scholarly journals Stochastic competitive exclusion leads to a cascade of species extinctions

2016 ◽  
Author(s):  
José A Capitán ◽  
Sara Cuenda ◽  
David Alonso
Keyword(s):  
Community Ecology ◽  
Competitive Exclusion ◽  
Deterministic Model ◽  
Niche Partitioning ◽  
Environmental Stochasticity ◽  
Exclusion Principle ◽  
Limiting Similarity ◽  
Demographic Stochasticity ◽  
Deterministic Models ◽  
Analytical Approximations

AbstractCommunity ecology has traditionally relied on the competitive exclusion principle, a piece of common wisdom in conceptual frameworks developed to describe species assemblages. Key concepts in community ecology, such as limiting similarity and niche partitioning, are based on competitive exclusion. However, this classical paradigm in ecology relies on implications derived from simple, deterministic models. Here we show how the predictions of a symmetric, deterministic model about the way extinctions proceed can be utterly different from the results derived from the same model when ecological drift (demographic stochasticity) is explicitly considered. Using analytical approximations to the steady-state conditional probabilities for assemblages with two and three species, we demonstrate that stochastic competitive exclusion leads to a cascade of extinctions, whereas the symmetric, deterministic model predicts a multiple collapse of species. To test the robustness of our results, we have studied the effect of environmental stochasticity and relaxed the species symmetry assumption. Our conclusions highlight the crucial role of stochasticity when deriving reliable theoretical predictions for species community assembly.

Ecological Theory and the Superfluous Niche

2019 ◽  
Vol 47 (1) ◽  
pp. 105-123
Author(s):  
James Justus ◽  
Keyword(s):  
Competitive Exclusion ◽  
Ecological Theory ◽  
Character Displacement ◽  
Exclusion Principle ◽  
Limiting Similarity ◽  
Competitive Exclusion Principle ◽  
Ecological Equivalence

Perhaps no concept has been thought more important to ecological theorizing than the niche. Without it, technically sophisticated and well-regarded accounts of character displacement, ecological equivalence, limiting similarity, and others would seemingly never have been developed. The niche is also widely considered the centerpiece of the best candidate for a distinctively ecological law, the competitive exclusion principle. But the incongruous array and imprecise character of proposed definitions of the concept square poorly with its apparent scientific centrality. I argue this definitional diversity and imprecision reflects a problematic conceptual indeterminacy that challenges its putative indispensability in ecology.

scholarly journals Cancer Community Ecology

2020 ◽  
Vol 27 (1) ◽  
pp. 107327482095177
Author(s):  
Burt P. Kotler ◽  
Joel S. Brown
Keyword(s):  
Community Ecology ◽  
Cancer Cells ◽  
Cancer Biology ◽  
Competitive Exclusion ◽  
Variance Partitioning ◽  
Exclusion Principle ◽  
Ecological Communities ◽  
Closely Related Species ◽  
Local Conditions ◽  
Competitive Exclusion Principle

Here we advocate Cancer Community Ecology as a valuable focus of study in Cancer Biology. We hypothesize that the heterogeneity and characteristics of cancer cells within tumors should vary systematically in space and time and that cancer cells form local ecological communities within tumors. These communities possess limited numbers of species determined by local conditions, with each species in a community possessing predictable traits that enable them to cope with their particular environment and coexist with each other. We start with a discussion of concepts and assumptions that ecologists use to study closely related species. We then discuss the competitive exclusion principle as a means for knowing when two species should not coexist, and as an opening towards understanding how they can. We present the five major categories of mechanisms of coexistence that operate in nature and suggest that the same mechanisms apply towards understanding the diversification and coexistence of cancer cell species. They are: Food-Safety Tradeoffs, Diet Choice, Habitat Selection, Variance Partitioning, and Competition-Colonization Tradeoffs. For each mechanism, we discuss how it works in nature, how it might work in cancers, and its implications for therapy.

scholarly journals Does deterministic coexistence theory matter in a finite world?

