Clinal Genetic Growth Variation within Two Douglas-Fir Breeding Zones
Abstract:Twelve- and ten-year results of progeny tests of 1,275 wind-pollinated families of coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) are presented along with maps of clinal genetic variation within two breedings zones. Data originate from the two oldest progressive tree-improvement cooperatives, called Vernonia and Molalla. In both, the top 20 percent of the families were 7 percent taller and 15 to 22 percent greater in volume than the mean family. Division of the parent group at the outset into sets of 50 families at Vernonia and 25 families at Molalla revealed that set means differed with origin within the breeding zone. Scattergrams of all parents in each cooperative showed that a downward shift of 1,000 feet in parent elevation, or a 10-mile horizontal shift to the east or north, should provide 5 percent more family height growth. Thus, there was evidence of considerable clinal geographic variation within breeding zones. Isoheight patterns of clinal variation are complex and three-dimensional, conforming to major topographic features in each cooperative area.
Document Type: Journal Article
Affiliations: Project Mathematical Statistician
Publication date: April 1, 1983
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