|Title||The comparison of phenotypic plasticity and genetic variation in populations of the grass Danthonia spicata|
|Publication Type||Journal Article|
|Year of Publication||1984|
|Authors||Scheiner SM, Goodnight CJ|
A quantitative definition for plastic variance is presented. Plastic variation is defined as the deviation of the mean phenotype of a genotype within an environment from the mean phenotype of that genotype across all environments. For a population, plastic variation is then xxx = xxxx + xxxx. Plasticity, by analogy with heritability, is defined as the ratio of plastic variance to total phenotypic variance, x = xxx/xxx. These definitions are analogous to previous qualitative definitions of phenotypic plasticity. Individuals from five populations of the grass Danthonia spicata from a set of habitats of different successional age were clonally replicated and grown in six different environments. Comparisons of 12 morphological, phenological, reproductive, and growth traits revealed highly significant differences in amounts of phenotypic variance, plastic variance, and residual variance among the pouplations. There were no significant differences in amounts of genetic variance. No populations had consistently more or less plastic variation or genetic variation. There was no decrease in genetic variation or plastic variation in ecologically marginal populations. There was no significant correlation, either negative or positive, in amounts of genetic variation and plastic variation. These results are discussed in the context of previous hypotheses concerning genetic variation in ecologically marginal populations and correlations between genetic and plastic variation.