The Northern Flicker serves as a model for studies on the evolutionary process of speciation. The ranges of two rather distinct subspecies overlap on the western Great Plains where they form an extensive hybrid zone. The distinctness of the subspecies is maintained even though the two hybridize extensively. Previous work strongly suggests that selection is a major force in maintaining the characteristics of the two subspecies across the hybrid zone. Current research is designed to determine whether natural selection or sexual selection is most important. Natural selection would be in the form of ecological variables associated with the hybrid zone whereas sexual selection would reflect the ability of the subspecies to establish breeding territories outside of their native ranges. Resolving these questions will advance our understanding of how speciation occurs and how so much diversity evolves in such a short time.
