Galen Candace, Shore Joel S, Deyoe Hudson
Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403.
Department of Biology, York University, North York, Ontario, M3J 1P3, CANADA.
Evolution. 1991 Aug;45(5):1218-1228. doi: 10.1111/j.1558-5646.1991.tb04388.x.
Polemonium viscosum has a continuous distribution from 3,500 m in the krummholz to 4,025 m on the summit ridges of Pennsylvania Mountain, Colorado. Seeds produced by plants at opposite ends of this cline, 1.5 km apart, differed significantly at allozyme loci in two consecutive breeding seasons. Mean multilocus F values for both years (0.015 and 0.069) were significantly different from zero, indicating restricted gene exchange between subpopulations. Average allele frequencies at two individual loci also differed significantly between families comprising krummholz and summit subpopulations. Progeny of plants growing on the summit had higher leaf production rates, more densely packed leaflets, and lower resistance to aphids than progeny of plants growing in the krummholz site, when tested under greenhouse conditions. These differences probably reflect the restricted opportunities for growth and severe exposure at high elevations, and the increased risk from herbivores near timberline. The two subpopulations did not differ in leaf length (stature), leaf width, or pubescence. Reciprocal transplanting of seedlings between krummholz and summit sites confirmed that the differences were adaptive, since progeny from each subpopulation performed significantly better in their parent's habitat. Coordinated studies of genetic structure, quantitative variation, and local adaptation across the elevational range of P. viscosum provide a comprehensive view of ecotypic divergence in this widespread alpine plant.
粘叶花葱在科罗拉多州宾夕法尼亚山的矮曲林带海拔3500米处至山顶山脊海拔4025米处连续分布。在这个渐变群两端相距1.5公里的植株所产生的种子，在两个连续繁殖季节的等位酶位点上有显著差异。这两年的平均多位点F值（0.015和0.069）均显著不同于零，表明亚种群间基因交流受限。在矮曲林带和山顶亚种群的家系中，两个单独位点的平均等位基因频率也有显著差异。在温室条件下进行测试时，生长在山顶的植株的后代比生长在矮曲林带的植株的后代具有更高的叶片生长速率、更密集的小叶以及对蚜虫更低的抗性。这些差异可能反映了高海拔地区生长机会受限和暴露程度严重，以及林线附近食草动物造成的风险增加。这两个亚种群在叶长（株高）、叶宽或柔毛方面没有差异。在矮曲林带和山顶之间对幼苗进行 reciprocal transplanting 证实了这些差异是适应性的，因为每个亚种群的后代在其亲本栖息地的表现明显更好。对粘叶花葱整个海拔范围内的遗传结构、数量变异和局部适应性进行的协调研究，提供了对这种广泛分布的高山植物生态型分化的全面认识。
