Genetic, plastic and epigenetic sources of variation for climate change responses in conifers

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The capacity of conifer populations to adapt to new climatic conditions is important because of their large roles in the global carbon cycle, ecological roles as foundation species in many ecosystems, and importance for resource production. The extent to which we should change forest conservation and management strategies in consideration of climate change will depend on the natural capacity of populations to respond. My research group will explore the potential for adaptive responses from standing variation in core and marginal populations, epigenetic responses to parental environments, tolerance of new conditions through phenotypic plasticity, and contributions to standing variation from somatic mutations. The proposed projects will address the following questions. ***Can tree populations adapt to new climatic conditions from standing genetic variation? We will use new modelling and analytical approaches to analyze existing data on sequence variation in 50K candidate and control SNPs generated for 284 populations of lodgepole pine in AB and BC, and generate new data for marginal populations in Yukon and the US to predict capacity for adaptation. We will also study accumulation of genetic variation, changes in inbreeding, and allele surfing during colonization by analyzing age cohorts of Sitka spruce (Picea sitchensis) at the leading edge of migration in Alaska.***Will epigenetic effects of parental environments help adapt their progeny to new climatic conditions? We will phenotype 12-year-old interior spruce common gardens containing a large number of progeny from 80 controlled matings of the same parents cloned and planted in two contrasting environments: Vernon, BC (mean annual temperature 7.5C) and Prince George (4.3C). If phenotypic effects are detected, we will conduct genome-wide association mapping of markers linked to epigenetic effects.***Is phenotypic plasticity sufficient to allow trees to adjust their growth and dormancy cycles to synchronize with new climatic conditions? We will use temperature, moisture and photoperiodic treatments in controlled environment chambers to study the plasticity of Sitka spruce (Picea sitchensis) seedling phenotypes, with an emphasis on phenology and mechanisms of determinate versus indeterminate (plastic) primary growth.***Do somatic mutations contribute substantively to standing variation for adaptation to new conditions? The large number of mitotic cell divisions that occur between seed germination and seed production in large trees can result in genetic mosaicism in their crowns, and some of that variation may contribute to adaptive potential or cause deleterious effects, but no good estimates exist for somatic mutation rates in conifers. Building on a partnership with big tree climbers in BC, we will sample and sequence many genes in the crowns of some of BC's largest Sitka spruce to estimate mutation rates.**