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Body size distributions signal a regime shift in a lake ecosystem
Citation:
Spanbauer, T., C. Allen, D. Angeler, T. Eason, S. Fritz, A. Garmestani, K. Nash, J. Stone, C. Stow, AND S. Sundstrom. Body size distributions signal a regime shift in a lake ecosystem. Proceedings of the Royal Society B. Royal Society Publishing, London, Uk, 283(1833):20160249, (2016).
Impact/Purpose:
Communities of organisms from mammals to microorganisms have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at discrete spatial and temporal scales within ecosystems. Here, a paleoecological record of diatom community change is used to evaluate discontinuities in diatom body size. A prior analysis using Fisher Information and multivariate time-series modeling, demonstrated that Foy Lake (Montana, USA) had a climate-induced regime shift at ~2,000 ybp (years before present, present defined as 1950).
Description:
Communities of organisms, from mammals to microorganisms, have discontinuous distributions of body size. This pattern of size structuring is a conservative trait of community organization and is a product of processes that occur at multiple spatial and temporal scales. In this study, we assessed whether body size patterns serve as an indicator of a threshold between alternative regimes. Over the past 7000 years, the biological communities of Foy Lake (Montana,USA) have undergone a major regime shift owing to climate change. We used a palaeoecological record of diatom communities to estimate diatom sizes, and then analysed the discontinuous distribution of organism sizes over time. We used Bayesian classification and regression tree models to determine that all time intervals exhibited aggregations of sizes separated by gaps in the distribution and found a significant change in diatom body size distributions approximately 150 years before the identified ecosystem regime shift. We suggest that discontinuity analysis is a useful addition to the suite of tools for the detection of early warning signals of regime shifts.
