Statistical analysis was undertaken using S Plus v7.0 (Insightful, New York, US), R v2.8.0 and STATA v8.0 (Station College, Texas, US) Software. Genotype data were used to search for duplicates and closely related individuals amongst all samples in Phase 1. Identity by state values were calculated for each pair of individuals on 22,120 SNPs, and for any pair with allele sharing >80%, the sample generating the lowest call rate was removed from further analysis. In Phase 1, genotyped samples were excluded from further analyses for the following reasons: gender discrepancy (n = 6), duplicated (n = 0), relatedness (n = 0).
