How does the autosexing gene work?

[danceswithronin]

Example: Say I have a Bielefelder rooster and I throw him over... a buff Orp. Will those chicks be autosexed chicks, or no?

 

[Brahma Chicken5000]

Autosexing breeds as I understand it carry the barring gene. The cock carries 1 barring gene which he gives to his daughters and the hen carries 2 barring genes and she gives one to her daughters and one to her sons. This results in male chicks hatching out lighter in color and female chicks hatching out darker in color. @The Moonshiner is the genetics guru and he can explain it better than I can.

 

[The Moonshiner]

There isn't an autosexing gene. Auto sexing is possible with the right combination of genes.
Sex link barring is 1/2 the equation.
With barring the hens only have one spot for the gene. They either have the gene and are barred or they have the non barred gene and are not barred.
They pass their gene to their sons and get it from their fathers.
Males have two spots so they can have two copies for barring, two copies for non barring or one gene for barring and one for non barring. They pass one of their genes to all offspring and receive one from each parent..
For it to work the hen has to have the barring gene and the rooster has to have two copies of it. He has to have two copies to insure that all chicks receive a barring gene.
The other 1/2 of what is needed is an e locus gene that the effects will show on. Most common is the wild type. The chipmunk striped chicks.
Both parents have to be pure for that gene.
What happens is when combined the barring gene will dilute the wild type pattern.
The females only have one copy of barring so the wild type pattern is barely diluted. But the males have two copies of barring so their wild type pattern gets a double dose of diluting resulting in the lighter pattern they have at hatch.
Wild type isn't the only pattern that works but it is the most common. Some other patterns that are Wild type with other genes can also work. Example being Isabel. Which is Wild type with lavender.

 

[Amer]

As the Moonshiner said, there isn't an autosexing gene.
There are many sex-linked genes such as barring, silver, chocolate, and dermal melanin inhibitor just to name a few.
The autosexing Bielfelder is created by putting barring on a duckwing pattern. Crele chicks are naturally autosexing, however, if you breed only the chicks that have obvious distinction between the sexes.
This is because while males carry two copies of the barring gene, females can only carry one, because the female sex chromosome is much smaller, and the barring only fits on a Z chromosome. Females only have half the Z chromosomes of a male chicken.
That makes the males much lighter in color.
Now, sexlinkage is different. Because of the chromosome difference, the hen only passes the barring to her son, and only can receive it from her father. So if you breed a barred hen to a non-barred, non-white cock, you get barred cockerels and non-barred pullets.

Now, a Bielefelder cock over a buff hen has neither autosexing nor sexlinked traits in their offspring.
This should give you all barred buff chicks.

Do the cross the other way, and you will get sexlinks.

 

[The Moonshiner]

So if you breed a barred hen to a non-barred, non-white cock, you get barred cockerels and non-barred pullets.

You can use certain white roosters for black sex links if they have the right genes. They would need to be recessive white and something underneath that when combined with the hens genes would show the head spot.
Recessive white on black produces the same as a black rooster would for example.
For red sex links you can also use white hens though many say you can. They just need to be silver based so same thing you have to know what's underneath.
Lots of RSL are made with hens that have dominate white. Dominate white doesn't have much effect on gold based colors so the pullet chicks can still express it. If you notice many are created using RIR type roosters but the pullet chicks grow to look like RIR but with white in the areas that the roosters had black. That's the dominate white gene being expressed.

 

[nicalandia]

Barring gene + wildtype will yield pretty good autosexing traits(can be bred to be enhanced in the case of Autosexing breeds) Barring gene + the Wheaten allele(the worst of the bunch) don't produce autosexing chicks that is why Delawares are not autosexing, neither Lemon Cuckoo/Buff Barred chicks.

 

[Amer]

You can use certain white roosters for black sex links if they have the right genes. They would need to be recessive white and something underneath that when combined with the hens genes would show the head spot.
Recessive white on black produces the same as a black rooster would for example.
For red sex links you can also use white hens though many say you can. They just need to be silver based so same thing you have to know what's underneath.
Lots of RSL are made with hens that have dominate white. Dominate white doesn't have much effect on gold based colors so the pullet chicks can still express it. If you notice many are created using RIR type roosters but the pullet chicks grow to look like RIR but with white in the areas that the roosters had black. That's the dominate white gene being expressed.

This is true.

