دانلود رایگان مقاله بررسی تنوع ژنتیکی و ساختار جمعیت مارماهی مرداب Monopterus آلبوس

Abstrac

Swamp eel has become one of the most economically important fish in China. However, the wild swamp eel is facing the serious challenge of declining population and germplasm degeneration because most of farming swamp eel fingerlings was collected by fishing wild individuals. In this study, the genetic variation of Monopterus albus in six dominant farming regions was investigated based on the mitochondrial DNA D-Loop of 1008 bp in length. 180 individuals from 6 populations were examined and 74 haplotypes were observed. The overall genetic diversity was abundant and which its SD population was highest but CQ population was lowest. There was obvious genetic differentiation among investigated populations. Phylogenetic analysis revealed that these individuals were divided into four distinct genetic clades, clade A, B, C, and D. Clade A should be the most common ancestor clade. AH and CQ populations might originate from one single ancestor in maternal clade A. Clade C should be a native important clade in China. Though the genetic diversity did not suffered obvious decreasing, it is still imperative to take effective conservation measurements and establish an efficient selective breeding program.

4. Discussion

Mitochondrial DNA was widely used to analyze the population genetic structure and phylogeny in different species. The mitochondrial D-Loop region, with the highest variation and mutation rate of mtDNA, has been thought as an appropriate marker to study the genetic diversity and genetic differentiation in fishes, such as common carps (Thai et al., 2005; Liang et al., 2009) and tilapia (Szitenberg et al., 2012; Zou et al., 2015). The aquaculture of swamp eel as an economically important fish has made rapid progress, however the genetic resources of wild swamp eel has suffered serious challenge because of overfishing (Lei et al., 2012). Thus, background knowledge of genetic diversity and population structure is necessary to effectively protect and sustainably utilize swamp eel. In this study, the genetic diversity of six wild populations from dominant culturing regions in China was analyzed. The results showed overall haplotype diversity was high in the six investigated populations. Among them, genetic diversity from CQ population of Monopterus albus was the lowest. Only two haplotypes with four variation sites were observed and uniquely existed in the CQ population. Cai et al. (2008) also analyzed the genetic diversity of swamp eel of Sichuan Basin and found that genetic diversity in Chongqing populations was low (Hd ¼ 0.404, p ¼ 0.0007). Lacking of genetic variation of swamp eel populations may result from the founder effects, intrinsic traits and/or genetic drift (Ray et al., 2015). The haplotype diversity (Hd) and nucleotide diversity is always used to measure the degree of polymorphism within a population. The haplotype diversity results showed that the genetic variation of swamp eel in the Anhui province were abundant (0.708)