When heterozygous with bw variegating chromosomes, In(2R)bwVDe1, In(2LR)bwV1 or T(2;3)bwVDe4, viability is increased. The bw+ cis-effect in different inversion chromosomes is ranked: In(2R)bwVDe1 > In(2R)bwVDe2 > In(2R)bwVK.
Homozygous viable. In comparison with In(2R)bwVDe2, In(2R)bwVK has noticeably decreased heterochromatization and frequent inactivation of the bw+ gene.
Unchanged from progenitor.