Polymorphism for Interspecific Cross-Compatibility in Phlox

摘要

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.