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Mutation protocols share with sexual reproduction
the physiological role of producing genetic variation
within 'constraints that deconstrain.'

David G. King

Department of Anatomy, School of Medicine, and
Department of Zoology, College of Agricultural, Life, and Physical Sciences
Southern Illinois University Carbondale

Abstract

Because the universe of possible DNA sequences is inconceivably vast, organisms have evolved mechanisms for exploring DNA sequence space while substantially reducing the hazard that would otherwise accrue to any process of random, accidental mutation.  One such mechanism is meiotic recombination.  Although sexual reproduction imposes a seemingly paradoxical 50% cost to fitness, sex evidently prevails because this cost is outweighed by the advantage of equiping offspring with genetic variation to accommodate environmental vicissitudes.

The potential adaptive utility of additional mechanisms for producing genetic variation has long been obscured by a presumption that the vast majority of mutations are deleterious.  Perhaps surprisingly, the probability for adaptive variation can be increased by several mechanisms which generate mutations abundantly.  Such mechanisms, here called 'mutation protocols', implement implicit 'constraints that deconstrain'.  Like meiotic recombination, they produce genetic variation in forms that minimize potential for harm while providing a reasonable high probability for benefit.  One example is replication slippage of simple sequence repeats (SSRs); this process yields abundant, reversible mutations, typically with small quantitative effect on phenotype.  This enables SSRs to function as adjustable 'tuning knobs'.  There exists a clear pathway for SSRs to be shaped through indirect selection favoring their implicit tuning-knob protocol.  Several other molecular mechanisms comprise likely components of additional mutation protocols.

Biologists might plausibly regard such mechanisms of mutation not primarily as sources of deleterious genetic mistakes but also as potentially adaptive processes for 'exploring' DNA sequence space.

Full text pdf:  The Journal of Physiology, https://doi.org/10.1113/JP285478..

Comments and questions: dgking@siu.edu

SIUC / Zoology / David King
https://dgkinglab.siu.edu/JP-abstractDGK.htm
Last updated:  12 January 2024