A comparative study of morphological integration in Apis mellifera (Insecta, Hymenoptera)

Morphometric correlation matrices from 11 Mediterranean and European honey bee races have been compared. The degree of integration, measured by the eigenvalue variance of the correlation matrix or by Cheverud's index of integration, varies considerably between races but covaries neither with overall body size nor with the variance of the respective sample. Hence, the degree of morphological integration does not depend on body size or the level of variability The patterns of morphometric correlation are significantly similar among all races, but some minor differences in the patterns could be detected: The similarity between the correlation matrices is independent of the degree of phylogenetic relatedness between the respective races. In all races characters belonin to the same functional and/or developmental unit (leg, wing, abdominal characters) have Eiter correlations than the average. Most of the variation in the pattern of correlation can be expfained as a side effect of variation in the degree of integration. Races with high levels of integration tend to have hiher correlations between the main groups of characters, and races with low levels of integration tave smaller correlations between the main grous of characters, while the basic pattern remains undisturbed. In summary, the comparative analysis of morphometric correlation matrices reveals a picture of stability with respect to the pattern of integration and of variation in the degree of integration, which is random with respect to body size, degree of variability, and phylogeny.