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Genetics. 2017 Dec;207(4):1577-1589. doi: 10.1534/genetics.117.300350. Epub 2017 Oct 4.

Gene Conversion Facilitates Adaptive Evolution on Rugged Fitness Landscapes.

Author information

1
BioCircuits Institute, University of California San Diego (UCSD), La Jolla, California 92093-0328 pbittihn@ucsd.edu ltsimring@ucsd.edu.
2
San Diego Center for Systems Biology, La Jolla, California 92093-0688.

Abstract

Gene conversion is a ubiquitous phenomenon that leads to the exchange of genetic information between homologous DNA regions and maintains coevolving multi-gene families in most prokaryotic and eukaryotic organisms. In this paper, we study its implications for the evolution of a single functional gene with a silenced duplicate, using two different models of evolution on rugged fitness landscapes. Our analytical and numerical results show that, by helping to circumvent valleys of low fitness, gene conversion with a passive duplicate gene can cause a significant speedup of adaptation, which depends nontrivially on the frequency of gene conversion and the structure of the landscape. We find that stochastic effects due to finite population sizes further increase the likelihood of exploiting this evolutionary pathway. A universal feature appearing in both deterministic and stochastic analysis of our models is the existence of an optimal gene conversion rate, which maximizes the speed of adaptation. Our results reveal the potential for duplicate genes to act as a "scratch paper" that frees evolution from being limited to strictly beneficial mutations in strongly selective environments.

KEYWORDS:

adaptive evolution; fitness landscape; gene conversion; gene duplication; pseudogenes

PMID:
28978673
PMCID:
PMC5714467
[Available on 2018-12-01]
DOI:
10.1534/genetics.117.300350
[Indexed for MEDLINE]

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