can use nuclear gene and mitochondria to analyze the system relationship of gobies.3.The Phylogenetic relationship of 28 species of gobies based on nuclear gene and COI.The phylogenetic relationship of 28 species of gobies in the East China Sea was constructed based on the mtCOI and nuclear gene PTR and plagl2 genes.The results showed that 28 species of fish in the East China Sea were divided into two branches expect the eleotridae,one was the subfamily Gobionellinae,the other included the subfamily of Oxudercinae,Amblyoinae and Gobiinae.From the tree we can see that the Lophiogobius ocellicauda,which be considered to be the Gobiinae in the previous study,clustered into the subfamily Gobionellinae.Combined with the morphological characteristics,we indicated that it should belong to the subfamily Gobionellinae.The Amblychaeturichthys hexanema and Chaeturichthys stigmatias are clustered together,it is considered that they should be merged into one genus.Tridentiger bifasciatus and Tridentiger trigonocephalus clustered together as the sister group of Tridentiger barbatus.They were identical with the morphological characteristics,but the mean genetic distance of all those three species was about 0.2,and there was no significant difference.The Pseudogobius javanicus is clustered between the subfamily Amblyoinae and Gobiinae and it was closer to the subfamily Amblyoinae.It is classified into the subfamily Gobionellinae in the traditional classification.Through the analysis of morphological characteristics,it is presumed to be closer to the subfamily Gobiinae,but this need more morphological and molecular evidence to prove it.The taxa of Rhinogobius giurinus is branched out from the subfamily of Gobionellinae.The classification status of the fish is not definite,and more data and deeper morphological features are needed to analyze.It is consistent with prior research that The Oxudercinae embedded in Amblyoinae.