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Deriving space use patterns from animal interaction mechanisms Jonathan Potts, Postdoctoral Fellow, University of Alberta, May 2013
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From mechanism to pattern Movement
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From mechanism to pattern Direct interactions
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From mechanism to pattern Mediated interactions
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From mechanism to pattern Environmental interactions
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From mechanism to pattern
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Outline
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Modelling animal movement: the “correlated random walk” framework
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Outline Modelling animal movement: the “correlated random walk” framework Adding in environmental interactions: step selection functions
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Outline Modelling animal movement: the “correlated random walk” framework Adding in environmental interactions: step selection functions Including animal-animal interactions: coupled step selection functions
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Outline Modelling animal movement: the “correlated random walk” framework Adding in environmental interactions: step selection functions Including animal-animal interactions: coupled step selection functions Throughout: how do these models help us understand space use phenomena?
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Movement: correlated random walk
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Example step length distribution:
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Movement: correlated random walk Example step length distribution: Example turning angle distribution:
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Mathematical formulation
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Adding environmental interactions A, B, C different habitats. B = worse, A = better, C = best.
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The step selection function Fortin D, Beyer HL, Boyce MS, Smith DW, Duchesne T, Mao JS (2005) Wolves influence elk movements: Behavior shapes a trophic cascade in Yellowstone National Park. Ecology 86:1320-1330.
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Example 1: Amazonian bird flocks Potts JR, Mokross K, Stouffer PC, Lewis MA (in review) Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds. Ecology
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Example 1: Amazonian bird flocks Potts JR, Mokross K, Stouffer PC, Lewis MA (in review) Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds. Ecology
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Example 1: Amazonian bird flocks Potts JR, Mokross K, Stouffer PC, Lewis MA (in review) Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds. Ecology
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Hypotheses
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Maximum likelihood technique
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Deriving space use patterns: stochastic simulations Potts JR, Mokross K, Stouffer PC, Lewis MA (in review) Step selection techniques uncover the environmental predictors of space use patterns in flocks of Amazonian birds. Ecology
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Deriving space use patterns: master equations and PDEs Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA (in prep) Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model
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Deriving space use patterns: master equations and PDEs Moorcroft and Barnett (2008) Mechanistic home range models and resource selection analysis: a reconciliation and unification. Ecology 89(4), 1112–1119 Potts JR, Bastille-Rousseau G, Murray DL, Schaefer JA, Lewis MA (in prep) Predicting local and non-local effects of resources on animal space use using a mechanistic step-selection model
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Movement data Mathematical analysis Simulations Step selection functions Statistical tests, e.g. MLE Master equations, PDEs
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Coupled step selection functions Potts JR, Mokross K, Stouffer PC, Lewis MA (in prep) A unifying framework for quantifying the nature of animal interactions
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Amazon birds: testing hypotheses
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Amazon birds: space use patterns
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Acknowledgements Mark Lewis (UofA) Karl Mokross (Louisiana State) Guillaume Bastille-Rousseau (Trent) Philip Stouffer (Louisiana State) Dennis Murray (Trent) James Schaefer (Trent) Members of the Lewis Lab (UofA)
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Movement and interaction data Mathematical analysis Simulations Coupled step selection functions Statistical tests The final frontier! Conclusion “The challenge is to develop a statistical mechanics for ecological systems” Simon Levin Spatial patterns
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Thanks for listening!
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