Unidirectional Hybridization and Introgression in an Avian Contact Zone: Evidence from Genetic Markers, Morphology, and Comparisons with Laboratory-Raised F1 Hybrids

[摘要] 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 data showed that both types of mixed matings produced viable F₁ offspring. Taken together, the results indicate the existence of a unimodal hybrid zone with asymmetric introgression from S. capicola into S. vinacea. The origin of this hybrid zone is most likely a combination of geographic and behavioral factors and suggests a balance between dispersal and selection.

[学科分类] 动物科学

[关键词] AFLP;doves;genetics;hybrid zone;morphology;mtDNA;Streptopelia;vocalization