Study On Sexual Selection And Genetic Diversity Of Procambarus Clarkii

The red swamp crayfish, Procambarus clarkii, native to Noutheastern Mexico, hasbeen transplanted to Japan, and they were introduced to China from Japan in1930s. Ithas rapidly reproducted to many provinces in our country, and has become theadvantage population in many areas. The red swamp crayfish has been eating all of theworld, has well economic benefits and broad market. It is exquisite, delicious andnutritious, popular with all of the people. In addition, the red swamp crayfish is one ofthe most important export of aquatic products, and it plays a vital role in the inlandfishing economy industry in our country. But the development of technology of seedlinghas been slow, and high standard, high quality seedling has been a bottleneck.In this study, the red swamp crayfish were from Hubei, Shandong, Zhejiang,Jiangsu. Study on sexual selection, sperm competition and genetic diversity, was carriedout for different geographic populations. This study improve the basic research of thereproductive biology of the red swamp crayfish, and it provide some scientific basis forprotecting and rationally utilizing the resource of the red swamp crayfish and seedlingcultivation. The main result and conclusion are as follows:1. Sexual selection of different geographic populations of Procambarus clarkii.Vitro labeling was used to detect the Sexual Selection of five populations ofProcambarus clarkii from Ningbo(NB), Nantong(NT), Guli(GL), Dayi(DY) andBaimao(BM). The experiment observed220groups mating redswamp crayfish,including186groups that male and female were from different geographic populations,the ratio was84.55%(P<0.01), and there were positive correlations between genetic andgeographic distance. The ratio of the weight difference below5g and length from0cmto1cm respectively were64.09%and85%in220groups(P<0.01). The results indicatedthat there is a tendency of Procambarus clarkii choosing different geographicpopulation for spouse to reduce inbreeding and improving genetic diversity ofpopulations; and choosing some populations that have the similar size for spouse to increase the ratio of mating success.2. Study on sperm competition of Procambarus clarkii. Using a single pair matingfor the experiment materials, and AFLP was used to explore the red swamp crayfish.4of the6testing groups appear the particularity mark, and the P2values of3testinggroups are more than70%, average75.19±1.80%. The results show that, the red swampcrayfish exist the phenomenon of sperm competition, and the last mating male spermpriority for fertilization, and exist sperm replacement when mating.3. Analysis of genetic diversity of different populations of Procambarus clarkii byAFLP. Amplified fragment length polymorphism (AFLP) was used to detect the geneticdiversity and divergence of four wild populations of Procambarus clarkii fromSuizhou(SZ), Jinan(JN), Ningbo(NB)and Changshu(CS). Five EcoRI and MseI primercombinations produced241polymorphic markers out of the total of276bandsamplified from120individuals. The average heterozygosity of0.2009,0.2009,0.2282,0.1437and Shannon’s Information index of0.2929,0.2929,0.3399,0.2139wererespectively determined in the Suizhou(SZ), Jinan(JN), Ningbo(NB)and Changshu(CS)population,which clearly showed high1evels of genetic diversity of four populations.AMOVA analysis demonstrated that39.76%hereditary changes contribute by thecommunity,60.24%variations distribute in the community between the individual,heredity differentiation index Fst=0.39765(P<0.01). The UPGMA tree based on AFLPdata revealed that these four populations were classified into their own cluster ongeographic populations, it shows that the SZ, JN community differences are small, maydivide into one, and the NB, the CS communities become one respectively.