| Fenneropenaeus merguiensis is the major economically shrimp caught in the South China Sea.It has high edible and economic value.It has a wide distribution in the world and is an important shrimp fishery resources.It has a good potential as an alternative cultured shrimp species in China.In this study,we aimed to develop a new culture varieties,and studied the germplasm resources,growth characteristics and breeding methods of this shrimp.The main research contents include:genetic structure analysis of Fenneropenaeus merguiensis in the northern South China Sea,morphological characteristics of wild caught population,growth characteristics of artificial shrimp culture,evaluation of genetic parameters of G1 generation population,study on the method of selecting the positive mean value from family breeding approach and analysis of the predictive results of different breeding methods based on genetic marker information and pedigree information.1.Five eco-geographical populations of F.merguiensis in the northern South China Sea were studied.The simplified genomic information of 75 individuals from five geographical ecological groups was obtained by RAD-Seq sequencing method.The genetic diversity,genetic structure and population dynamics of five geographical ecological populations of F.merguiensis were analyzed.The results showed that the average nucleotide diversity index of each population ranged from2.88×10-4～3.43×10-4,which was a medium-low level,but the nucleotide diversity index of the neutral evolution segment was significantly higher than the average nucleotide diversity index.However,the results of PCA analysis showed that although there was no significant stratification among groups,some individuals within the group show a trend of variation and separation.At the same time,we also found that there were a large number of intra-population specific mutation sites among different populations by outlier analysis of SNP diversity indices among populations.2.The morphological characteristics of F.merguiensis were analyzed by collecting the phenotype information of wild shrimp.The results showed that the ecological population of the F.merguiensis had higher fatness.Among them,the population in the Qinzhou Bay shrimp farm had the highest fatness.At the same time,it was found that F.merguiensis have a high meat yield rate up to 0.68.In the phenotypic correlation analysis,it was found that the person-related level between each growth-related phenotypic trait and net weight reached a strongsignificant correlation.Among them,The correlation between body weight,body length,carapace length,total length,abdominal length and net weight were the highest,and the correlation coefficients were 0.926,0.876,0.831,0.825,and 0.764,respectively.All of which were highly phenotypically correlated.3.Results from the study on the early growth of F.merguiensis in two different culture environments showed that the shrimps had a greater growth difference under the conditions of soil-based pond culture and the culture conditions of the cement ponds.The growth rate of soil-based pond culture was significantly faster than that of cement pond culture.In addition,it was found that the rapid growth period of the Fenneropenaeus merguiensis was between 10 and 50 days old under two different culture conditions.4.The multi-trait animal model was used to evaluate the heritability and genetic correlation of the body weight,body length,carapace length,and abdominal length of the G1 generation of the banana shrimp in different culture environments and different culture stages.The results of genetic evaluation showed that the growth-related traits of the G1 generation group of the F.merguiensis were all high-level heritability,and the growth related traits were highly genetic correlation.At the same time,it was found that at 30 days old,the heritability difference of body weight traits under two culture conditions reached a significant level.In addition,heritability of body weight traits did not reach significant difference between 30,90and 180 days of age in cement pond culture.5.Family selection approach was carried out using two criteria of the average breeding value of the family and the positive average breeding value of the family.The results obtained by the two selection methods showed that the rankings of the families have changed partially.In the progeny population verification,it was found that the mean P population was slightly higher than the M population,but there was no significant difference between them.6.This study compared the estimated accuracy of body weight breeding values using the five methods ABLUP,GBLUP,ss GBLUP,Bayes A,and BayesB.The results showed that the accuracy of breeding values based on ABLUP and ss GBLUP methods was significantly higher than that of GBLUP,Bayes A and BayesB.Among them,the ss GBLUP method has the highest accuracy for estimating the breeding value of the body weight traits（0.653±0.055）.By comparing the accuracy of estimated breeding value of body weight with BayesB and GBLUP based on different types of SNP data obtained by GWAS and random sampling,it was found that GBLUP model was better than the BayesB model. |
