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3 PEAS BIRD FARM
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PEAFOWL GENETICS
SEX-LINKS
CAMEO, PURPLE, OATEN
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Some basics to get us started.
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Each bird carries 2 sex chromosomes which determine if that bird is a male or a female.
If it is a male it carries 2 'Z' chromosomes, and is referred to as ZZ.
If it is a female, it has 1 'Z' and 1 'W' chromosome, and is referred to as ZW.
The Z chromosomes are quite large (for a chromosome) and have room on them to carry lots of
information.
On the other hand, the W chromosome is tiny, and is only large enough to carry the information
required to make the bird a female.
These ZZ and ZW chromosomes are carried on each and every cell in the birds' body... with one
exception. The sex cells.
In the male, the sperm cells carry 1 copy of the Z chromosome.
In the female, the ova (or egg cell) carries either a Z chromosome or a W chromosome.
If the egg carries the Z, then that egg will become a male bird.
If the egg carries the W, then that egg will become a female bird.
So, as you can see, the females egg cells are pre-destined to be male or female.
When the 2 cells unite during the mating process, the male will always contribute a Z chromosome.
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Many of you who have studied genetics in high school or college may be thinking....
Hey, Valerie, this is bass ackwards!
And, you would be correct.
It's just the opposite in mammals (including humans)
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The only sex linked peafowl I am aware of are the Cameo, the Purple and any of their combinations.
By combinations, I mean cameo pied, purple pied, cameo black shoulder (which is an Oaten), etc.
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LET'S BEGIN
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As I mentioned above, W is tiny and only carries information to make the bird a female.
Z is large, and carries all the sex-link color information.
Since the female only has 1 Z chromosome, she only needs one copy for the color to be expressed.
The male has 2 Z chromosomes, so he will need 2 copies for the color to be expressed.
Male sex-linked birds are hard to get.
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Zs----Zs----purple male parent
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Zs
W
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s will refer to either sex-linked color.
Think of 's' as purple or cameo
I will call it purple.
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ZsZs---ZsZs---male chicks
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ZsW---ZsW---female chicks
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This first mating will assume that you have a pair of purple peafowl. The male is ZsZs the female is ZsW
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100% of the offspring are purple
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ZBZs---ZBZs---male chicks
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Now, let's assume you DON'T have a pair.
Female purples are much easier to come by, so let's assume you have a purple hen and an India blue cockbird.
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ZB---ZB
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Zs
W
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ZBW---ZBW---female chicks
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Males:
Genotype= 100% ZBZs hetero blue
Phenotype= 100% India blue
these males carry 1 s gene
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Females:
Genotype= 100% ZBW India blue
Phenotype= 100% India blue
these females have no s gene
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Next, we will do 2 different matings to show the possibilities.
1) We will mate these siblings together. ZBZs and ZBW
2) We will mate the original purple hen ZsW (mother) to the male offspring ZBZs
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ZB----Zs----male parent
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ZB
W
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brother sister mating (ZBZs X ZBW)
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mother son mating (ZBZs X ZsW)
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ZB----Zs----male parent
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Zs
W
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ZBZs---ZsZs---male chicks
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ZBW---ZsW---female chicks
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ZBZB---ZBZs--male chicks
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ZBW---ZsW--female chicks
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Males:
Genotype= 50% ZBZB 50% ZBZs
Phenotype= 100% India blue
50% homozygous India blue (ZBZB)
50% heterozygous India blue (ZBZs)
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Females:
Genotype= 50% ZBW 50% ZsW
Phenotype= 50% blue 50% purple
50% homozygous India blue (ZBW)
50% homozygous purple (ZsW)
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Males:
Genotype= 50% ZBZs ZsZs
Phenotype= 50% blue 50% purple
50% heterozygous blue (ZBZs)
50% homozygous purple (ZsZs)
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Females:
Genotype= 50% ZBW 50% ZsW
Phenotype= 50% blue 50% purple
50% homozygous India blue (ZBW)
50% homozygous purple (ZsW)
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In this mother son mating we have reached out goal.
We have produced both male and female purples.
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Using the information we have learned on these pages, see if you can create the following:
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OATEN: this is a cameo X black shoulder (sort of)
Female oaten= ZcWbb
Male oaten= ZcZbbc
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Purple blackshoulder (no fancy name for this one yet)
Female= ZpWbb
Male= ZpZbbp
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Cameo pied:
Female= ZcWPT
Male= ZcZcPT
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Purple Pied:
Female= ZpWPT
Male= ZpZpPT
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If you come up with ZsZsTT....or a ZsWTT then e-mail me, and I'll tell you what you've got.
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