Logo of geneticsGeneticsCurrent IssueInformation for AuthorsEditorial BoardSubscribeSubmit a Manuscript
Genetics. Nov 1997; 147(3): 953–959.
PMCID: PMC1208270

The Advantage of Sex in the RNA Virus [var phi]6


When laboratory populations of the RNA bacteriophage [var phi]6 are subjected to intensified genetic drift, they experience a decline in fitness. These experiments demonstrate that the average effect of mutations is deleterious, and they are used to suggest that Muller's ratchet can operate in these viruses. However, the operation of Muller's ratchet does not alone guarantee an advantage of sex. When [var phi]6 populations were subjected to a series of bottlenecks of one individual and then crossed, the measured advantage of sex was not significant. To determine whether a small sample size, as opposed to allelism or another explanation, can account for the negative result, we repeated the [var phi]6 experiments by crossing a larger set of populations. We found that bottlenecked populations of [var phi]6 could recover fitness through mutations. However, hybrids produced by crossing the populations recovered an additional amount over the contribution of mutations. This additional amount, which represents an advantage of sex to [var phi]6, was determined to be significantly greater than zero. These results provide indirect support for an advantage of sex through Muller's ratchet. However, we also use our experimental design and results to propose an alternative to Muller's ratchet as a model for the evolution of sex.

Full Text

The Full Text of this article is available as a PDF (747K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Chao L. Fitness of RNA virus decreased by Muller's ratchet. Nature. 1990 Nov 29;348(6300):454–455. [PubMed]
  • Duarte E, Clarke D, Moya A, Domingo E, Holland J. Rapid fitness losses in mammalian RNA virus clones due to Muller's ratchet. Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):6015–6019. [PMC free article] [PubMed]
  • Duarte EA, Novella IS, Ledesma S, Clarke DK, Moya A, Elena SF, Domingo E, Holland JJ. Subclonal components of consensus fitness in an RNA virus clone. J Virol. 1994 Jul;68(7):4295–4301. [PMC free article] [PubMed]
  • Gottlieb P, Metzger S, Romantschuk M, Carton J, Strassman J, Bamford DH, Kalkkinen N, Mindich L. Nucleotide sequence of the middle dsRNA segment of bacteriophage phi 6: placement of the genes of membrane-associated proteins. Virology. 1988 Mar;163(1):183–190. [PubMed]
  • Haigh J. The accumulation of deleterious genes in a population--Muller's Ratchet. Theor Popul Biol. 1978 Oct;14(2):251–267. [PubMed]
  • McGraw T, Mindich L, Frangione B. Nucleotide sequence of the small double-stranded RNA segment of bacteriophage phi 6: novel mechanism of natural translational control. J Virol. 1986 Apr;58(1):142–151. [PMC free article] [PubMed]
  • Mindich L, Sinclair JF, Levine D, Cohen J. Genetic studies of temperature-sensitive and nonsense mutants of bacteriophage phi6. Virology. 1976 Nov;75(1):218–223. [PubMed]
  • Mindich L, Nemhauser I, Gottlieb P, Romantschuk M, Carton J, Frucht S, Strassman J, Bamford DH, Kalkkinen N. Nucleotide sequence of the large double-stranded RNA segment of bacteriophage phi 6: genes specifying the viral replicase and transcriptase. J Virol. 1988 Apr;62(4):1180–1185. [PMC free article] [PubMed]
  • Vidaver AK, Koski RK, Van Etten JL. Bacteriophage phi6: a Lipid-Containing Virus of Pseudomonas phaseolicola. J Virol. 1973 May;11(5):799–805. [PMC free article] [PubMed]

Articles from Genetics are provided here courtesy of Genetics Society of America


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • MedGen
    Related information in MedGen
  • PubMed
    PubMed citations for these articles

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...