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Abstract Despite the well known scale‐dependency of ecological interactions, relatively little attention has been paid to understanding the dynamic interplay between various spatial scales. This is especially notable in metacommunity theory, where births and deaths dominate dynamics within patches (the local scale), and dispersal and environmental stochasticity dominate dynamics between patches (the regional scale). By considering the interplay of local and regional scales in metacommunities, the fundamental processes of community ecology—selection, drift, and dispersal—can be unified into a single theoretical framework. Here, we analyze three related spatial models that build on the classic two‐species Lotka–Volterra competition model. Two open‐system models focus on a single patch coupled to a larger fixed landscape by dispersal. The first is deterministic, while the second adds demographic stochasticity to allow ecological drift. Finally, the third model is a true metacommunity model with dispersal between a large number of local patches, which allows feedback between local and regional scales and captures the well studied metacommunity paradigms as special cases. Unlike previous simulation models, our metacommunity model allows the numerical calculation of equilibria and invasion criteria to precisely determine the outcome of competition at the regional scale. We show that both dispersal and stochasticity can lead to regional outcomes that are different than predicted by the classic Lotka–Volterra competition model. Regional exclusion can occur when the nonspatial model predicts coexistence or founder control, due to ecological drift or asymmetric stochastic switching between basins of attraction, respectively. Regional coexistence can result from local coexistence mechanisms or through competition‐colonization or successional‐niche trade‐offs. Larger dispersal rates are typically competitively advantageous, except in the case of local founder control, which can favor intermediate dispersal rates. Broadly, our models demonstrate the importance of feedback between local and regional scales in competitive metacommunities and provide a unifying framework for understanding how selection, drift, and dispersal jointly shape ecological communities.
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Natural selection at multiple scales
Abstract Natural selection acts on traits at different scales, often with opposing consequences. This article identifies the particular forces that act at each scale and how those forces combine to determine the overall evolutionary outcome. A series of extended models derive from the tragedy of the commons, illustrating opposing forces at different scales. Examples include the primary tension between conflict and cooperation and the evolution of virulence, sex ratios, dispersal, and evolvability. The unified analysis subsumes interactions within and between species by generalizing multitrait interactions. Expanded notions of recombination and cotransmission arise. The core theoretical approach isolates the fundamental forces of selection, including marginal valuation, correlation between interacting entities, and reproductive value. Those fundamental forces act as partial causes that combine at different temporal and spatial scales. Modeling focuses on statics, in the sense of how different forces at various scales tend to oppose each other, ultimately combining to shape traits. That type of static analysis emphasizes explanation rather than the calculation of dynamics. The article builds on the duality between explanation versus calculation in terms of statics versus dynamics. The literature often poses that duality as a controversy, whereas this article develops the pair as complementary tools that together provide deeper understanding. Along the way, the unified approach clarifies the subtle distinctions between kin selection, multilevel selection, and inclusive fitness, subsuming these topics into the broader perspectives of fundamental forces and multiple scales.
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- Award ID(s):
- 2325755
- PAR ID:
- 10664445
- Publisher / Repository:
- Oxford Univ Press
- Date Published:
- Journal Name:
- Evolution
- Volume:
- 79
- Issue:
- 7
- ISSN:
- 0014-3820
- Page Range / eLocation ID:
- 1166 to 1184
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/evolut/qpaf037
