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Non-local Dispersal Models for a Population under Climate Change (Joy) Ying Zhou, Mark Kot Department of Applied Mathematics University of Washington 1
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Cartoon of a Range Shift 2
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3 Global mean: 0.42km/yr
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Cartoon of a Range Shift 4 Population Dynamics Matter
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Talk Outline 5 Population Models on Range Shifts under: Constant-speed climate change Accelerated climate change
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Organisms of Interest Well-defined life stages (growth, dispersal) Growth and dispersal occur in separate time periods Non-overlapping generations Larvae Adult Egg mass Flower Seed Seedling Cocoon
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Integrodifference equation 7 Integrodifference eqn (IDE) kernel Assuming no Allee effects
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How To Mathematize Climate Warming? 8
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Climatically Suitable Habitat Habitat shifts 9 Combination of two classical problems Zhou and Kot 2011 Theoretical Ecology
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Two Classic IDE Models 10
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Two Classic IDE Models 11
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What Population Dynamics Will We Observe? A Steady Range Shift For Small c 12 Zhou and Kot 2011 Theoretical Ecology
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Extinction When c Large 13 Zhou and Kot 2011 Theoretical Ecology
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Critical Speed “c*” Viability of a population Ability to establish itself at a low density Instability of the trivial equilibrium Dominant eigenvalue of an integral operator exceeding 1 14
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Eigenvalue Problem Net reproductive rate Analytic method for “separable” kernels Numerical method “Nystrom’s method” Delves and Wash 1974
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Larger Net Reproductive Rate Helps 16 Zhou and Kot 2011 Theoretical Ecology
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More Dispersal, But Not Over-dispersal 17 Dispersal radius radius Zhou and Kot 2011 Theoretical Ecology
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18 Lockwood et al. 2002
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Clark 1998 Mean deviation 19 Schultz 1998
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Result for a typical leptokurtic kernel The “Tail” of The Dispersal Kernel Result for a typical leptokurtic kernel Result for a typical platykurtic kernel 20 Zhou and Kot 2011 Theoretical Ecology
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Population projection matrix Matrix of dispersal kernels Vector of population density in each stage
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Climatically Suitable Habitat Habitat shifts Heterogeneous Habitat Suitability 22 Habitat quality function Latore et al. 1999
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Consider linearized equation For normally distributed habitat quality a Gaussian dispersal kernel
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and a special initial condition (Gaussian initial profile), then we have an ansatz : peak of the pulse : amplitude of the pulse Latore et al. 1999
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26 “climate deficit”
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27 Declining population if
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Accelerated Climate Change Same ansatz
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The mean of the Gaussian ansatz
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30 The “climate deficit”
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Time Speed T
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32 vs. For large t Comparison of climate deficit
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Summary An integrodifference equation model with shifting boundaries Critical speed Acceleration may hurt a lot (more than average) 35
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Thank you! Questions? 36
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