Increasing diversity under domestication

Abstract

In any group of plants and animals evolution is the history of changes in genetic diversity. These changes are the result of subtle interactions between internal factors such as mutations, and external factors, mostly natural selection. The basic biological unit which is the subject of evolutionary process is the breeding population, i.e. a group of individuals which are bound by breeding relationships. At any given point in space and time genetic diversity is an outcome of three different, and sometimes conflicting, forces: factors and mechanisms acting toward greater diversity; factors decreasing diversity; and mechanisms to maintain existing diversity. The effect of these forces in shaping plant and animal evolution has been studied in detail in natural populations and they are also effective under domestication. The difference between the two is that in the latter, man has become an important element affecting trends and rates. To learn more about the nature of evolution under domestication it would be useful to examine the relative importance of each of the various forces and their effect.