Figure 1
Relation between a vQTL and an epistatic interaction. Panel (a) plots phenotype values in arbitrary units for a population of 500 outbred individuals stratified by genotype at a hypothetical vQTL. Panel (b) shows how the pattern in (a) could have arisen through a simple (mean-controlling) epistatic interaction with a second locus, possibly on another chromosome, that segregates two genotypes (black and gray).