Inheritance of colorations in Pigeons - A Science in Itself
Forum on the 119th Lipsia on December 5, 13:00
Prof. Dr. Axel Sell
Colorations in the early literature and in pigeon standards
The
different colorations of the domestic pigeon were stressed still in
the works of early writers on ornithology like Gessner 1557.
Among the documents of Markus zum Lamm
can be found, inter alia, drawings of white, red, black and pied
marked pigeon, e.g. saddles and swallows (about 1600). The great
German pigeon book from Prütz 1885 contains first standards of
pigeon breeds and mentioning of the most common colorations of the
breed. The book from Schachtzabel (about 1910) with about 100 color
plates of the different breeds and written standards at the backside
is a first preliminary standard of pigeon breeds. Though not yet an
official standard the enumeration of colorations gets the character
of an exclusive schedule of colorations allowed in a breed. Since
then the former 'Bund Deutscher Geflügelzüchter' (BDG) and today
'Bund Deutscher Rassegeflügelzüchter e.V.' (BDRG) as the head
organization in Germany of the
four sections responsible for the different kinds of poultry
(poultry and water fowl, bantam fowl, pigeons, and finally fancy
fowl) claims the right to decide about the colorations within a
breed that are allowed to be shown at the exhibitions or not.
Fig. 1: Basic Sources on pigeon colorations
Enumerations of colorations usually
start with the most common in a breed and do not follow a genetic
order, thus demonstrating that at that time genetic research on
pigeons was just at a begin. So there are many inconsistencies and
errors that in some cases prevail up to to¬day. Still today the
enumeration of coloration does not follow a genetic logic.
Decoding of Pigeon Colorations in the 20th Century
The variety of pigeons colorations must have seemed confusing not
only for fanciers but also for scientists who at that time tried to
confirm the Mendelian laws in pigeons. Research on pigeons was
concentrated at American Universities, but there was an exchange of
expe-riences worldwide. The fundamental discoveries were made
between 1900 and 1950 and the explorations of details continues. It
was a great achievement to get the results in a mindset that could
be used for educational purpose. Thank to this is especially Prof.
W. F. Hollander from the US, but also genetically interested
breeders like Joe Quinn and many other hobby researchers. Key to the
success was the early realization that a coloration must be
consi¬dered as the result of a combination of genetic factors, which
act in a different way to the coloration and genetically are not
allelic (alternatives at a specific gene locus), but rather act
alongside and with each other.
The didactic preparation
The enumeration of colorations and just beginning with the most
common is not a proper start for an explanation of the
interdependencies. We will begin with the coloration of the blue bar
Rock Pigeons used as reference standard in genetics. At this
standard it is possible to show the effect of the numerous mutations
that took place in the process of the diversifica¬tion of
colorations up to now (Hollander 1983). The basic pigment of the
plumage is eumela¬nin (black melanin) with minor parts of
phaeomelanin (red melanin). The black bars are caused by higher
concentrations of melanin (Haase et al. 1992).
Mutations at the pattern locus
As first mutations with the loss of bars (barless) and the
appearance of checks the first two mutations at the so called
pattern locus might have happened. More mutations followed. To-day
we usually classify barless, bars (the wild-type), checks and
T-pattern checks, and more recently dark as a pattern where the
checks get so large that the entire shield appears black. The
combination of one basic color and 5 pattern results in 5 different
colorations, also sepa-rated in the show pen.
|
Blue dark |
↑ |
|
|
Blue dark check (T-pattern) |
|
|
Blue check |
|
|
Blue bar (Wild-type) |
+ |
|
|
Blue barless |
↓ |
|
|
Basic color
black |
Fig. 2: Different pattern at a black color basic
Mendelian Law
With Mendelian Laws we may easily explain the inheritance of the
different pattern. Punnett Squares are used to explain the transfer
of genes from one generation to the next as a didac-tic tool, and
they are helpful in other cases (Sell 2012, 2015).
|
parent homzygous
barless ♀ |
c |
c |
parent ♂
homozygous bars + |
+ |
c//+ |
c//+ |
+ |
c//+ |
c//+ |
Fig. 3: Punnett Square for the mating of a barless hen (c//c) and a
checker cock (+//+)
In this
example a homozygous barless is mated with a homozygous bar, and all
of their offspring are heterozygous bars (c//+) with barless (c )
being a recessive. It is important to notice that the barless trait
c is still present in the offspring and it is easy to demonstrate in
a Punnett Square as well as in the breeding pen, that in the next
generation the trait will show up in a quarter of barless young
(c//c).
