Dominique Meeùs
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Bibliographie : table des matières, index des notions — Retour à la page personnelle
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Gabriel Dover, « Anti-Dawkins », 2000

Genes are so battered, misunderstood and abused that I make no apologies for starting from the beginning with the genetic material. Genes are not self-replicating entities; they are not eternal; they are not units of selection; they are not units of function; and they are not units of instruction. They are modular in construction and history; invariably redundant; each involved in a multitude of functions; and misbehave in a bizarre range of ways. They co-evolve intimately and interactively with each other through their protein and RNA products. They have no meaning outside their interactions, with regard to any adaptive feature of an individual: there are no one-to-one links between genes and complex traits. Genes are the units of inheritance but not the units of evolution: I shall argue that there are no ‘units’ of evolution as such because all units are constantly changing. They are intimately involved with the evolution of biological functions, but evolution is not about the natural selection of ‘selfish’ genes.

P. 48.
Exaptations: Functions for Nothing

Stephen Jay Gould and Elizabeth Vrba have coined a new word, ‘exaptation’, to cover established biological functions that did not arise as Darwinian adaptations6. My favourite exaptive process arises from the neutral theory of evolution. Neutral theory7 predicts that mutations in sequences of DNA which have no, or very little, consequence for reproduction may spread in a population by chance given the inherent instabilities in sizes of populations with time. Such mutant sequences are not prevented from spreading by selection for they have no important effects on phenotypes.

S. J. Gould and E. Vrba, ‘Exaptation — a Missing Term in the Science of Form’, Paleobiology, 8, pp. 4-15; S. J. Gould and R. C. Lewontin, ‘The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme’, Proceedings of the Royal Society, 205 (1978), pp. 581-98.
M. Kimura, The Neutral Theory of Molecular Evolution (Cambridge, Cambridge University Press, 1983).
P. 63.