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华南植物园栲树适应性分化研究取得进展

摘要 : 中国科学院华南植物园植物科学研究中心副研究员孙晔指导硕士研究生李春利用EST-SSR 分子标记对栲树自然群体适应性分化进行了大格局的取样研究。该研究成果已在线发表在国际科学期刊Heredity上。

气候变化常常导致森林群落组成以及物种分布范围、物候、遗传多样性和遗传结构的改变。研究气候因子如何影响自然群体的遗传多样性和遗传结构对了解森林树种应对全球气候变化具有重要作用。栲树(Castanopsis fargesii)是我国亚热带常绿阔叶林最重要的建群树种之一。我国亚热带地区存在明显的南北向温度差异和东西向降水差异,这种温度和降水的空间异质性预期对栲树自然群体造成强烈的选择压力,进而驱动栲树群体的适应性分化。

中国科学院华南植物园植物科学研究中心副研究员孙晔指导硕士研究生李春利用EST-SSR (expressed sequence tag-derived simple sequence repeat) 分子标记对栲树自然群体适应性分化进行了大格局的取样研究。通过群体遗传学分析来寻找选择作用留下的遗传印记,并进一步利用气候因子和等位基因频率的关联分析来验证温度和降水梯度对栲树群体遗传结构的影响。

气候变异和等位基因频率间的关联

气候变异和等位基因频率间的关联

研究结果发现温度和降水,特别是最干旱月份、最干旱季度和最冷季度降水对栲树群体遗传结构有重要影响,尽管绝大多数的遗传位点表现为选择中性,但4个EST-SSR位点明显受到歧化选择的影响。说明基因交流在栲树自然群体中普遍发生,歧化选择只作用于基因组特定区段。

该研究得到国家自然科学基金(30871959)等的资助。该研究成果已在线发表在国际科学期刊Heredity上。

原文摘要:

Footprints of divergent selection in natural populations of Castanopsis fargesii (Fagaceae)

C Li, Y Sun, H W Huang and C H Cannon

AbstractGiven predicted rapid climate change, an understanding of how environmental factors affect genetic diversity in natural populations is important. Future selection pressures are inherently unpredictable, so forest management policies should maintain both overall diversity and identify genetic markers associated with the environmental factors expected to change most rapidly, like temperature and rainfall. In this study, we genotyped 648 individuals in 28 populations of Castanopsis fargesii (Fagaceae) using 32 expressed sequence tag (EST)-derived microsatellite markers. After removing six loci that departed from Hardy–Weinberg equilibrium, we measured genetic variation, population structure and identified candidate loci putatively under selection by temperature and precipitation. We found that C. fargesii populations possessed high genetic diversity and moderate differentiation among them, indicating predominant outcrossing and few restrictions to gene flow. These patterns reduce the possible impact of stochastic effects or the influence of genetic isolation. Clear footprints of divergent selection at four loci were discovered. Frequencies of five alleles at these loci were strongly correlated with environmental factors, particularly extremes in precipitation. These alleles varied from being near fixation at one end of the gradient to being completely absent at the other. Our study species is an important forest tree in the subtropical regions of China and could have a major role in future management and reforestation plans. Our results demonstrate that the gene flow is widespread and abundant in natural populations, maintaining high diversity, while diversifying selection is acting on specific genomic regions.

来源: 中科院 浏览次数:18

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