Developmental noise, entropy, and biological system condition.

Abstract

Developmental noise is considered as a permissible level of entropy, as a compromise between the cost and needed precision of the realization of genetic information. In terms of entropy, noise is a measure of acceptable level of disorder to ensure a reliable system operation. Developmental noise plays a role in the observed phenotypic diversity and is associated with other indicators of the biological system condition. The thermodynamic characteristic of entropy by the energy metabolism also turns out to be related to the developmental noise. Phenotypic variability is largely determined by developmental homeostasis, including both canalization (an ability to form a similar phenotype under different conditions) and developmental stability (a capability for perfect development measured by noise level). It is shown that the change in the noise level, as an expression of the certain entropy level, unlike other forms of phenotypic variability, is a reflection of a change in the system condition. Although the entropy indices of ontogeny and community under certain conditions can change simultaneously, the entropy index at the level of developmental noise proves to be a more unambiguous and universal measure of the disorder of a biological system, compared to biodiversity indices at the community level.