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The discovery of
sex-linkage in pigeons: learning at the example of butterflies
In 1908, Doncaster first
experimentally demonstrated the concept of sex-linked inheritance in
animals, namely on two varieties of gooseberry moth (Abraxas
Lacticolor and Abraxas Grossulariata, 2016 Butterfly of the Year).
This moth has the WZ / ZZ sex chromosome system, so that from the
combination of a male lightened 'Lacticolor' with ZZ chromosome
features and a female darker 'Grossulariata' with WZ features, and
thus a shorter W chromosome, only female Lacticolor and male
Grossulariata are raised.
Fig. 1: Crossing of an
♂ Abraxas Lacticolor and an
♀ Abraxas Grossulariata at Doncaster 1908,
quoted as an excerpt from Crew (1927).
Pigeon fanciers will hardly
be interested in the abraxas. However, knowledge of this inheritance
mechanism may have contributed to the fact that shortly afterwards
the resolution for some previously mysterious observations in
domestic pigeons was found. So why silver chicks occasionally are
raised out of blue pairs of pigeons and that these are exclusively
females. Darwin had already dealt with this in a footnote in Chapter
V 'Pigeons' in 1868 without finding an answer. Bonhote and Smalley
showed in 1911 that it is one of the effects of this inheritance
observed in the moth. Cole 1912 broadened the view almost
simultaneously by the ratio of black to dun colored and from red to
yellow pigeons. An observation of far-reaching importance? Not just
by using an inheritance mechanism found in one species to explain
appearances in another. In the case of pigeons, the scheme proved to
be useful for explaining breeding results for hereditary factors
such as ash red, brown, stipper, rubella, reduced, lethal web-foot,
etc. For Reduced, Fig. 2 shows, in parallel to Fig. 1, an example of
the effect of gender-specificity in mating a pigeon with reduced
inheritance to a pigeon who does not carry the gene.
Fig. 2: Homozygous reduced
cock x black hen and F1, reduced-colored hens and black
cocks. Source: Sell, Genetik der Taubenfärbungen, Achim 2015.
You can quickly become
familiar with the 'mechanics' of the transmission of sex-linked
genes and the results that are important for breeding. With a little
practice and mental agility, a breeder can easily transfer the
statements from Fig. 1 and Fig. 2 to other combinations: a blue cock
will breed blue hens with an ash red hen and heterozygous (for color)
ash red cocks. In the diagram we simple replace Reduced by blue and
black by ash red. From a dilute blue (silver) cock and a blue hen
one obtains hemizygous dilute (silver) hens. The cocks are blue,
however, heterozygous for the 'dilution factor' that in homozygous
cocks and hemizygous hens is responsible for dilution of the color
to silver. A yellow cock and a red hen produce yellow hens and
heterozygous red cocks. Combinations of color, dilution, and other
gender-related factors can be built in with a little practice. Once
you understand the schema, you can apply it to the reverse mating,
to the inheritance of heterozygous cocks and to the transmission of
genes across generations. Incidentally, the fact that Reduced is
inherited in a sex-linked manner was discovered with Carl Graefe by
a genetically experienced pigeon fancier, Frosty by Andreas Leiß,
who in addition to pigeon genetics was particularly fond of city
pigeons.
http://www.taubensell.de/reduced_ein_erb factor_geht_um_die_Welt.htm
In the case of Stipper,
Faded, Frosty and other factors, there are also some special
features due to a color gender dimorphism. Homozygous cocks with
these traits differ from hemizygous hens and allow sexing by color.
An inheritance scheme, many applications and thus a potentially
important element for efficient breeding planning. Because it's not
just about explanation. You can use the knowledge for a systematic
breeding, which can be shown most easily with the help of the Punnet
square as a didactic aid (Sell 2012, 2015, 2019). The young cock on
the book cover in Fig. 3 and the couple owes their appearance to the
interaction of two sex-related recessive factors, it is pure Rubella
and also pure Frosty. If bred true a sex-linked strain similar to
Faded and Frosty, but more pronounced. Thus an introduction in
another exciting level of observation.
 
Fig. 3: Homozygous cock for
both sex-linked genes Frosty and Rubella at the cover of the book ‘Taubenzucht’,
and a homozygous frosty and homozygous rubella cock with a
hemizygous frosty and hemizygous rubella hen at the right
www.taubensell.de
Literature:
Bonhote, J.L., und F.W.
Smalley (1911), On the Colour and Colour Pattern inheritance in
pigeons, Zoölogical Societey of London, Proceedings, pp. 601-619
(quoted from Levi 1969)
Cole, L.J. (1912), A case of
sex-linked inheritance in the domestic pigeon. Science 36.
Crew, F.A.E. (1927), The
Genetics of Sexuality in Animals, Cambridge at the University Press.
Darwin, Charles (1868),
Animals and Plants Under Domestication, Chapter V Pigeons, London.
Doncaster, L. (1908), On sex
inheritance in the moth, Abraxas grossulariata. 4th Rep.
Evol. Comm., Roy. Soc. London (quoted from Crew 1927).
Levi, W.M. (1969), The
Pigeon, first edition 1941, Sumter.
Sell, Axel (2012), Pigeon
Genetics. Applied Genetics in the Domestic Pigeon, Achim.
Sell, Axel (2015), Genetik der Taubenfärbungen,
Achim.
Sell, Axel (2019), Taubenzucht, Möglichkeiten
und Grenzen züchterischer Gestaltung, Achim.
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