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    Brewer spruce (Picea breweriana), a relict of the widespread Arcto-Tertiary forests, is now restricted to a highly fragmented range in the Klamath Region of California and Oregon. Expected heterozygosity for 26 isozyme loci, averaged over 10 populations, was 0.121. More notable than the relatively high level of diversity when compared to other woody endemics was the strong decrease in expected heterozygosity with latitude. Differentiation (FST) was 0.152, higher than values for many north temperate conifers with larger distributions. The number of migrants per generation (Nm) was 1.34 or 2.70, depending on the method of estimation. Inbreeding appeared low; FIS was only 0.003, in agreement with multilocus population outcrossing rates (tm), which were generally well above 0.90. No difference in tm was found between isolated vs. clustered trees.

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    Ledig, F. Thomas; Hodgskiss, Paul D.; Johnson, David R. 2005. Genetic diversity, genetic structure, and mating system of brewer spruce (Pinaceae), a relict of the acto-tertiary forest. American Journal of Botany 92(12):1975-1986


    Fragmentation, genetic structure, heterozygosity, isozymes, relict species, selfing

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