Phenotypic Integration in Chestnut (Castanea sativa Mill.): Leaves versus Fruits

There is increasing attention in the literature to a more complex view of the phenotype in natural populations. Modern morphometric studies rely on more than single traits, and the classical approaches of size and shape analysis are being coupled with studies on amounts and patterns of phenotypic covariances and correlations, i.e., morphological integration. In this study, we describe the morphometrical differentiation of eight populations of chestnut (Castanea sativa Mill.), focusing on phenotypic integration of two anatomical structures: leaves and fruits. Our results show that (1) the amount of integration (i.e., the overall strength of trait correlations) is higher for fruit than for leaf characters; (2) the patterns of integration (i.e., the direction of trait correlations) are more variable for fruits than for leaves; and (3) the two anatomical structures are completely unrelated to each other in both amounts and patterns of phenotypic integration. These results are discussed in relation to how artificial selection could have acted on the underlying genetic mechanisms of these different aspects of chestnut phenotype.