| Since the ancient times, the Marine fishery occupies a decisive position in our Country. It is belongs to the important industry in the national economy in our country. The fishery resources is also the foundation of Chinese fishery production, in recent years, Chinese elongate ilisha(Ilisha elongate) fishery output ranked the top five in our country. A comprehensive understanding of the population structure and genetic diversity of elongate ilisha is to implement the elongate ilisha resources protection and sustainable development. A comprehensive understanding of elongate ilisha population structure and genetic diversity of elongate ilisha fisheries management policy also play a positive role, is the fundamental guarantee of fishery sustainable development strategy. In recent years, due to ignore the elongate ilisha population genetic structure of the research, overfishing it, led to a sharp decline in elongate lilsha population catches and attenuation, serious population in elongate ilisha was caught on the total amount and the size of the elongate ilisha, and the distribution of it also gradually narrowed. Therefore, the sustainable development of the elongate ilisha resource and its utilization in urgent need of management of science. In order to further understand the western ilisha elongate population evolution and forming mechanism of geographical landscape, we have also developed in the western Pacific Ocean molecular system of geography research.Elongate ilisha(Ilisha elongate), belongs to the Clupeiformes, Clupeidae, middle and upper strata, a kind of warm water fish, mostly in the water, the lower activity during the day, in the cloudy day, dusk and dawn like to live in the water of the upper classes. Elongate ilisha concentration distribution in the western Pacific to Malaysia Sarawak Java sea. In our country, the Bohai Sea, Yellow Sea, East China Sea, and the South China Sea are elongate ilisha distribution, most production in the East China sea. We adopt the mitochondrial DNA(mtDNA) control area(D- Loop) and about 1000 nuclear coding genes as molecular markers, 16 sampling sites in Western Pacific group of elongate ilisha population structure and genetic diversity research, as well as western Pacific elongate ilisha population geography study of molecular systems. The main results of this study are as follows:1. Collected in the western Pacific Ocean along China’s coast, including South Korea and Japan, 16 sampling points of 125 samples of elongate ilisha, test the fish were collected from the Yellow Sea(Yellow Sea, YS) in Yantai(YT), Dandong(QD), Qingdao(DD), East China Sea(ECS), Wenzhou(WZ), Xiangshan(XS), Shengsi(SS), Xiapu(XP), Taiwan Strait(TWS) Minqing(MQ) and Xiamen(XM), and the South China Sea(SCS) of Haian(HA), Zhanjiang(ZJ), Zhapo(ZP), Shanwei(SW), and Japan, Ariake Sound(AS), South Korea’s Jeju-do island(the Jeju- do, JJ) and Mokpo(Mokpo, MP), according to the territorial waters are divided into 6 groups, using the mtDNA D-Loop control sequences, studied the Western Pacific elongate ilisha population structure and genetic diversity. According to the results of Dandong population with other significant haploid type differentiation between populations, in addition to Dandong and other populations outside of Japan between haploid type in the field of frequency distribution does not exist significant differences, namely the population genetic structure was not significant. This speculation, elongate ilisha in the pleistocene interglaciations may form two different shelters, including Dandong popilation form a shelter, all other different populations may be mixed together, formed another shelter, therefore failed to form a significant genetic differentiation and hierarchical structure.2. From the two aspects of genetics and morphology of 16 groups of 125 elongate ilisha can quantity character and numbered properties characteristics are analyzed, and discuss the two kinds of caudal fin symmetrical and asymmetrical elongate ilisha genetic relationship. Results show that the two kind of elongate ilisha had the extremely significant difference in addition to the asymmetry of caudal fin, the other can amount and numbered properties characteristic does not exist significant differences. From the aspects of molecular genetics, mitochondrial DNA of two kind of elongate ilisha complete control D-loop fragment sequence comparison analysis, the result is that two elongate ilisha genetic distance was only about 2.7%, belongs to a kind of genetic distance, reconstruction of RAx ML phylogenetic tree, also showed the two elongate ilisha mixed together, close relatives, and there is no significant difference.3. Research on 125 elongate ilisha individual D- loop, the result shows that the elongate ilisha population high levels of genetic diversity(h =0.98, π =0.006), in addition to Dandong population of AMOVA analysis indicates that the genetic variation of most populations from within groups, there is only between genetic variation from the group of Dandong. From the genetic differentiation among elongate ilisha population diversity index Φst valueis displayed in the elongate ilisha population distribution range, there is no significant genetic structure. But elongate ilisha groups exist certain geographical isolation model(R2 =0.0591; P =0.006). From nucleotides not matching distribution analysis and neutral test, speculated that the western group of elongate ilisha in Pleistocene Interglacial period after expansion, different groups after expansion when joined together, the gene exchange, thus the genetic differentiation between different groups is not obvious.4.Single nucleotide polymorphism(SNP) markers coupled with the next-generation sequencing technologies are powerful tools for studying population genetics, as well as for species delimitation. Target gene capture could be used to enrich homologous fragments across divergent species. We showed that by targeting a set of universal single-copy nuclear gene markers of vertebrates, we could retrieve thousands of SNPs from the Japanese grenadier anchovy(Coilia nasus) sampled from three locations: coastal region close to the estuary of the Yangtze River, the main stem of the river and Lake Dongting, a lake connected to the middle reach of the Yangtze River. Our study demonstrated that gene capture could be used to generate SNP data... |
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