Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
, 24, 323-70

The Molecular Basis of the Evolution of Sex

Affiliations
Review

The Molecular Basis of the Evolution of Sex

H Bernstein et al. Adv Genet.

Abstract

Traditionally, sexual reproduction has been explained as an adaptation for producing genetic variation through allelic recombination. Serious difficulties with this explanation have led many workers to conclude that the benefit of sex is a major unsolved problem in evolutionary biology. A recent informational approach to this problem has led to the view that the two fundamental aspects of sex, recombination and outcrossing, are adaptive responses to the two major sources of noise in transmitting genetic information, DNA damage and replication errors. We refer to this view as the repair hypothesis, to distinguish it from the traditional variation hypothesis. On the repair hypothesis, recombination is a process for repairing damaged DNA. In dealing with damage, recombination produces a form of informational noise, allelic recombination, as a by-product. Recombinational repair is the only repair process known which can overcome double-strand damages in DNA, and such damages are common in nature. Recombinational repair is prevalent from the simplest to the most complex organisms. It is effective against many different types of DNA-damaging agents, and, in particular, is highly efficient in overcoming double-strand damages. Current understanding of the mechanisms of recombination during meiosis suggests that meiosis is designed for repairing DNA. These considerations form the basis for the first part of the repair hypothesis, that recombination is an adaptation for dealing with DNA damage. The evolution of sex can be viewed as a continuum on the repair hypothesis. Sex is presumed to have arisen in primitive RNA-containing protocells whose sexual process was similar to that of recombinational repair in extent segmented, single-stranded RNA viruses, which are among the simplest known organisms. Although this early form of repair occurred by nonenzymatic reassortment of replicas of undamaged RNA segments, it evolved into enzyme-mediated breakage and exchange between long DNA molecules. As some lines of descent became more complex, their genome information increased, leading to increased vulnerability to mutation. The diploid stage of the sexual cycle, which was at first transient, became the predominant stage in some lines of descent because it allowed complementation, the masking of deleterious recessive mutations. Out-crossing, the second fundamental aspect of sex, is also maintained by the advantage of masking mutations. However, outcrossing can be abandoned in favor of parthenogenesis or selfing under conditions in which the costs of mating are very high.(ABSTRACT TRUNCATED AT 400 WORDS)

Similar articles

  • Origin of Sex
    H Bernstein et al. J Theor Biol 110 (3), 323-51. PMID 6209512.
    The competitive advantage of sex consists in being able to use redundancy to recover lost genetic information while minimizing the cost of redundancy. We show that the ma …
  • The Evolutionary Role of Recombinational Repair and Sex
    H Bernstein et al. Int Rev Cytol 96, 1-28. PMID 2416705. - Review
    We have argued that sexual reproduction arose very early in the evolution of life as a way of overcoming informational damage or loss through recombinational repair. As o …
  • The Evolution of Meiotic Sex and Its Alternatives
    G Mirzaghaderi et al. Proc Biol Sci 283 (1838). PMID 27605505. - Review
    Meiosis is an ancestral, highly conserved process in eukaryotic life cycles, and for all eukaryotes the shared component of sexual reproduction. The benefits and function …
  • Recombinational Repair of Hydrogen Peroxide-Induced Damages in DNA of Phage T4
    D Chen et al. Mutat Res 184 (2), 87-98. PMID 3627145.
    Recently, hydrogen peroxide and its free-radical product, the hydroxyl radical (OH.) have been identified as major sources of DNA damage in living organisms. They occur a …
  • Genetic Damage, Mutation, and the Evolution of Sex
    H Bernstein et al. Science 229 (4719), 1277-81. PMID 3898363. - Review
    The two fundamental aspects of sexual reproduction, recombination and outcrossing, appear to be maintained respectively by the advantages of recombinational repair and ge …
See all similar articles

Cited by 16 PubMed Central articles

See all "Cited by" articles

Publication types

Feedback