At least a hundred times I’ve been asked to explain the inheritance of blue. If you don’t know the answer already, I hope you will be shocked. Blue is not inherited. Inheritance implies transmission from parent(s) to offspring by eggs and sperms. As every school child knows, the parents keep their color, at least until they molt, and even then they don’t transmit it to the squabs. Look in any egg and you’ll never see a bit of blue - - just white and yellow.
Now that we are straight on that point, somebody will of course ask, “Well then where does the squab get the blue?” Get it?? No, he doesn’t get it; he grows it. And next somebody will ask, “Isn’t there some inheritance at all?” Sure there is - - chromosomes. But chromosomes aren’t naturally blue.
Next question: “But I thought it was genes that are inherited. Aren’t they?” Hmmmm. Well, its theorized by the pundits that chromosomes are long chains of genes. However, it is so far impossible to see these hypothetical units, whereas chromosomes are visible enough.
“Then we shouldn’t talk about genes?”
Oh, did I say that? Sorry, talk all you
like about ‘em.
“O.K., I’ll talk about a blue gene.” “Talk away, but I won’t
listen.”
“You mean you don’t think there is a blue gene?”. "Blue jeans, yes; blue gene no. Not any more than a blue chromosome".
“But there must be one so the pigeon can be blue!”
“I’m blue too because you are missing my point.
You think that because you use the word gene that you are on
the verge of understanding blue pigeons. Alas, not so."
"O.K., you explain it. That's what I wanted in the first place."
"It's too complicated for me to understand."
"You're a big help." "I hope so. It was really nothing."
"Even less. All I've learned is that you think blue isn't inherited and there isn't even a gene for it."
"Exactly. But I didn't say blue has
no inherited basis. The basis is probably so complex that
the whole story would take a book to explain."
"I don't see why you make it so difficult.
don't you talk about a gene for recessive red or a gene for dilution?"
"Indeed we do. Those are units
identified by being different from blue. Blue is the
wild-type, normal standard reference. Recessive red or
dilution are departures, changes, single and identifiable.
Many other mutants are also known."
"Then blue isn't single and identifiable?"
"Correct! If you want a crude
analogy, blue is health, while recessive red is a specific disease, so
to speak."
"My red birds are just as healthy as my blues."
Well, I tried. Discussion: In my opinion, about all, we can learn from his
story “The Inheritance of Blue” is that there are a series of genes
required to produce a blue pigeon and all of them are identified as
being wild type. We can also see that Doc felt it was a complicated
subject. One that even he didn't know all the answers to and that it
would take a book to explain. I wish he had taken the time to write
that book but sadly he didn't. However, had he done so I am sure he
would have gone into more detail on exactly what the wild-type naming
system is and why it's used. Wild-type is not limited to the blue color or
the bar pattern question. It also addresses things like the number of
primary wing feathers; the number of tail feathers; the color of the
eyes; the color of the beak; the length and shape of the beak; even the
presence or absence of an oil gland. You see each of those things I
just listed are things that we can identify as being observable in our
pigeons. The overall phenotype for wild-type is defined by each one and
when they met the standard they are identified as being wild-type.
Anything that deviates from the standard is considered a mutation and
given a name. Example being such things as brown pigment, dilute,
reduced, recessive red, pearl eye etc etc.. Anything that can be
identified and compared to the standard description of the typical
species found in the wild is classified as being wild-type. Any
deviation from that standard is classified as a mutant and given a name
and assigned a symbol. It doesn't mean that every gene in a blue
pigeon must be wild-type; rather it means that every gene required to
make a pigeon blue is to be classified as being wild-type for that
phenotype standard. There are over 17,300 genes in the birds DNA and
only a set number are required to be present for the outcome to result
in a blue color. Each of them is to be classified as wild-type for
blue. All of the other genes are classified as being wild-type for
whatever their function is in meeting the overall wild-type standard so
that the bird has the correct eye color, the correct number of tail
feathers, the correct beak color, and shape etc. etc.. Think of it this way, all Goldfish are fish but
not all fish are Goldfish. In the same way, all genes required for the
blue color in pigeons are wild-type but not all of the wild-type genes
in pigeons are necessary for the color blue. If they were then there
would not be blue fantails with 30 some tail feathers and blue rollers
with only 12. There would not be blue pigeons with pearl eyes and blue
pigeons with wild-type yellow eyes. However, all of the blue pigeons
must have all of the standard genes required for that phenotype color
standard to result in the blue color and each of those genes in
question will be classified as being wild-type. Any gene that deviates
from that standard will be classified as a mutant and given both a name
and a symbol. When Doc wrote that short story we did not have
the ability to sequence each and every gene within the bird's DNA.
Today we do and there are people busy doing so right now.
by DR. Willard F. Hollander
Decembet 1965
Let me copy and past some of what Dr. Richard Cryberg wrote on the blue
question back on Feb 14th, 2012.
As we have come to understand the biochemistry involved in heredity and
life; it has simply become more obvious that naming or symbolizing a
wild-type gene based on phenotype is a fool’s errand. Today’s rule is
simple and unambiguous. Wild-type is named for the first discovered
mutant at that locus. For example, wild-type at brown is a proper name
for a particular wild-type gene in pigeons. Other examples would be
wild type at dilute, wild-type at recessive red, etc. The exception is
if the exact biochemical function of that wild-type gene becomes known
and the gene’s DNA has been sequenced. If both criteria are satisfied
it is perfectly acceptable to name it for its biochemical function. For
example, the wild-type at the albino gene is also properly named the
tyrosinase gene as tyrosinase is the enzyme that wild-type gene
produces. It is symbolized Try. Both biochemical function and DNA
sequence are absolute requirements for such a name. Absent either no
name is permitted.
Dr. Richard Cryberg, The Blue Question, Feb 14, 2012
So
now we come full circle to the original question of “How many genes
does it take to make a Wild-Type Colored, Blue Bar Pigeon?"
The correct answer is not “All of them” as claimed by some
but rather only the actual number needed to produce the blue color in a
bar pattern. To date, the exact number is not known but it certainly is
not all 17,300 genes in the birds total DNA. If it
takes all 17,300 then there are no true blue bar fantails or rollers or
homers. They would be nothing more than some form of a blue
bar mimics and not a real blue bar. I
simply do not buy into that thought process. You might but I won’t.
All Goldfish are fish but not all fish are Goldfish. All
blue bars are wild-type genes for the blue bar standard but not all
wild-type genes for the overall standard are for the blue bar.