Chapter 4 - "The Ten Commandments of every Pedigree".
One of the things I talked about in the previous chapter was sex-linked matings. I promised to show how this information can be used to check the accuracy of a bird's pedigree. This will be our primary focus here.
times, I have been asked to review pedigrees to see if they were
you might ask.
Well primarily, to
insure it was possible for the parents
and or grandparents to produce the bird in question.
Since you, the buyer,
have paid your hard-earned money for
offspring from certain stock, you're entitled to get what you
the pedigree have obvious genetic errors then there is a high
possibility that the bird is not the product of the stock listed.
times, while conducting these pedigree checks, I have found
discrepancies that were without question, genetically incorrect.
Two blue bars producing
a red check or two non-grizzles
producing a grizzle are examples.
bring the legitimacy of the pedigree
these birds were bred in an open loft and are the product of a
non-monogamous coupling; or they are the result of some new
possibility or adulterous chance mating is very common in open
lofts while the odds for the second, a mutation, is more like
winning the lottery.
yes but highly unlikely.
the hen is the one who lays the eggs, we tend to accept her as
being legitimate while the cock may or may not be.
Well this is normally
the case but not always.
Some cocks will attract
more than one hen into their nest. The
first to lay her eggs is not always the
one to set them.
older hens will accept eggs placed in their nest as being their
she can become very possessive and may drive the true mother
If she had not
begun the process of coming down on eggs herself, she simply goes
into the brood condition and begins the incubation.
Thus she becomes a
simply cannot live in their lofts 24 hours a day so they're not
aware of everything that goes on.
youngsters produced in an open loft should
be suspect as to its true lineage.
The only way to be sure
of parentage is via breeding in
how do we go about checking to see if the seller is telling the
truth when he says that his birds were hatched in individual
they are truthful then there should be no discrepancies. I say
this on the assumption that the breeder can classify the bird's
phenotype correctly. In racing homer circles, this is one of our
flyers simply have no basic understanding of the different
phenotypes and this can cause confusion when reading their
like chocolate, slate, self, silver and mosaic all have different
meanings to different flyers.
It is best to learn the
proper terms for these phenotypes
and avoid the confusion and or embarrassment when misunderstood.
Example, the term
silver when used by US flyers to
describe a mealy is incorrect.
The majority of the
English speaking racing world
including the US Show Fancy uses the term silver to describe a
dilute blue bar.
there is a world of difference between an ash-red bar (mealy) and
a dilute blue bar (silver).
We as racing types
should learn to speak the same pigeon
language as the rest of the world.
Should you not be
familiar with the proper terms or need
to brush up on them, I suggest you start with Wendell Mitchell
Levi's two books The Pigeon and the Encyclopedia of Pigeon
Breeds. If you are the reader of the pedigree check with the
breeder to learn his understanding of the terms he used.
If you are the breeder,
avoid the use of local terms and
use the more excepted ones for clarity.
But I digress so let me
come off my soapbox and get back
to the subject at hand: Checking the validity of a pedigree.
how does all this work?
isn't enough time to go into all the details but let me hit the
high spots and give you the tools you need to conduct a check on
we will use are the rules governing dominant, co-dominant and
recessive genes both when sex-linked and non sex-linked.
We have already
discussed many of these in our previous
discussions so this shouldn't be to difficult to follow.
begin with the non sex-linked genes.
If you recall these are
the ones found on the autosome
rules here are not associated with the bird's gender.
In other words, they
apply to cocks and hens in the exact
These rules are simple
They are in essence
applying the principals of
dominance over less dominant or recessive.
With pedigree in hand,
begin by looking at all the birds
marking patterns such as bar, checker etc..
We know that every
pigeon carries two genes for pattern,
having inherited one from each parent.
possibilities are t-pattern, dark checker,
checker, light checker, bar and barless.
There is an order of
dominance associated with these.
It starts with the
t-pattern markings (also known as
t-check or velvet) as being the most dominant in the pattern
series and runs down to barless being the least dominant or most
recessive. The simplest way to remember this order of dominance
is to say that the more pattern shown the higher it is on the
when faced with the problem of two gene possibilities solves the
dilemma by always selecting the most dominant as the
Commandments of every
Rule #1: A darker pattern can
produce a lesser pattern but never the other way around.
so what happens if some other modifier such as grizzle or spread
is masking the pattern?
starters, when a bird only carries one gene for grizzle, we will
still see some pattern.
Bar for example when
present indicates it's a
bar under the grizzle effect.
Dark grizzle indicates
the presence of checker but it is
hard to distinguish which type of checker it is. Its
much easier to
break it down with a bird in the hand
than from words or general terms on a piece of paper.
you see a grizzle noted on the pedigree you should forget the
pattern and turn to the fact that grizzle is dominant over
Rule #2: A dominant modifier
can produce a lesser dominant but never the other way around.
