Phase separation driven by density-dependent movement: A novel mechanism for ecological patterns.

Area of Science:

• Ecology
• Theoretical Ecology
• Mathematical Biology

Background:

• Ecosystems exhibit regular spatial patterns due to small-scale organism interactions, a process known as spatial self-organization.
• These patterns influence ecosystem functioning, organism survival, and adaptation to environmental changes.
• While spatial heterogeneity in establishment, growth, and mortality has been the primary explanation, recent studies highlight the role of organism movement.

Purpose of the Study:

• To review studies demonstrating movement-based pattern formation in diverse ecological settings.
• To identify and explain a common underlying principle driving these patterns.
• To highlight the significance of density-dependent movement as a general mechanism for self-organized complexity in ecology.

Main Methods:

• Review of existing ecological studies on spatial pattern formation.
• Analysis of movement-based pattern formation across contrasting ecological contexts.
• Explanation of the Cahn-Hilliard principle of phase separation as applied to ecological movement.

Main Results:

• A common principle of density-dependent organism movement underlies spatial pattern formation in various ecosystems.
• This principle, previously unrecognized in ecology, is analogous to phase separation in physics.
• Animal movement, alone or with other processes, is a significant factor in generating regular spatial patterns.

Conclusions:

• Density-dependent organism movement provides a unifying mechanism for understanding self-organized spatial patterns in ecosystems.
• The Cahn-Hilliard principle offers a framework for discerning and experimentally testing this mechanism.
• Recognizing the role of movement enhances our understanding of ecological complexity and pattern formation.