Genetic Diversity Of Mitochondrial Cytochromes B In Black Carp From The Yangtze And The Pearl River

Mylopharyngodon piceus (Mp) is one of most important kinds in freshwater fish. The Yangtze and the pearl river in China are two of the main rivers which is the crucial output of Mp resource. In recent years, as the population excessive growing and the development of society, the technology, especially the industrialization, environmental pollution, reclaiming, overfishing and dike-building, the Mp resource has fell sharply. So, it is very important to protect the Mp genetic resource in the Yangtze and the pearl river for the persistent and stable development of Freshwater Fishing.The study of heredity diversity is the foundation of biological resources protection and germplasm breeding. It will provide important data for the protection of fishes and ecological resources. The present studies detected and analysed the heredity differences of cytochrome b in the 54 specimens of Mp which came from the four different places of the Yangtze and the pearl river. The conclusion as follow:1. The length of mitochondrial gene cytb is 1074 bp. The heredity differences in four places are 0.001 to 0.002 and did not achieve the differentiation criterion of subspecies. There are 12 haplotypes in 54 Mp which 7 haplotypes are in Nanyuepo of Hunan province and Wuhu city of Anhui province and 4 haplotypes are in Douchang county of Jiangxi province and Yunan county of Guangdong province. The total heredity diversity (Hd) of haplotype is 0.79804, the total polymorphism (Pi) is 0.00159, the average nucleotide difference (K) is 1.70929, suggesting the lower level of heredity differences in Mp. In four places, The level of heredity difference in Wuhu is highest and the level of heredity differences in Yunan is lowest.2. According to the differentiation index (Fst) and the gene folw (Nm), there is no difference among the 4 populations and the results showed no heredity differentiation in 4 populations. The Nm is 7.437 in Douchang and Wuhu, which is higher than 4, suggesting that the genetic communication is very frequently between the Wuhu and Douchang and geographical isolation did not affect the genetic communication. The Nms of Nanyuepo and Wuhu, Nanyuepo and Yunan are 0.212 and 0.416 respectively. The Nm is lower than 1, suggesting that the frequency of genetic communication was little and geographical isolation was the barrier in genetic communication in Nanyuepo and Wuhu as well as Nanyuepo and Yunan.3. The detected results of the Tajima's and the Fu's test of population dynamic showed that the Mp populations has no a rapid expansion of population in recent history. The analysis of net branch of MP haplotype did not show a radial structure in total net picture, suggesting that the population was not suffered the bottleneck stage in history and expanded rapidly. According to the location and geographical distribution of the haplotypes in NJ, ME and UPGMA, The Mp 12 haplotypes did not form distinct population, because of no distinct pedigree structure. Each haplotype distributed dispersedly in different populations and did not form distinct georgaphical distribution.