| Genus Pelteobagrus belongs to Osteichtliyes, Siluriofmres, Bagrida. As a kind of small and famous economic fish, Pelteobagrus is well accepted by consumers. There are five rivers in Jiangxi Province which are Gan River,Fu Rive,Xinjiang River,Rao River,Xiu River. Five rivers gather together the majority of surface runoff in Jiangxi Province and flow into the Poyang Lake which is the largest fresh lake in China and is one of the two biggest lakes still linked with the Yangtze River, so it contains the rich fish resource. At the present time, researches of P. fulvidraco are concentrated in area of Yangtze River and Hubei province. The reports of P. fulvidraco in Jiangxi water area are few. The unique topography of Poyang Lake's "five rivers" and different geographic environment provide good places to study P. fulvidraco. The research of different groups of P. fulvidraco in Jiangxi water area on this paper is based on morphology and molecular genetics. So it can provide primary data and scientific guidance for Pelteobagrus's protection reasonable exploitation and breeding improved varieties.1:Investigation of Pelteobagrus's germplasm resourcesWe have made a complete investigation of Pelteobagrus's germplasm resources in five rivers and Poyang Lake during 2009.05-2010.10. We got 862 wild Pelteobagrus in 14 sample pointsThe result shows that Pelteobagrus's germplasm resources in Jiangxi water area are relatively rich and safe, but we should pay attention to the trend of lower age and take any appropriate action. A number of Pimelodus fulvidiraco distribute in five rivers and Poyang Lake. We find Bagrus vachelli in Wanan and Hukou, the size of Bagrus vachelli is much bigger than Pimelodus fulvidiraco in Hukou. We also find Pseudobagrus eupogon in Ganzhou and Pseudobagrus nitidus in Nanchang. Pelteobagrus's germplasm resources are the mostly rich in Hukou. The result of this investigation of Pelteobagrus's germplasm resources is similar to what Zhu Xinluo (1999) wrote in Fauna Sinica, Osteichthyes, Siluriformes. Meanwhile, it was discovered that destruction of Pelteobagrus's spawning grounds and the trend of lower age were primarily due to over-fishing and abuse of Schwimmbagger. It is necessary to pay attention and adopt corresponding protection and measures.2:Comparison of morphological differentiation between different groups of PelteobagrusThis study use multivariate statistical analysis which are cluster analysis, discriminant analysis and principal component analysis to elaborate the morphological differentiation of nine wild Pelteobagrus populations in Jiangxi province from morphological and analyze the causes. At the same time, we also choose a breeding population to compare. The conclusions are as follows:Obvious morphological differences can be found in different Pelteobagrus groups by using multivariate analysis to analyse measurable character. Cluster analysis shows that nine populations can be divided into three groups:the first group include Poyang,Yongxiu,Fuzhou and Yugan because the genetic distance between them are small. So is the second group which include Nanchang,Ganzhou,Xiajiang and Wanan. The third group is Hukou because of its large genetic distance. The breeding population's genetic distance is between Hukou and Wanan. Principal component analysis shows group differences of Hukou are the most notable, next is Wanan. Discriminant analysis finds that comprehensive identification rate of discriminant function is 81.67%, it can get 77.49% after cross-validation. The result showed by three kinds of multivariate analysis indicate that nine Pelteobagrus populations in Jixangxi water area exist morphological differentiation among the individuals to a certain extent, focusing on the index of lengthways length of head and tail, especially for Hukou and Wanan populations. In order to adapt the geographic isolation water environment, Pelteobagrus appeared the morphological differentiation.3:Researches on the genetic diversity of P. fulvidracoWe have done some researches on the genetic diversity of three wild P. fulvidraco populations which were GZ,WAN and HK by using 12 pairs of SSR primers of P. fulvidraco which had been exploited by other scholars. The results are as follows:By optimizing the reaction conditions, we find 10 of 12 pairs of SSR primers are effective and get 7 microsatellite locis which all have polymorphism.48 alleles were detected from 7 microsatellite locis. The size of each microsatellite loci which has 2-8 alleles is between 84-280bp. Average observed heterozygosity of three populations is 0.62, the highest one is HK (0.6509), the next is GZ (0.6209), the last one is WAN (0.5882). Average PIC of three populations is 0.5633,GZ (0.5618),HK (0.5944,WAN(0.5336). We found that genetic similarity index was 0.7314 between WAN and GZ which was the highest and genetic distance is 0.3128 which was the lowest. Genetic similarity index and genetic distance was the second between GZ and HK. Genetic similarity index which was 0.7002 between WAN and GZ was the lowest and genetic distance which was 0.3517 was the highest. So we can make an inference that there was a closer genetic relationship between WAN and GZ, while genetic relationship between WAN and HK was furthest.The result of SSR showed Pelteobagrus's germplasm resources in GZ and HK water area were still in safe and genetic diversity was rich. Indexes of genetic diversity were close to or slightly higher than other populations which had reported. As building-up of Wanan hydropower station caused the long-term geographical isolation, WAN population's germplasm resource is decreasing. So corresponding protection and measures should be done to keep the germplasm resources of Pelteobagrus. |
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