Signature of Selection on the Eastern Derived Cat Breeds

Modern cat breeds were established over the past 150 years by intense selection for generally aesthetic traits, which are caused mainly by single-gene variants.  Many of these traits were present random bred cat populations, pre-breed development, segregating under neutral selection or with milder positive or negative selection due to human and environmental influences.  More recent de novo mutations in cats often undergo rapid and intense positive selection to establish new breeds, which often reach fixation within the breed population.  This fixation complicates classical genome-wide case-control studies attempting to localize the trait since controls, cats without the trait, are not available in the same population.  The difference in allele frequency around the locus under selection compared to general neutral variations can be captured by commonly used measures of selective sweep, such as Tajima’s D, nucleotide diversity, and stretches of homozygosity.  In this study, three different breeds with Eastern origins (Birman, Burmese, and Siamese), an Eastern random bred population and a western origin breed, Ragdoll, which has similar phenotypes, were analyzed using data from the Illumina Infinium Feline 63K iSelect DNA array.  The natural variation in cats was estimated in the random bred population.  Signatures of selective sweep between the different breeds remapped several known coat color traits, including traits such as brachycephaly and the white glove spotting pattern.  Pre-breed development traits were not detected, suggesting the presence of several haplotypes and or contributions from multiple loci.  Moreover, the analysis revealed several chromosomal regions under strong selection, likely harboring yet undiscovered traits.

Submitter's email address: bgandolfi@ucdavis.edu