Plant and animal distribution in relation to domestication

Distributions of wild progenitors provide useful information concerning regions of domestication and ecological limits of adaptation of domesticated plants and animals. The evidence, however, must be carefully qualified by: (1) possible changes in climate since the initiation of domestication, (2) the effects of human activities which may either decrease or enlarge the ranges of wild progenitors, (3) the possibility that progenitors have evolved as well as the domesticates, and (4) the possibilities of transdomestication. The distributions of races of domesticated plants and breeds of animals provide useful information on the history and diffusion of domesticates, but patterns of variation differ greatly among species. Variation patterns have been identified that may be termed endemic, semi-endemic, monocentric, oligocentric, or noncentric. Interpretation depends, to a large degree, on an understanding of the processes of domestication.