Modifier theory: The population genetics of biological noise

Daniel M Weinreich

Daniel M Weinreich

Department of Ecology, Evolution and Organismal Biology, Brown University, Providence, Rhode Island, USA

weinreich@brown.edu

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Link to seminar:TBA

Modifier theory has historically been concerned with the population genetics of alleles that influ-ence genetic parameters such as the rates of mutation and recombination. The selective fate of such modifier alleles is influenced by their statistical associations with whatever phenotypic novel-ties they induce in their carriers. Importantly, recent work has shown that even transient statistical associations are sufficient for this selective effect to operate. This motivates us to propose refram-ing modifier theory as the population genetics of alleles that heritably influence the amount of bio-logical noise. We argue from first principles that biological noise is a double-edged sword: almost always deleterious but also occasionally yielding high fitness phenotypes. We suggest that his in turn implies the existence of an equilibrium amount of noise, at which the advantage of producing additional, rare beneficial phenotypes is exactly balanced by the cost of producing the vastly more common deleterious phenotypes. Our broader conception of modifier theory integrates previously disparate areas of inquiry. For example, it, offers a deeper understanding of how natural selection can simultaneously operate on multiple levels of population structure, and it resolves teleological criticisms of the hypothesis that evolvability can evolve. It also motivates exciting new experimental and theoretical questions.

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