POPULATION-STRUCTURE OF MORPHOLOGICAL TRAITS IN CLARKIA-DUDLEYANA - II - CONSTANCY OF WITHIN-POPULATION GENETIC VARIANCE

Recent quantitative genetic studies have attempted to infer long-term selection responsible for differences in observed phenotypes. These an alyses are greatly simplified by the assumption that the within-popula tion genetic variance remains constant through time and over space, or for the multivariate case, that the matrix of additive genetic varian ces and covariances (G matrix) is constant. We examined differences in G matrices and the association of these differences with differences in multivariate means (Mahalanobis D-2) among 11 populations of the Ca lifornia endemic annual plant, Clarkia dudleyana. Based on nine contin uous morphological traits, the relationship between Mahalanobis D-2 an d a distance measure summarizing differences in G matrices reflected n o concomitant change in (co)variances with changes in means. Based on both broad-and narrow-sense analyses, we found little evidence that G matrices differed between populations. These results suggest that both the additive and nonadditive (co)variances for traits have remained r elatively constant despite changes in means.