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Updated: Jul 10, 2026
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Ohno's dilemma: evolution of new genes under continuous selection
Ulfar Bergthorsson1, Dan I Andersson, John R Roth
1Department of Biology, University of New Mexico, Albuquerque, NM 87131-0001, USA.
Summary
Gene duplication allows new functions but faces challenges. A model shows selection can favor both gene copy maintenance and functional divergence, resolving Ohno's dilemma for evolutionary innovation.
Area of Science:
- Evolutionary Biology
- Molecular Evolution
- Genetics
Background:
- Gene duplication is a primary source of novel genes and functions.
- Maintaining duplicated genes while allowing divergence presents evolutionary challenges (Ohno's dilemma).
- Selection for the original gene function can hinder the acquisition of new functions by duplicates.
Purpose of the Study:
- To present a model explaining how selection can favor both the maintenance of gene duplicates and their divergence.
- To resolve the evolutionary paradox of how new gene functions arise via duplication and divergence.
Main Methods:
- Theoretical modeling of gene duplication and selection dynamics.
- Analysis of selection pressures acting on duplicated gene copies.
- Exploration of the role of ancestral 'trace' activities in driving new functions.
Main Results:
- A model where selection favors amplification of a gene's minor ancestral activity when it becomes advantageous.
- Selection for the amplified minor function maintains duplicate copies and increases their population frequency.
- Selection also favors mutational improvement (divergence) of duplicate copies, independent of the original function.
Conclusions:
- Selection can simultaneously maintain gene duplicates and promote their divergence into new functions.
- Ancestral trace activities, when amplified by dosage, provide a mechanism to overcome Ohno's dilemma.
- This process facilitates the evolution of new gene functions through duplication and subsequent adaptive divergence.
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