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Studies on the Population Biology of the Genus Viola. II. The Effect of Plant Size on Fitness in Viola Sororia
Otto T. Solbrig
Vol. 35, No. 6 (Nov., 1981), pp. 1080-1093
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2408122
Page Count: 14
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Populations of plants typically show a size hierarchy with many small and a few large individuals. Mortality is heavily concentrated in the smallest individuals. It is, therefore, of great interest to determine the factors responsible for the establishment of size hierarchies. Field observations are presented that show that in a population of Viola sororia survival and fecundity of individuals are strongly size dependent. Quantitative genetical laboratory experiments using offspring of the field plants indicate that there is additive genetic variance for percent germination, speed of germination, and some quantitative morphological characters but not for growth rate. Experiments conducted under three different densities and in two different environments show that competition and physical environment have a substantial effect on attained plant size and growth rate. It is concluded that under natural field conditions environment is a more important factor in determining the size hierarchy than genetic differences among individuals.
Evolution © 1981 Society for the Study of Evolution