Wappoke
Chirping
- Dec 5, 2015
- 336
- 99
- 81
The plumage color of a chicken is determined by the genes on the chromosomes of the birds. There are two major places on the chromosomes that determine the basic color of a bird. A place on a chromosome is called a locus. There is the extension locus and the sex-linked silver locus- these two loci determine the basic color of a chicken. At the extension locus , there are different alleles that can occupy the locus. Alleles are genes that are similar in structure that can be found at the same locus. Even though the alleles are similar in structure- the disparity can cause minor differences or major differences in color. A chromosome normally carries one allele per locus and since chromosomes are normally found in pairs- to keep things simple lets say it takes two alleles to cause a trait (plumage color) to be expressed.
The wheaten plumage color pattern is a basic color pattern. The wheaten allele is one of the alleles that is found at the extension locus. Wheaten birds should carry two wheaten alleles, Over the years, researchers thought there was a dominant wheaten allele and a recessive wheaten allele at the extension locus. When the structure of each allele was examined- it was determined that both alleles were the exact same structure. The scientists decided that there is another piece of DNA that is causing one to be recessive and another to be dominant. But to keep things simple lets say marans are dominant wheaten. Dominant wheaten roosters have a basic male plumage color pattern referred to as black breasted red. The problem with males is that other alleles at the extension locus also cause males to be black-breasted red. Do an internet search and compare a male light brown leghorn and a wheaten marans rooster. In the females plumage color is where the main differences can be seen between the color plumages produced by the alleles. Go on line and compare light brown leghorn females and wheaten females.
The red in the wheaten rooster is caused by the sex-linked gold allele. Earlier, I posted that there was the sex-linked silver locus- there are two common alleles found at this locus, one is silver the other is gold. Gold is recessive to silver, The sex chromosomes in male chickens are paired but females are different and only carry one of the chromosomes that the males carries. A female wheaten will carry one gold allele ( one chromosome) at the silver locus and males will carry two gold alleles (two chromosomes) at the silver locus.
Chickens can carry wheaten at the extension locus and also carry sex-linked silver- they would be called silver wheaten.
There are other genes that act upon the Extension locus and sex-linked silver locus to cause other plumage color patterns.
Last edited:
