Extensive phenotypic variation is a common feature among village chickens
found throughout much of the developing world, and in traditional chicken
breeds that have been artificially selected for traits such as plumage
variety. We present here an assessment of traditional and village chicken
populations, for fine mapping of Mendelian traits using genome-wide
single-nucleotide polymorphism (SNP) genotyping while providing
information on their genetic structure and diversity. Bayesian clustering
analysis reveals two main genetic backgrounds in traditional breeds,
Kenyan, Ethiopian and Chilean village chickens. Analysis of linkage
disequilibrium (LD) reveals useful LD (r2greater than or equal to0.3) in
both traditional and village chickens at pairwise marker distances of
~10 Kb; while haplotype block analysis indicates a median block size of
11–12 Kb. Association mapping yielded refined mapping intervals for duplex
comb (Gga 2:38.55–38.89 Mb) and rose comb (Gga 7:18.41–22.09 Mb)
phenotypes in traditional breeds. Combined mapping information from
traditional breeds and Chilean village chicken allows the oocyan phenotype
to be fine mapped to two small regions (Gga 1:67.25–67.28 Mb, Gga
1:67.28–67.32 Mb) totalling ~75 Kb. Mapping the unmapped earlobe
pigmentation phenotype supports previous findings that the trait is
sex-linked and polygenic. A critical assessment of the number of SNPs
required to map simple traits indicate that between 90 and 110K SNPs are
required for full genome-wide analysis of haplotype block
structure/ancestry, and for association mapping in both traditional and
village chickens. Our results demonstrate the importance and uniqueness of
phenotypic diversity and genetic structure of traditional chicken breeds
for fine-scale mapping of Mendelian traits in the species, with village
chicken populations providing further opportunities to enhance mapping
resolutions. dryad_genoGenotype data following genotyping on the Illumina 57k SNP chip for chicken. Data is provided in a format compatible with GenABEL for R.dryad_phenoPhenotype file for the accompanying genotype file. Present in a format compatible for use with GenABEL for R.