Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
Mol Ecol. 2011 Jun;20(11):2318-28. doi: 10.1111/j.1365-294X.2011.05105.x. Epub 2011 Apr 26.
In plants, ecologically important life history traits often display clinal patterns of population divergence. Such patterns can provide strong evidence for spatially varying selection across environmental gradients but also may result from nonselective processes, such as genetic drift, population bottlenecks and spatially restricted gene flow. Comparison of population differentiation in quantitative traits (measured as Q(ST) ) with neutral molecular markers (measured as F(ST) ) provides a useful tool for understanding the relative importance of adaptive and nonadaptive processes in the formation and maintenance of clinal variation. Here, we demonstrate the existence of geographic variation in key life history traits in the diploid perennial sunflower species Helianthus maximiliani across a broad latitudinal transect in North America. Strong population differentiation was found for days to flowering, growth rate and multiple size-related traits. Differentiation in these traits greatly exceeds neutral predictions, as determined both by partial Mantel tests and by comparisons of global Q(ST) values with theoretical F(ST) distributions. These findings indicate that clinal variation in these life history traits likely results from local adaptation driven by spatially heterogeneous environments.
在植物中，生态上重要的生活史特征通常表现出种群分歧的渐变模式。这种模式可以为环境梯度上空间变化的选择提供强有力的证据，但也可能是由非选择性过程引起的，如遗传漂变、种群瓶颈和空间限制的基因流。比较数量性状（以 Q(ST) 衡量）和中性分子标记（以 F(ST) 衡量）的种群分化，为理解适应性和非适应性过程在渐变变异的形成和维持中的相对重要性提供了有用的工具。在这里，我们证明了在北美广泛的纬度横断线上，二倍体多年生向日葵物种 Helianthus maximiliani 存在关键生活史特征的地理变异。开花时间、生长速度和多个与大小相关的特征存在强烈的种群分化。通过偏 Mantel 检验和比较全球 Q(ST) 值与理论 F(ST) 分布，这些性状的分化大大超过了中性预测，表明这些生活史特征的渐变变异可能是由空间异质环境驱动的局部适应引起的。
