Recessive Pied Budgerigar Mutation - Genetics

Genetics

The Recessive Pied is an autosomal mutation causing recessive changes which inhibit melanin pigmentation in seemingly random areas over the body. The distribution of melanin pigment is not affected at all—in the pigmented areas the melanin patterns are exactly the same as the patterns in a Normal budgerigar. The mutation does affect the distribution of the yellow pigment, causing it to appear in some areas which are white or greyish in the Normal (see Appearance above).

There is no universally accepted genetic symbol for either the locus or mutant allele, so the simple symbol r+ for 'recessive' will be adopted here for the wild-type allele at this locus, and the symbol r for the Recessive Pied mutant allele, in keeping with the symbol used by Taylor and Warner and Martin.

In its visual effect, the Recessive Pied mutation is recessive to its wild-type allele, so a bird possessing a single Recessive Pied allele (the heterozygote, r+/ r ) is identical in appearance to the wild-type Light Green. That is, the presence of a single wild-type allele is sufficient to permit the full production and normal distribution of the black melanin pigment. Among the budgerigar fancy such a bird is said to be a Light Green split recessive pied, usually written Light Green/recessive pied.

In a bird which has two Recessive Pied alleles (the homozygote, r / r ), the lack of the wild-type allele means that normal black melanin pigment is suppressed in random areas over the body.

The factors governing the distribution of the residual pigmentation are not known.