Any dominant type gene will always be seen and on a pedigree it
should be traceable back in an un-broken chain to its origin.
However, this only works in one direction so we have rule #4.
dominant genes may not always be inherited, the chain of
inheritance may be broken in direction from the older to younger.
other words, a dominant characteristic such as grizzle must come
from another grizzle parent without any break in the lineage back
through the oldest grandparents; but should the chain of
inheritance be broken then it is gone forever and can not
is no such thing as a throw back in dominant genes.
there are times when out of the blue we have something appear
from past ancestors.
is the result of a recessive gene being expressed. Autosome
genes must reside on both sides of the
family tree to be passed along and recombined in the offspring. Sex-linked
genes operate in the same way as
autosome genes in respect to cock birds only. In
other words it still
takes two to express, however; for
a hen it only requires one recessive sex-linked gene to express
due to her hemizygous state.
autosome throw back only occurs when two autosome recessive
genes are reunited.
sex-linked throw back only occurs in hens.Â It
is the inheritance
of a recessive gene from her sire.
only applies to recessive genes. Every
must have at least one parent, one
grandparent, one great grandparent and so on which are all listed
as also being a grizzle on the pedigree. This
is in keeping with
rule # 3.
A pigeon carrying this
dominant gene will always display
it unless it is being masked by white. Should
white be listed for one of the parents
then you must look further up the pedigree to see where the
grizzle originally came from.
Should there be no
further reference to white or grizzle
then the pedigree comes into dispute. Two
birds can not produce a grizzle. However
two grizzles can very possibly produce a non-grizzle. This
is only possible
when both parents are carrying a
single gene for non-grizzle and each has passed it along to their
are dealing with the order of precedence and the possibilities of
This entire process applies to any dominant type gene and not just grizzle. Some of the more common types of dominant genes are Spread, Almond, Indigo and Dominant Opal. There are others but they are not common in racing homer stock. If you are not familiar with any of these, you can see examples of them on this web site.
Okay what about using sex-linked colors in checking the validity of a pedigree. This is only possible through the process of dominant over non-dominant as well as the sex-linked mechanism put into play by the hemizygous condition for all hens. Here the process is just a little more complicated. I guess what we should first do is review some of the material and terms covered last month.
birds, the gender or sex chromosomes are labeled Z and W. All
are classified as autosome
chromosomes just as they are in other beings. It
follows that an autosome gene
is defined as a gene found
on any autosome chromosome and a
sex-linked gene is one found on the sex or gender
you recall, the combination of these two sex chromosomes results in
the bird's gender.
cock always inherited one Z chromosome from each of his parents
resulting in a sex chromosome set or pair of two. A
hen inherits a single
W from her dam and a single
Z from her sire.
thing that is significant is that there are no know genes on the
a hen will always receive fewer genes in her genetic makeup than
will a cock.
think about it.
A blue cock must
be pure for blue or split for blue
If he had
any ash-red genes then they would be dominant and show but since
they do not we can rule them out. If
he doesn't have ash
red then he certainly can not pass
it along to his progeny.
always be pure for brown to be
you pick up on the fact that hens will always be the same pigment
color as their sire or one which is of lesser dominance than her sire? Her color
will never be greater in order of dominance than her sire,
regardless of what else is found in the her family history. Just
like the dominant
genes, there are no throw backs in
exists to be passed along or it doesn't.
lets examine this process for a cock colors inheritance.Â Since
he will receive
his color from both parents and if his
dam is a more dominant pigment color than his sire then he will
be the color of his dam.
his sire is the more dominant color of the pair then he may be that
color or less.
I said "may" and not "will". The
reason for this is due to the fact that his sire has two gene
possibilities and either can be passed along. So
in the case of a
cock, it will first be the color of
his dam if she is the more dominant of the two. Should
she be the same
as the cock then this would still
should her color be lesser in dominance then the son will be the color
of his sire or less, depending on what the sire's two gene
Just like a hen, no cock will be more dominant in color that either of his two parents. Again there are no throwbacks associated with these three pigment possibilities, ash-red, blue/black and brown. We find that on the Z chromosome, in addition to the three basic pigment colors, we also have both dominant and recessive color modifiers. These too play a part in evaluating pedigrees. We find a complete series of genes know as the Almond series which consist of Almond, Qualmond, Faded, Hickory, Sandy and Frosty which are dominant to their non-almond alternative. For cocks and hens these all operate in a fashion similar to Rules # 2 through # 5 and # 10.
Rule #9: A
hen receives all her
sex-linked color modifiers both
dominant and recessive from her sire and these will always be
expressed or displayed.
