XVI International Botanical Congess

In the last decade, genetic diversity of chloroplast and mitochondria genomes has been analyzed in many species including trees. The identification of polymorphic universal" markers by PCR-derived techniques was used to study the geographic distribution of gene diversity. As compared to nuclear genes, organelle markers partition a larger amount of diversity among populations, resulting in clear-cut geographic patterns, mainly because of the uniparental inheritance and hence the absence of recombination of these genomes. Mode of inheritance and life-history attributes are predictors of the differentiation level detected with these markers. The study has also shed light on phylogeography and post-glacial recolonization processes in many species, pointing to frequent non-equilibrium situations. Studies of some European tree species will be presented.