title: Genotype networks shed light on evolutionary constraints.
abstract: An evolutionary constraint is a bias or limitation in phenotypic variation that a biological system produces. One can distinguish physicochemical, selective, genetic and developmental causes of such constraints. Here, I discuss these causes in three classes of system that bring forth many phenotypic traits and evolutionary innovations: regulatory circuits, macromolecules and metabolic networks. In these systems, genotypes with the same phenotype form large genotype networks that extend throughout a vast genotype space. Such genotype networks can help unify different causes of evolutionary constraints. They can show that these causes ultimately emerge from the process of development; that is, how phenotypes form from genotypes. Furthermore, they can explain important consequences of constraints, such as punctuated stasis and canalization.
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Y27-J-54, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. andreas.wagner@ieu.uzh.ch
authors.forename: Andreas
authors.initials: A
authors.lastname: Wagner
mesh_terms: D001419:Bacteria / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D056890:Eukaryota / Q000235:genetics / Q000502:physiology*; D019143:Evolution, Molecular; D053263:Gene Regulatory Networks; D014644:Genetic Variation; D005838:Genotype; D046911:Macromolecular Substances / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D010641:Phenotype
chemical_list: D046911:Macromolecular Substances