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Global Modelling of Megafaunal Extinction Climate and Colonisation: Results from a high resolution analysis Lewis Bartlett 1,2, Andrea Manica 2, Graham.

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Presentation on theme: "Global Modelling of Megafaunal Extinction Climate and Colonisation: Results from a high resolution analysis Lewis Bartlett 1,2, Andrea Manica 2, Graham."— Presentation transcript:

1 Global Modelling of Megafaunal Extinction Climate and Colonisation: Results from a high resolution analysis Lewis Bartlett 1,2, Andrea Manica 2, Graham Prescott 2, David Williams 2, Andrew Balmford 2 & Rhys Green 2 1 Environment and Sustainability Institute, University of Exeter; 2 Department of Zoology, University of Cambridge.

2 Research Premise: A Global Analysis for a Global Phenomenon Need for global, integrative assessment of extinction – builds on work of Prescott et al. 2012 1 Split globe into zones: map extinction, expansion, and climate Compare predictive power of climate and early humans – 80,000 year analysis; 4000 year time steps 1 Prescott et al 2012, Quantitative global analysis of the role of climate and people in explaining late Quaternary megafaunal extinctions. Proc. Natl. Acad. Sci.. 109, 4527–4531

3 ExtinctSurviving Research Premise: Assembling Global Datasets Size of circle represents taxonomic abundance

4 Analysis Non-linear models: climate only, human only, and combined - iterate over many re-sampled datasets Predict human impact using arrival and zone area

5 100 60 20 80 40 0 Early Human Arrival Late Human Arrival Percentage Variation Explained (Nagelkerkes R 2 ) Unique to Humans Unique to Climate Shared Explanatory Power: Results: Overall Global Model Performance

6 Results: Predicting in sequence…

7 Results: …predicting one major effect…

8 Results: … predicting in parallel …

9 Results: … or indeed not at all

10 Interpretation & Direction Strongly implicates human colonisation – More informative predictor than climate Asia: the next frontier – Well studied zones resolved: look to zones we dont explain

11 Thank You for Your Attention! Any Questions? l.bartlett@ex.ac.uk

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13 Start of Arrival Time Step (ky BP) AfricaPapuaAustraliaTasmaniaIndo-MalayaJapanMadagascarAlaska & CanadaNorth AmericaNew ZealandEuropeSiberiaCentral AsiaSouth America 8060 446424820 448 8016 8044 4824816 444487212 8056 446424816 448 8016 8056 446424816 448 8012 8052 446424816 448 8016 8052 446424816 448 8012 8048 446424816 448 8016 8048 446424816 448 8012 Human Arrival Scenarios

14 logit(prob.extinction)= a*(1+b/LogArea)*T.Human*exp(c*(1+d/LogArea)*T.Human) Predicting Human Effect where T.Human is time since human arrival Function based on the Ricker Model for population density


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