Mutation at
the color locus
The
coloration of black and blue pigeons is caused by a large overweight
of black melanin compared to red. Conversely, it is in the mutation
to the red color. A second mutation lead to the appearance of brown
that is characterized by an intermediate proportion of black and red
pigments. Important for understanding it is to realize that there is
no separate pattern for the black, dominant red and brown color. The
pattern genes are identical for and in all three colors. If you have
understood this, then it will no longer surprise one in breeding
practices that a pattern can be transferred from one color to
another easily, for dominant genes often by a single cross.
The colors
black, ash red and brown usually are named basic colors. The reasons
behind might become obvious from the next figure. Black, ash red and
brown are the basis of 5 blue/black colorations in different
pattern, 5 ash red colorations, and finally 5 brown colorations.
Adding a further mutation, dilution, black, ash red and brown become
the basis of all together 30 colorations in the non-dilute and
dilute kind. Thus the term 'basic color' is derived from the
history of the fancy. It is a didactic term to cover the three main
groups of colorations in the domestic pigeon.
The
emphasis of the basic colors and
classification into these three groups is also
justified by the fact that the basic colors inter se are inherited
sex-linked in a stable way. It is also justified by the fact that
every pigeon genetically has a color code even if it is invisible as
is the case of white pigeons.
The inheritance of colors can be demonstrated in a similar way as
was shown for pattern by a Punnett Square, however adjusted for a
sex linked inheritance.
Blue dark (black
velvet) |
Ash red dark (ash red velvet) |
Brown dark (brown velvet) |
Blue T-patten |
Ash red T-check |
Brown T-check |
Blue check |
Ash red check |
Brown check |
Blue bar |
Ash red bar |
Brown bar |
Blue barless |
Ash red barless |
Brown barless |
Basic color
black |
Basic color ash red |
Basic color brown |
Fig. 4: Combinatorial effect at 3 basic colors and 5 pattern ( 3 x
5 = 15 colorations)
All the
colorations enumerated can be mated with each other without any
danger of intermingling of genes. If we mate e.g. homozygous ash
red bar with blue check hens all young will be ash red checks. In
the next generation we will get from couples of red checks some blue
bar and blue check hens where the dominant red is lost despite their
red parents. Mated with blue bars and checks they will not produce
any dominant red. Using Punnett squares for the explanation we need
one square to follow the inheritance of pattern and a second one for
the sex-linked inheritance of color. Finally we have to combine both
squares (for the transfer on many other cases see Sell 2007, 2012,
2015).
Mutation
Dilution
Dilution
was an early mutation that leads to a reduction of melanin in all
colorations discussed up to now (Haase et al. 1994). Thus one
mutation leads to a doubling of the colorations.
Blue dark (black
velvet) |
Blue dark dilute |
Ash red dark (ash red velvet) |
Ash yellow dark (ash yellow velvet) |
Brown dark (brown velvet) |
Khaki dark (khaki verlvet) |
Blue T-patten |
Blue T-pattern dilute |
Ash red T-check |
Ash yellow T-check |
Brown T-check |
Khaki dark check |
Blue check |
Blue check dilute |
Ash red check |
Ash yellow check |
Brown check |
Khaki check |
Blue bar |
Blue bar dilute |
Ash red bar |
Ash yellow bar |
Brown bar |
Khaki bar |
Blue barless |
Blue barless dilute |
Ash red barless |
Ash yellow barless |
Brown barless |
Khaki barless |
Basic color
black |
Basic color ash red |
Basic color brown |
Fig. 5: Combinatorial effect for 3 basic colors, 5 pattern und
dilute and non-dilute (3 x 5 x 2 =30)
Extension of the 'house of pigeon colorations' in height and width
If you want to extend the concept to the bronze colors typical for
many Modena and Modeneser (see the cover at the right in Fig. 1),
then you will not experience any duplication, but an extension to 56
colors only. For the ash red color the bronzing cannot clearly show,
and at the barless patten the bronze also cannot show up. We get
therefore only 26 additional colorations. If we now separate Gazzi
(pied marking shown at the cover in Fig. 1 at the right) and
Schietti (Non-Pied), then we arrive at 112 colors for Modeneser.
