Climate change and evolution of plant phenology

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Global warming will drastically alter Canada's vegetation landscape, thereby presenting challenges for forest management, preservation of natural sites, weed control and delivery of ecosystem services. Climate change is arguably Canada's most pervasive environmental threat since all other such problems have a climatic element. The short time scale of global warming leads many to think about its biological consequences in ecological terms. Many predict pole-ward migration from more thermally adapted populations from the south. Others anticipate phenotypicaly plastic shifts in physiology and development in resident populations. Such responses can ameliorate the impact on natural populations, but only to the degree allowed by their current genetic repertoire. Importantly, altered climate imposes altered selection regimes and hence the total biological response to global warming will have evolutionary dimensions. A small number of studies, including one form my group, already indicate evolutionary responses climate change. Evolutionary change on a decadal time frame could be widespread among species with short to medium life cycles. I propose a research program to understand the rate of evolutionary change-particularly genetic adaptation to extended growing seasons-and how natural selection, gene flow, and non-random mating might affect it. Projects will test specific hypotheses, including: 1. Although pole-ward migrants may bring thermal tolerance genes, introgression of these adaptive loci will be inhibited by a) gametic (linkage) disequilibrium with loci causing maladaptive reproductive phenology under the photoperiodic cycle of northern latitudes, and b) assortative mating caused by this maladaptive phenology; 2. Extended growing seasons will select for delayed flowering times in resident populations; 3. Evolutionary shifts in flowering time are accelerated by phenolgical assortative mating; and 4. The rate of evolutionary response to climate change increases with latitude. The program will employ several species of annual and short-lived perennial plants, and will be executed with the use of artificial warming plots at the Koffler Scientific Reserve at Jokers Hill.