EvolRescueOnline-Topic 2

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Global environmental change is causing unprecedented rates of population extirpation, giving rise to concern that the rate of environmental change may exceed the capacity of populations to adapt. I will present experimental results that show the conditions required for evolutionary rescue to prevent range collapse and extinction across many, potentially interconnected populations. Ecological and evolutionary theory predicts a variety of different range dynamics following environmental change, including range collapse, expansion, and directional shifts, but although some field evidence exists these predictions have remained untested by experiment. We used high-throughput, robot-based, technology to track the eco-evolutionary dynamics of model species’ ranges composed of many populations, with and without dispersal, during environmental deterioration. Range adaptation and persistence was favored by local dispersal and gradual deterioration. Adaptation to an episode of abrupt and severe environmental stress was greatest in ranges that had previously experienced environmental deterioration and dispersal. Evolutionary rescue in response to abrupt change occurred at the level of the population and the range. Adaptation was surprisingly frequent and rapid in small peripheral populations, a result we believe requires theoretical analysis. These results demonstrate the importance of evolutionary dynamics for range persistence and adaptation following environmental deterioration.

In this talk, we present two approaches investigating large-scale, eco-evolutionary dynamics of plants exposed to environmental change. The first approach is a landscape-scale, individual-based simulation framework developed to address conceptual questions on the interactive effects of local adaptation, genetic drift and demographic processes on species’ responses to climate change. Two polygenic traits – the level of adaptation to the local environment and to global climate – are considered to control population fitness and to evolve under changing climatic conditions. Systematic variation of the degree of gene flow, selection pressure and habitat fragmentation allows to evaluate under which conditions evolutionary rescue is possible. Secondly, we consider how rates of microevolution over sub-continental scales can be assessed by combining individual-based, eco-evolutionary models with demographic and quantitative genetic data. This approach is exemplified by a model for how the growth period length of boreal trees evolves under global warming. The detailed description of demographic processes in this model also enables one to assess how climate change effects on adult tree mortality and long-distance dispersal by wind might alter the rules of the eco-evolutionary game.