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Weak signals, strong debates: Density dependence and population regulation through the lens of model uncertainty
  • Evan Johnson
Evan Johnson
Smithsonian Tropical Research Institute

Corresponding Author:ejohnson.ecobot@gmail.com

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Abstract

Ecologists have long argued about the strength of density dependence and population regulation, respectively defined as the short-term and long-term rate of return to equilibrium. Here, I argue that we cannot reliably quantify population regulation with time series data. An analysis of the Global Population Dynamics Database reveals that conclusions about population regulation are heavily dependent on model choice, with no clear way to select a particular model. A parallel debate in macroeconomics — regarding whether GDP shocks have permanent effects — remains unresolved despite extensive research, implying that the population regulation question is similarly intractable. However, we can measure the short-term property of density dependence, which is moderate on-average and shows considerable variation across populations: half-lives of perturbations typically last 0.7 to 4.2 years (interquartile range). Rather than a universal balance of nature, stability varies widely across populations in ways that correlate with life history and taxonomy.
30 Dec 2024Submitted to Ecology Letters
15 Jan 2025Submission Checks Completed
15 Jan 2025Assigned to Editor
15 Jan 2025Review(s) Completed, Editorial Evaluation Pending
17 Jan 2025Reviewer(s) Assigned