入侵地和原产地太湖新银鱼群体遗传结构

为了探讨太湖新银鱼快速适应新环境和快速入侵的遗传学机制,本研究利用10个微卫星位点对5个入侵地和2个原产地的群体遗传结构进行了分析。遗传多样性参数结果显示,入侵地滇池、邛海、抚仙湖和三峡库区群体的遗传多样性水平比原产地高,入侵地洱海群体的遗传多样性水平低于原产地太湖而高于巢湖群体,原产地巢湖群体的遗传多样性最低。遗传距离和UPGMA聚类结果表明邛海群体和其他群体的遗传关系最远,太湖与抚仙湖的遗传关系最近。ANOVA显示大多数遗传变异存在于太湖新银鱼群体内(95.78%),群体间的遗传变异为4.22%,固定系数(Fst=0.0422)显著,表明太湖新银鱼群体间存在显著的小尺度遗传分化,两两遗传分化指数也证实了这一点。MVSP主成分分析显示邛海、三峡库区、巢湖和滇池群体有明显的分化。由此推断,高水平的遗传多样性和显著的遗传结构差异性可能是太湖新银鱼成功入侵的重要原因。

Population genetic structure of Neosalanx taihuensis between invasive and original areas revealed by microsatellite DNA

Neosalanx taihuensis is a small-sized freshwater fish from the Salangidae family, and is found mainly in the middle and lower reaches of the Yangtze River, including its tributaries and affiliated lakes. N. taihuensis has a high commercial value, and was therefore introduced to lakes and reservoirs in many Chinese provinces during the 1980s. It very rapidly adapted to the new conditions present in these lakes and reservoirs, quickly becoming the dominant species of fish. This caused a population decline in several native species, which led to notable changes in the community structure of fish and even local extinctions. It is currently understood that the level of genetic variation present in a population influences its ability to adapt to changing conditions. Therefore, in order to better understand the genetic mechanisms that allow N. taihuensis to successfully invade and adapt to new ecosystems, 10 microsatellite loci were performed to comparatively analyze population genetic structure of N. taihuensis between 5 invasive areas and 2 original areas. Genetic diversity parameters indicated that invasive populations from Dianchi Lake, Qionghai Lake, Fuxianhu Lake and Three Gorges reservoir had higher levels of genetic diversity than those living in original areas of Taihu Lake and Chaohu Lake, and invasive population from Erhai Lake had the lower level of genetic diversity than that from Taihu Lake, but higher level of genetic diversity than that from Chaohu Lake, whilst original area of Chaohu Lake had the lowest level of genetic diversity. The value of pairwise genetic distance was from 0.0062 to 0.1013. The genetic distance between Qionghai and Chaohu populations was the greatest, whilst the genetic distance between Taihu Lake and Fuxianhu Lake populations was the smallest. Both genetic distance and UPGMA clustering results showed that the Qionghai population had the farthest genetic relation with the other populations, whilst relationship between Taihu Lake and Fuxianhu Lake populations was the nearest. ANOVA analysis revealed most of the total variation occurred within populations (95.78%) and a small amount of differentiation among populations (4.22%). F_st value (0.0422) was significant, which exhibited a low and significant population differentiation. Out of 21 pairwise comparisons of populations, significant genetic divergence was detected in 18 pairs (85.7%) of populations, which also confirms the significant population differentiation. The value of F_st between Qionghai Lake and Chaohu Lake populations was maximum among all pairwise comparisons. Significant genetic differentiation was not found in three pairs of populations: Taihu Lake vs. Fuxianhu Lake, Taihu Lake vs. Erhai Lake and Fuxianhu Lake vs. Erhai Lake. MVSP principal component analysis demonstated the populations from Qionghai Lake, Three Gorges reservoir, Chaohu Lake and Dianchi Lake displayed a clear differentiation. It could conclude that high level of genetic diversity and the significant difference of genetic structure might be the important reasons for successful invasion of N. taihuensis.