Red Queen

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For the super computer in the Resident Evil movie, see Red Queen (Resident Evil).


The Red Queen's Hypothesis, Red Queen, "Red Queen's race" or "Red Queen Effect" is an evolutionary hypothesis to explain the advantage of sex at the level of individuals, and the constant evolutionary arms race between competing species. In the microevolutionary version, by making every individual an experiment when mixing mother's and father's genes, sex may allow a species to adapt quickly just to hold onto the ecological niche that it already has in the ecosystem.

The term is taken from the Red Queen's race in Lewis Carroll's Through the Looking Glass. The Red Queen said, "It takes all the running you can do, to keep in the same place."

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Arms races

The metaphor of an evolutionary arms race has been found appropriate for the descriptions of biological processes with dynamics similar to arms races (e.g. Vermeij, 1987). These comparisons may be made in the fields of military hardware, competition in commercial product markets and competition between people in society for wealth or esteem, but, most famously, the idea was originally introduced by Leigh Van Valen. He proposed the Red Queen's Hypothesis (1973) as an explanatory tangent to his proposed Law of Extinction (also 1973) which he derived from observation of constant probabilities of extinction within families of organisms across geologic time. The Red Queen's Hypothesis as formulated by Van Valen provides a conceptual underpinning to discussions of biological evolutionary arms races, even though a direct test of the hypothesis remains elusive, particularly at the macroevolutionary level.

It should be noted that discussions of sex and reproduction were not part of Van Valen's Red Queen's Hypothesis, which addressed evolution at scales above the species level. The microevolutionary version of the Red Queen's Hypothesis was proposed by Bell (1982), also citing Lewis Carroll, but not citing Van Valen.

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The paradox of sex: The "cost" of males

Science writer Matt Ridley wrote a book The Red Queen in which he discussed the debate in theoretical biology over the adaptive benefit of sexual reproduction to those species in which it appears. The connection of the Red Queen to this debate arises from the fact that the traditionally accepted theory (The Vicar of Bray) only showed adaptive benefit at the level of the species or group, not at the level of the gene. By contrast, a Red-Queen-type theory that organisms are running cyclic arms races with their parasites can explain the utility of sexual reproduction at the level of the gene by positing that the role of sex is to preserve genes which are currently disadvantageous, but which will become advantageous against the background of a likely future population of parasites.

Sex is an evolutionary puzzle. In most sexual species, males make up half the population, yet they bear no offspring directly and generally contribute little to the survival of offspring; indeed in some species males pose a positive threat to live young fathered by another male (although this is simply a manifestation of Dawkins' so-called selfish gene, whose goal is to reproduce itself and suppress the reproduction of other genes). Obviously there are species which are exceptions to this rule, such as humans, seahorses, and penguins, amongst others. In addition, males and females must find each other to mate, and sexual selection often favors traits that reduce the survival of organisms. Thus, sexual reproduction is highly inefficient.

One possible explanation for the fact that nearly all vertebrates are sexual is that sex increases the rate at which adaptation can occur. This is for two reasons. First, if an advantageous mutation occurs in an asexual line, it is impossible for that mutation to spread without wiping out all other lines, which may have different advantageous mutations of their own. Second, it mixes up genes. Some genes might be advantageous only when paired with other genes, and sex increases the likelihood that such pairings will occur.

For sex to be advantageous for these reasons requires constant selection for changing conditions. One factor that might cause this is the constant arms race between parasites and their hosts. Parasites generally evolve quickly, due to their short lifespans. As they evolve, they attack their hosts in a variety of ways. Two consecutive generations might be faced with very different selective pressures. If this change is rapid enough, it might explain the persistence of sex.

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References

  • Bell, G. (1982). The Masterpiece Of Nature: The Evolution and Genetics of Sexuality. University of California Press, Berkeley, 635 pp.
  • Lewis Carroll. 1960 (reprinted). The Annotated Alice: Alice's Adventures in Wonderland and Through the Looking-Glass, illustrated by J. Tenniel, with an Introduction and Notes by M. Gardner. The New American Library, New York, 345 pp. Through the Looking-Glass and What Alice Found There [1]
  • Dawkins, R. & Krebs, J. R. (1979). Arms races between and within species. Proceedings of the Royal society of London, B 205, 489-511.
  • Pearson, Paul N. (2001) Red Queen hypothesis Encyclopedia of Life Sciences http://www.els.net
  • Matt Ridley (1995) The Red Queen: Sex and the Evolution of Human Nature, Penguin Books, ISBN 0140245480
  • Leigh Van Valen. (1973). "A new evolutionary law". Evolutionary Theory 1: 1—30.
  • Vermeij, G.J. (1987). Evolution and escalation: An ecological history of life. Princeton University Press, Princeton, NJ.fr:Théorie de la reine rouge
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