Jolivet Céline, Bernasconi Giorgina
Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland.
Ann Bot. 2007 Jul;100(1):119-27. doi: 10.1093/aob/mcm088. Epub 2007 Jun 12.
Among-population differentiation in phenotypic traits and allelic variation is expected as a consequence of isolation, drift, founder effects and local selection. Therefore, investigating molecular and quantitative genetic divergence is a pre-requisite for studies of local adaptation in response to selection under variable environmental conditions.
Among- and within-population variation were investigated in six geographically separated European populations of the white campion, Silene latifolia, both for molecular variation at six newly developed microsatellite loci and for quantitative variation in morphological and life-history traits. To avoid confounding effects of the maternal environment, phenotypic traits were measured on greenhouse-reared F(1) offspring. Tests were made for clinal variation, and the correlations among molecular, geographic and phenotypic distances were compared with Mantel tests.
The six populations of Silene latifolia investigated showed significant molecular and quantitative genetic differentiation. Geographic and phenotypic distances were significantly associated. Age at first flowering increased significantly with latitude and exhibited a Q(st) value of 0.17 in females and 0.10 in males, consistent with adaptation to local environmental conditions. By contrast, no evidence of isolation-by-distance and no significant association between molecular and phenotypic distances were found.
Significant molecular genetic divergence among populations of Silene latifolia, from the European native range is consistent with known limited seed and pollen flow distances, while significant quantitative genetic divergence among populations and clinal variation for age at first flowering suggest local adaptation.
由于隔离、漂变、奠基者效应和局部选择，预计表型性状和等位基因变异在种群间会出现分化。因此，研究分子和数量遗传分化是在可变环境条件下研究对选择的局部适应性的先决条件。
对欧洲六个地理隔离的白剪秋萝（Silene latifolia）种群的种群间和种群内变异进行了研究，包括六个新开发的微卫星位点的分子变异以及形态和生活史性状的数量变异。为避免母本环境的混杂效应，在温室培育的F(1)代后代上测量表型性状。进行了渐变变异测试，并通过Mantel检验比较了分子、地理和表型距离之间的相关性。
所研究的六个白剪秋萝种群表现出显著的分子和数量遗传分化。地理和表型距离显著相关。首次开花年龄随纬度显著增加，雌性的Q(st)值为0.17，雄性为0.10，这与对当地环境条件的适应性一致。相比之下，未发现距离隔离的证据，分子和表型距离之间也没有显著关联。
来自欧洲原生范围的白剪秋萝种群间显著的分子遗传分化与已知的有限种子和花粉传播距离一致，而种群间显著的数量遗传分化和首次开花年龄的渐变变异表明存在局部适应性。
