Department of Botany, Dept. 3165, 1000 E. University Ave., University of Wyoming, Laramie, Wyoming 82071, USA.
Am J Bot. 2011 Apr;98(4):669-79. doi: 10.3732/ajb.1000378. Epub 2011 Mar 24.
Population genetic analyses provide information on the population context in which evolutionary processes operate and are important for understanding the evolution of geographically variable traits. Earlier studies showed that cone structure of lodgepole pine in the Rocky Mountains diverged among populations because of geographic variation in coevolutionary interactions involving mammalian and avian seed predators. Analyses of population genetic variation are needed to determine whether this divergence has arisen despite extensive gene flow and whether populations to the east and west of the Rocky Mountains have evolved convergent phenotypes independently.
We investigated genetic structuring across 22 stands of lodgepole pine in the central Rocky Mountains and in isolated peripheral populations that experience different seed predators and exhibit parallel divergence in cone traits using a set of nine simple sequence repeats and 235 AFLP loci.
Our analyses reveal high levels of genetic diversity within and low genetic differentiation among populations. Nonetheless, geographic and genetic distances were correlated, and isolated populations to the east and west of the Rocky Mountains had higher levels of differentiation than did populations in the central part of the range.
These data indicate not only that adaptive divergence of cone traits across a geographic mosaic of coevolution has occurred despite minimal genetic differentiation, but also that isolated populations to the east and west of the Rocky Mountains have evolved distinctive cones independently and in parallel. The population structure quantified here will inform future research aimed at detecting genetic variants associated with divergent adaptive traits.
群体遗传学分析提供了有关进化过程运作的种群背景的信息，对于理解具有地理差异的特征的进化非常重要。早期的研究表明，落基山脉的黑云杉的球果结构在种群之间发生了分歧，这是因为涉及哺乳动物和鸟类种子捕食者的共同进化相互作用在地理上发生了变化。需要对种群遗传变异进行分析，以确定这种分歧是否是在广泛的基因流的情况下产生的，以及落基山脉东西部的种群是否独立进化出了趋同的表型。
我们使用一组九个简单序列重复和 235 个 AFLP 基因座，研究了落基山脉中部的 22 个黑云杉种群和孤立的外围种群的遗传结构，这些种群经历了不同的种子捕食者，并且在球果特征上表现出平行的分歧。
我们的分析显示，种群内的遗传多样性水平较高，种群间的遗传分化程度较低。尽管如此，地理距离和遗传距离是相关的，落基山脉东西部的孤立种群比山脉中部的种群具有更高的分化水平。
这些数据不仅表明，尽管遗传分化程度较低，但在共同进化的地理镶嵌体中，球果特征的适应性分歧已经发生，而且落基山脉东西部的孤立种群已经独立且平行地进化出了独特的球果。这里量化的种群结构将为未来旨在检测与趋同适应性特征相关的遗传变异的研究提供信息。
