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:
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.
Research Premise: A Global Analysis for a Global Phenomenon Need for global, integrative assessment of extinction – builds on work of Prescott et al 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
ExtinctSurviving Research Premise: Assembling Global Datasets Size of circle represents taxonomic abundance
Analysis Non-linear models: climate only, human only, and combined - iterate over many re-sampled datasets Predict human impact using arrival and zone area
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
Results: Predicting in sequence…
Results: …predicting one major effect…
Results: … predicting in parallel …
Results: … or indeed not at all
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
Thank You for Your Attention! Any Questions?
Start of Arrival Time Step (ky BP) AfricaPapuaAustraliaTasmaniaIndo-MalayaJapanMadagascarAlaska & CanadaNorth AmericaNew ZealandEuropeSiberiaCentral AsiaSouth America Human Arrival Scenarios
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