Adaptive strategies of forest trees to climate changes: microevolution and plasticity

Larix decidua, the European larch, is an excellent model to evaluate the association between genetic and phenotypic variation with environmental gradients in forest species. In the present work we evaluated the genetic variation of neutral and selective SNP markers together with the variation of eight quantitative traits along an altitudinal gradient in a natural population of this species located in the Provence-Alpes-Côte d'Azur Region (France). Four samples of about 200 trees each were obtained respectively from plots situated at 1350, 1700, 2000, and 2300 m above sea level. In each sampled individual four tree ring variables and four plasticity variables were evaluated. The molecular dataset consisted of the individual patterns of 46388 SNP loci. The joint analysis of molecular and quantitative trait data allowed evaluating population structure, detecting presumptively selective loci, and demonstrating the adaptive significance of the quantitative variables considered.