Comparison And Analysis Of Self-fertilized And Hybridized Families Of Four Cultured Population In Haliotis Discus Hannai

Haliotis discus hannai,which belongs to gastropoda,is one of the economic shellfish in China.However,self-breeding,germplasm degradation and deterioration of the culture environment resulted from the rapid development of abalone aquaculture industry in recent years,has affected the healthy development of the industry.Therefore,make an intensive study of germplasm and cultivate improved variety with high yields and resistance are important means to ensure the sustainable development of the farming industry.In this study,hybridization experiments were carried out by using four cultured populations of H.discus hannai.The research is divided into three parts: In the first part,the genetic distance of the four different cultured populations were estimated and compared based on ITS1,16 S,COI and microsatellite.In the second part,a certain number of F₁ were selected from four different growth stage,using microsatellite to identify the family of each individual,and the growth and survival of each family were compared.In the third part,a certain number of F₂ individuals were selected from two different growth stage to identify the family and compare their growth and survival.Below are key research findings: 1.Genetic distance between four different cultured populations based on different molecular markersAccording to theanalysis of ITS1,16 S and COI sequence and microsatellite alle data,the genetic distance between parents was estimated and the phylogenetic tree was constructed.The results showed that there was no strict correlation between genetic distance and geographic distance.Phylogenetic trees based on different molecular markers were different from each other.And phylogenetic tree based on ITS + 16 S + COI dataset was most ideal and trustworthy.The results above can lay the foundation for the selection of appropriate molecular markers to analyze genetic differences of abalone in intracranial level.2.Growth and survival of F₁ Generation of H.discus hannaiEight polymorphic microsatellite loci were used to genotype several individuals in four different growth stage of F₁ generation.Excluded non-family individuals and assigned most of the rest to a single family.Eight sites for paternity tests showed polymorphic.92 alleles were detected,observed heterozygosity,expected heterozygosit and PIC value were between 0.4762 to 0.8000,0.6800 to 0.9111 and 03.6460 to 0.8930,respectively.Based on the results of paternity test combined with the physical data of F₁ generation,the growth and survival of different families were analyzed.It turned out that HDRC,HDDL and DLHD showed obvious heterosis in growth parameters and growth rate,and HDDL,RCDL and DLHD had significant heterotic survival.These families could be used as a reference for the production of abalone.3.Growth and survival of F₂ generation of H.discus hannaiIndividuals with good gonadal and physical conditions from F₁ families as the parents of F₂ generation constructed 13 full-sib families.According to physical data and paternity test conducted for F₂ individuals from two different growth stage,growth and survival of different families were analyzed.The results showed that some F₂ generation produced by HDDL family was better at growth and survival,which means fine traits can be inherited from parents featuring of instability.Also,F₁ and F₂ produced by ?HD and ?DL demonstrated excellent growth and survival traits,thus the parental combination can be used to produce stable and high-quality larvae for H.discus hannai.