Genetics - so easy even a caveman can do it?

[Davaroo]

I was doing a little research on the Delaware breed and came across the musings of a fellow who was part of the breed formation. After going over his comments about ten times, I’m reminded of another one of those bewildering moments I suspect everyone can relate to.

GEICO, the insurance company, has a series of commercials featuring a caveman and the slogan, "GEICO.com - so easy even a caveman can do it."
In one of these commercials the spokesman caveman and a psychiatrist are sharing a split-screen TV interview with an announcer. Do you know the ad I mean?
The commercial opens with the psychiatrist blathering some psycho-babble crap, like:

“Well, it is cleeeeearly evident that the socio-manifestations currently exhibited are symptoms of a deep neurosis within the inner cortex, leading to a general malaise and relationship discomfiture.”
The announcer then says, “Any comments?” to which the caveman replies, after a moment of pregnant silence...
“Yeah, I have a comment … WHAT?!”

Well, call ME the caveman, since that’s how I felt after reading the following about the Delware breed creation:

“In those days the popular broiler cross was Barred Plymouth Rock x New Hampshire. If the barred broiler males were inadvertently mated with New Hampshires, the progeny would be heterozygous for dominant black extension. A heterozygous male mated to a New Hampshire might be the progenitor of the silver (but barred) sports we occasionally saw. All the other sports were inferior.

Of course the sports had to be silver or we would have had a barred red. We knew nothing about the inheritance of Colombian but in hindsight, two crosses to New Hampshire might give a few homozygous Colombian (CoCo) individuals.

In hindsight he had big problems because the silver in the Colombian pattern is dominant to red. So his birds needed to be progeny tested to identify the purebreeding silvers.”

So, can anybody explain this in a way that even a caveman can understand it?

 

[tiffanyh]

If the barred broiler males were inadvertently mated with New Hampshires, the progeny would be heterozygous for dominant black extension.

Heterozygous male would be the one that carries two different alleles on a genes, or basically this offspring would carry one gene from each parent- say aa for dad with the barred gene and bb for mom--, since those parent could only give up one type of genes, their offspring would get one type of each- say ab-, making it a heterzygous with the dominant gene being the black extension. Homozygous would mean they were teh same, as the parents were. If the offspring is barred, it would mean the barring was a dominant trait.

A heterozygous male mated to a New Hampshire might be the progenitor of the silver (but barred) sports we occasionally saw. All the other sports were inferior.

This male-ab- is then mated to a pure breed, or another homozygous--say cc. Therefore, if this NH red is mated to the heterzygous offspring-ab- it can either give the "a" gene when it mates, which would produce barring or the b genes when it mates, which would not give barring, since only one gene is passed along to the offspring. THe offspring could genetically be ac or bc. There is also these funny little things that can occur in genetics which cause funny little offspring traits.

Basically the second generation didnt carry the trait they were looking for consistently due to the random allele or gene choice during procreation.

In hindsight he had big problems because the silver in the Colombian pattern is dominant to red. So his birds needed to be progeny tested to identify the purebreeding silvers

So, genetic test would have to be done so see if the desire offspring, the silve bird, is PURE-- has homozygous genes (aa) rather than a heterzygous pair (ab) with the silver coloring just ending up dominant.

Im not sure if that makes any more sense than the original!

 

[Davaroo]

I see youre from CT, so right off I reckon that makes you pretty smart (My wife is from there and it holds true for her...).

But, I gotta resond to this:

Im not sure if that makes any more sense than the original!

by saying, uhhhh......dohhhhh.....errrrrr - not really.

 

[greyfields]

If this seems hard, don't ever consider getting into duck breeding. ><

 

[tiffanyh]

It is basically getting an understanding of what the chickens genes look like inside, based on what you see and know on the outside. My husband is smart, he actually work at Yale in Genetics, I have a minor is biotech which has some genetics concentration-- I teach chem full time at a local university. I know some chemistry, but dont ask me to write a proper bibliography or use the correct plural form of a word! Ill leave that to the smart people!!!

 

[Davaroo]

All right, there, then, Tiff (that's caveman talk). How is a neanderthal like me to go about getting that understanding of what the outside means for the genetic inside?

 

[DoctorGoose]

Quote:
Okay, so terminology here: hetero=different. The chicken has two different "alleles". Homo=the same. The chicken has the same alleles. Each allele "codes" for a different "phenotypic" expression. The phenotype is what the chicken looks like. Genotype is what the chicken can breed for, what it has in its genes.

Some genes are dominant to other genes. E.g. in humans, brown eyes are dominant to blue eyes. This gene is expressed as the letter "B"--capital, because it is dominant. Recessive genes are expressed as lowercase letters so the gene for blue eyes would be "b".

An individual heterozygous for brown eyes would be expressed as "Bb" or, if you take the columbian gene, "Coco" (not sure what the recessive Columbian gene is, but they just used "Co" for the dominant Columbian gene, I'm assuming, equal to our "B")

Now, a homozygous individual, CoCo; when put on any other chicken (assuming that no other color trumps it), will result in a Columbian colored chicken. People like homozygous. It results in "pure offspring".

So, in the article, it says that red is recessive to Columbian.

Another thing that can happen is called incomplete dominance. This means that the two genes bump heads, and they they get mixed up. An example would be a roan horse--it's an incomplete mix of the bay color and (grey) I think.

Tell me if you have any questions!

 

[Davaroo]

Alright! I'll get back to you...

 

[PurpleChicken]

Uhhhhhhhhh What?

Dang u gys r smert.

 

[Davaroo]

So, lets see if I get this straight, according to caveman logic.

There are recessive and dominant genes, of which coloring is but one example. Depending on a colors genetic position in the “bridge deck of genetic cards,” it will predominate (trump) or recede (be trumped) depending on the other genes present and their respective position in the deck.
Dominant genes are labeled with a capital letter and receding ones with a lower case letter .

So, a person with a big butt possibly has a homozygous allele pairing, which we might choose to call BUBU, the BU referring to the dominant big butt genetic allele.

If that same BUBU mated with a “bu,” or small butt recessive, the offspring would have a heterozygous allele pairing, called BUbu. In this example, even though there are two different resultant butt genes, the dominance of the big butt allele assures a phenotypic big heinie.

There could be a third allelic variant, also homozygous. This one we might call, “bubu.” But, that would result in a phenogenic small butt - which, as an aisde, is not nearly as interesting as a BU dominant allele.

Finally, is it possible for a recessive gene to be in a position of dominance? For example, I don’t suppose our wide-bottomed person could have a heterozygous pairing of buBU, since that would result in the phenotypic result of a small butt.
(Given that I am right, what do you suppose Jennifer Lopez to be? How about Nicole Ritchie?)

We were talking about chickens, right?

If I am even close to being right, then it seems one needs to know how the genetic “deck” is stacked in chickens. How do you know what dominates or recedes? Where is that information?