. Ecological genetics of Pinus contorta in the Upper Snake River Basin of eastern Idaho and Wyoming. Lodgepole pine Idaho; Lodgepole pine Wyoming; Forests and forestry Research United States; Forest genetics; Trees Genetics. increasing elevation of the seed source, but freezing tolerance increases. The strong relationship between ele- vation and adjusted height indicates that, at the low elevational planting, populations from mild environments still would have been tallest even if all trees had been the same height at age 2. Quadratic models provided a significant reduction in the residual mea
. Ecological genetics of Pinus contorta in the Upper Snake River Basin of eastern Idaho and Wyoming. Lodgepole pine Idaho; Lodgepole pine Wyoming; Forests and forestry Research United States; Forest genetics; Trees Genetics. increasing elevation of the seed source, but freezing tolerance increases. The strong relationship between ele- vation and adjusted height indicates that, at the low elevational planting, populations from mild environments still would have been tallest even if all trees had been the same height at age 2. Quadratic models provided a significant reduction in the residual mean square of the linear model for only the cessation and duration of elongation. The geographic model (table 5) was statistically signifi- cant for only half of the variables. At most, this model accounted for less than a third of the variance in the dependent variables that was not explained by elevation. Consequently, geography accounted for less than 25 per- cent of the variance among populations. Thus, eleva- tional clines tend to be steep, and geographic clines are relatively gentle. Nevertheless, geographic variables plus elevation (the combined model) accounted for 43 to 83 percent of the variance of populations. Geographic patterns of genetic variation that are independent of elevation are presented in figure 4 for several traits. These patterns were generated from values predicted by the geographic model. The contour interval is scaled to a value equaling half the least sig- nificant difference (Steel and Torrie 1960) between popu- lations at the 80 percent level of probability [V2 lsd{)]. Because values of Isd were calculated from the analysis of variance (table 2), contours represent about half the geographical distance associated with population differentiation at the 80 percent level of probability. Contouring was begun with the overall mean, the zero deviation from the elevational regression. All variables for which the geographic model was sig- nificant present
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