| 1.Heterosis analysis and diallel crosses between Argopecten irradians concentricus and “Bohai Red”The Argopecten irradians concentricus” and Bohai Red” are two close related shellfish species and are also two most important cultured scallop in China,which are cultured in southern and southern China.In order to increase yield by exploring heterosis,two of hybrid group IB(I?×B?),BI(B?×I?)and two pure populations BB(B?×B?),II(I?×?)using a diallel cross design to establish hybrid group and pure group with the parents of “Bohai Red”from Qingdao of Shandong and Argopecten irradians concentricus from Beibu Bay.The result show that the fertilization rate of all group exceed 95% and there was no significant difference among the groups;the hatching rate of the reverse group(IB)was 62.1%,which was significantly worse than other groups.During the whole culture cycle,the hybrid group showed heterosis in growth and survival.The heterosis of shell height and the heterosis of the survival rate was 7.54% at larval stage.At growth-out stage,the heterosis of shell length,body weight and survival rate were: 6.45%,7.43%,9.88%,8.45%,12.43% and 300%,19.19%,22.80%,20.10%,21.65%, respectively.Our study showed that hybridization between Argopecten irradians concentricus and “Bohai Red” was expected to solve the problem of germplasm degradation of Argopecten irradians concentricus in the southern China.2.Establishment and growth and survival analysis of the mixed generations(inbred and hybrid)of Argopecten irradians concentricus and “Bohai Red”In order to provide some practical reference for the exploration of shellfish breeding methods and understand the growth and survival of the mixed population of“Bohai Red” × Argopecten irradians concentricus in the Beibu Bay?We observed the growth and survival of mixed group which contain the hybrid group and pure group from March to December 2017.The results showed that: the shell color of the mixed group is black and white or orange,and there is purple shell color of "Bohai Red".The mixed progeny are the hybrids of “Bohai Red” × Argopecten irradians concentricus after progeny identification.(2)The survival rate is 29.2% in the mediumculture period,in forming stage is 86.2%,the cumulative survival rate is 25.2%,after2 months of medium culture,the shell length,shell height and body mass were17.0mm?18.2mm and 0.74 g,respectively,and the daily growth was0.283mm/d?0.303mm/d and 0.012 g/d;at the end of the cultivation,the shell length,shell height and body mass were 50.95mm?50.44 mm and 19.52 g,respectively,and the daily growth was 0.189mm/d?0.187mm/d and 0.072 g/d;3.Effect of high temperature on growth and survival of juvenile hybrids(Argopecten irradians concentricus×Bohai Red)In order to provide reference for the hybrid(Argopecten irradians concentricusדBohai Red”)juvenile on the South China Sea,the study about tolerance of hybrid juvenile(average shell height 20.71 ±0.011 mm,average shell length20.94±0.013 mm and average body weight 1.91 ±0.024 g)in the temperature(14 – 33 ?)for15days by the ecological methods.The result show that the survival rate reach 100%when the temperature range from 14? to 29? The final survival rate of 30?was29.3%.The survival rate was 100% in the first 4 days of the 29 ?group,and the final survival rate was 25.3%.The survival rate was 100% in the first 3 days of the32 ?group,and the final survival rate was 18.3%.The survival rate was 100% in the first2 days of the 33 ?group,and the final survival rate was 0%.The high-temperature starting sensitivity point of the hybrid shell was 31 ?.Under different temperature conditions,the optimum temperature for hybrid juvenile shell length,shell height and body weight growth is 22?.The results mean that the high temperature tolerance of the hybrid was improved when compared “Bohai Red”but worse than Argopecten irradians concentricus.4.Microsatellite-based analysis of genetic diversity of parent and hybrid of Argopecten irradians concentricus×Bohai RedThe genetic diversity and structure of 90 individuals in the 3 populations of Argopecten irradians concentricus,”Bohai Red” and their hybrids were analyzed by SSR molecular marker technique.The results showed that a total of 67 alleles were amplified by 8 microsatellite loci,the number of alleles ranged from 4 to 14,of which the average was 8.5;the average effective number of alleles(Ne)of the ”Bohai Red”,Argopecten irradians concentricus and their hybrids were 2.3947,2.048 and1.8316,respectively;the polymorphism information content(PIC)were 0.462,0.4373 and 0.358,respectively;the average observed heterozygosity(Ho)were 0.5045,0.2016 and 0.2458,respectively;The genetic differentiation index(Fst),gene flow(Nm),andfixed coefficient(Fis)was 0.1398,1.5387 and 0.3698,respectively;genetic distance(Dxy)was 0.1188 and genetic similarity coefficient was 0.888 between the hybrids and Argopecten irradians concentricus,and 0.2793,0.7563,rrespectively between the hybrids and “Bohai Red” The results of the study indicated that the three populations had higher genetic diversity,the Bohai Red has the highest genetic diversity,and the Argopecten irradians concentricus have the lowest genetic diversity.The genetic structure of hybrids is more inclined to Argopecten irradians concentricus. |
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