Environment and Genetic Accommodation

Waddington’s experiments on genetic assimilation showed that selection on environmentally induced phenotypic variants can cause inherited evolutionary changes in the phenotype. We have recently extended this work by demonstrating that it is possible to select for a polyphenism (alternative phenotypes in two different environments) in a monophenic species (with the same phenotype in those two environments). We found that a mutation in the juvenile hormone regulatory pathway in Manduca sexta enabled heat stress to reveal a hidden reaction norm of larval coloration. Artificial selection for increased color change in response to heat-shock resulted in the genetic accommodation of a black/green larval color polyphenism, caused by an environment-sensitive threshold switch mediated by the endocrine system.

Duke Scholars

Author H. Frederik Nijhout Biology