Changes in the genetic makeup, or genotype, of an organism can lead to changes in its traits and characteristics, also known as its phenotype. The sloped surface represents the hypothetical ideal relationship between genotype and phenotype in different environments, but in the absence of stabilizing mechanisms. (A) As part of a thought experiment, consider a population where at first all individuals have the same phenotype (shown as a red ellipse). This phenotype is stabilized by developmental mechanisms, which allow some genetic variation to accumulate (depicted as open ellipses expanding to the right). The evolution of a polyphenism (arrow 1) establishes a new phenotype (yellow ellipse) in a different environment, but with the same genotype. More genetic variation will accumulate (arrow 2) that has no effect on the phenotypes but improves stabilization of the alternative phenotypes in different environmental conditions. (B) When the polyphenism is lost (arrow 3), the mechanisms that stabilized the second phenotype are also lost. The accumulated genetic variation can now produce new phenotypes that (initially at least) fall on the ideal sloped surface, and that establish the foundation for the evolution of new traits and characteristics.