Predicting the capacity of conifer populations to adapt to new climates using ecologically relevant genetic markers

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Coniferous forests dominate many of Canada's natural landscapes, and have tremendous importance both economically, providing wood and fiber to the forest industry, and ecologically, providing habitat for other organisms and a range of ecosystem services. Climate warming is already affecting the health of forests in Canada and in other parts of the world through changing average and extreme temperatures, available moisture, competition, insects and diseases. The extent to which natural populations can adapt to rapid climate change will be determined by a myriad of factors. Genetic variation for traits involved in local adaptation to climate will play an important role. We have identified genes that are collectively involved in how Sitka spruce (Picea sitchensis) populations synchronize their growth rhythms with their local climate to maximize growth without risking cold injury. By studying the geographic distribution of variation in these genes in Sitka spruce, white spruce (P. glauca) and Engelmann spruce (P. engelmannii), as well as naturally occurring hybrid populations, we will be able to predict how rapidly populations can adapt through natural selection to new seasonal climatic conditions, e.g, a longer growing season resulting from global warming. We will also retrospectively study the colonization and genetic dynamics of an isolated population of Sitka spruce on Kodiak Island, Alaska that was first established through long distance seed dispersal approximately four centuries ago to better understand how colonization, migration and adaptation interact as species ranges expand. Finally, we will compare adaptation to temperature along latitudinal and elevational gradients to see if adaptive variation and photoperiod responses are distributed differently at different geographic scales. The results of these studies will be used to predict how quickly natural conifer populations can adapt to new temperature regimes; and will inform the current dialogue in our society about whether we should be assisting the migration of these populations and species to new locations as climates change. They will also provide information to tree breeders and forest managers about levels of genetic diversity within natural populations and in spruce breeding programs.