Also an extension upwards is easy to install in the chart. The color
spreading factor covers the patterns. The group of blue/blacks (blue
barless, etc.) becomes solid black, or solid dun in the dilutes. The
group of ash reds becomes monochromatic ashen, and the dilutes
monochrome cream. The group of brown is uniformly brown, and the
dilutes monochrome khaki. The model is 'off and tillable' as a wall
unit.
You can still 'put one on it', by involving the recessive red. This
factor covers in homozygous state the basic colors and patterns and
also the color spreading factor. The non-dilutes recessive reds are
brown-red, and the dilutes yellow. Finally we can add 'recessive
white' that is epistatic in respect to all other traits discussed
and cover over all.
Recessive white |
|
Rec. red |
Rec . yellow |
Rec. red |
Rec. yellow |
Rec. red |
Rec. yellow |
|
|
|
|
|
|
Black |
Dun |
Spread Ash |
Creme |
Brown |
Khaki |
|
|
|
|
|
|
Blue dark (black
velvet) |
Blue dark dilute |
Ash red dark (ash red velvet) |
Ash yellow dark (ash yellow velvet) |
Brown dark (brown velvet) |
Khaki dark (khaki verlvet) |
Blue T-patten |
Blue T-pattern dilute |
Ash red T-check |
Ash yellow T-check |
Brown T-check |
Khaki dark check |
Blue check |
Blue check dilute |
Ash red check |
Ash yellow check |
Brown check |
Khaki check |
Blue bar |
Blue bar dilute |
Ash red bar |
Ash yellow bar |
Brown bar |
Khaki bar |
Blue barless |
Blue barless dilute |
Ash red barless |
Ash yellow barless |
Brown barless |
Khaki barless |
Blue dark (black
velvet) |
Blue dark dilute |
Ash red dark (ash red velvet) |
Ash yellow dark (ash yellow velvet) |
Brown dark (brown velvet) |
Khaki dark (khaki verlvet) |
Basic color
black |
Basic color ash red |
Basic color brown |
Fig. 6: Combinatorial effect at 3 basic colors, 5 patterns, Dilute
and non-dilute, Spread, recessive red and recessive white (3 x 5 x 2
= 30 pattern colorations and 9 epistatic ones in addition)
We know for
all listed coloration the genetic traits involved. Those are 2 basic
colors besides the wild-type, 4 pattern besides the wild-type,
dilute and non-dilute, recessive red and non-recessive red and
finally recessive white and the wild-type at the recessive white
locus. All colorations can be mated together by known rules. The
true colorations will be back after such crosses in the first or at
least in the following generations. The experienced fancier will
recognize heterozygosity at small indicators like ink spots for
blue/ash-red cocks.
Molecular
genetic findings
It is
impressive to see how many research institutions and young
scientists today are interested in the research of the domestic
pigeon and perform molecular genetic investigations. A recent study
that was repeated in several science related magazines was published
online in Current Biology by a team that involved researchers from
the University of Utah, the University of Texas at Arlington, the
University of Cincinnati College of Medicine (Ohio) and the Oregon
Health & Science University in Portland.
The title
aptly describes the basic message: Epistatic and Combinatorial
Effects of Pigmentary Gene Mutations in the Domestic Pigeon.
Recessive red in homozygous state covers the basic colors dominant
red (BA), black color (+) and brown (b). Recessive red thus acts
epistatic (D in Fig. 7). Finally the dilution factor in combination
with the three basic colors and recessive red produces an additional
set of 4 dilute colors (E, F, G and H in Fig. 7).
