Genetic structure of marginal populations of white spruce (Piceaglauca) at its northern limit of distribution in Nouveau-Québec

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Abstract
The genetic structure of six marginal populations of white spruce (Picea glauca (Moench) Voss) located at Richmond Gulf in the subarctic region of Nouveau-Quebec, and one southern population located at Kuujjuaraapik (Poste-de-la-Baleine) were analyzed by acrylamide gel electrophoresis for seven enzyme systems. The analysis of 27 loci disclosed an average polymorphism of 76.2% and a level of heterozygosity of 0.319. Data based on Wright''s statistics indicated a deficiency of heterozygotes for 60% of the loci, as calculated from the Hardy-Weinberg equilibrium. These results, coupled with the very low percentage of filled seeds in cones of all populations, suggest that a certain level of inbreeding or gene exchange among near-neighbour relatives influences the genetic structure of these populations. The genetic differentiation among populations is relatively high for a conifer (.cxa.FM = 0.11) and is not correlated with geographic distance. The age of trees, covering a period of 400 years affected by climatic changes, does not contribute to the genetic differentiation of the populations.