2018 ◽  
Author(s):  
Sebastian J. Schreiber ◽  
Jonathan M. Levine ◽  
Oscar Godoy ◽  
Nathan J.B. Kraft ◽  
Simon P. Hart
Keyword(s):  
Growth Rates ◽  
Species Coexistence ◽  
Deterministic Model ◽  
Empirical Studies ◽  
Finite Size ◽  
Niche Overlap ◽  
Demographic Stochasticity ◽  
Deterministic Models ◽  
Deterministic Theory ◽  
Population Sizes

AbstractContemporary studies of species coexistence are underpinned by deterministic models that assume that competing species have continuous (i.e. non-integer) densities, live in infinitely large landscapes, and coexist over infinite time horizons. By contrast, in nature species are composed of discrete individuals subject to demographic stochasticity, and occur in habitats of finite size where extinctions occur in finite time. One important consequence of these discrepancies is that metrics of species coexistence derived from deterministic theory may be unreliable predictors of the duration of species coexistence in nature. These coexistence metrics include invasion growth rates and niche and competitive differences, which are now commonly applied in theoretical and empirical studies of species coexistence. Here we test the efficacy of deterministic coexistence metrics on the duration of species coexistence in a finite world. We introduce new theoretical and computational methods to estimate coexistence times in a stochastic counterpart of a classic deterministic model of competition. Importantly, we parameterized this model using experimental field data for 90 pairwise combinations of 18 species of annual plants, allowing us to derive biologically-informed estimates of coexistence times for a natural system. Strikingly, we find that for species expected to deterministically coexist, habitat sizes containing only tens of individuals have predicted coexistence times of greater than 1, 000 years. We also find that invasion growth rates explain 60% of the variation in intrinsic coexistence times, reinforcing their general usefulness in studies of coexistence. However, only by integrating information on both invasion growth rates and species’ equilibrium population sizes could most (> 99%) of the variation in species coexistence times be explained. Moreover, because of a complex relationship between niche overlap/competitive differences and equilibrium population sizes, increasing niche overlap and increasing competitive differences did not always result in decreasing coexistence times as deterministic theory would predict. Nevertheless, our results tend to support the informed use of deterministic theory for understanding the duration of species coexistence, while highlighting the need to incorporate information on species’ equilibrium population sizes in addition to invasion growth rates.

scholarly journals Determinism

2021 ◽  
Vol 20 (5) ◽  
pp. 1-34
Author(s):  
Edward A. Lee
Keyword(s):  
Quantum Physics ◽  
Deterministic Model ◽  
Physical World ◽  
Deterministic Models ◽  
Newtonian Physics ◽  
Physical Systems ◽  
Newton’S Laws ◽  
And Behavior

This article is about deterministic models, what they are, why they are useful, and what their limitations are. First, the article emphasizes that determinism is a property of models, not of physical systems. Whether a model is deterministic or not depends on how one defines the inputs and behavior of the model. To define behavior, one has to define an observer. The article compares and contrasts two classes of ways to define an observer, one based on the notion of “state” and another that more flexibly defines the observables. The notion of “state” is shown to be problematic and lead to nondeterminism that is avoided when the observables are defined differently. The article examines determinism in models of the physical world. In what may surprise many readers, it shows that Newtonian physics admits nondeterminism and that quantum physics may be interpreted as a deterministic model. Moreover, it shows that both relativity and quantum physics undermine the notion of “state” and therefore require more flexible ways of defining observables. Finally, the article reviews results showing that sufficiently rich sets of deterministic models are incomplete. Specifically, nondeterminism is inescapable in any system of models rich enough to encompass Newton’s laws.

Journal-conference interaction and the competitive exclusion principle

interactions ◽  
2013 ◽  
Vol 20 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Jonathan Grudin
Keyword(s):  
Competitive Exclusion ◽  
Exclusion Principle ◽  
Competitive Exclusion Principle

Gause’s Competitive Exclusion Principle

2008 ◽  
pp. 1731-1734 ◽  
Author(s):  
J. Kneitel
Keyword(s):  
Competitive Exclusion ◽  
Exclusion Principle ◽  
Competitive Exclusion Principle

scholarly journals Strong violation of the competitive exclusion principle

2011 ◽  
Author(s):  
Lev Kalmykov ◽  
Vyacheslav Kalmykov
Keyword(s):  
Competitive Exclusion ◽  
Exclusion Principle ◽  
Competitive Exclusion Principle
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