| Genus Coilia fishes, the small-to moderate-size fishes in the FamilyEngraulidae, Order Clupeiformes, are widely distributed in the northwestand western Pacific Ocean. There are four kinds of Coilia fishes, i.e., C.ectenes, C. mystus, C. brachygnathus and C. grayii, recorded in China.Among them, C. ectenes and C. mystus are very popular with higheconomic value. Due to environmental deterioration and great capturepressure, the resources of C. ectenes and C. mystus are declining and theprotection of Coilia resources is very urgent. In this study, we usedmicrosatellite markers to analyze the genetic structure and genetic diversitywithin and genetic differentiation between populations of C. ectenes and C.mystus, in order to facilitate the development of resource managementstrategy and sustainable utilization of C. ectenes and C. mystus fisheryresources. The detailed contents are as follows: 1. Development of34novel microsatellite markers in C. ectenes andcross-species amplification in closely related taxaA repeat-enriched genomic library was constructed by the combinedbiotin capture method in C. ectenes.198pairs of primers were designedsuccessfully from546sequences, and34microsatellite loci were proved tobe polymorphic. A total of325alleles were detected. The numbers ofalleles per locus ranged from4to23. The observed (Ho) and expected (He)heterozygosities ranged from0.14to1.00and from0.54to0.91,respectively. Ten loci deviated signifcantly from Hardy–Weinbergequilibrium (HWE) and no linkage disequilibrium (LD) between pairs ofloci was found after Bonferroni correction. The applicability of thesemarkers in a closely related species C.mystus was evaluated by thecross-species amplification. All but9loci (DJ232, DJ241, DJ310, DJ312,DJ568, DJ578, DJ588, DJ639, DJ670) in C.mystus and one locus (DJ161)in C. e. taihuensis would successfully be useful for amplification. Thesemarkers will be benefit for the studies on population genetics, conservativegenetics, fishery management, and construction of genetic linkage maps ofC. ectenes, C. mystus and C. e. taihuensis. 2. Genetic diversity evaluation of ten populations of C. ectenesTen microsatellite markers were chosen for genetic analysis of tenwild populations including285individuals of C. ectenes. The resultsshowed that994alleles were detected and the average number of allelesper locus is9.94, which the highest number of alleles per locus is Lian yungang (LYG) population (Na=11.9) and lowest is Fuzhou (FZ) population(Na=6.5). The effective number of alleles (Ne), average observed (Ho) andexpected (He) heterozygosity ranged from1.29to15.02, from0.36to0.58,and from0.65to0.88, respectively. Analysis of molecular variance(AMOVA) showed that between population variations accounting for15%of total variation, while85%of total variation arised from withinpopulations. The fixation index (Fst) showed that population Fuzhou (FZ)had the largest genetic differentiation from other populations. Nei’s geneticdistances were used to construct the dendrogram by using UPGMA meanand the results showed Dongting Lake population and Wuhan populationalso have a certain degree of differentiation between other populations, inaccordance with the result of principal component analysis and Bayesianclustering analysis. The results provided a scientific basis and data supportfor the protection of resources of C. ectenes. 3. Microsatellite DNA diversity of C. mystus in three populationsGenetic diversity of three populations of C. mystus, i.e., Yangtze Riverestuary-CJ, Minjiang River estuary-MJ, and Pearl River estuary-ZJ, wereinvestigated by using eight pair’s microsatellite markers in this study. Theresults showed that1) we detected totally720amplified fragment. Thenumbers of alleles for each locus ranged between2and20. The averagePolymorphic Information Contents (PIC) of each population is from0.64to0.78. The mean observed (Ho) and expected (He) heterozygosities rangedfrom0.09to0.21and from0.68to0.81, respectively. The polymorphism ofCJ and MJ populations were higher than ZJ population. Highly significantdeviations from Hardy–Weinberg equilibrium, mostly due to deficits ofheterozygote, were found in these three populations;2)Pairwise Fst and thePrincipal Component Analysis (PCA) indicated that the three estuarypopulations were genetically distinct, in accordance with and the Bayesianmodel-based clustering algorithm analysis. The results suggested that thelevel of genetic differentiation between these three estuary populations wasrelatively high and may have diverged at the subspecies level. |
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