EVOLVABILITY

Evolvability is an organism's capacity to generate heritable phenotypi c variation. Metazoan evolution is marked by great morphological and p hysiological diversification, although the core genetic, cell biologic al, and developmental processes are largely conserved. Metazoan divers ification has entailed the evolution of various regulatory processes c ontrolling the time, place, and conditions of use of the conserved cor e processes. These regulatory processes, and certain of the core proce sses, have special properties relevant to evolutionary change. The pro perties of versatile protein elements, weak linkage, compartmentation, redundancy, and exploratory behavior reduce the interdependence of co mponents and confer robustness and flexibility on processes during emb ryonic development and in adult physiology, They also confer evolvabil ity on the organism by reducing constraints on change and allowing the accumulation of nonlethal variation. Evolvability may have been gener ally selected in the course of selection for robust, flexible processe s suitable for complex development and physiology and specifically sel ected in lineages undergoing repeated radiations.