The Effect of Deleterious Alleles on Adaptation in Asexual Populations

Corresponding author: Toby Johnson, University of British Columbia, 6270 University Blvd., Vancouver, BC V6T 1Z4, Canada., johnson{at}zoology.ubc.ca (E-mail)

Communicating editor: W. STEPHAN

We calculate the fixation probability of a beneficial allele that arises as the result of a unique mutation in an asexual population that is subject to recurrent deleterious mutation at rate U. Our analysis is an extension of previous works, which make a biologically restrictive assumption that selection against deleterious alleles is stronger than that on the beneficial allele of interest. We show that when selection against deleterious alleles is weak, beneficial alleles that confer a selective advantage that is small relative to U have greatly reduced probabilities of fixation. We discuss the consequences of this effect for the distribution of effects of alleles fixed during adaptation. We show that a selective sweep will increase the fixation probabilities of other beneficial mutations arising during some short interval afterward. We use the calculated fixation probabilities to estimate the expected rate of fitness improvement in an asexual population when beneficial alleles arise continually at some low rate proportional to U. We estimate the rate of mutation that is optimal in the sense that it maximizes this rate of fitness improvement. Again, this analysis relaxes the assumption made previously that selection against deleterious alleles is stronger than on beneficial alleles.

This article has been cited by other articles:

				A. J. Betancourt Genomewide Patterns of Substitution in Adaptively Evolving Populations of the RNA Bacteriophage MS2 Genetics, April 1, 2009; 181(4): 1535 - 1544. [Abstract] [Full Text] [PDF]

				C. A. Fogle, J. L. Nagle, and M. M. Desai Clonal Interference, Multiple Mutations and Adaptation in Large Asexual Populations Genetics, December 1, 2008; 180(4): 2163 - 2173. [Abstract] [Full Text] [PDF]

				Z Patwa and L.M Wahl The fixation probability of beneficial mutations J R Soc Interface, November 6, 2008; 5(28): 1279 - 1289. [Abstract] [Full Text] [PDF]

				D. Bachtrog The Temporal Dynamics of Processes Underlying Y Chromosome Degeneration Genetics, July 1, 2008; 179(3): 1513 - 1525. [Abstract] [Full Text] [PDF]

				M. M. Desai and D. S. Fisher Beneficial Mutation Selection Balance and the Effect of Linkage on Positive Selection Genetics, July 1, 2007; 176(3): 1759 - 1798. [Abstract] [Full Text] [PDF]

				E. S. Dolgin and B. Charlesworth The Fate of Transposable Elements in Asexual Populations Genetics, October 1, 2006; 174(2): 817 - 827. [Abstract] [Full Text] [PDF]

				R. B. Schinazi A Stochastic Model for Cancer Risk Genetics, September 1, 2006; 174(1): 545 - 547. [Abstract] [Full Text] [PDF]

				J.-B. Andre and B. Godelle The Evolution of Mutation Rate in Finite Asexual Populations Genetics, January 1, 2006; 172(1): 611 - 626. [Abstract] [Full Text] [PDF]

				S. F. Elena and R. Sanjuan Adaptive Value of High Mutation Rates of RNA Viruses: Separating Causes from Consequences J. Virol., September 15, 2005; 79(18): 11555 - 11558. [Full Text] [PDF]

				V. Furio, A. Moya, and R. Sanjuan The cost of replication fidelity in an RNA virus PNAS, July 19, 2005; 102(29): 10233 - 10237. [Abstract] [Full Text] [PDF]

				L. De Gelder, J. M. Ponciano, Z. Abdo, P. Joyce, L. J. Forney, and E. M. Top Combining Mathematical Models and Statistical Methods to Understand and Predict the Dynamics of Antibiotic-Sensitive Mutants in a Population of Resistant Bacteria During Experimental Evolution Genetics, November 1, 2004; 168(3): 1131 - 1144. [Abstract] [Full Text] [PDF]

				C. O. Wilke The Speed of Adaptation in Large Asexual Populations Genetics, August 1, 2004; 167(4): 2045 - 2053. [Abstract] [Full Text] [PDF]

				A. Navarro and N. H. Barton Chromosomal Speciation and Molecular Divergence--Accelerated Evolution in Rearranged Chromosomes Science, April 11, 2003; 300(5617): 321 - 324. [Abstract] [Full Text] [PDF]