The genetic structures of a range of Douglas-fir provenance collections after planting in different European countries, assessed with two biochemical marker systems.
Genetic diversities of Douglas-fir provenance trials planted on several European sites were compared using both isozyme and terpene markers. A principal coordinate analysis based on similarity coefficients calculated from isozyme data indicated that, with the exception of two populations, differences between populations were small. There were no consistent trends in the variation in allele frequencies between populations. Most populations contained an excess of homozygotes, perhaps due to high selection pressure. Terpene composition was analysed in two resin systems, and showed a decreasing level of population diversity by planting site in the order: Spain-France-England-Scotland-Italy. Thus isozymes, which are generally considered to be neutral markers, indicated a modest degree of genetic drift due to sampling effects, while terpenes showed that some reduction in genetic diversity had occurred due to local selective pressures.
Forrest
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Forest Research Agency, Northern Research Station, Roslin, EH25 9SY, Midlothian, UK
Tabbener
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Cottrell
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Connolly
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