title: Early warning of critical transitions in biodiversity from compositional disorder.
abstract: Global environmental change presents a clear need for improved leading indicators of critical transitions, especially those that can be generated from compositional data and that work in empirical cases. Ecological theory of community dynamics under environmental forcing predicts an early replacement of slowly replicating and weakly competitive "canary" species by slowly replicating but strongly competitive "keystone" species. Further forcing leads to the eventual collapse of the keystone species as they are replaced by weakly competitive but fast-replicating "weedy" species in a critical transition to a significantly different state. We identify a diagnostic signal of these changes in the coefficients of a correlation between compositional disorder and biodiversity. Compositional disorder measures unpredictability in the composition of a community, while biodiversity measures the amount of species in the community. In a stochastic simulation, sequential correlations over time switch from positive to negative as keystones prevail over canaries, and back to positive with domination of weedy species. The model finds support in empirical tests on multi-decadal time series of fossil diatom and chironomid communities from lakes in China. The characteristic switch from positive to negative correlation coefficients occurs for both communities up to three decades preceding a critical transition to a sustained alternate state. This signal is robust to unequal time increments that beset the identification of early-warning signals from other metrics.
authors.affiliation: Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: C Patrick
authors.initials: CP
authors.lastname: Doncaster
authors.affiliation: Biological Sciences, Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Vasthi
authors.initials: V
authors.lastname: Alonso Chávez
authors.affiliation: Institute for Complex Systems Simulation, University of Southampton, Southampton, SO17 1BJ, UK.|University of Nice Polytech Nice-Sophia, Sophia-Antipolis Cedex, 06903, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Viguier
authors.affiliation: Geography and Environment, University of Southampton, Southampton, SO17 1BJ, UK.|State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Enlou
authors.initials: E
authors.lastname: Zhang
authors.affiliation: Aarhus Institute of Advanced Studies, Høegh-Guldbergs Gade 6B, Aarhus C, DK-8000, Denmark.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Dong
authors.affiliation: Geography and Environment, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: John A
authors.initials: JA
authors.lastname: Dearing
authors.affiliation: Geography and Environment, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Langdon
authors.affiliation: Institute for Complex Systems Simulation, University of Southampton, Southampton, SO17 1BJ, UK.|Geography and Environment, University of Southampton, Southampton, SO17 1BJ, UK.
authors.forename: James G
authors.initials: JG
authors.lastname: Dyke
mesh_terms: D000818:Animals; D044822:Biodiversity; D017377:Diatoms / Q000502:physiology*; D007313:Insecta / Q000502:physiology*; D008954:Models, Biological; D011157:Population Dynamics; D013269:Stochastic Processes
keywords: critical slowing down; early warning signal; ecosystem canary; lake sediment; leading indicator; nestedness temperature; regime shift; tipping point