Unidirectional Hybridization and Introgression in an Avian Contact Zone: Evidence from Genetic Markers, Morphology, and Comparisons with Laboratory-Raised F1Hybrids

Abstract

ABSTRACT. Examination of contact zones between closely related species is important for understanding speciation, because the interactions in such zones may change the evolutionary direction of one or both taxa. To expose the composition and dynamics of a contact zone between two dove species, Streptopelia vinacea and S. capicola, we used mitochondrial DNA, amplified fragment-length polymorphism (AFLP) markers, and morphological and color measurements. We combined a field study on contact-zone and parental-species individuals with an examination of F1 hybrids reared in captivity. We found that the contact zone is a narrow hybrid zone characterized by a high frequency of hybrids, a lack of clear parental species forms, a high incidence of S. capicola mtDNA, and an AFLP marker distribution more similar to that of S. vinacea. In morphology and color, field hybrids were more similar to S. vinacea and significantly different from S. capicola. F1 hybrids were more similar to S. capicola in color. The laboratory...