Venable D Lawrence, Alberto Burquez M
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721.
Centro de Ecología, Universidad Nacional Autónoma de México, Mexico City, 04510, MEXICO.
Evolution. 1989 Jan;43(1):113-124. doi: 10.1111/j.1558-5646.1989.tb04211.x.
We document phenotypic and genetic variation within and among populations of the seed heteromorphic species Heterosperma pinnatum Cav. (Compositae) in the production of seed morphs and in a variety of life-history and morphological characteristics that might be correlated with seed and head traits. Each trait is found to have significant genetic variance in most or, usually, all populations. Significant among-population genetic variation exists for all traits except number of achenes per head and seedling shape, although some traits have much less genetic variation among than within populations. Number and percentage of intermediate achenes per head, total number of achenes per head, and lengths of central and peripheral achenes had little among-population genetic variation compared to within-population variation. Most traits had slightly less genetic variation among than within populations; however, some traits (percentage of central achenes, length of awns, date that the first flowering head opened, date that the first fruiting head opened, and death date) had more among-population genetic variation. The proportions of achene morphs produced had high broad-sense heritabilities and high among-population genetic variance, except in the case of intermediate achenes. All phenological variables had high among-population genetic variation. Within-population heritabilities were high for dates of first flowering head and fruiting head but low for death date and reproductive interval. Family and population means measured in the greenhouse for traits having high broad-sense heritability or among-population genetic variance were closely correlated with field means for the corresponding families or populations. The amounts of phenotypic variation were similar for traits that were measured in both the field and the greenhouse. These lines of evidence suggest that greenhouse results provide reasonable estimates of genetic variation in the field for this species. Numerous studies have reported variation in the proportion of seed morphs for different heteromorphic-seeded species and have discussed adaptive scenarios for the evolution of seed proportions; however, our investigation is one of only a few that have documented the amount of phenotypic and genetic variation within and among populations.
我们记录了种子异型物种羽叶异籽菊（菊科）种群内部和种群之间在种子形态产生以及各种可能与种子和头状花序性状相关的生活史和形态特征方面的表型和遗传变异。发现每个性状在大多数或通常在所有种群中都具有显著的遗传方差。除了每头状花序瘦果数和幼苗形状外，所有性状都存在显著的种群间遗传变异，尽管有些性状的种群间遗传变异比种群内的要少得多。与种群内变异相比，每头状花序中间瘦果的数量和百分比、每头状花序瘦果总数以及中央和外围瘦果的长度在种群间的遗传变异较小。大多数性状的种群间遗传变异略少于种群内；然而，一些性状（中央瘦果的百分比、芒的长度、第一个开花头状花序开放的日期、第一个结果头状花序开放的日期以及死亡日期）的种群间遗传变异更大。除了中间瘦果的情况外，所产生的瘦果形态比例具有较高的广义遗传力和较高的种群间遗传方差。所有物候变量都具有较高的种群间遗传变异。种群内遗传力在第一个开花头状花序和结果头状花序的日期较高，但在死亡日期和生殖间隔方面较低。在温室中测量的具有高广义遗传力或种群间遗传方差的性状的家系和种群均值与相应家系或种群的田间均值密切相关。在田间和温室中测量的性状的表型变异量相似。这些证据表明，温室结果为该物种田间的遗传变异提供了合理的估计。许多研究报告了不同异型种子物种种子形态比例的变异，并讨论了种子比例进化的适应性情景；然而，我们的研究是少数记录了种群内部和种群之间表型和遗传变异量的研究之一。
