THE CARPINUS CAROLINIANA COMPLEX IN NORTH-AMERICA .1. A MULTIVARIATE-ANALYSIS OF GEOGRAPHICAL VARIATION

The Carpinus caroliniana Walter complex (Betulaceae) is a morphologically variable group extending geographically from southeastern Canada to northern Central America. In this study, a series of multivariate procedures has been applied to morphological data obtained from throughout the range of the complex to identify and characterize patterns of regional variation. The methods used include principal components analysis, an a posteriori test procedure (SNK test), and stepwise discriminant analysis. Coefficients of phenetic variation were obtained to estimate the within- and among-population variabilities of subgroups, and multiple regression analyses were used to determine the relationships between variation patterns of morphological and environmental variables. These analyses demonstrate patterns of significant morphological differences corresponding to large geographical regions having distinct environmental conditions. Four major morpho-geographic groups are recognizable, these integrating in relatively narrow zones at their points of contact. Within the various groups, which possess character states linked to different ecological roles or survival strategies, the expression of individual characters is often in divergent directions, the changes related to different ecological features.