Asymmetrical introgression in a freshwater fish hybrid zone as revealed by a morphological index of hybridization
Abstract:Two cyprinid species, Barbus barbus and Barbus meridionalis, form a hybrid zone in the River Lergue (southern France). Hybrids were distinguished morphologically by discriminant function analysis based on samples from the two parental taxa using only three measurements. This morphological hybridization index showed a strong asymmetry in introgression between the two taxa. B. meridionalis can live in the habitats typical of B. barbus and also in habitats where the latter cannot (small upstream tributaries), while remaining essentially unaffected by the hybridization process. By contrast, B. barbus is strongly introgressed because its habitat is invaded at least sporadically by B. meridionalis migrants. There is no behavioral barrier to hybridization, suggesting that an asymmetrical gene flow is probably partly responsible for the asymmetry in introgression.
Document Type: Original Article
Affiliations: 1: Laboratoire Génome et Populations, UPR 9060, Université Montpellier II cc063, Place Eugéne Bataillon, 34095 Montpellier cedex 5, France 2: Laboratoire de Biométrie CJVRS, CEFE 1919 route de Mende, 34293 Montpellier cedex 5, France
Publication date: May 1, 1999