OOS 69

Intraspecific Genetic Adaptation in Forest Trees and Its Ecological Implications Under a Changing Climate

More than 200 hundred years of genecology studies, including provenance and common garden tests, have demonstrated that many forest tree species have ample intra specific genetic variation which is often associated with climatic gradients. These have been largely interpreted as evidence of local adaptation to climate. Populations have different climate optima and their adaptation involves adjusting traits such as phenology, and cold and drought tolerance. In general, populations from colder climates have increased cold hardiness and shorter growing seasons than those inhabiting milder climates. Despite being adapted, populations of some species inhabit suboptimal climates as a result of a combination of lag in natural selection and biotic competition. The degree of suboptimal climate inhabited differs among populations and thus a given change in climate will affect populations differently. The fate of a species under a changing climate is commonly evaluated assuming species are relatively homogenous; this however can lead to biased projections due to intraspecific variation. In recent years, understanding and modeling intra-specific genetic and ecological variation to changes in climate has received increased attention in order to address the challenge of species’ shifting range boundaries. The focus of research has encompassed “rediscovering” historic provenance tests as experiments in climate change, the assessment of genetic variation and traits using molecular markers, and modeling with extensive field data via new computational methods. Ecological understanding and quantification of populations’ responses to changes in climate has the potential to integrate and synergize several fields dealing with tree species conservation and management. Projecting changes in species ranges and assemblages, and understanding changes in species recruitment, mortality, and inter-specific competition dynamics, will be aided by a better understanding of populations’ adaptive responses to changing climate. Elucidating the spread and the effects of other biotic pressures, such as pests and diseases, under a changing climate will require quantification of the interaction between intra specific differences in adaptation and pest or pathogen biology. Populations inhabiting the edge of the species range are often at the limit of their environmental tolerance, thus the vulnerability to a biotic stressor may be amplified. The purpose of this session is to engender collaboration in this rich, inter-disciplinary and crucial field by assembling recent research and modeling work that 1) elucidates populations’ responses to changes in climate, 2) evaluates the ecological implications of these differential responses, and 3) shows how this research can be utilized to aid forest adaptation.