POPULATION-STRUCTURE OF MORPHOLOGICAL TRAITS IN CLARKIA-DUDLEYANA .1.COMPARISON OF F-ST BETWEEN ALLOZYMES AND MORPHOLOGICAL TRAITS

Studies of genetic variation at allozyme loci, assumed to be selective ly neutral, have provided valuable insights into the genetic structure of numerous populations. The degree to which population structure of allozyme variation reflects that of quantitative traits, however, is n ot well resolved. Here, we compare estimates of population differentia tion (F-ST) Of 11 populations for allozymes with those for nine discre te and nine continuous morphological traits. Overall, the allozymes ha ve the lowest F-ST estimates, indicating relatively little population differentiation. Excepting two traits, petal width and long internode length, the continuous morphological traits have estimates similar to those from allozymes. The discrete morphological traits tend to have t he highest estimates. On a single trait basis, estimates of F-ST for f our discrete and two continuous traits are higher than those for alloz ymes. A more detailed (narrow-sense quantitative) genetic study of two populations suggests that these estimates of F-ST may underestimate t he true value because of dominance. Clustering analyses show that the pattern of differentiation for the discrete morphological traits stron gly reflects the geographical distribution of the populations, whereas the patterns for the continuous traits and allozymes do not. These re sults suggest that selection has been occurring on the discrete morpho logical traits, selecting to-ward a common optimum within each geograp hic group, and optima differing among geographic groups.