Research On Species Identification And Phylogenetic Analysis Of Gobiidae In The Yangtze Estuary

The Yangtze Estuary is the largest estuary in China with a complex fauna and diverse species types.Many kinds of fish evolved specific characters adapt to the environment,being special noctuid species of this region.Fishery resources survey showed that the number of Gobiidae fishes has played an important role in the Yangtze estuary,most of which become estuarine fish.Privious studies has been revealed that early resources of some Gobiidae fishes are food organisms of Chinese Sturgeon inhabited in the estuary during migration.Therefore,Gobiidae fishes are very important in maintaining ecological balance of Yangtze Estuary.Investigation in the Yangtze Estuary found that early resources of Gobiidae fishes had a great diverse species and high proportions of number.However,less studies has been researched on the Gobiidae fishes' early resource in the Yangtze estuary.This study focused on identification of Gobiidae fishes during early developmental stage using molecular biology method.A categories study was conducted on 9 Gobiidae fishes to find differences in morphological characters of early development with the purpose of providing a basis for identifying Gobiidae fishes,fast and accurately.At the same time,the study provides some information for classification of Gobiidae fishes in early development in the Yangtze Estuary.The paper is composed of three chapters.First,early resources of 9 Gobiidae fishes in Yangtze Estuary were identified using 16s RNA and differences between base compositions were discussed and analyzed.Second,system categories were conducted on Gobiidae fishes identified,applicability and accuracy of identifying by molecular marker were assessed.Third,8 Gobiidae fishes which were successfully identified were morphological described and analyzed to find characters that set different Gobiidae fishes apart.And,a simple identification key of developmental stage of Gobiidae fishes was made.The main research results are as follows:1.The identification of nine Gobiidae fishes' early resources in the Yangtze Estuary based on 16S rRNA gene:16S rRNA sequence of eight genera,nine species and sixty nine individuals of Gobiidae in the Yangtze Estuary has been obtained.The common length is 534bp,encoding 181 amino acids.By alignment with 16S rRNA gene or the whole-genome in NCBI,sequence ident degree is 99%?100%,nine Gobiidae species has been identified primarily.Analyzing the composition of bases of 16S rRNA gene in nine Gobiidae species by using MEGA software,the results shows that the frequency of bases distribution in 16S rRNA gene of every goby exists significant difference,but the trend of base composition is consistent:the average content of A(29.3%)is significantly higher than that of other three bases,and the average content of A+T(52.2%)is higher than the G+C content(47.8%).It indicates that there is obvious bias in the base frequency of 16S rRNA.2.Phylogenetic analysis of nine identified Gobiidae fishes' early resources:by using MEGA software with K2P model,calculating the intraspecific and interspecific distance of nine Gobiidae species 69 individuals,and making saturation analysis with 16S rRNA gene,as the same time making UPMGA phylogenetic tree based on K2P model.The results showed:Gobiidae species in the Yangtze Estuary could form a obviously monophyletic group,which further conformed that classification of Scartelaos histiophorus and Odontamblyopus rubicundus,as Gobiidae was reasonable.3.Describe and analysis morphological characteristics of eight identified Gobiidae fishes,early resources:combing the research results that had reported,describing morphological characteristics of eight Gobiidae fishes,and filtering the index information that can identify eight Gobiidae fishes' early stage.For example,if there is pigment on the body;the shape,quantity and position of the pigment;the shape and the distribution of pigment of swim bladder and the location of anus.At last,make a retrieval table based on the information of classification and identification of eight Gobiidae fishes' early development stage.