Similitude génétique et mode de dispersion : la nature des populations clonales de peupliers baumiers (Populus balsamifera L.) au Nouveau-Québec

Abstract

In an attempt to understand the genetic make-up of northern populations of the balsam poplar, their genetic similarity has been estimated by means of foliar morphological and enzymatic characters. A factorial principal component analysis has shown that the morphological characters could be reduced to leaf size and shape, as well as to three accessory variables: the length of the petiole, the number of teeth and the top angle of the leaf tip. The shape and accessory characters were the most discriminant when comparing poplar stands. The fringing of poplar stands at the forest edges is determined mainly by the population density. Partition analyses of discriminant morphological characters and electrophoretically determined allele frequencies point to heavy gene exchange between poplar stands. The centres of genetic diversity of the east coast of Hudson Bay allows us to visualize species dispersal according to the "stepping stone" pattern, i.e. according to a progression that stems from successive discrete events. [Journal translation]