Estimating the functional form for the density? Dependence from life history data

• Published in: Ecology
• Main Authors: Coulson, Tim, Tavecchia, Giacomo
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Ecological Society of America 2008
• Subjects: Age-structure fluctuations; Time series analysis; Soay sheep; Ovis arics; North Atlantic Oscillation; Nonlinear dynamics; North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10261/103630; https://doi.org/10.1890/07-1099.1

Coulson, Tim . et al. Two contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified; and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and individual-level processes to the dynamics of populations in stochastic environments. © 2008 by the Ecological Society of America. Peer Reviewed