title: Recurrent hybridization and recent origin obscure phylogenetic relationships within the 'white-headed' gull (Larus sp.) complex.
abstract: Species complexes that have undergone recent radiations are often characterized by extensive allele sharing due to recent ancestry and (or) introgressive hybridization. This can result in discordant evolutionary histories of genes and heterogeneous genomes, making delineating species limits difficult. Here we examine the phylogenetic relationships among a complex group of birds, the white-headed gulls (Aves: Laridae), which offer a unique window into the speciation process due to their recent evolutionary history and propensity to hybridize. Relationships were examined among 17 species (61 populations) using a multilocus approach, including mitochondrial and nuclear intron DNA sequences and microsatellite genotype information. Analyses of microsatellite and intron data resulted in some species-based groupings, although most species were not represented by a single cluster. Considerable allele and haplotype sharing among white-headed gull species was observed; no locus contained a species-specific clade. Despite this, our multilocus approach provided better resolution among some species than previous studies. Interestingly, most clades appear to correspond to geographic locality: our BEAST analysis recovered strong support for a northern European/Icelandic clade, a southern European/Russian clade, and a western North American/canus clade, with weak evidence for a high latitude clade spanning North America and northwestern Europe. This geographical structuring is concordant with behavioral observations of pervasive hybridization in areas of secondary contact. The extent of allele and haplotype sharing indicates that ecological and sexual selection are likely not strong enough to complete reproductive isolation within several species in the white-headed gull complex. This suggests that just a few genes are driving the speciation process.
authors.affiliation: Department of Vertebrate Zoology, Division of Birds, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA; Laboratories of Analytical Biology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA; U.S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA. Electronic address: ssonsthagen@usgs.gov.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Sonsthagen
authors.affiliation: U.S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Wilson
authors.affiliation: U.S. Geological Survey, Patuxent Wildlife Research Center, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA.
authors.forename: R Terry
authors.initials: RT
authors.lastname: Chesser
authors.affiliation: UMR 7205 Institut de Systématique, Evolution, Biodiversité, CNRS, MNHN, UPMC, EPHE, Sorbonne Universités, Département Systématique et Evolution, Muséum National d'Histoire Naturelle, CP 51, 55 rue Buffon, 75231 Paris Cedex 05, France; UMS MNHN/CNRS 2700 Outils et Méthodes de la Systématique Intégrative (OMSI), Muséum National d'Histoire Naturelle, 57 rue Cuvier, F-75231 Paris Cedex 05, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Pons
authors.affiliation: CEFE UMR 5175, CNRS - Univ. Montpellier - Univ. Paul Valéry Montpellier - EPHE, 1919 route de Mende, 34293 Montpellier, Cedex 5, France.
authors.forename: Pierre-Andre
authors.initials: PA
authors.lastname: Crochet
authors.affiliation: Laboratories of Analytical Biology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Driskell
authors.affiliation: Department of Vertebrate Zoology, Division of Birds, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Dove
mesh_terms: D000483:Alleles; D000818:Animals; D005075:Biological Evolution; D046091:Charadriiformes / Q000145:classification* / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000145:classification / Q000235:genetics; D014644:Genetic Variation; D006239:Haplotypes; D006824:Hybridization, Genetic; D007438:Introns; D018895:Microsatellite Repeats / Q000235:genetics; D010751:Phosphopyruvate Hydratase / Q000235:genetics; D010802:Phylogeny; D025341:Principal Component Analysis; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial; D004247:DNA; D010751:Phosphopyruvate Hydratase
keywords: Hybridization; Laridae; Multilocus phylogeny; Speciation; White-headed gulls