Polymorphism for interspecific cross-compatibility in phlox.
Extensive polymorphism for the cross-compatibility of Phlox pilosa with P. glaberrima occurs within Illinois populations. The polymorphism is genetically determined. Thus, there is an opportunity for selection to enhance existing cross-compatibility barriers in areas of species contact. There is no evidence that selection has favored the reinforcement of such barriers.
Department of Botany, University of Texas at Austin, Austin, Tex. 78712.
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Levin