a Quantile-quantile (QQ) plot of GWA p-values. QQ-plot shows only minor deviations from the null distribution, expected for the top associated SNPs. b Manhattan plot from the GWAS analysis of Beech Bark Disease in 327 individuals. Beech bark disease is associated with a locus on chromosome 5. The x-axis represents chromosomal locations and the y-axis, −log10 p-values from genotypic associations. Four markers on chromosome 5 reached genome-wide significance (p-values >1.585 × 10−5)