| Population genetics and molecular phylogeny are the important contents for research of mollusc genetics. Allozyme and RAPD markers were developed and applied in scallop genetic structure analysis in this dissertation. The population genetic variation and growth difference of bay scallop, Argopecten irradians, were studied by RAPDs and quantitative traits. 16S rDNA genes partial fragments of 8 species of scallop were sequenced and the molecular phylogeny of Pectinidae was analyzed based on the 16S rDNA genes.In order to search for the suitable method for the tissue preservation and DNA isolation of marine animals, the adductor muscle of bay scallop (Argopecten irradians) were treated with different ways, such as frozen at -20℃, fixed with 70% ethanol or 10% formaldehyde for more than 10 days. DNA templates about 20 kb were extracted successfully from the fresh, frozen and 70% ethanol fixed tissues. RAPD analysis indicated that PCR products had no obvious distinction among them in the same individual. No usable DNA was gotten from the fixed tissue in formaldehyde. The result suggests that the 70% ethanol is appropriate for tissue preservation andDNA extraction for RAPD analysis.To compare genetic markers for the use of population genetics analysis, allozyme electrophoresis and RAPD (Random Amplified Polymorphic DNA) were used to detect the genetic structure of wild Zhikong scallop Chlamys farreri population. A total of 40 individuals from the same species were investigated using 10 arbitrarily selected primers (10 base). 40.74% of 54 RAPD fragments were polymorphic and revealed an average of heterozygosity with 0.194. 13 enzymes (IDH, GPI, PGM, PEP-B, PEP-D, ACP, AK, PK, GOT, SOD, EST) were selected and 22 loci were used for the population genetic analysis, among them 7 loci (Gpi, Pgm, Pep-Bl, Pep-D, Got-2, Est-2, Est-3) were polymorphic which attributed 31.82% of polymorphism.The average of heterozygosity was 0.113 and most of the studied loci showed a heterozygote deficiency. RAPDs revealed more genetic variation than isozyme electrophoresis, but the two kinds of markers reflected the consistent trend about the genetic structure of the population.Bay scallop, Argopecten irradians, was introduced to China from America in 1982, it has become one of mair) cultured species in the north of China. After culturing for more than decadal generations, its genetic structure might has changed because of the inbreeding. The RAPD markers were used to investigate the population genetic structure and their variation in four populations of A. irradians. Three populations of A. irradians irradians, one wild population was from Massachusetts of America, two cultured populations from Laizhou reared 12th generation and Dalian reared 6th generation respectively, the other cultured population, subspecies A. irradians concentricus, from Qingdao. The value of population polymorphism fluctuated from 31.54% to 35.28%, and the average of heterozygosity varied from 0.1248 to 0.1631, the wild population had the highest level of polymorphisms as well as the average heterozygosity. Dalian population revealed the higher level of polymorphisms and heterozygosity than that in Laizhou population, but there was no significant difference in body weight and shell height between them by statistical method, this result indicated that there had no distinct association between heterozygosity and growth of bay scallop. There was greater genetic distance between the population of wild A. i. irradians and A, i. concentricus (D=0.0093) than that between the wild and two cultured populations of A. i. irradians (D=0.0028, 0.0034). Our data provided some evidences that some genetic variation occurred between the different generations. The lost of genetic diversity usually caused decrease the repellency of scallop. However, the authors think the high cultured density and the deteriorating water environment are still the main reasons that caused high mortality in cultured scallop.A total of 139 individuals from three cultured bay scallop, A. irr...
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