Patterns of adaptive genetic variation in eastern white pine (Pinus strobus) from Quebec

Genetic structure and patterns of genetic variation among provenances for eastern white pine (Pinus strobus L.) in Quebec were examined by a provenance-progeny test. A sample of 66 provenances of eastern white pine from Quebec and adjacent Ontario was tested, with each provenance composed of one to eight separate families (a total of 159 families). Data were collected on total seedling heights at different ages up to 4 years, 4-year branch number, and 3-year bud burst and bud set. Analysis of variance showed significant differences in each trait among provenances and among families within provenances, with one exception; Variance due to provenances was on average twice that due to families within provenances. All traits were intercorrelated at the provenance level. Two principal components summarized 77% of the total variation for all traits. Regressions of different traits on geographical variables accounted for 16% to 62% of provenance variation and disclosed complex patterns of genetic variation among provenances. Provenances from the southeastern part of the sampling area were taller and burst and set terminal buds later than the northwestern ones. The regression models were tested using 10-year height and survival from three field tests, which gave mixed results. We used the models describing patterns of provenance variation to guide seed transfer and delineated two provisional breeding zones for eastern white pine in Quebec.