Armbruster W Scott
Department of Biology and Wildlife and Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775-0180, USA.
Evolution. 1991 Aug;45(5):1229-1244. doi: 10.1111/j.1558-5646.1991.tb04389.x.
I examined patterns of covariation of three morphometric blossom characters [gland area (GA), gland-stigma distance (GSD), and bract length (BL)] within genets, among genets, and among populations of the tropical vine, Dalechampia scandens (Euphorbiaceae). Covariance between BL and GA was evenly distributed among the three levels. This observation, coupled with developmental information, indicates that the two characters change size similarly during development, that there is probably genetic covariance between them (apparently caused by pleiotropy), and that the genetic covariance may have constrained (at least proximally) the course of population differentiation with respect to these characters. Most covariance between GSD and GA occurred at the among-population level. This observation, coupled with developmental information, indicates that there is negligible ontogenetic covariance and that within populations there is probably little or no genetic covariance between the two characters. Among-population covariance has probably been caused by natural selection operating in a correlated fashion on characters that functionally interact in pollination.
我研究了热带藤本植物匙羹藤（大戟科）的无性系内、无性系间以及种群间三个形态学花部特征[腺体面积（GA）、腺体-柱头距离（GSD）和苞片长度（BL）]的协变模式。BL和GA之间的协变在三个水平上均匀分布。这一观察结果，结合发育信息，表明这两个特征在发育过程中大小变化相似，它们之间可能存在遗传协变（显然是由基因多效性引起的），并且这种遗传协变可能（至少在近端）限制了这些特征在种群分化过程中的进程。GSD和GA之间的大多数协变发生在种群间水平。这一观察结果，结合发育信息，表明个体发育协变可忽略不计，并且在种群内这两个特征之间可能几乎没有或不存在遗传协变。种群间协变可能是由自然选择以相关方式作用于在授粉中功能相互作用的特征所导致的。
