Canalisation (genetics)

In this metaphor, a canalised trait is illustrated as a valley (which he called a creode) enclosed by high ridges, safely guiding the phenotype to its "fate".

Waddington claimed that canals form in the epigenetic landscape during evolution, and that this heuristic is useful for understanding the unique qualities of biological robustness.

[17] Canalisation of a large set of genotypes into a limited phenotypic space has been suggested as a mechanism for the accumulation, in a neutral manner, of mutations that could otherwise be deleterious.

This hidden diversity could then be unleashed by extreme changes in the environment or by molecular switches, releasing previously cryptic genetic variation that can then contribute to a rapid burst of evolution,[18] a phenomenon termed decanalisation.

In 2002, Lindquist showed that pharmacological inhibition of HSP90 in Arabidopsis thaliana also lead to a wide range of phenotypes, some of which could be considered adaptive, further supporting the canalising role of HSP90.

Further analysis showed that low conductivity in the cave water induces a stress response mimicking the inhibition of HSP90, providing a mechanism for decanalisation.

[26] The presence of this so-called bias in genetic variability allows us to gain further insights into how certain phenotypes are more successful in terms of their actual morphology, biochemical makeup, or behavior.

This extends to morphology, where variations must occur in a systematic order; otherwise, phenotypic mutations will not persist due to the occurrence of natural selection.

[28] Ultimately, this results in a lower amount of diversity observed throughout evolution, as the majority of phenotypes do not persist beyond a few generations due to their inferior morphology, biochemical makeup, or physical movement or appearance.