Aussie Finch Forum

thanks for the replies and links. Have had a quick look at all 3 and plan to have a good read of the first one. My knowledge of genetics is limited to high school biology so I get lost when it goes outside of the dominant/autosomal recessive genetic inheritance. