title: Multiple sources of reproductive isolation in a bimodal butterfly hybrid zone.
abstract: An important evolutionary question concerns whether one or many barriers are involved in the early stages of speciation. We examine pre- and post-zygotic reproductive barriers between two species of butterflies (Heliconius erato chestertonii and H. e. venus) separated by a bimodal hybrid zone in the Cauca Valley, Colombia. We show that there is both strong pre- and post-mating reproductive isolation, together leading to a 98% reduction in gene flow between the species. Pre-mating isolation plays a primary role, contributing strongly to this isolation (87%), similar to previous examples in Heliconius. Post-mating isolation was also strong, with absence of Haldane's rule, but an asymmetric reduction in fertility (< 11%) in inter-specific crosses depending on maternal genotype. In summary, this is one of the first examples of post-zygotic reproductive isolation playing a significant role in early stages of parapatric speciation in Heliconius and demonstrates the importance of multiple barriers to gene flow in the speciation process.
authors.affiliation: Instituto de Genética, Universidad de los Andes, Bogotá D.C., Colombia. as-munoz@uniandes.edu.co
authors.forename: Astrid G
authors.initials: AG
authors.lastname: Muñoz
authors.forename: C
authors.initials: C
authors.lastname: Salazar
authors.forename: J
authors.initials: J
authors.lastname: Castaño
authors.forename: C D
authors.initials: CD
authors.lastname: Jiggins
authors.forename: M
authors.initials: M
authors.lastname: Linares
mesh_terms: D000818:Animals; D002080:Butterflies / Q000502:physiology*; D003116:Color; D005260:Female; D008297:Male; D008954:Models, Biological; D012098:Reproduction; D012726:Sexual Behavior, Animal