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Integrating large-scale survey data sets with climate and land use data to model species distribution dynamics Andrew M. Latimer and John A. Silander Department of Ecology & Evolutionary Biology University of Connecticut Biodiversity Over Space
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“distribution and abundance of species”
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Data-model integration –New large data sets –Issues: Diverse kinds and scales of data Spatial and temporal covariance structures –Tools: Bayesian hierarchical models
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In this talk Static single-species distribution models –Areal-unit models –Environment and colonization –Land use –Abundance Biodiversity – joint distribution of species Point process models –Computational advances –Multispecies models Current work: making these dynamic
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Species observations Presence/absence Abundance Diversity Abiotic environment Why absent? -Not suitable -Not available -Not colonized E(Abundance) ≈ P(Presence)? Land use data
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Hierarchical single-species model P(colonized | suitable & available) P(suitable) P(available | suitable) Neighborhood & connectivity info Land use data (satellite imagery) Environmental data (weather stations, soils) P(present) Species sample data
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Hierarchical single-species model P(colonized | suitable & available) P(suitable) P(available | suitable) P(·) = f(U i ) = 1-U i where U i ≡ prop. human-altered P(·) = dbin(n i, p i ) logit(p i ) = X T β + w i P(·) = dbin(n i, q i ) logit(q i ) = g(‘neighborhood’) Latimer et al. (2006) Ecological Applications
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Where the species was observed: L(y i ) = Binomial(n i, q i ) * f(p i ) Where not observed: L(y i ) = (1-f(p i )) + f(p i )*(1-q i ) n i Probability present given suitable & available Suitability, adjusted by availability function Probability unsuitable and/or unavailable Probability suitable & available but not observed P(present) Likelihood
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P. lacticolor P. aurea P. punctata P. lacticolor P. aurea White Proteas (Protea spp.)
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Hierarchical model: P(suitable)
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Hierarchical model: P(available)*P(suitable)
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Hierarchical: P(colonized | suitable & available)
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Inference Primarily environmental limit on presence Some constraint at “colonization” stage
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Adding an abundance level P(present) P(abundance (k) | present)Ordinal abundance scores, environmental data Introduce latent (log-scale) abundance surface Z and cutpoints {c 1, c 2, …, c k }. Abundance score = 1 if z i ≤ c 1 2 if z i > c 1 and z i ≤ c 2 … k if z i > c k
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Latent log-scale abundance surface (Z)
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Inference Different factors drive abundance –Cool winter temperature vs warm & wet growth season Mechanism? –Germination vs growth Latimer et al. Oecologia (in review)
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Multi-species models Potential richness in the absence of human landscape alterations: Adjusted (transformed) richness given human transformed landscapes: Gelfand et al. (2005) Bayesian Analysis
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Modeled subregion (for a subset of 40 species) Computational issues… Please help!
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Species Richness
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Multi-species results Different land uses; differential impacts. Latimer et al. (2004) S.A. Journal of Science
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Modeling with point data Predictive process approach Banerjee, Gelfand et al. “Curse of dimensionality”
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Multiple spatial processes: Multi-species model Cel. orbiculatus Rosa multiflora Berberis thungbergii Euonymus alatus
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Canopy Closure Berberis thunbergii Celastrus orbiculatus Rosa multiflora Euonymus alatus Regression coefficient value Density
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Celastrus orbiculatus Rosa multiflora Berberis thungbergii Euonymus alatus present absent Sample data:
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Summing up Opportunities: –Physiological responses, abundance structure –Land use change impacts –Integrating satellite data Limitations: –Colonization and other spatial factors –Computer power
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Current work Making dynamic: climate change Data: population-level performance data over time –Field survey plants and populations over gradients –Satellite data for phenology and productivity Latimer & Wilson et al. (in prep.) Global Change Biol
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Acknowledgments U.S. NSF Grant DEB 0516320 SANBI (Esp. Tony Rebelo & Guy Midgley) Duke ISDS (Esp. Alan Gelfand & Huiyan Sang) UCONN EEB (Esp. Inés Ibáñes, Adam Wilson)
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