Canalization in evolutionary genetics: a stabilizing theory?

✍ Scribed by Greg Gibson; Günter Wagner

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 153 KB
• Volume: 22
• Category: Article
• ISSN: 0265-9247
• DOI: 10.1002/(sici)1521-1878(200004)22:4<372::aid-bies7>3.0.co;2-j

✦ Synopsis

The stability of the morphogenetic system is destroyed (rendered labile) due either to variation in environmental factors or to mutation. On the other hand, in the course of evolution stability is reestablished by the continuous action of stabilizing selection. Stabilizing selection produces a stable form by creating a regulating apparatus. This protects normal morphogenesis against possible disturbances by chance variation in the external environment and also against small variations in internal factors (i.e. mutations). In this case, natural selection is based upon the selective advantage of the norm (often the new norm) over any deviations from it.'' I.I. Schmalhausen, 1949 (p 79 of 1986 reprinted edition).

Summary

Canalization is an elusive concept. The notion that biological systems ought to evolve to a state of higher stability against mutational and environmental perturbations seems simple enough, but has been exceedingly difficult to prove. Part of the problem has been the lack of a definition of canalization that incorporates an evolutionary genetic perspective and provides a framework for both mathematical and empirical study. After briefly reviewing the importance of canalization in studies of evolution and development, we aim, with this essay, to outline a research program that builds upon the definition of canalization as the reduction in variability of a trait, and uses molecular genetic approaches to shed light on the problems of canalization. BioEssays 22:372±380, 2000.