Capacity of conifer populations for climate adaptation

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Climate change is affecting the health of many tree species globally, disrupting adaptation of populations to local climates, and increasing mortality due to drought, insects and wildfire. This is particularly the case for long-lived forest trees that are experiencing high rates of environmental change per generation. For two centuries, forest scientists have been studying the adaptation of tree populations to historic climates through common garden experiments. For the past two decades, I have been studying local adaptation of conifers to climate, first with phenotypic approaches and later with population genomic tools. My long-term research objective is to understand the evolutionary ecology, demographic history, and local adaptation of conifer populations, and to use that understanding to inform conservation, reforestation and restoration decisions. The goal of this research is to predict the capacity of conifer populations to adapt to or tolerate rapidly changing climates using phenotypic, genomic and simulation approaches. Adaptive potential of range margin populations: My research group's previous studies have characterized relationships between climate and phenotypes or genotypes of populations from broad geographic areas for several conifer species, but have not included range margin populations that are important for climate change responses. We will sample populations of Pinus contorta from throughout western North America, emphasizing populations at or near range margins, and genotype them for previously identified markers associated with climate or climate-related traits. Models will be constructed to predict the capacity of these populations to adapt to new climates. Drought adaptation: Temperate conifers are generally drought hardy, yet drought-related mortality is increasing across western North America. We will analyze population variation in Pseudotsuga menziesii drought tolerance and identify genomic markers associated with drought. New experiments will characterize drought responses of populations of Larix occidentalis and Thuja plicata. Finally, gene expression plasticity in response to drought will be compared in P. menziesii and L. occidentalis. Capacity for adaptation and assisted gene flow: We need to move from characterizing adaptive state to predicting adaptive potential in response to climate change. The opportunity for adaptive or maladaptive gene flow among populations of Pinus contorta will be modelled based on the extent of overlap in reproductive phenology, pollen transport distance, and wind patterns. Genomic and phenotypic datasets for Pinus contorta and Pseudotsuga menziesii will be used to parameterize population simulation models and evaluate the capacity for adaptation under different scenarios. Finally, phenotypic and genomic datasets will be used to assess whether the major climatic drivers of local adaptation within species are those that define species climatic niches for several species.