title: Introgressive hybridization and morphological transgression in the contact zone between two MediterraneanSoleaspecies.
abstract: Hybrid zones provide natural experiments where new combinations of genotypes and phenotypes are produced. Studying the reshuffling of genotypes and remodeling of phenotypes in these zones is of particular interest to document the building of reproductive isolation and the possible emergence of transgressive phenotypes that can be a source of evolutionary novelties. Here, we specifically investigate the morphological variation patterns associated with introgressive hybridization between two species of sole,Solea senegalensisandSolea aegyptiaca. The relationship between genetic composition at nuclear loci and individual body shape variation was studied in four populations sampled across the hybrid zone located in northern Tunisia. A strong correlation between genetic and phenotypic variation was observed among all individuals but not within populations, including the two most admixed ones. Morphological convergence between parental species was observed close to the contact zone. Nevertheless, the samples taken closest to the hybrid zone also displayed deviant segregation of genotypes and phenotypes, as well as transgressive phenotypes. In these samples, deviant body shape variation could be partly attributed to a reduced condition index, and the distorted genetic composition was most likely due to missing allelic combinations. These results were interpreted as an indication of hybrid breakdown, which likely contributes to postmating reproductive isolation between the two species.
authors.affiliation: Université de Tunis El Manar Faculté des Sciences de Tunis UR 11ES08 Biologie integrative et écologie évolutive et fonctionnelle des milieu aquatiques, 2092 Tunis Tunisie; Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Souissi
authors.affiliation: Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France.
authors.forename: Pierre-Alexandre
authors.initials: PA
authors.lastname: Gagnaire
authors.affiliation: Université de Montpellier Montpellier France; CNRS - Institut des Sciences de l'Evolution UMR 5554 UM-CNRS-IRD-EPHE Station Méditerranéenne de l'Environnement Littoral Sète France.
authors.forename: François
authors.initials: F
authors.lastname: Bonhomme
authors.affiliation: Université de Tunis El Manar Faculté des Sciences de Tunis UR 11ES08 Biologie integrative et écologie évolutive et fonctionnelle des milieu aquatiques, 2092 Tunis Tunisie.
authors.forename: Lilia
authors.initials: L
authors.lastname: Bahri-Sfar
keywords: Solea aegyptiaca; Solea senegalensis; body shape; genetic–phenotypic correlation; introgressive hybridization; transgressive phenotypes