If  a  deletion  covers  dominant
   genes,  a  heterozygous individual may exhibit the recessive phenotype
   in  those loci due to pseudodominance, as shown by genes linked to the
   Notch locus in D. melanogaster.

   D.  melanogaster possesses polytene chromosomes in the salivary glands
   that allows visualizing the banding pattern of the deficiency loop.