Patchiness in marine and terrestrial systems: from individuals to populations

The phenomenon of patchiness is critical to understanding biological diversity. Individuals respond to patchiness in their environments by movement patterns, by allocation strategies, and by other mechanisms. On an evolutionary timescale, these responses to variability change the scales on which organisms perceive the environment; and through the effects of individuals on their environments, such evolutionary responses alter the ecological and evolutionary context experienced by other organisms. Understanding the causes and consequences thus requires an understanding of individual responses, and of how those responses lead to non-uniform patterns of distribution. In this paper, the dynamics of aggregation are explored from both a terrestrial and a marine perspective. Through a spectrum of models that are individual-based, aggregations are seen to develop, and macroscopic descriptions are derived.