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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1974 Aug;71(8):3041–3044. doi: 10.1073/pnas.71.8.3041

A Biological Least-Action Principle for the Ecological Model of Volterra-Lotka

Paul A Samuelson 1
PMCID: PMC388616  PMID: 4528377

Abstract

The conservative model of Volterra for more-than-two predator-prey species is shown to be generated as extremals that minimize a definable Lagrange-Hamilton integral involving half the species and their rates of change. This least-action formulation differs from that derived two generations ago by Volterra, since his involves twice the number of phase variables and it employs as variables the cumulative integrals of the numbers of each species that have ever lived. The present result extends the variational, teleological formulations found a decade ago by the author to the more-than-two species case. The present result is anything but surprising, in view of the works by Kerner, Montroll, and others which apply Gibbs' statistical mechanics to the all-but-canonical equations of the standard Volterra model. By a globally linear transformation of coordinates, the Volterra equations are here converted into a completely canonical system isomorphic with the classical mechanics models of Newton, Lagrange, Hamilton, Jacobi, Boltzmann, Gibbs, Poincaré, and G. D. Birkhoff. The conservative nature of the Lotka-Volterra model, whatever its realism, is a crucially necessary condition for the applicability of the variational formalisms, microscopically and macroscopically.

Keywords: predator-prey, ecology, least-action

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Samuelson P. A. Generalized predator-prey oscillations in ecological and economic equilibrium. Proc Natl Acad Sci U S A. 1971 May;68(5):980–983. doi: 10.1073/pnas.68.5.980. [DOI] [PMC free article] [PubMed] [Google Scholar]

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