FAQ: goldenface budgerigar versus bl1-bl2/bl1 Agapornis fischeri

FAQ: is it possible that the “goldenface” budgerigar [Melopsittacus undulatus] is genetically identical with the bl1-bl2/bl1 Agapornis fischeri (*aqua* phenotypes) ?

That is possible. We know that there are blue 1 and blue2 in budgerigars, but they never considered the possibility of phenotypes created by crossing-over between blue1 and blue2. In order to be able to prove or disprove this theory, we need sufficient breeding reports. But the chance is real because there are phenotypically lots of similarities.


  1. Dear Dirk,
    Thank you very much for this subject very interesting and very ambitious.

    I have a question please. Since the genes blue1 and blue2 have the same position in the chromosome (bl-locus) how can we obtain a crossing-over ? There is not any distance between these two genes to allow the phenomenon of crossing-over. Or it is possible even they occupate the same locus ?

    Best regards.

    1. Hello,

      the blue (MuPKS) gene has several thousands base pairs and six exons, so there are plenty of possibilities to have crossing-overs. (in Humans genes vary in size from a few hundred DNA bases to sometimes more than 2 million bases).

      1. Thank you dear Dirk for this reply and explanations.
        Best regards.

  2. Hi there, does bl1-bl2 mean a crossover has occurred within the bl gene to leave two alleles present on one chromosome? What sort of breeding results would be needed to prove this theory?

    1. Indeed, a crossing-over between alleles is possible. We need a lot of test mating, but for a start golden mask x golden mask is already a start.

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