title: No population genetic structure in a widespread aquatic songbird from the Neotropics.
abstract: Neotropical lowland organisms often show marked population genetic structure, suggesting restricted migration among populations. However, most phylogeographic studies have focused on species inhabiting humid forest interior. Little attention has been devoted to the study of species with ecologies conducive to dispersal, such as those of more open and variable environments associated with watercourses. Using mtDNA sequences, we examined patterns of genetic variation in a widely distributed Neotropical songbird of aquatic environments, the Yellow-hooded Blackbird (Icteridae, Chrysomus icterocephalus). In contrast to many forest species, Yellow-hooded Blackbirds showed no detectable genetic structure across their range, which includes lowland populations on both sides of the Andes, much of northeastern South America, Amazonia, as well as a phenotypically distinct highland population in Colombia. A coalescent-based analysis of the species indicated that its effective population size has increased considerably, suggesting a range expansion. Our results support the hypothesis that species occurring in open habitats and tracking temporally dynamic environments should show increased dispersal propensities (hence gene flow) relative to species from closed and more stable environments. The phenotypic and behavioral variation among populations of our study species appears to have arisen recently and perhaps in the face of gene flow.
authors.affiliation: Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia. ccadena@uniandes.edu.co
authors.forename: Carlos Daniel
authors.initials: CD
authors.lastname: Cadena
authors.forename: Natalia
authors.initials: N
authors.lastname: Gutiérrez-Pinto
authors.forename: Nicolás
authors.initials: N
authors.lastname: Dávila
authors.forename: R Terry
authors.initials: RT
authors.lastname: Chesser
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D006239:Haplotypes; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D020308:Songbirds / Q000235:genetics*; D013020:South America
chemical_list: D004272:DNA, Mitochondrial