O gene egoísta revisitado: a reconciliação de Williams-Dawkins as definições convencionais

segunda-feira, maio 30, 2011

The Selfish Gene Revisited: Reconciliation of Williams–Dawkins and Conventional Definitions

Donald R. Forsdyke

Department of Biochemistry, Queen's University, Kingston, Ontario, Canada. forsdyke@queensu.ca


Sightings of the revolutionary comet that appeared in the skies of evolutionary biology in 1976—the selfish gene—date back to the 19th and early 20th centuries. It became generally recognized that genes were located on chromosomes and compete with each other in a manner consistent with the later appellation “selfish.” Chromosomes were seen as disruptable by the apparently random “cut and paste” process known as recombination. However, each gene was only a small part of its chromosome. On a statistical basis a gene should escape disruption for many generations. This led George Williams and Richard Dawkins to a new definition of the gene, differing from conventional biochemical definitions in that there were no consistent genic boundaries. There had been no previous sightings of another revolutionary, albeit less verbally spectacular, comet that appeared in 1975—the homostability principle of Akiyoshi Wada. Each gene has a base composition “accent” that distinguishes it from its neighbors. We now see that recombination can be triggered by the shift in base composition at genic boundaries. Hence, the Williams–Dawkins definition approaches the conventional definitions.