I'm Simple Minded, Please Explain

[sylviethecochin]

Check an online site. Edelras is great. It explains nearly every part of chicken genetics theory from the basics up.

 

[sylviethecochin]

See, I'm not getting it . . . my EE carries one blue gene? How many blue genes does one chicken have? And you are correct, the JG's don't have very dark eggs, they may be green like eggs, not olive. Thanks for responding, I am an idiot when it comes to this genetic thing!

Chickens (and humans and frogs and kittens and alligators) each have two copies of every gene.

But most genes have mutated over time, so there are some genes that are like they were originally, and other genes are different. The gold gene is the original form of the gold/silver gene. The Silver gene is a mutation of the gold gene. They're the same gene, but they're different forms or alleles of the same gene. Though they're nominally the same, they produce different colours.

Similarly, eggshells are white o But in South America, that gene mutated to form a blue eggshell O. Remember, one copy of each gene, so chickens can be (O/O) or (O/o) or (o/o)

Since Easter Eggers aren't rigorously bred for blue eggs, a lot of them aren't (O/O) So your chicken could carry one copy of o and one copy of O to make (O/o) Since O is dominant, she would still produce blue eggs.

But when she has offspring, she'll pass O to half of her chicks and o to the other half. It's completely random which gene she passes, but if the chicks don't inherit O from her, they won't lay blue eggs.


Here's the complex explanation for that:
Genes are basically codes stored on a chromosome. Every gene has a specific location on the chromosome.

Every diploid animal (pretty much every animal) has several sets of two matching chromosomes, (humans have twenty-four chromosomes, or twelve sets) One of each pair of chromosomes is inherited from the father, and one from the mother.

When sperm are produced, the father's body mixes and matches his two chromosomes. This results in two chromosomes that are a mix of information from his father and from his mother. Because each gene has a specific location, those chromosomes still carry one copy of each gene. The chromosomes are separated into separate sperm, so that each sperm carries half of the genetic information of the father.

The same thing happens with the egg.

When sperm and egg combine, (1/2 of the father's information + 1/2 of the mother's), the offspring now has two of each chromosome. Some of it's dominant, and some of it's recessive.

 

[Peppercorngal]

Which books did you find on chicken genetics?

Well, I found "Genetics of Chicken Colours" by Sigrid van Dort $110
"Genetics of the Fowl" by F. B Hutt $50
"Art & Science of Breeding" by Margaret Derry $58
"Genetics and Evolution of Domestic fowl" by Lewis Stevens $144 and finally the one I can afford:
"ABC's of Poultry Genetics" by Dr. W.F. Holander Ph.D $11
I hesitate to buy any of these books without actually seeing how they are written. They may (most likely) be way beyond my understanding and/or what I want to know. I'll look in the library first and see what I can glean.

 

[Peppercorngal]

Check an online site. Edelras is great. It explains nearly every part of chicken genetics theory from the basics up.

Thank you, I'll check it out!

 

[nicalandia]

Yes, on breeding project males take precedence to females, aside from the polygenic trait of the brown eggshell trait(a few are sex-linked) there are also brown shell mutation inhibitors(as with many genes there are inhibitors, enhancers and wild mutations that seem to do nothing for example, Mahogany Mh, cream ig and mh+, Ig+).

A research found that some lines of white eggshell layers have inhibitors of the brown gene when crossed to other white eggshell layers thatdon'tt' have such inhibitor mutations the F1 produce "Tinted/cream" eggshell. Let me try to find the paper

Sorry, I could not find the research paper that years ago I was reviewing, but here on this short description it basically says the same:

https://www.ncbi.nlm.nih.gov/pubmed/1561206

excerpt from research: "Distribution comparisons indicated that two major autosomal loci affected the trait in these lines: one gene having incomplete dominance controls the amount of pigment deposition; the second completely inhibits pigment deposition when homozygous recessive."

 

[Peppercorngal]

Sorry, I could not find the research paper that years ago I was reviewing, but here on this short description it basically says the same:

https://www.ncbi.nlm.nih.gov/pubmed/1561206

excerpt from research: "Distribution comparisons indicated that two major autosomal loci affected the trait in these lines: one gene having incomplete dominance controls the amount of pigment deposition; the second completely inhibits pigment deposition when homozygous recessive."

Thanks!

 

[MROO]

That chart is terrible for a beginner. You need punnet squares.
https://scratchcradle.wordpress.com/2012/07/08/gms2-breeding-for-blue-eggs/

Blue is a simple dominant gene. I always explain it like a pair of light switches to light bulbs. Every gene has two pairs kind of like having two light switches.

For a dominant gene if you turn a switch on, the room is lit. If you turn them both on the room is still lit and there's not much of a difference. So with blue eggs if one gene is "on" they lay blue, and if both are "on" it's maybe a little darker blue but not very noticeable.

Each parent passes on one of their genes at random. So a chicken with two switches on will ALWAYS pass one blue gene down, and a chicken with no switches on will NEVER pass one blue gene down, and a chicken with one switch on will pass it down half the time.

The blue color goes into the shell. Brown color is a different gene and is a coating. So to get green eggs you have a blue shell with a brown coating. The darker the brown the more olive colored the eggs are.

So mixing the blue with white comes out blue, mixing it with brown comes out green and mixing it with dark brown comes out olive.

This is absolutely THE BEST layman's description of Punnett Squares vs Chicken Egg Color! THANK YOU!