I know anonymous is going to jump on me for asking this, but I want to know anyway. I know that to make black sex-link pullets you cross a red rooster on a barred hen. What will I get if I cross my Dominique rooster onto some RIR hens? What will the color pattern be. I plan to try this in the spring but I am curious now. Thanks.
One of the defining characteristics of sex-linkage is that the results of crosses are asymetric. The red male X black barred female works for sexing chicks because the female has the dominant sex-linked alleles. Your cross will not work because the male has the dominant sex-linked barring. The male also has dominant extended black so all progeny will be mostly black and barred in the Dominique male X RIR females.
Makin' us work, are ya? (I'll never get this genetic stuff!)
Do Dominiques carry Silver? Sex linked silver is a gold inhibitor so that red bars would not be created when this gene is passed.
Lori is correct.
Al Estimado Sn. Gonzales ... no quiesiera
By Rokimoto on Sunday, December 2, 2001 - 07:54 pm:
The hybrid males can be backcrossed to RIRs and you will get about 1/8 of the progeny red barred (Co- eWheWh sex-linked gold and barred) instead of black barred. Crossing the female hybrids back to RIRs will not give you any red barred progeny. I'll let you try and figure out why before I post the reason.
By HannahH on Sunday, December 2, 2001 - 11:17 pm:
By LoriON on Monday, December 3, 2001 - 09:06 am:
By Rokimoto on Monday, December 3, 2001 - 02:51 pm:
The females of the cross in question inherit dominant sex-linked silver from their Dominique dad and only the sons inherit the recessive sex-linked gold from their mothers.
The reason that sex-linked inheritance is asymetric is because there are two types of sex chromosomes. Males have two Z sex chromosomes and females have one Z and one W chromosome. The female determines the sex of the offspring in chickens. If a zygote inherits the W chromosome it is female, and if a zygote inherits the Z chromosome it is a male. The fathers can only donate a Z to all their progeny, but they have two of them. The hybrid males would be Bb and Ss (heterozygous barred and silver/gold). So they can sire silver or gold offspring in a backcross to RIR females. They can also sire barred or non barred progeny, and black and non black, so you have three genes to worry about to get red barred. Each has a 1/2 chance of being inherited from the sire (this is true even for Silver and barring even though they are linked they are far enough apart on the Z chromosome that they segregate independently), so you have a 1/2 X 1/2 X 1/2 = 1/8 chance of getting a red barred bird in the backcross to RIRs.
The hybrid females have only one Z chromosome and it is silver-barred. If you crossed these females back to RIR you could not get a red barred bird because there is no chance of recombination in the female and all the sons would inherit the silver-barred Z chromosome, and the daughters would all be gold-nonbarred. You can sex 1/2 the progeny at hatch. All the black chicks with head spots will be male and most of the chicks without head spots will be females, just like the RIR male X Barred Rock female sex-linked production cross.
Sex-linkage is exactly opposite in humans. Males are XY and females are XX, so if a husband tries to blame the sex of the baby on his wife he has some explaining to do himself. Only he can donate a Y chromosome and make the zygote a male. This sort of backfires in pattern baldness. If you are bald you got the X chromosome from your mother, so its mom's fault for your hair loss. If you want to know if you have a chance of going bald you have to look at your mother's brothers and your mothers father. If her father is bald you have a 50% chance of going bald (mom got one of her X chromosomes from him), and if her father isn't bald, but one or more of her brothers are bald you have at least a 25% chance of going bald (50% chance of your mom inheriting the X from her mother and 50% chance of inheriting the same X with the baldness gene from your mom). If you have an older brother that is already loosing his hair you now know that your mother is a carrier and you have a 50% chance of following your sibs lead.
By Anonymous on Monday, December 3, 2001 - 03:13 pm:
lanzarse sobre a nadie ... y le pido disculpa que mi
castellano esta tan malisimo. Espero solo que
me entiende ...