TY - JOUR
T1 - The revolution of canalization and the breaking of Von Baer's Laws
T2 - Modeling the evolution of development with epistasis
AU - Rice, Sean H.
PY - 1998
Y1 - 1998
N2 - Evolution can change the development processes underlying a character without changing the average expression of the character itself. This sort of change must occur in both the evolution of canalization, in which a character becomes increasingly buffered against genetic or developmental variation, and in the phenomenon of closely related species that show similar adult phenotypes but different underlying developmental patterns. To study such phenomena, I develop a model that follows evolution on a surface representing adult phenotype as a function of underlying developmental characters. A contour on such a 'phenotype landscape' is a set of states of developmental characters that produce the same adult phenotype. Epistasis induces curvature of this surface, and degree of canalization is represented by the slope along a contour. I first discuss the geometric properties of phenotype landscapes, relating epistasis to canalization. I then impose a fitness function on the phenotype and model evolution of developmental characters as a function of the fitness function and the local geometry of the surface. This model shows how canalization evolves as a population approaches an optimum phenotype. It further shows that under some circumstances, 'decanalization' can occur, in which the expression of adult phenotype becomes increasingly sensitive to developmental variation. This process can cause very similar populations to diverge from one another developmentally even when their adult phenotypes experience identical selection regimes.
AB - Evolution can change the development processes underlying a character without changing the average expression of the character itself. This sort of change must occur in both the evolution of canalization, in which a character becomes increasingly buffered against genetic or developmental variation, and in the phenomenon of closely related species that show similar adult phenotypes but different underlying developmental patterns. To study such phenomena, I develop a model that follows evolution on a surface representing adult phenotype as a function of underlying developmental characters. A contour on such a 'phenotype landscape' is a set of states of developmental characters that produce the same adult phenotype. Epistasis induces curvature of this surface, and degree of canalization is represented by the slope along a contour. I first discuss the geometric properties of phenotype landscapes, relating epistasis to canalization. I then impose a fitness function on the phenotype and model evolution of developmental characters as a function of the fitness function and the local geometry of the surface. This model shows how canalization evolves as a population approaches an optimum phenotype. It further shows that under some circumstances, 'decanalization' can occur, in which the expression of adult phenotype becomes increasingly sensitive to developmental variation. This process can cause very similar populations to diverge from one another developmentally even when their adult phenotypes experience identical selection regimes.
KW - Canalization
KW - Epistasis
KW - Evolution of development
KW - Phenotype landscape
KW - Quantitative genetics
UR - http://www.scopus.com/inward/record.url?scp=0031879153&partnerID=8YFLogxK
U2 - 10.1111/j.1558-5646.1998.tb03690.x
DO - 10.1111/j.1558-5646.1998.tb03690.x
M3 - Article
AN - SCOPUS:0031879153
VL - 52
SP - 647
EP - 656
JO - Evolution
JF - Evolution
SN - 0014-3820
IS - 3
ER -