title: Genetic, morphological, and acoustic evidence reveals lack of diversification in the colonization process in an island bird.
abstract: Songbirds with recently (i.e., early Holocene) founded populations are suitable models for studying incipient differentiation in oceanic islands. On such systems each colonization event represents a different evolutionary episode that can be studied by addressing sets of diverging phenotypic and genetic traits. We investigate the process of early differentiation in the spectacled warbler (Sylvia conspicillata) in 14 populations separated by sea barriers from three Atlantic archipelagos and from continental regions spanning from tropical to temperate latitudes. Our approach involved the study of sexual acoustic signals, morphology, and genetic data. Mitochondrial DNA did not provide clear population structure. However, microsatellites analyses consistently identified two genetic groups, albeit without correspondence to subspecies classification and little correspondence to geography. Coalescent analyses showed significant evidence for gene flow between the two genetic groups. Discriminant analyses could not correctly assign morphological or acoustic traits to source populations. Therefore, although theory predicting that in isolated populations genetic, morphological, or acoustic traits can lead to radiation, we have strikingly failed to document differentiation on these attributes in a resident passerine throughout three oceanic archipelagos.
authors.affiliation: Research Unit of Biodiversity (UO-CSIC-PA), Oviedo University, Campus of Mieres, Research Building, 5th Floor, C/Gonzalo Gutiérrez Quirós, s/n, 33600 Mieres, Asturias, Spain; Island Ecology and Evolution Research Group, IPNA, CSIC, 38206 La Laguna, Tenerife, Canary Islands, Spain. illerajuan@uniovi.es, jcillera@gmail.com.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Illera
authors.forename: Ana M
authors.initials: AM
authors.lastname: Palmero
authors.forename: Paola
authors.initials: P
authors.lastname: Laiolo
authors.forename: Felipe
authors.initials: F
authors.lastname: Rodríguez
authors.forename: Ángel C
authors.initials: ÁC
authors.lastname: Moreno
authors.forename: Miguel
authors.initials: M
authors.lastname: Navascués
mesh_terms: D000818:Animals; D005075:Biological Evolution; D055726:Cabo Verde; D004272:DNA, Mitochondrial / Q000235:genetics; D051456:Gene Flow; D005828:Genetics, Population; D062312:Islands; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D011174:Portugal; D017422:Sequence Analysis, DNA; D020308:Songbirds / Q000033:anatomy & histology / Q000235:genetics*; D013030:Spain; D014828:Vocalization, Animal
chemical_list: D004272:DNA, Mitochondrial
keywords: Avian evolution; Macaronesia; gene flow; lack of diversification; oceanic islands