Sex Linkage basics
Sex linkages are often used to make identifing males and females easier at day one. The basics behind this are explained below
Thanks to Grayzie on BackYardPoultry for allowing me to use the images. (all images unless otherwise stated.)
On a thread at BackyardPoultry forums a question was asked about a crossing of a Silkie Rooster and a Silver Pencilled Wyandotte Bantam hen.
"In the incubator I have fertile eggs from a white silkie rooster and a silver pencilled wyandotte bantam hen.
Will the chickens from this cross look like the wyandotte with fluff on the legs?"
This is a great example of a gold sex linked cross, as a Silkie is actually genetically gold (s+), although their appearance (phenotype) is white. The Silver Pencilled Wyandotte is Silver based (S)
So why does the Silkie look white? The answer lies in another gene that is hiding the gold colour, in this case, the gene is recessive white(c). So the SIlkie appears white, even though it is genetically on a gold base.
So why does the Silkie look white? The answer lies in another gene that is hiding the gold colour, in this case, the gene is recessive white(c). So the SIlkie appears white, even though it is genetically on a gold base.
So on the thread we mentioned what should happen. The male chicks should get a copy of Silver from the hen, and a copy of Gold from the Rooster. The female chicks can only receive a copy of gold (they only have space for one "colour" gene in this example, the males can get both). So the male chicks should come out a lot lighter then the females, because the Silver gene tries to hide the gold colour (Dominant).
Here are the resulting gorgeous little chicks. As we can see they are identifiable as male or female on day 1. The males being lighter and the female darker.
This is happening because females can only carry one copy of certain genes and the males can carry two. (the exact chromosome is called the Z chromosome).
By knowing this, we can tell what the females and males will look like from day one, because we know the effects of the colours in this cross. Red males over silver females should always produce this effect, unless there are other genes interfereing with the colours.
By knowing this, we can tell what the females and males will look like from day one, because we know the effects of the colours in this cross. Red males over silver females should always produce this effect, unless there are other genes interfereing with the colours.
This illustration is showing the same effect below. Whenever a gold male crosses with a silver female then the resulting sex link will always show silver or light yellow males, and gold or brown females. Silver behaves dominant here and that is the reason that the males are lighter, they also have the red or gold gene, but they have the additional silver one lightening them.
(http://www.edelras.nl/chickengenetics/theory.html). Reproduced with permission.
Here we are looking at the simplest possible cross, with only gold (s+) and silver (S) genes being shown. The reality is usually more complex!
(http://www.edelras.nl/chickengenetics/theory.html). Reproduced with permission.
Here we are looking at the simplest possible cross, with only gold (s+) and silver (S) genes being shown. The reality is usually more complex!