the influence of pigments on the plumage phenotype

[Marek]

Hi.

If somebody is interested to read the capitol about the influence of pigments (breast coloring) on the general plumage phenotype - then I invite you to my website.
Marek

http://www.gouldianfinches.eu/en/geneti ... -coloring/

P.S. If you like my post and you want to recommend it to the other, please mark on my website http://www.gouldianfinches.eu an option G+ or choose from the other offered options. Thank´s ).

[nixity]

Hmm.. a couple questions.
Top pictures DF Yellows by my screen the bird far right looks to be a LB SF Yellow, not a DF Yellow?

Also - the chart at the bottom is really confusing especially if you look at the breeding scenarios below which do not correspond.
I.e., why would you say that Purple/Lilac translates to P/w?
I find that to be confusing. I would think if you're describing three different alleles to eliminate confusion you would want to use P, L and W.

If you wanted to use white as the pure recessive in "Mendelian" form then I would think the appropriate form would be "P" for purple and "p" for white. So Pp would be Purple/White - which makes sense. So using "w" for lilac to me just is a little confusing.

I also thought it was the reduction of phaeomelanin that produced lilac breasted birds - is it truly eumelanin?

[Marek]

Greetings.

The labels for the birds in the pictures are labeled correctly, the upper 3 birds are DF yellow and lower 2 birds are SF yellow.

As far as breast color labeling goes: it is a matter, which enables the author to label the alleles as he sees fit, even though it might seem illogical. More important than labeling alleles by names they represent is their definition. The definitions are provided in the text.

Concerning breast coloring, it would seem it is a case of multiallelism, at least from a Mendelian genetics point of view. In reality we might consider several genes, which manifest in one trait in the phenotype.

I labeled the dominant allele for purple breast color as P, its recessive allele, the allele for white breast color as p. The label for lilac, w, comes from my decision, as this suited me considering the description of the entire genotype in Gouldian Finches. So P is dominant over both p and w, w is recessive to P and dominant over p. p is recessive to both P and w. I might have used an index label, such as B –breast, indexed BP, Bp and Bw… I chose the notation, which I did and it is defined in the text.
Concerning melanin in purple-breasted, white-breasted and lilac-breasted birds, especially the placement in the lower section of the feather – I think the photographs speak for themselves. If a request arises I may send the pictures in full resolution, the site crops them and the details get lost.

Best regards,
Marek Buransky

http://www.gouldianfinches.eu

[debbie276]

I'm just curious, isn't there a scientifically exceptable "notation" for bird genetics? Is it really up to the author to pick and choose what they want?

[Crystal]

I also thought it was the reduction of phaeomelanin that produced lilac breasted birds - is it truly eumelanin?

I am under the impression that Marek is attributing the reduction in the "intensity" of the lilac breast (compared to purple) to reduction in phaeomelanin primarily. (Feel free to correct me if I misinterpreted, Marek). It seems he's just trying to show that although phaeomelanin makes up the vast majority of the pigment present in the breast feather, some eumelanin is also present - albeit further down on the shaft and in such scant quantities that it likely does not significantly impact our perception of the breast's color (unless it is greatly increased/enhanced which can happen with melanistic birds for example - hence some of their breast feathers look black).

[Marek]

Hello Crystal.

White breast and lilac breast are in my opinion just a significant
trait, which points to complete loss of pheomelanin, or a sharp
decline of it in the plumage. Pheomelanin, with mutation, disappears
from the entire plumage of the bird. Therefore it is, for example in
the lutino mutation, necessary for the birds to be white or
lilac-breasted, in purple-breasted birds, meaning birds where there is
no decrease in pheomelanin levels, it is impossible to reach red eyes.
At least, as far as I know.

With lilac coloring it is a case of significant pheomelanin level
decrease, so a significant amount of blue structural color is not
created in the feathers, which would, with the characteristic color of pheomelanin, give a resulting purple breast color, therefore the
breasts are colored lilac.

The lack of pheomelanin is well observable on the head plumage of
white and purple-breasted birds, which I illustrate with pictures. It
is nicely visible in the central section of the feather, as well as the
entire plumage, where the medulla contains no pheomelanin at all. An example is the red head in white and purple-breasted, blue birds. The difference lies exactly in pheomelanin.

In time, I will take pictures, which will give additional weight to my claims.

Take care.
Marek

http://www.gouldianfinches.eu/en/geneti ... d-coloring

http://www.gouldianfinches.eu
http://www.facebook.com/Gouldianfinches.eu

[nixity]

Hi Marek,

My understanding from Winnie McAlpin (the Lutino/Albino Project breeder in the US) is that a true/pure Lutino is in fact a purple breasted bird, and the Lutino gene acts on it to change the Purple into the pale pink breast color that you see on her birds.

There are, however, WB and LB variations of Lutinos - but to my knowledge (and I could be wrong) the only birds she produces are PB and WB.

To prove this, you can look at what happens when she pairs a Lutino hen to a normal cock, and how the resultant offspring (depending on whether or not the Pastel gene has been separated out) are either PB Normal/Lutino or PB SF Pastel Green/Lutino males; or, depending, WB - but no LB were produced.

I could be misunderstanding you, in other words, perhaps what you're saying is that a Lutino will always appear either pale pink breast or white breast, and never purple due to the function of the Lutino gene on the pigments. If that's what you were saying, disregard. ;)