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Are there ergodic limits to evolution? Ergodic exploration of genome space and convergence

McLeish, T.C.B.

Are there ergodic limits to evolution? Ergodic exploration of genome space and convergence Thumbnail


T.C.B. McLeish


We examine the analogy between evolutionary dynamics and statistical mechanics to include the fundamental question of ergodicity—the representative exploration of the space of possible states (in the case of evolution this is genome space). Several properties of evolutionary dynamics are identified that allow a generalization of the ergodic dynamics, familiar in dynamical systems theory, to evolution. Two classes of evolved biological structure then arise, differentiated by the qualitative duration of their evolutionary time scales. The first class has an ergodicity time scale (the time required for representative genome exploration) longer than available evolutionary time, and has incompletely explored the genotypic and phenotypic space of its possibilities. This case generates no expectation of convergence to an optimal phenotype or possibility of its prediction. The second, more interesting, class exhibits an evolutionary form of ergodicity—essentially all of the structural space within the constraints of slower evolutionary variables have been sampled; the ergodicity time scale for the system evolution is less than the evolutionary time. In this case, some convergence towards similar optima may be expected for equivalent systems in different species where both possess ergodic evolutionary dynamics. When the fitness maximum is set by physical, rather than co-evolved, constraints, it is additionally possible to make predictions of some properties of the evolved structures and systems. We propose four structures that emerge from evolution within genotypes whose fitness is induced from their phenotypes. Together, these result in an exponential speeding up of evolution, when compared with complete exploration of genomic space. We illustrate a possible case of application and a prediction of convergence together with attaining a physical fitness optimum in the case of invertebrate compound eye resolution.

Journal Article Type Article
Online Publication Date Oct 23, 2015
Publication Date Dec 6, 2015
Deposit Date Aug 16, 2016
Publicly Available Date Oct 23, 2016
Journal Interface Focus
Electronic ISSN 2042-8901
Publisher The Royal Society
Peer Reviewed Peer Reviewed
Volume 5
Issue 6
Article Number 20150041
Public URL


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