Polygenic analysis of pattern formation: Interdependence among veins in the same compartment of the Drosophila wing

Polygenic modifiers of the L4 and L5 wing veins in Drosophila simulans were used to study the degree of genetic independence of veins within the same developmental compartment. The L4 and L5 were selected for opposite changes in length. Whole-chromosome assays of heterozygous effects showed that the L4 and L5 polygenic modifiers were associated with differences both in chromosomes and in interchromosomal interactions. A comparison of selection responses confirmed that, though some modifiers had strictly vein-specific action, others acted either upon all veins within the posterior compartment or upon all veins in the wing. The results support the idea that some genes control pattern formation in the wing as a whole, others regulate structures within a single compartment, and still others are limited to a single element within a compartment.