The Study Of Growth Rules,genetic Characteristics Analysis And Parental Contribution Rate In Sebastes Schlegelii

Sebastes schlegelii is an important economic marine fish.As an important part of marine biodiversity in the North of China,It has become one of the main economic fishes of cage farming,fishing,and enhancement and releasing.Thereby,the wild resources of Sebastes schlegelii have drastically decreased,the genetic diversity and genetic structure of wile populationhave beenaffected seriously.It is very important to breed.Firstly,this study understood the early growth and development laws of the breeding population by path analysis and grey correlation analysis.And cleared the ideal characters for selection breeding.It provided reference for breeding of Sebastes schlegelii.Then,combined microsatelite molecular marker technology and selective breeding.On gene level selected good traits.Finally,use multioplex-pcr in paternity testing,to avoid inbreeding and improve breeding efficiency.Provided the theoretical basis for selecting excellent parents.1.Early growth laws and curve fitting of the breeding population for three generations of Sebastes schlegeliiIn order to study the growth law of early growth,though Logistic,Gompertz and Von Bertalanffygrowth model,we measured the growth traitsof the offspring from 1 to8 months.We analyzed the growth traits by the nonlinear curve fitting growth model.And Analyzed the relationship between body weight and length by power function.The results showed that:（1）The correlation between body weight and length of the three generations（F₁,F₂,F₃）of the breedingwere:W₁=0.031L^2.937,R²=0.997,W₂=0.038L^2.787,R²=0.997;W₃=0.031L^2.900,R²=0.998.The three curves have a high degree of fit and good results.（2）The Von Bertalanffy growth model has the best fitting effect on the body weight of the three generations.The correlation index R² of the fitting and actual measurement values were 0.996,0.997,and 0.998,respectively.The Gompertz growth model wasthemost suitable for the body length,R² was 0.994,0.998,and 0.996,respectively.（3）Under the respective optimal models,The ages of inflection pointsof body weight in the three generationswere 7.456,6.671 and 4.828months,respectively,and the weight of inflection points were 34.262,33.195 and 26.399 g,respectively.The ages of inflection pointsof body length in the three generationswere2.294,2.444 and2.548 months respectively,and the inflection point lengths were 4.284,4.629,and 5.192cm,respectively.This resultcould provide theoretical basis for new strain breedingand aquacultureof Sebastes schlegelii.（4）There was no significant difference in fertility and survival rate among the three generations of breeding families（P>0.05）,and F₃ had obvious growth advantages in weight gain and specific growth rate,which could be used as further breeding materials.In summary,the F₃ was batterthan previous two generations（F₁ andF₂）in relative fatness,the average of weight gain and growth rate.2.path analysis and gray correlation analysisIn this study,three generations population（F₁,F₂,and F₃）at 8 months were respectivelyrandomly selected 80.Measure body weight（Y）and total length（X₁）,body length（X₂）,height at withers（X₃）,head length（X₄）,Tail length（X₅）,caudal peduncle length（X₆）,caudal peduncle height（X₇）,tongue length（X₈）,trunk length（X₉）,eye diameter(X₁₀),head length behind the eyes(X₁₁).We used those 12 morphological index to study the effect of the body weight by path analysis and gray correlation analysis.（1）The results showed that the relationship between morphological index and body weight was extremely significant levels（P<0.01）.（2）Path analysis results showed that the relationship between height at withers,trunk lengthand body length of the F₁ and F₂reach significant levels（P<0.05）.And the coefficient of determination reached 0.936,0.943.The height at withers,caudal peduncle lengthand body weight of F₃ generation reached significant level（P<0.05）.The coefficient of determination reached 0.893.Established the optimal linear regression equation for the breeding population of the three generations.The regression equation of F₁:y=-47.383+17.097X₃+7.308X₉;F₂regression equation:y=-34.615+15.779X₃+3.901X₉;F₃ regression equation:y=-54.496+21.966X₃+7.283X₆.（3）The results of gray correlation analysis showed that the correlation between body weight and morphological index ranked in the top four were height at withers,total length,body length and trunk length in F₁,F₂,and F₃ generation.But the main control traits washeight at withers.It shows that the height at withers can be used as an important evaluation index for the selection and breeding of Sebastes schlegelii,in order to improve the selection efficiency.This study make clear the ideal selection traits for selection and breedingof Sebastes schlegelii,provided reference for breeding,and extended the application of path analysis and grey correlation analysis methods in the selection breeding of aquatic animals.3.Analysis of genetic characteristics of fast-growing populations of Sebastes schlegeliiThe purpose of this studywas to carry out the genetic improvement and the breeding of new strains.The basic population was wildly from Rongcheng（R）and Cangdao（C）.Using the combination of mass breeding and family breeding,two population（R-F₁,RC-F₁）of mass breeding and four population（R-F₂,RC-F₂,R-F₃,RC-F₃）of family breeding ware selected.The genetic diversity and genetic structure were analyzed with 20 high polymorphic microsatellite DNA.The results showed that,20 locus showed high polymorphism.The average effective number of alleleswas from 2.9849 to 7.9598,average observed heterzy gosityand expected heterozygosity was respectively 0.7230-0.8405 and 0.6315-0.8716,average polymorphism information contention ranged 0.6472 to 0.8478.The average effective number of alleles was significantly reduced in R-F₃ and RC-F₃.The level of heterozygosity did not change obviously,therefore,R-F₃ and RC-F₃ still had a high level of genetic diversity.Through the analize of P value and genetic deviation index（d）,there were 10 primers existing heterozygote deficiency in all population.The average of coefficient of genetic differentiation(F_st)was 0.1279,suggesting that the differentiation was at middle level.The results showed that the genetic distance between R-F₁ and RC-F₃ was the farthest according to genetic distance and cluster anaylsis.We predected that there will be heterosis in R-F₁ and RC-F₃ mating pattern.4.Developmentof microsatellite multiplex PCR setsand paternal contribution rate in Sebastes schlegeliiIn this study,10 females and 10 males were selected and placed in the same breeding pond for free mating,and four females had a smooth birth.Using the 13 pairs of highly polymorphic microsatellite markers or sites developed in this laboratory,based on the optimized combination of amplified fragment size,annealing temperature,primer concentration,reaction system,three triples and two doubles were successfully constructed.The PCR reaction system used CERVUS 3.0 software to conduct parental identification of four maternal and 10 candidate male parents and 376 offsprings,and explored mating patterns and paternal contribution to offspring.The results showed that when the parental genotypes were known,when five sets of multiplex PCR reaction systems were used,the cumulative exclusion rate reached more than 0.999999 and the paternity test accuracy rate reached 100%,which could effectively identify the progenies of the 4 families;the number of paternal parents was identified as 3-6.In the♀Fe1-Fe4 lineage descendants,the number of paternal fathers was 6,5,4,and 3,and♂2 and♂7 were involved in the mating of four female parents.♂3,♂4,♂5 and♂10were all involved in the mating process of two females.There was a mating pattern of“one female polystery”and“one male multiple female”.Among all the offsprings,the highest contribution rate of the paternal parent was♂7>♂2>♂6,and the total contribution rate reached 67.82%.No progeny were found in♂1 and♂9,indicating that no participation in mating or mating was unsuccessful.The contribution rate was 0.This study will provide scientific theoretical basis for artificial breeding and proliferation.