Canalisation (genetics)
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Canalisation (canalization in American English) is a measure of the ability of a genotype to produce the same phenotype regardless of variability of its environment. The term canalisation was coined by C. H. Waddington, who also helped explain its developmental mechanisms. He also introduced the epigenetic landscape, in which a canalised trait is illustrated as a valley enclosed by high ridges, safely guiding the phenotype to its "fate".
A recent molecular example was given by Rutherford & Lindquist <ref>Rutherford SL, Lindquist S. (1998). "Hsp90 as a capacitor for morphological evolution". Nature (journal) 396: 336.</ref> Hsp90 is a chaperone protein, monitoring the correct folding of some polypeptides into proteins. Rutherford & Lindquist heat shocked drosophila embryos, therefore recruiting a vast proportion of cytoplasmic Hsp90 to respond to the stress. The decrease in the normal monitoring activity of Hsp90 resulted in many morphological changes in the adult flies. These changes would disappear at the next generation in the absence of the stress. One possible conclusion is that Hsp90 is buffering mutations : flies have accumulated many mutations, but their effect is suppressed by Hsp90. To test this hypothesis, they crossed flies displaying morphological changes, mimicking natural selection during big environmental changes. The resulting flies displayed morphological changes even in the absence of heat shock : the amount of accumulated mutations in these flies had overcome the buffering capacity of Hsp90 and these flies had changed their epigenetic valley.
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[edit] See also
| The development of phenotype
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| Key concepts: Genotype-phenotype distinction | Norms of reaction | Gene-environment interaction | Heritability | Quantitative genetics |
| Genetic architecture: Dominance relationship | Epistasis | Polygenic inheritance | Pleiotropy | Plasticity | Canalisation | Fitness landscape |
| Non-genetic influences: Epigenetic inheritance | Epigenetics | Maternal effect | Dual inheritance theory |
| Developmental architecture: Segmentation | Modularity |
| Evolution of genetic systems: Evolvability | Mutational robustness | Evolution of sex |
| Influential figures: C. H. Waddington | Richard Lewontin |
| Debates: Nature versus nurture |
| List of evolutionary biology topics |
