The genetic basis of variation in clutch size and onset of laying in a wild population of House Sparrows (Passer domesticus)

Understanding the basis of genetic variation is a general goal in evolutionary biology. Towards this goal, the architectures of the standing genetic variation in two life history traits, clutch size and onset of laying, were investigated in an insular house sparrow population off the coast of Northern Norway. A newly developed 200K SNP-array was used for genome-wide association mapping (GWAS) and genome partitioning. No genome-wide significant or suggestive loci were detected for either trait. Estimated heritabilities were 0.10 and 0.06 for clutch size and onset of laying, respectively. While genome partitioning was able to show that clutch size was polygenic, differences between subpopulations confounded attempts to characterize lay date. This study highlights the dangers of performing GWAS across diverging subpopulations