Genome wide association analyses
To identify the potential associations of genomic regions with dispersal
probability in the Helgeland house sparrow metapopulation, a GWA
analysis on dispersal was carried out using the R package RepeatABEL
(Rönnegård et al., 2016). In the GWA model, sex was included as fixed
factor to control its effect on dispersal whereas hatch year and natal
island were used as random factors to account for these environmental
effects, and finally, the genomic relatedness matrix (GRM) was also
added as a random effect to account for the genetic population structure
and relatedness between individuals. The GWA analysis was carried out
with a logistic model where dispersal was a binary response variable
(disperser = 1; resident = 0). To reveal the SNPs that potentially may
be in linkage disequilibrium (LD) with genetic variants affecting
dispersal propensity, Bonferroni correction was applied with a
family-wise error rate (FWER) of 0.05. The genes flanking any SNP
markers associated with dispersal were determined using the annotated
house sparrow genome (Elgvin et al., 2017), and any annotation of these
genes were investigated.