Genetic variation of growth rhythm traits in the limits of a latitudinal cline in Scots pine

Abstract

Scots pine ( Pinus sylvestris L.) has the widest distribution of pine species and the populations are locally adapted to very different environmental conditions. Adaptive traits such as those related to growth are optimal for understanding adaptation of populations to local conditions in widely distributed forest species. A study of the timing of growth during the first growing period of families in four populations from the latitudinal limits of the distribution range was conducted. Individual growth curves were fitted, and a set of variables related to growth rhythm and timing of budset was obtained for genetic analyses. Pooled heritabilities across populations were very high for most of the traits (0.43–1.09), and population differentiation for growth variables showed high values as well (QST= 0.19–0.71). Phenotypic correlations were higher than genetic ones, and most of them were positives. Even no general patterns of additive variances were found, the high additive genetic variance obtained (14% ± 8%, mean ± SE) suggests that additive genetic variance is not the limiting factor for adaptation to a new optimum within much of the range for these traits. Changes in means, additive genetic variances, and additive genetic coefficient of variation by population are also discussed.