Body size is tightly regulated in dogs homozygous for the derived alleles. (A) The standard breed weight (SBW) of each dog (y-axis) is plotted by genotype at each marker (x-axis). The SBWs of dogs homozygous for the derived allele (D/D) at the IGF1 marker are significantly smaller than dogs that are heterozygous (A/D) or homozygous for the ancestral allele (A/A), as determined by Kolmogorov-Smirnov and Mann-Whitney-Wilcoxon tests. (***) P < 0.001. The distribution of SBWs for a given genotype/marker combination is generally less for homozygous D/D dogs than for other genotypes (the median and first and third quartiles are indicated by the boxplots). Statistics for each genotype/marker combination are summarized in B. SBWs of genotype classes are reported as mean ± SD. Two females and two males were randomly selected from each breed for this analysis. The SBWs of all selected dogs are plotted in the leftmost column. Points were randomly scattered on the x-axis within each column to facilitate visualization.
