The evolution of pulse crops

Abstract

From a consideration of evolution under domestication in the pulses a common pattern emerges. It is suggested that positive selection for a single character, namely, seed size, could have set in motion a complex of selection pressures that not only produced larger seeds and fruits but concomitantly produced a modified shoot architecture. The ultimate production of dwarf plants capable of free-standing growth effectively liberated pulses from dependence on other species for mechanical support and from the implications of their ancestral ecology. Characteristic features of individual pulse species not found in their closest wild relatives can almost invariably be found in other members of the same tribe or elsewhere in the family. This suggests a deep underlying genetical homology in the family as a whole and that Vavilov’s law of homologous series could with benefit be extended beyond the cultigens and enable plant breeders to set themselves more ambitious yet realistic objectives. It appears that pulses have evolved not by producing novel characters under domestication, but rather novel combinations of characters already expressed in wild forms.