Am J Bot. 1997 Apr;84(4):471.
Chrysothamnus nauseosus (Asteraceae) is a complex polymorphic shrub species widely distributed in western North America. In a study of 86 populations belonging to 15 subspecies, achene mass varied among populations over a sevenfold range. Achene mass was closely correlated with capitulum size at the subspecies level, varied little between wild-growing and common-garden-grown members of a population, and was under strong genetic control. Subspecies with the heaviest achenes are restricted to specialized edaphic environments (dunes and badlands) or late seral montane riparian communities, while subspecies that are widely distributed and that occur in early seral habitats have less heavy achenes. Selection on achene mass has apparently been a notable feature of the adaptive radiation of Chrysothamnus nauseosus into the wide array of habitats it currently occupies. Within a wild population, achene mass was greater for plants fruiting in midautumn than for plants fruiting early or late in the autumn, and this same trend was observed within individual plants in garden populations, indicating environmental control, perhaps through resource limitation. Highly significant between-plant differences in achene mass were found in both wild and garden populations, suggesting that within-population genetic variation is sufficient to permit continuing selection.
黄花矶松（菊科）是一种广泛分布于北美西部的复杂多态灌木物种。在对属于 15 个亚种的 86 个种群的研究中，瘦果质量在种群间的变化范围为七倍。瘦果质量与亚种下头状花序的大小密切相关，在种群中野生和常见花园生长的成员之间变化很小，并且受到强烈的遗传控制。最重的瘦果的亚种局限于专门的土壤环境（沙丘和荒地）或后期演替的山地河岸社区，而分布广泛且出现在早期演替生境中的亚种则没有那么重的瘦果。在黄花矶松广泛的适应性辐射中，瘦果质量的选择显然是一个显著的特征。在野生种群中，秋中期结实的植物的瘦果质量大于秋季早期或晚期结实的植物，而在花园种群中，同一植物的这种趋势也存在，表明存在环境控制，可能是通过资源限制。在野生和花园种群中都发现了瘦果质量的高度显著的植物间差异，这表明种群内的遗传变异足以允许持续选择。
