| Channa maculate is widely distributed in the south of the Yangtze River,including Hainan Island and Taiwan. Due to its high growth rate, and high medicinalvalue and nutritional values, Channa maculate is now more and more welcomed andbecomes a delicacy for many people. In recent years, the number of wild Channamaculat is drastically reduced by the impacts of water construction projects,overfishing, water contaminations and other factors, which demands the the protectionof Channa maculata.In present study, the sequences of complete mitochondrial ND2genes of132Channa maculata from14different locations of the Pearl River, Moyang River,Nanliu River, Nandu River, Changhua River and Wanquan River were sequenced toanalyze the genetic diversity, genetic differentiation index and population historicaldynamic with the aim to evaluate the genetic background, to protect and sustainableexploit the Channa maculata germplasm resourses. The results were as following:1. The characteristics of Mitochondrial ND2sequence: The full length of theND2gene is1044bp. There are975conservative sites and66variable sites, included44single variable sites and22parsimony informative sites in the ND2genes of132samples. The four bases(A、T、G、C)average content are27.1%,23.8%,12.2%,36.9%respectively.The content of A+T is higher than G+C, which conforms to the majorityof fish.2. Genetic diversity and genetic differentiation:36haplotypes are detected from132ND2sequences, of which the shared haplotypes are15(about41.67%of allhaplotypes). HP and NK populations both have7haplotypes respectively, largestnumber of haplotypes in14geographic populations. Various phylogentic treesshowed that36haplotypes are closely related, and no lineage structure was formed.The average haplotype diversity of132individuals is0.857±0.024and theaverage nucleotide diversity is0.00284±0.00146, suggesting a high haplotypediversity and low nucleotide diversity pattern. The genetic differentiation index(Fst=0.01511) is a lowest between NDJ and CHJ groups among the6populations, suggesting no genetic differentiation and high gene flow between them.Fst between WQH and NLJ popolations is lagest(0.53119) is largest, the twopopulaitons is highly differentiationed. The fst values between ZJ and NLJ, ZJ andCHJ populations are0.l5349and0.18198respectively, suggesting they are middledifferentiated. MJY, NLJ, CHJ, WQH populations are highlyt differentiated to otherpopulations (Fst>0.25).No obvious genetic differentiation is found between NDJ andNLJ populations(Fst=0.02702).AMOVA showed that the genetic variance of Channa maculata among6riverdrainage is-0.58%, the genetic variation within the populations from the same riverdrainage is31.58%, and genetic variation for individuals within populations is69.00%, suggesting that genetic variation for Channa maculata in South Chinamainly comes from individuals within populations. The Genetic distances among14different locations are small and at the same level(0.000-0.004). Combined with fstvalues, phylogenetic trees and TCS network, the degree of differentiation among14locations haven’t reached subspecies level and they should be treated as the samespecies.3、Demographic history: The neutrality test results showed that the Tajima’s D andFu’s Fs are negative, of which p values of NLJ, NDJ and CHJ populations aresignicant, suggesting that a groups as a whole has experienced population expansionin history. Meanwhile, largely unimodal patterns appeared in the nucleotide mismatchdistribution diagrams of Channa maculate in the six river drainages also proved thehistorical signal of population expansion, and deduced expansion time ranged from20000to30000years in the Pleistocene.4. Genetic diversity from NF population has the highest genetic diversity in the14studied populations, it should be protected in priority. Genetic diversity of GPpopulation from the Pearl River, HP population from Nanliujiang are relatively highand they are highly differentiated, they are better protected too. |
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