| Procambraus clarkii,is a species of freshwater crayfish.Taxonomically,Procambraus belongs to the phyla Arthropoda,Crustacea,Decapoda,Reptilia,Procambraidae and Procambarus.In our country,the breeding area and output are increasing continuously,the consumer market is booming,and the research and application prospects are large.Based on the research progress of Procambarus clarkii at home and abroad,this study described and evaluated the current situation of Procambarus Clarkii germplasm resources,providing certain basis for sustainable utilization and rational development of Procambarus Clarkii.This paper mainly includes the following parts:1.Genetic structure analysis of Procambarus clarkii population in the middle and lower reaches of Yangtze RiverIn order to understand the genetic structure of typical Procambarus clarkii culturing populations in the middle and lower reaches of the Yangtze River,nine populations in Jianli,Hubei,Wuhu,Xuancheng,Hefei,Tongling and Ma ’anshan of Anhui and Jianhu,Hu Hu and Xinghua of Jiangsu are selected for this study.Genetic diversity and genetic structure of Procambarus clarkii were studied by using 10 pairs of microsatellite primers.The results showed that the average number of effective alleles(Ne)for 9 populations of Jianli(JL),Wuhu(WH),Xuancheng(XC),Hefei(HF),Tongling(TL),Ma ’anshan(MAS),Jianhu(JH),Enhu(GH)and Xinghua(XH)were2.70-4.40.The mean expected heterozygosity(He)and polymorphism information content(PIC)were 0.54 to 0.74 and 0.48 to 0.67,and the genetic differentiation coefficient(Fst)of most populations showed moderate to high differentiation.Ten loci in 9 populations deviated significantly from Hardy-Weinberg equilibrium after Bonferroni method correction,and most loci showed insufficient heterozygosity.AMOVA analysis showed that genetic variation was determined within the population..Gene flow demonstrates the extensive exchange of genes between different populations,especially between the Hu and Jianhu populations.Based on the Nei’s genetic distance between populations and the results of UPGMA cluster trees,the Wuhu,Gehu,Ma ’anshan and Jianhu populations are combined into one group,the Xuancheng and Hefei populations belong to one group,and the Jianli,Tongling and Xinghua populations belong to one group respectively.The STRUCTUR results show that Xuancheng and Hefei populations have the same origin.The results showed that Procambarus clarkii populations in Anhui and Jiangsu had high genetic diversity.The results provided a reference for the conservation and improvement of Procambarus Clarkii germplasm resources.2.Comparative analysis of growth,morphological characteristics and ecological adaptability of Procambarus clarkii in five populationsIn order to compare the growth and ecological adaptation of Procambarus clarkii in different populations,five breeding groups of Procambarus clarkii(Jiangsu Gehu(GH),Xinghua(XH),Jianhu(JH),Wuhu(WH)and Jianli(JL)are introduced in Wuhu,Anhui Province in 2020.Combined breeding process is planned for the same period in2021.The growth characteristics,diffusion rate,creeping rate and dry dew tolerance of different populations of Procambarus clarkii seedlings under the same culture conditions were compared and analyzed.The results showed that:(1)growth performance: both the body length and body quality of both males and females in May are combined for the Gehu combined population(Female: 7.52±0.15 cm,13.4±0.85g;Male: 7.53±0.12 cm,14.25±0.90g)was the best.Except Wuhu group,the body length and weight of male individuals in all groups were significantly higher than that of females in May.The growth rates of body length and weight of Jianhu population were the highest in March and April(41% and 167%,respectively),and that of Wuhu population was the highest in April to May(24% and 83%,respectively).In May,the combined survival rate of the Gehu group is the highest 59.33%,and the lowest 50.67%in Jianli group.In terms of meat yield,the ranking of female in March was Jianhu>Wuhu>Gehu>Jianli>Xinghua,there was no significant difference in males among all groups(P> 0.05);The ranking of female in April is: Gehu> Jianhu> Wuhu>Jianli> Xinghua;There was no significant difference in the male population(P> 0.05);There were no significant differences between male and female groups in May(P>0.05),but the meat yield of female was higher than that of male.