title: Spatiotemporal dynamics of gene flow and hybrid fitness between the M and S forms of the malaria mosquito, Anopheles gambiae.
abstract: The M and S forms of Anopheles gambiae have been the focus of intense study by malaria researchers and evolutionary biologists interested in ecological speciation. Divergence occurs at three discrete islands in genomes that are otherwise nearly identical. An "islands of speciation" model proposes that diverged regions contain genes that are maintained by selection in the face of gene flow. An alternative "incidental island" model maintains that gene flow between M and S is effectively zero and that divergence islands are unrelated to speciation. A "divergence island SNP" assay was used to explore the spatial and temporal distributions of hybrid genotypes. Results revealed that hybrid individuals occur at frequencies ranging between 5% and 97% in every population examined. A temporal analysis revealed that assortative mating is unstable and periodically breaks down, resulting in extensive hybridization. Results suggest that hybrids suffer a fitness disadvantage, but at least some hybrid genotypes are viable. Stable introgression of the 2L speciation island occurred at one site following a hybridization event.
authors.affiliation: Vector Genetics Laboratory, Department of Pathology, Microbiology and Immunology, and Department of Entomology and Nematology, University of California, Davis, CA 95616.
authors.forename: Yoosook
authors.initials: Y
authors.lastname: Lee
authors.forename: Clare D
authors.initials: CD
authors.lastname: Marsden
authors.forename: Laura C
authors.initials: LC
authors.lastname: Norris
authors.forename: Travis C
authors.initials: TC
authors.lastname: Collier
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Main
authors.forename: Abdrahamane
authors.initials: A
authors.lastname: Fofana
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cornel
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Lanzaro
mesh_terms: D000354:Africa, Western; D000818:Animals; D000852:Anopheles / Q000235:genetics* / Q000502:physiology; D051456:Gene Flow / Q000235:genetics*; D056084:Genetic Fitness / Q000235:genetics*; D005828:Genetics, Population; D005838:Genotype; D006824:Hybridization, Genetic / Q000235:genetics*; D016013:Likelihood Functions; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D013045:Species Specificity; D013997:Time Factors
keywords: Anopheles coluzzii; population structure; reproductive isolation