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Genetic diversity of European black poplar, Populus nigra L., in France and the role of vegetative reproduction in natural stands
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International audience. Genetic resources of P. nigra L. were described in France using neutral diversity (isozymes) and naturally selected traits. The number of genetically identical trees due to vegetative reproduction was estimated in one stand using STS and RAPD markers.The amount of diversity was slightly smaller in the French collection than in a set of clones representing other countries from the species' natural range. Within France, however, the Alps region had almost the same diversity as the foreign set. We found the same levels of differences in terms of allele frequencies and gene diversity indices between stands from the same drainage than between stands from different drainages.The genetic differentiation for three hierarchical levels was small: this shows that the mating system and the ways the species propagates ensure a high level of exchange between stands and between drainages. Low levels of differentiation have often been described for North American poplar species and other pioneer species.Although vegetative propagation was commonly observed in some natural sites at a young stage, the analyzed stands were found to include almost as many genotypes as individuals: this suggests that seedlings are more effective than vegetative copies in colonizing new stands.
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