(2)Ecological adaptability: the order of inflow diffusion rate: Jianhu>Xinghua >Gehu>Jianli>Wuhu.The Jianhu population and Xinghua population were significantly superior to the other three groups.The Jianhu population had the fastest diffusion time of 291.67±25.43 s,while the Wuhu population had the slowest diffusion time of 661.33±32.94 s.The crawling rate showed no significant difference among the groups.The desiccation stress experiment showed that the desiccation stress time of juvenile shrimp should not exceed 18 h,and the survival rate of desiccation stress 48 h was sorted as follows:Wuhu>Gehu> Xinghua >Jianli>Jianhu.The survival rate was the highest of Wuhu population was 87.78±1.11% and the lowest was 68.89±1.92% of Jianhu population.(3)Difference in morphological characteristics: Cluster analysis shows that the Xinghua and Jianli populations have the shortest Euclidean distance cluster,which is one Gehu group together with Jianhu and Wuhu,and one Gehu group alone.Principal component analysis showed that total length,body length,headplastron length,abdominal length and body weight were the main factors determining the morphological classification of the five populations,and the cumulative contribution rate of the first two principal components was more than 50%.In the discriminant analysis,the diagnostic accuracy of the five populations of Gehu,Xinghua,Jianhu,Wuhu and Jianli is 80%,55%,55%,7.5% and 25%,respectively,and the combined discriminant rate is 44.50%.The discriminant accuracy of females were 75%,60%,10%,30% and 15%,respectively.The male population was 70%,45%,55%,15%,5%,and the comprehensive discriminant rate of both sexes was 38.00%.The study showed that there were some morphological characteristics differences among the five populations,which were mainly reflected in body length,body mass,cephalopsternal length and abdominal length.However,these differences had not reached the level of forming subspecies,which required comprehensive analysis of various indicators to distinguish different populations.This study provides a reference for the evaluation of growth performance,morphological differences and ecological adaptability of Procambarus clarkii in different populations,and lays a foundation for the next breeding.It has certain application value and practical significance.3.Hybridization dominance and ecological adaptability analysis of growth performance of three population diallel cross combinations of Procambarus clarkiiSix combined dienius hybridization groups are obtained based on three excellent germplasm of Procambarus clarkii from Jiangsu,Jianhu and Wuhu,Anhui [Gehu ♀ x Jian Hu ♂(GJ),Jian Hu♀ x Gehu ♂(JG),Gehu ♀ x Wuhu ♂(GW),Wuhu ♀ x Gehu ♂(WG),Jian Hu ♀ x Wuhu ♂(JW),Wuhu♀ x Jian Hu ♂(WJ)] and three groups of selfing [Gehu ♀ x Gehu(GG),Jianhu ♀ x Jianhu ♂(JJ),Wuhu ♀ × Wuhu ♂(WW)],the growth performance,crossbreeding advantage and ecological adaptability of the offspring:(1)In May,the body length of all combinations was WW> JJ>JW> GG>WJ> WG> GJ> GW> JG,and JJ and WW were significantly higher than other combinations(P<0.05),both female and male of WW combination were significantly higher than those of other combinations(P< 0.05);The order of body mass was: JJ<WW<;JW< WJ< GG< WG< GJ< GW<JG,and JJ and WW combinations were significantly greater than other combinations(P< 0.05),and their cross combinations JW and WJ were the best among all the cross combinations.(2)The total heterosis of body mass was-19.30%,and the heterosis of HM and HB in body length,length of cephalopastron,width of cephalopastron,length of abdomen,width of abdomen and body weight were all negative,and the body length was reduced by 4.33%-8.87% on average.Body weight decreased by 10.66% to 27.15% on average.There were some differences in crossbreeding superiority among the three populations,but the differences were not obvious.(3)The diffusion speed of nine combinations of Procambarus clarkii into the pond was GG> GW>WW>WJ>JJ>WG>JW>GJ>JG,GG and GW hybrids was significantly higher than that of JG hybrids(P<0.05)and had no significant difference with other groups(P< 0.05).All groups died after 24 hours of desiccation stress,and the survival rate at 36 hours was less than 50%.The survival rate at 48 hours was sorted as WW> WJ> JW> GW> WG= GG= GJ> JG>JJ;The survival rate was the highest of WW groups was 34.44±0.96%(P<0.05),the lowest of JJ group was 3.33±1.67%(P< 0.05),the survival rate of all combinations was 0 at 72 h.In general,the WW self-crossing combination had the best growth and desiccation stress,but the growth of all hybrid combinations showed negative heterosis,which may be related to the low purity of the parents and low genetic diversity due to the mixed introduction,but it had obvious advantages in resistance.For example,GW hybrid combination showed positive heterosis in the diffusion rate of pond.The hybrid combination of WJ,JW,GW and WG has obvious advantages in desiccation stress.This provided the basis for selecting Procambarus clarkii with strong resistance in the next step. |
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