Highly Polymorphic Microsatellite Loci From The Giant Mottled Eel Anguilla Marmorata And Population Genetic Structure Of The Japanese Eel Anguilla Japonica

1. Highly polymorphic microsatellite loci from the giant mottled eel (Anguilla marmorata)Eighteen polymorphic microsatellite loci from the giant mottled eel (Anguilla marmorata) were identified and their characteristics were described. These markers were tested in two wild populations from China (n=20) and Australia (n=20) respectively. The number of alleles ranged from 9 to 14 with an average of 11.28 per locus. The Mean expected heterozygosity (He) was 0.8696 in the population from China, 0.8823 in the population from Australia. No locus deviates significantly from Hardy–Weinberg equilibrium proportions (P<0.05). These markers have being employed in population genetic studies on the giant mottled eel in our lab and may be also useful in studies on other species of Anguilla.2. Population genetic structure of the Japanese eel (Anguilla japonica) in Chinese: evidence of panmixia populationsThe stock of the Japanese eel, Anguilla japonica, has dramatically declined in East Asia since the 1970s. In order to conserve and resource manage this species, its genetic structure should be well known. However, previous results from genetic studies on Japanese eel have been conflicting. In our study, the population structure of the Japanese eel was investigated through the control region DNA of mitochondrial and 19 polymorphic microsatellite DNA loci analyses using 362 individuals from 10 localities in China from south to north including Xinhui (Guangdong), Shantou (Guangdong), Xiamen (Fujian), Fuqing (Fujian), Ningde (Fujian), Yuhuan (Zhejiang), Taizhou (Zhejiang), Cixi (Zhejiang), Jiuduansha (Shanghai) and Dafeng (Jiangsu).Based on mitochondrial DNA: Overall, tests of genetic differentiation among the 10 samples were low yet significant for mtDNA (Fst = 0.016, P = 0.027). However, pairwise F-statistic values showed no significant genetic differentiations except the P values ofΦst between Ningde and Jiuduansha locations have significant level after Bonferroni correction. The minimum spanning haplotype network constructed by control regions revealed no clear phylogeographic structure, indicating Japanese eel probably constitutes only a single panmixia population in the study area. The Mantel test revealed no significant correlation with coastal geographical distances and each type of genetic differentiation indices for mtDNA.Based on the microsatellite DNA: Overall, tests of genetic differentiation among the 10 samples were low yet significant for microsatellite data (Fst = 0.003, P = 0.008). However, pairwise F-statistic values for microsatellites showed no significant genetic differentiations after Bonferroni correction. AMOVA for each locus indicated that most of the total genetic variation was within samples (99.38%), and only 0.49% was between samples. Bayesian clustering analyses indicated similar patterns of population structure as F-statistics, population for Japanese eel in 10 locations could not be partitioned into discrete genetic clusters. The Mantel test revealed no significant correlation with coastal geographical distances and each type of genetic differentiation indices for microsatellites DNA.Our results suggest the existence of a single panmixia population of Japanese eel in China. Therefore, the Japanese eel should be considered as a single management unit for conservation.