Bottom-up and top-down effects on natural selection, evolution, and population dynamics of boreal mammals

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Canada's boreal forest, like many parts of the world, is undergoing unprecedented change due to aggressive human landuse and climate change. The challenge for ecologists is to provide society with answers to the question of what this ecosystem will look like in the future. To do so we need to understand the effects of environmental change on natural selection, population dynamics, and species interactions. I have been working in the boreal forest at Kluane Lake Yukon to understand how two herbivores, red squirrels and snowshoe hares, respond to changes in their food supply, their own densities, and the predators that consume them. The Kluane Red Squirrel Project (KRSP) has amassed phenotype and fitness information for 15,000 individual red squirrels spanning 12 generations and 30 years. We use this information to understand within individual (plasticity), between individual (selection), and between generation (microevolution) responses to important environmental and biotic drivers. I will take advantage of the territorial nature of red squirrels to measure individual resource availability (territory quality) and link this to individual territory selection, juvenile survival, and fitness. This work will fill a major gap in the study of the ecological and evolutionary consequences of individual differences. Many of the studies of potential climate change effects on species have focused on phenological (timing) responses as we have done with red squirrels. Forecasting impacts of climate change on species demography, however, remains challenging due to the complexities associated with biotic interactions and in particular, predator-prey dynamics. In the boreal forest this means we need to understand how climate change might affect the snowshoe hare-lynx cycle. Our ongoing monitoring has produced a database spanning 40 years and 5 hare peaks which provides the necessary backdrop to explore how climate change might affect this iconic predator-prey dynamic. I will take advantage of advances in bio-logging technology to examine the detailed interactive effects of hare food supply and predators (consumptive and non-consumptive effects) on hare demography and address the potential for climate change to alter the classic hare-lynx cycle.