Selection strategies and choice of breeding methods.

The shift from a hunting and gathering economy to agriculture was possible because natural and artificial modifications in wild species allowed for a lasting interaction between biological organisms and man in such a way that they became dependent on each other. The placing of plants and animals in a disturbed environment provided the selective pressure required to produce new forms, well differentiated from the wild stock. This was named automatic selection by Harlan (1975) who described the conditions for its existence in crop plants. Very briefly, harvesting and repeated sowing of the harvested material (not collecting any more from the wild) was a powerful filter for selecting mutants of agricultural value such as absence of dormancy, synchronous flowering and maturity, large seeds, hard spikes in cereals, indehiscence in legumes and better regeneration ability in vegetatively propagated crops.