Biology subjects

Tekwa, E. W.

Publications and source records attributed to Tekwa, E. W..

2 recordsLinked to original sources

bioRxiv2020

Inferring Models with Alternative Stable States from Independent Observations

Multiple attractors and alternative stable states are defining features of scientific theories in ecology and evolution, implying that abrupt regime shifts can occur and that outcomes can be hard to reverse. Here we describe a statistical inferential framework that uses independent, noisy observations with low temporal resolution to support or refute multiple attractor process models. The key is using initial conditions to choose among a finite number of expected outcomes using a nonstandard finite mixture methodology. We apply the framework to contemporary issues in social-ecological systems, coral ecosystems, and chaotic systems, showing that incorporating history allows us to statistically infer process models with alternative stable states while minimizing false positives. Further, in the presence of disturbances and oscillations, alternative stable states can help rather than hamper inference. The ability to infer models with alternative stable states across natural systems can help accelerate scientific discoveries, change how we manage ecosystems and societies, and place modern theories on firmer empirical ground.

ecology↗

bioRxiv2020

Geometric Analysis of Regime Shifts in Coral Reef Communities

Coral reefs are among the many communities believed to exhibit regime shifts between alternative stable states, single-species dominance, and coexistence. Proposed drivers of regime shifts include changes in grazing, spatial clustering, and ocean temperature. Here we distill the dynamic regimes of coral-macroalgal interaction into a three-dimensional geometry, akin to thermodynamic phase diagrams of state transitions, to facilitate analysis. Specific regime-shifting forces can be understood as bifurcation vectors through the cubic regime geometry. This geometric perspective allows us to understand multiple forces simultaneously in terms of the stability and persistence of interacting species. For example, in a coral-macroalgae community, grazing on macroalgae can lead to alternative stable states when there is no spatial clustering (e.g., high habitat connectivity). However, with spatial clustering, grazing can lead to coexistence because of elevated local intraspecific competition. The geometrical analysis of regime shifts is applicable to any two-species communities and can help conservation efforts navigate complexity and abrupt changes.

ecology↗