Fig. 7: Combinatorial Effect for the three basic colors, recessive
red and dilution (Domyan et al. (2014).
Lessons for the practice of licensing?
That the great number of colorations in the domestic pigeon is the
result of the combination of relatively few mutations has long been
known. Fig. 7 is a detail from the color spectrum of Fig. 6 and a
confirmation of the well-known from classical experimental genetics.
We know about the epistatic effect of color spreading factor
'Spread', of the recessive red and the recessive white and that
they can hide different colorations. We know how the patterns are
among themselves inherited, as the basic colors relate to each
other, as diluted and non-diluted are inherited, recessive red and
recessive white.
On this basis you can consider all colorations as 'intermediate'
colorations that can be systematic bred of existing colors again
if one of them should be missing. The only requirement is that the
relevant traits of the specific color code are present in the race.
Anyone who has a little concerned with the genetic basis of pigeons
coloring should know that you get the dun coloration e.g. in the
first generation when mating a dilute blue cock and a black hen.
Rezessiv Gelb x
Schwarz = Dun
Why these still need a license by the recognition process for 'new
colorations' as at this exhibitions the Chinese Owls in the 'new
varieties class', is inexplicable. Stargard Shaker e.g. are not a
standard color and to become one they would have to go also through
a complicated and costly 'licensing procedure'. Though every
experienced fancier knows and everybody else could know that some
dun are produced by mating the standard colorations yellow cock and
black hen in the first round.
It is occupational therapy for the staff involved in recognition
committees and on top of that costs or a 'taxation' for the
fanciers. In the business world, one would speak of an abuse of a
monopoly situation. Maybe it's time after molecular genetic
investigations confirmed the combinatorial effects for recognition
of the 'intermediate' colors of traits present in a breed as a
general rule.
Inheritance
of pigeon coloration - A science in itself?
From the perspective of a layman the breeding of pigeons of
different colorations appears like an unpredictable endeavor.
However, the genetics of pigeons colorations is based on facts that
can be checked by everyone. From classical investigations the
genetic codes of the most important colorations are well known, and
the basics of these findings now are confirmed by molecular genetic
investigation. The knowledge about the genetic basis enables the
fancier to mate the different colorations of a breed in a reasonable
way. That is 'applied genetics' in pigeon breeding, and has
parallels in other animal species. That does not exclude that there
are still many questions that have to be answered yet. Pigeon
genetics is not at an end and fanciers can help to analyze some of
the mysteries.
Literature
Domyan et
al. (2014), Epistatic and Combinatorial Effects of Pigmentary Gene
Mutations in the Domestic Pigeon, Current Biology, http://dx.doi.org/10.1016/j.cub.
2014.01.020.
Haase, E.,
S. Ito, A. Sell and K. Wakamatsu (1992), Melanin Concentrations in
Feathers from Wild and Domestic Pigeons. Journal of Heredity, Vol.
83 (1), pp. 64-67.
Hollander,
W.F. (1983), Origins and Excursions in Pigeon Genetic, Burrton ,
Kansas 1983.
Quinn, J.
W. (1971), The Pigeon Breeder's Notebook. An introduction to pigeon
science, Atwater, Ohio.
Sell, Axel und Jana (2005), Taubenfärbungen.
Colorations
in the Domestic Pigeon, Oertel & Spörer, Reutlingen.
Sell, Axel und Jana (2007), Vererbung bei Tauben. Oertel & Spörer,
2. Auflage, Reutlingen.
Sell, Axel (2015), Genetik der Taubenfärbungen, Achim 2015.
Sell, Axel
(2012), Pigeon Genetics, Achim.
35 years
'Applied Pigeon Genetics'
Axel Sell, Vererbung bei
Tauben (Inheritance in Pigeons), Traventhal 1980
Homepage www.taubensell.de
e-mail: axel.sell@web.de
Prof.
Dr. Axel Sell
Potsdamer Str. 23
D
28832 Achim bei Bremen
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