title: The role of immigration and local adaptation on fine-scale genotypic and phenotypic population divergence in a less mobile passerine.
abstract: Dispersal and local patterns of adaptation play a major role on the ecological and evolutionary trajectory of natural populations. In this study, we employ a combination of genetic (25 microsatellite markers) and field-based information (seven study years) to analyse the impact of immigration and local patterns of adaptation in two nearby (<7 km) blue tit (Cyanistes caeruleus) populations. We used genetic assignment analyses to identify immigrant individuals and found that dispersal rate is female-biased (72%). Data on lifetime reproductive success indicated that immigrant females produced fewer local recruits than their philopatric counterparts whereas immigrant males recruited more offspring than those that remained in their natal location. In spite of the considerably higher immigration rates of females, our results indicate that, in absolute terms, their demographic and genetic impact in the receiving populations is lower than that in immigrant males. Immigrants often brought novel alleles into the studied populations and a high proportion of them were transmitted to their recruits, indicating that the genetic impact of immigrants is not ephemeral. Although only a few kilometres apart, the two study populations were genetically differentiated and showed strong divergence in different phenotypic and life-history traits. An almost absent inter-population dispersal, together with the fact that both populations receive immigrants from different source populations, is probably the main cause of the observed pattern of genetic differentiation. However, phenotypic differentiation (PST) for all the studied traits greatly exceeded neutral genetic differentiation (FST), indicating that divergent natural selection is the prevailing factor determining the evolutionary trajectory of these populations. Our study highlights the importance of integrating individual- and population-based approaches to obtain a comprehensive view about the role of dispersal and natural selection on structuring the genotypic and phenotypic characteristics of natural populations.
authors.affiliation: Grupo de Investigación de la Biodiversidad Genética y Cultural, Instituto de Investigación en Recursos Cinegéticos (CSIC-UCLM-JCCM), Ciudad Real, Spain; Departamento de Ciencias Ambientales, Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla-La Mancha, Toledo, Spain.
authors.forename: V
authors.initials: V
authors.lastname: García-Navas
authors.forename: E S
authors.initials: ES
authors.lastname: Ferrer
authors.forename: J J
authors.initials: JJ
authors.lastname: Sanz
authors.forename: J
authors.initials: J
authors.lastname: Ortego
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D005075:Biological Evolution; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D005828:Genetics, Population; D005838:Genotype; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D046109:Passeriformes / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D060047:Reproductive Isolation; D012641:Selection, Genetic; D012737:Sex Factors; D013030:Spain
keywords: Cyanistes caeruleus; dispersal; gene flow; population differentiation; sex-biased dispersal