| The alligator snapper(Macroclemys temminckii), the biggest freshwater turtle in the world, is introduced into our country from North America. The alligator snapper has high values which can be edible, ornamental and medical. In recent20years, because of overfishing by humans, wild Macroclemys temminckii gradually decline. Meanwhile, the research of conservation biology is being widely concerned. The alligator snapper is one of important members in the World Endangered Wild Animal Redbook. Lamprotula leai is one species who has high yield and widely distribution. It has high economic value because of its thick shell and edible meat. What is more, it is the main raw materials which can be used as pearl nuclei for larger nucleated pearl. This freshwater mussel is endemic species in China which is mainly distributed in the medium and large lakes and rivers of Anhui, Jiangsu, Zhejiang, Jiangxi and so on. Due to the pollution of environment and overfishing, its wild resource is rapidly decreased and the range is narrowing. Now the species has been listed as first-class protected aquatic wildlife of Anhui province and second-class protected species of Hubei province.Macroclemys temminckii and Lamprotula leai are popular varieties of aquaculture in our country, which lead the development of regional economy. So far, the germplasm resources information is not perfect. Besides, the study of the genetic diversity and genetic structure are not covered. With the trend of rapid development of artificial breeding, the theory research is not enough which greatly restricts the sustainable development of these two economic animals. In order to establish germplasm resources, provide theoretical basis for the molecular-derived breeding and protect wild resources, this study isolated microsatellite markers of Macroclemys temminckii and Lamprotula leai through cross-amplification. Meanwhile, we analysed genetic diversity and the genetic structure of the alligator snapper and Lamprotula leai. The main research results are as follows: 1. Eight polymorphic microsatellite loci isolated from the alligator snapper (Macroclemys temminckii) by cross-amplification were used to analyse genetic diversity of the population. A total of30alleles were detected, and the average number of alleles was3.75. The observed heterozygosity (Ho) ranged from0.042to0.955, and expected heterozygosity (He) was0.042to0.812. PIC value was from0.040to0.759, averaging0.423. After chi-square test, some loci corresponded to Hardy-Weinberg equilibrium (PX49^BHT32, BHT64^Cc-8). By Micro-checker, null alleles were found in PX49and BHT64which was the main cause of deviating from Hardy-Weinberg equilibrium. High density cultivation, less sample size may also result in this deviation. In general, these loci are good molecular markers which can study genetic structure for Macroclemys temminckii.2. Fifteen polymorphic microsatellite markers isolated from Lamprotula leai using cross-amplification were used to analyse the genetic structure of four populations, Poyang Lake (PY), Dongting Lake (DT), Hung-tse Lake (HZ), and Anqing Lake (AQ). A total of114alleles were detected. The average allele number was7.6per locus (range:2to21). Among the four stocks, PY had the highest observed heterozygosity (0.455) while HZ had highest expected heterozygosity(0.868). These four populations of Lamprotula leai have high polymorphisms information content and heterozygosity which means that the four stocks had abundant genetic diversity and good genetic structure. We did not find linkage disequilibrium in these loci after Bonferroni correction which showed the workable of these markers. Pairwise Fst ranged from0.073to0.146, indicating medium genetic differentiation among the populations. AMOVA showed that12.56%and44.68%genetic variances were among populations and within individuals, respectively. From the UPGMA, we can find DT and AQ were clustered together. A possible reason was that the individuals of L. leai in the Anqing Lake may come from Dongting Lake. Meanwhile, PY joined with HZ which reflected that genetic distance has correlation with geographic distribution. At last, these two branches got together. This research provide genetic data for the breeding procedure and germplasm development. |
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