Comb questions & genetics

[Rare Feathers Farm]

Quote:
okay, I completely glazed over at the recessive allele part...can you dumb that down for me, please?

Yea, I can tell you why a Cat 416 Shuttle Shift loader has no transmission gear clash when shifting from foward to reverse under power, but this is WAY over my head.

 

[Rare Feathers Farm]

Quote:
hmmm.....

 

[Sonoran Silkies]

A gene is a piece of DNA at a particular location on a particular chromosome.

Alleles are the various alternatives for a specific gene: blue versus not-blue; white versus not-white; silver versus gold; short legs versus not-short-legs; pea comb versus not-pea-comb; silkie feathers versus not-silkie-feathers; etc. For some genes there are only two alleles (blue versus not-blue, columbian versus not-columbian. For other genes there are more than just two alternatives: the E locus alleles are E (extended black), E^R (birchen), E^Wh (wheaten), e+ (not-extended-black, aka duckwing), e^b (brown).

Amongst the alleles for a particular gene there is an order of dominance. With the exception of the genes on the sex chromosomes, every creature has two of every gene. When both alleles for a gene are the same, that particular allele will control the associated features. When the creature has two different alleles, the dominance for that particular gene controls. Simplest explained is dominant and recessive for a gene with two alleles. Not-silkie is dominant to silkie; so, if a bird has a not-silkie allele, regardless of the other allele, the not-silkie allele controls: a bird who is HH or Hh will not have silkie feathering; only one who is hh (recessive alleles only) will be silkie feathered, because no more dominant allele for that gene is present.


Having two copies of the same allele is called homozygous, sometimes denoted "hom." Having two different allels is called heterozygous, sometimes denoted "het."

Incompletely dominant means that a bird who is heterozygous displays characteristics intermediate between homozygous for the dominant allele and homozygous for the recessive allele. The blue gene is a good example of this: hom blue, BlBl displays as splash (very diluted); het blue displays as blue (diluted); hom not-blue displays as black (undiluted).

 

[Kev]

Rose and pea comb genes combine to give a walnut comb.

AFAIK, single comb is pretty much recessive to any other comb type.

Single comb x pea= all pea (but they look kinda different)

Single comb x rose= all rose. However single comb floating around in rose is 'not uncommon' so this pairing has a relatively high potential to produce 1/2 rose 1/2 single.

In response to earlier comment- pea comb is not dominant to rose. If both are present, they 'act together' to create a walnut comb. That was an interesting result, if they truly were pea combs, then it had to be with a wyandotte not pure for rosecomb and by amazing chance all of the chicks inherited the single comb gene from the wyandotte, resulting in pea combs.

 

[Krys109uk]

The genes of the Red Jungle Fowl are said to be the norm or standard & have a little + written after their symbol.

Without trying to define every word.....

For every genetic trait (not counting sex linked traits) there is a pair of genes. The chicken (or whatever) has to have two approprate genes for that position (locus), it does not have on & it does not have three.
Both of the genes could be of the same type (homozygous) or they could be one of various alternatves (heterozygous). All the possible genes for a particular position are called 'alleles'. Genes which are not alleles cannot fit into that position on that chromosome.
So in this case P (pea comb) & p+ (not pea comb) are alleles to each other & they are the only genes which will fit into their specific locus on the chromosome.
There is another locus on a different chromosome for the alleles R (rose comb) & r+ (not rose comb).
In order for a bird to have a single comb it will have a pair of not pea comb genes (p+//p+) on one pair of chromosomes & on a different pair of chromosomes there will be a pair of not rose comb genes (r+//r+). The P alleles & the R alleles are independent of each other. But as these genes, while independent of each other both affect comb one or two P genes & one or two R genes together will cause a walnut comb.


Sorry I was writing that at the same time as someone else explaining.

 

[big medicine]

equibling,
I have a similar project of Blue Laced Gold/Red Brahmas started.

/Red