Saturday, February 25, 2006
[evomech] Genetic assimilation of an acquired character (Classic Paper)
Genetic assimilation of an acquired character
[Waddington, Evolution, Jun '53]
Under the influence of natural selection development tends to become canalized so that more or less normal organs and tissues are produced even in the face of slight abnormalities of the genotype or of the external environment (Waddington, 1940).
It has been suggested that if an animal is subjected to unusual circumstances to which it can react in an adaptive manner, the development of the adaptive character might itself become so far canalised that it continued to appear even when the conditions returned to the previous norm (Waddington, 1942). This mechanism would provide a means by which an "acquired character" in the conventional sense could be "assimilated" by the genotype, and eventually appear comparitively independent of any specific environmental influence.
Schmalhausen (1947) has independently suggested a very similar process, which he has discussed at some length under the name "stabilising selection"; a phrase which, however, he uses in a number of different senses, as Simpson (1947) has pointed out.
Full text at:
Model of an Internal Evolutionary Mechanism:
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