GROWTH AND GENETIC ANALYSIS ON THE SELECTED BREEDING HYRIOPSIS SCHLEGELI

Hyriopsis schlegeli was originally from BiWa Ko Lake in Japan which was introduced into China by Fuzhou HongmenReservoir Exploitation Corporation Company in 1997.Artificial propagation was achieved in the next year.With the expectationto gain high-blooded breed, Hyriopsis schlegeli had been selected for several generations.43 individuals from 108 stock intro-duced directly from Japan was selected as parents and its offspring F1generation was gained in 1998.5000 individuals of F1wereselected as reserve parents every year based on the shell which characteristics weremeasured including the ratio of shell length toshell width and weight.F2and F3were also gotten in 2001 and 2004, respectively.The shape and the growth of Hyriopsis schlegeliand its descendants by artificial selected breeding had been researched.600 individuals of each generation as sample in the threegenerations were investigated.The average ratio of shel-l length to shel-l width of the F2 was 4.21±0.27 in one-year-old whiledecreased to 4.01±0.30 in the next year.Individuals which the ratio of shel-l length to shel-l width was lower than the averageratios were selected as parents.The selected effects showed advantages in theF3.The average ratio of shel-l length to shel-l widthof F3was 4.07±0.27 in one-year-old while decreased to 3.72±0.18 in the next year.Results indicated that in the growth rateof shel-l length, shell width and weight, the F3generation was the fastest among three generations during the culture period from 22 to 34 months.At 34 month, the average shell length of each generation were (110.50±6.21) mm, (113.93±6.47) mmand (120.87±5.91) mm, respectively.The average shell width of the F3was (32.32±2.63) mm while F2and F1were(28.52±2.31) mm and (27.61±2.13) mm.The weight of F3 was (174.83±30.87) g, while F2 and F1were (145.53±14.35) g and (127.84±13.75) g separately.The weight of F3generation was heavier than that of F2and F1.The results ind-icated that the descendant by artificial selected breeding could have better capacity on growth and pearl performance.Random amplification polymorphic DNA (RAPD) technique was used to analysis the genetic characteristics and to evaluatethe artificial selection effect among the four generations.10 primers, with more stable and reproducible characteristics, were se-lected from 99 random primers in RAPD to evaluatethe selection effect.45 bands were amplified in all.In the four generations,there were 8, 5, 3 and 2 polymorphic fragments were detected fromP, F1, F2and F3, respectively.Accordingly, the proportionsof polymorphic loci were 21.0%, 12.8%, 7.8% and 5.4%.In each generation, all the individuals had the similar geneticcharacteristics.The results showed that the genetic diversity of the four generations is similar and the level of genetic differentia-tion in the homo-generation is lower.It indicated that the genetic characteristics of the Hyriopsis schlegeli tends to be stable andbecome pure strain after three generation artificial selected.