Levels of Confidence in the Analysis of Hybridization in Plants

HYBRIDIZATIONOne of the hypotheses often used to explain many present-day variation patterns in plants is that they result from interspecific hybridization followed by stabilization of hybrid derivatives.To test this hypothesis we make use of several criteria.Our level of confidence depends on the adequacy of the criteria and the extent to which they are satisfied.This, in turn, depends on various features of the biology of the plants under study.For example, several criteria are employed at the polyploid level which cannot be applied at the diploid level.These criteria have to do with chromosome number, chromosome pairing in experimental inter-ploidal hybrids, tetrasomic inheritance, and the colchicine-synthesis of artificial polyploids from F, hybrids between the progenitors.The use of these additional criteria provides a stronger test of hybridity at the polyploid level than can be made at the diploid level.At the diploid level, the number of criteria are fewer, and they are equivocal.As a result it is more difficult to recognize stabilized diploid hybrid entities, and the literature contains only a small number of examples relative to the number of examples of allopolyploids.The putative diploid hybrids include Corn Belt Dent corns (Anderson & Brown, 1952), Potentilla glandulosa subsp.