Barring gene + wildtype will yield pretty good autosexing traits(can be bred to be enhanced in the case of Autosexing breeds) Barring gene + the Wheaten allele(the worst of the bunch) don't produce autosexing chicks that is why Delawares are not autosexing, neither Lemon Cuckoo/Buff Barred chicks.

You are right about that. The thing I don't understand is why red columbian (bantam Buckeyes) seem to have autosexing traits in their chicks. They are wheaten based but while the females have stripes the males have greyish backs. Theoretically. According to the breeder. I will have to test out that theory some time, since I have a multitude of these chicks.
Rhodebars are wheaten based too, right?

 

[nicalandia]

The thing I don't understand is why red columbian (bantam Buckeyes) seem to have autosexing traits in their chicks. They are wheaten based but while the females have stripes the males have greyish backs. Theoretically. According to the breeder. I will have to test out that theory some time, since I have a multitude of these chicks.
Rhodebars are wheaten based too, right?

Buckeyes are not know to be Autosexing their wheaten based chick down will not allow that, but perhaps you can do the test and let us know about it.

Rhodebars are Wildtype based

 

[Amer]

Buckeyes are not know to be Autosexing their wheaten based chick down will not allow that, but perhaps you can do the test and let us know about it.

Rhodebars are Wildtype based

Thank you. Yes. The bantams are a different color. While the adults are a soft reddish yellow color, the bantams have definitely brown and stripes on them.

 

[Amer]

Ok, so far, I've found unambiguous evidence to my theory, though it sounds like red columbian combined with the barring gene, because of the color variation autosexing genes will not work, just as you said.
Source: Genetics of the Fowl by F.B. Hutt
On page 211, it states: "Pease has developed the Buffbar, Brussbar, and Dorbar from Buff Orpingtons, Brown Sussex, and Dorkings, respectively."
Buffbars, seemingly wheaten based, would disprove your theory, however, I read durther and discovered "It was pointed out by Pease that auto-sexing Rhode Island Reds are not likely to be satisfactory as some of the other breeds to which the barring gene has been added. This is because in pure Rhode Island reds there is so much variation in down color that the distinction between BB males and B- females is not likely to be so readily discernable as in breeds with less variation in the color of the down. This was confirmed by Jaap, who found that identification of sex by the dichromatism resulting from the gene for barring was completely accurate in striped downs but less so in chicks with red or dark brown down." So it seems that the wheaten base is not what causes them to be not-auto-sexing but rather the down coloring in these birds.
But I back-tracked a little to page 196 where it described the red variety, and on 197 discovered an experiment uncannily similar to mine.
"Rhode Island Red chicks vary in color from pale buff to dark chestnut. A few are striped. Using five arbitrary classes of color, Warren differentiated in four years two strains distinctly different as down color was concerned. In the light strain, 82 percent were the lightest grade, and none had either of the two darkest grades. In the dark strain, none showed the lightest of the five grades and 49 percent qualified for the two darkest shades." This holds true for me as well. While the LF Buckeyes have a very light down color, bantam Buckeyes are a very dark color, and this has been very consistent.
"Sex Dicromatism. It was noted by Warren that the majority of the striped chicks were females...
Although identification of the striped at spotted chicks such as females is likely to be accurate in over 80 percent of such cases, these classed together formed only 27 percent of Hay's large population. Since sex cannot be identified so accurately without spots or stripes, a class that includes considerably more than half the chicks, the limitations of this method of identifying sex in newly hatched Rhode Island Red chicks is evident. Hays distinguished between black spots and brown ones and found only about 85 percent of the chicks with black spots were females, while only 74 percent of brown ones were that sex."
This could prove my theory faulty, however, I had another observation between chicks that is proven in the next paragraph.
"A much more accurate method of sexing in Rhode Island Red chicks at hatching was discovered by Homer Rowell, of Essex County, Massachusetts...
When the chicks are held so that both wings are outstretched, the difference is quite clear in all but those having down that is comparatively light in color. Wings of females are uniformly reddish. In males there is a white spot, the extent of which varies considerably in different chicks. In its smallest expression there is merely a short streak of white or creamy down in the prepatagium, or web of wing; but there is all graduations in size from that to extreme white or cream over the whole web and part of the anterior border of the metacarpal region...
With an accuracy of 90-95 percent in Rhode Island Reds and 80-90 percent in New Hampshires. Jaap found also that the accuracy of the procedure is increased in stock selected to enhance the difference between the sexes."
So now in my experiment I will use these methods in sexing and enhance them through selective breeding.