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Fragile
combinations: The example of Frosty-Rubella Pigeons
Combinations of genetic factors often produce
interesting colors. So the combination of Frosty and Rubella. The
sex-linked color difference of Frosty in cocks and female is
increased. Frosty alone does not change the female color.
Fig. 1:
Thuringian Self, blue grounded cock-color with bleached bars and
blue bar hen-colour. Source: Pigeon Genetics
Rubella is a sex-linked recessive trait but does not
show a great difference in the color at cocks and hens in the bar
and check pattern variety.
Fig. 2:
Rubella bar and check Racing Homer. Source: Pigeon Genetics
But if Frosty meets a female rubella, then the factor
unfolds its effect. The young are not short downed. The hens appear
like overthrown with hoar-frost, thus frosty in literal sense. At
the light silver cocks the pattern, bar or checks, show through soft
reddish.
Fig. 3:
Sex-Dimorphism at Frosty-Rubella with darker hens in front and two
light silver cocks at the outer right
The result of the combination is a small
sex-dimorphic strain, which transmits the pronounced gender
differences purely. In mating with other colors, including the wild
type, this is quickly lost. Both factors are located on the sex
chromosome, but far apart. In backcrossing, therefore, one can not
assume that the two factors will reappear together in one offspring.
Fig. 4:
Sex-Dimorphism at a couple of Frosty-Rubella
Genetically interesting is not so much the resulting
color. It is shown by the example that an invisible factor in the
hen's wild-type acts as an 'Enabler' and modifies rubella-colored
hens. This gives rise to the assumption that the sexual dimorphism
originally present in some Spread rubella was also caused by
modifiers. These have probably been lost in crossbreeding with blue
and blue checks from other strains. Modifiers of a similar kind may
also have played or play a role in recessive opal colored racing
homers with the Spread factor. Also for them was written in the past
in some strains of sexual dimorphism.
Literatur:
Sell, A., Genetik der Taubenfärbungen, Achim 2015
Sell, A., Pigeon Genetics. Applied Genetics in the
Domestic Pigeon, Achim 2012
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