title: Fine-scale genetic structure in a wild bird population: the role of limited dispersal and environmentally based selection as causal factors.
abstract: Individuals are typically not randomly distributed in space; consequently ecological and evolutionary theory depends heavily on understanding the spatial structure of populations. The central challenge of landscape genetics is therefore to link spatial heterogeneity of environments to population genetic structure. Here, we employ multivariate spatial analyses to identify environmentally induced genetic structures in a single breeding population of 1174 great tits Parus major genotyped at 4701 single-nucleotide polymorphism (SNP) loci. Despite the small spatial scale of the study relative to natal dispersal, we found multiple axes of genetic structure. We built distance-based Moran's eigenvector maps to identify axes of pure spatial variation, which we used for spatial correction of regressions between SNPs and various external traits known to be related to fitness components (avian malaria infection risk, local density of conspecifics, oak tree density, and altitude). We found clear evidence of fine-scale genetic structure, with 21, seven, and nine significant SNPs, respectively, associated with infection risk by two species of avian malaria (Plasmodium circumflexum and P. relictum) and local conspecific density. Such fine-scale genetic structure relative to dispersal capabilities suggests ecological and evolutionary mechanisms maintain within-population genetic diversity in this population with the potential to drive microevolutionary change.
authors.affiliation: Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, OX1 3PS, United Kingdom. colin.garroway@zoo.ox.ac.uk.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Garroway
authors.forename: Reinder
authors.initials: R
authors.lastname: Radersma
authors.forename: Irem
authors.initials: I
authors.lastname: Sepil
authors.forename: Anna W
authors.initials: AW
authors.lastname: Santure
authors.forename: Isabelle
authors.initials: I
authors.lastname: De Cauwer
authors.forename: Jon
authors.initials: J
authors.lastname: Slate
authors.forename: Ben C
authors.initials: BC
authors.lastname: Sheldon
mesh_terms: D025041:Animal Migration; D000818:Animals; D004777:Environment; D019143:Evolution, Molecular; D008289:Malaria, Avian / Q000453:epidemiology / Q000235:genetics; D008957:Models, Genetic; D046109:Passeriformes / Q000235:genetics* / Q000469:parasitology; D058974:Phylogeography; D010961:Plasmodium / Q000472:pathogenicity; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors; D012641:Selection, Genetic
keywords: Genome-environment association study; Moran's eigenvector maps; Parus major; SNPs; landscape genetics; plasmodium