genetics/description question about Andalusian blue

[AinaWGSD]

Ok, so I have a pretty firm understanding on the basics of how andalusian blue works. One copy of the blue gene dilutes black to blue, two copies dilutes black to splash. I also know that the degree of dilution can vary greatly resulting in a wide range of blue from very pale grey to so dark as to appear black at a glance. However, something that I keep seeing again and again in reference to the ideal is that the standard calls for an "even slate blue" with the edges clearly and crisply "laced in black."

What I am having a hard time understanding is how it is possible for the edges of the feather to be laced in black when the blue gene dilutes black pigment. It is my understanding that the dilution gene dilutes all of the black pigment to blue (at least that's how it works in mammals), which would make it physically impossible for the edges of the feathers to be black.

Am I missing something about how this dilution gene works in poultry? Or is it just that the standard was written before there was a good understanding of the genetics (I understand the andalusian was imported to the US in the 1850's when very little about the nitty gritty details of genetics was understood and breeders relied instead on observations of what happened when they bred bird x to bird y)? Is the lacing on a good andalusian truly black? Or is it just such a dark blue that it appears visually to be black?

 

[nicalandia]

Ok, so I have a pretty firm understanding on the basics of how andalusian blue works. One copy of the blue gene dilutes black to blue, two copies dilutes black to splash. I also know that the degree of dilution can vary greatly resulting in a wide range of blue from very pale grey to so dark as to appear black at a glance. However, something that I keep seeing again and again in reference to the ideal is that the standard calls for an "even slate blue" with the edges clearly and crisply "laced in black."

What I am having a hard time understanding is how it is possible for the edges of the feather to be laced in black when the blue gene dilutes black pigment. It is my understanding that the dilution gene dilutes all of the black pigment to blue (at least that's how it works in mammals), which would make it physically impossible for the edges of the feathers to be black.

Am I missing something about how this dilution gene works in poultry? Or is it just that the standard was written before there was a good understanding of the genetics (I understand the andalusian was imported to the US in the 1850's when very little about the nitty gritty details of genetics was understood and breeders relied instead on observations of what happened when they bred bird x to bird y)? Is the lacing on a good andalusian truly black? Or is it just such a dark blue that it appears visually to be black?

Blue(Bl/bl) cant dilute Melanotic and Pg(lacing gene) on an Extended Black(E/E) background, leaving a bird with a blue background and black pyle sones(hackle and saddle) and black lacing on the rest of the body.. with this in mind some are working to have a Chocolate Laced Blue Andalusians(by adding heterozygous Dun I^D to the andalusian genetic background, Blue will mix with dun and create a lighter blue form but leave the pyle sones and lacing to be diluted by Dun to a dark chocolate color)

 

[nicalandia]

further reading on the genetic make up of Andalusian blues...

http://www.ncbi.nlm.nih.gov/pubmed/2017404

 

[nicalandia]

info on the genotype of andalusians(scans of Crawford´s Breeding and Genetics book)





seems like Co is also on the genetic make up, making them E/E Co/Co Pg/Pg Ml/Ml Bl/bl+

 

[AinaWGSD]

Thank you so much! Now it makes more sense. Like I said, my basic color genetic knowledge comes from mammals and in mammals the dilution gene responsible for blue dilutes all black pigment. Knowing that the pattern genes are not affected the same way as the background color helps the description make more sense to me.

 

[nicalandia]

Thank you so much! Now it makes more sense. Like I said, my basic color genetic knowledge comes from mammals and in mammals the dilution gene responsible for blue dilutes all black pigment. Knowing that the pattern genes are not affected the same way as the background color helps the description make more sense to me.

this is only true for Extended Black(E/E)