A cock on the other hand would need for both his Z chromosomes to have the same recessive gene present on both Z chromosomes for them to be expressed. His dominant genes of course would always be expressed regardless if present in a pure or impure state.
a simpler way to say all this would be; a hen will always express
her single sex linked recessive genes when present since there
would be no dominant alternative. All
genes, both the sex-linked ones of a
cock and all the autosome recessive genes, regardless of gender,
would still require both be present to be shown or expressed.
that means there is a major difference for recessive gene
expression between the sexes. Terms like homozygous,
two of the same type or being pure for that condition and heterozygous,
two which are different from
each other or non-pure for that condition would simply not apply
to a hen due to her single Z chromosome. It
sets up an
additional term for her known as hemizygous
where a pure condition
exists with only one gene being
imbalance in the number of sex chromosomes between the sexes
along with the various gene mutations that can be found there
gives us a mechanism for sex
between a youngsters produced and its opposite
say, without any doubt, that all sex-linked genes found on a hen
came from her sire even though her sire may not have shown
evidence of such genes.
take the gene for dilute as an example. This
mutant gene will
cause color intensity to be much
lesser than the intensity of a non-mutation gene normally found
at this gene locus point of the chromosome. It
changes a black to
appear gunmetal dun, an ash-red to
appear yellow and a brown to appear khaki. Since
this dilute gene
is recessive to normal color
intensity, all cocks when heterozygous (impure) cannot display
their dilute factor expression.
To do so they would
have to be homozygous or pure for the
a daughter if she were to inherit it would show its effects. There
is no second
option to override its function. She
would be pure for
the condition in her hemizygous
state. The term hemizygous can not
be applied to autosome genes, as the autosome chromosomes will
always exist in pairs while hemizygous is a single gender
lets put some of this info into practice as it relates to color
and see if it works.
pigeons there are only three pigment colors. These
associated with the Z chromosome at the b
pigment possibilities are ash-red, blue/black and brown. Blue/black
sounding like two separate colors is (in
pigeons) only one and that is black. The
blue we see is produced by the way black
pigment is distributed.
while we often refer to a blue bar as being a blue, it is in
reality, a black and not a blue.
as there is an order of dominance in autosome pattern marking
genes, there is an order of dominance between these three
the most dominant followed by blue/black and then brown. What
between the sex-linked genes is that
every cock bird will have two gene possibilities for all genes
found on the sex chromosomes including color while the hen only
The cock when
not homozygous or pure will be governed by this order of
dominance, whereas the hen will be whatever she is.
This does not
the autosome chromosome genes for
which there is no difference between the sexes.
we know a hen will receive her single Z chromosome from her sire,
we therefore also know that her pigment color was without doubt
from her sire as well.
being the case, it becomes impossible for an ash-red hen to have
a blue or brown sire; or a blue hen to have a brown sire.
A cock will
never be more dominant in color or color modifiers that either of
his two parents.
is impossible for an ash red cock to have two blue or two brown
parents or any combination of the two; or a blue cock to have two
brown cock must have a brown dam but his sire may be a blue or
ash red if these are split for brown.
In addition to the dominant Almond series of sex-linked genes we also have some recessive sex-linked genes. These are pale, dilute, reduced and rubella. Each of these will have an effect on color intensity for any of the three basic colors. Dilute for example turns an ash red into yellow, a blue into silver dun and a brown into khaki. Since these are recessive and sex-linked all cocks must be pure or homozygous to display their effect. A hen on the other hand being hemizygous or having only one Z chromosome will always be pure for these conditions and regardless if recessive or dominant these color modifiers will display their effect. Thus we have rules number seven and nine.
recap I will list these ten rules again or what I like to call
"The Ten Commandments of every Pedigree". So
to put it simply,
when checking a pedigree,
none of these ten rules may be violated. All
the birds listed
must pass muster on each and every
If any do not,
then the pedigree is in question and another look needs to be
given to learn why.
Rule #2: A dominant modifier can produce a lesser dominant but never the other way around.
Rule #3: Any dominant type gene will always be seen and on a pedigree it should be traceable back in an un-broken chain to its origin on the pedigree.
Rule #4: Since dominant genes may not always be inherited, the chain of inheritance may be broken in direction from the older to younger.
Rule #5: There is no such thing as a throw back in dominant genes.
Rule #6: An autosomal throw back only occurs when two autosome recessive genes are reunited.
Rule #7: A sex-linked throw back only occurs in hens.
Rule #8 A hen receives her color from her sire. It is impossible for an ash-red hen to have a blue or brown sire; or a blue hen to have a brown sire.
,br> Rule #9 A hen receives all her sex-linked color modifiers both dominant and recessive from her sire and these will always be expressed or displayed.
Rule #10: A cock Will never be more dominant in color or color modifier that either of his two parents. It is impossible for an ash red cock to have two blue or two brown parents or any combination of the two; or a blue cock to have two brown parents. A brown cock must have a brown dam but his sire may be a blue or ash red if these are split for brown.
Ok, that's more than enough for now.
To Chapters 3
Next Chapter - The Color Brown
Back To Start Page
Ronald R. Huntley
Web Page Designer
Duncan, SC 29334