Origin of sex revisited

Mauro Santos, Elias Zintzaras, E. Szathmáry

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Why did sex ever arise in the first place? Why it does not disappear in view of the greater efficiency of asexuals? These are clearly two different questions, and we suggest here that the solution for the origin of sex does not necessarily come from theoretical considerations based on currently existing genetic systems. Thus, while we agree with a number of authors in that the emergence of sex (understood as the exchange of genetic material between genomes) is deeply rooted in the origin of life and happened during the very early stages in the transition from individual genes ('replicators') to bacteria-like cells ('reproducers'), we challenge the idea that recombinational repair was the major selective force for the emergence of sex. Taking the stochastic corrector model as a starting point, we provide arguments that question the putative costs of redundancy in primitive protocells. In addition, if genes that cause intragenomic conflict (i.e., parasites) are taken into account, it is certainly wrong to suggest that cellular fusion would be beneficial at the population level (although this strong claim needs some qualifications). However, when a continuous input of deleterious mutations that impair the fitness of the protocell as a whole is considered in the model (in the realistic range in which stable mutant distributions of quasi-species within compartments are established), there are circumstances when sex could be beneficial as a side effect of the dynamic equilibrium between cellular fusion-mutation-selection. The scenario we have explored numerically is fully consistent with the idea that the universal ancestor was not a discrete entity but an ensemble of proto-organisms that exchanged much genetic information.

Original languageEnglish
Pages (from-to)405-432
Number of pages28
JournalOrigins of Life and Evolution of the Biosphere
Volume33
Issue number4-5
DOIs
Publication statusPublished - Oct 2003

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mutation
origin of life
gene
gender
Artificial Cells
ancestry
repair
parasite
fitness
genome
bacterium
Genes
Mutation
cost
Parasites
genes
biogeography
adverse effects
Genome
Bacteria

Keywords

  • Competition
  • Cooperation
  • Deleterious mutations
  • Genomic conflict
  • Origin of sex
  • Parasites
  • Selfish replicators
  • Stochastic corrector model

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Ecology, Evolution, Behavior and Systematics

Cite this

Origin of sex revisited. / Santos, Mauro; Zintzaras, Elias; Szathmáry, E.

In: Origins of Life and Evolution of the Biosphere, Vol. 33, No. 4-5, 10.2003, p. 405-432.

Research output: Contribution to journalArticle

Santos, Mauro ; Zintzaras, Elias ; Szathmáry, E. / Origin of sex revisited. In: Origins of Life and Evolution of the Biosphere. 2003 ; Vol. 33, No. 4-5. pp. 405-432.
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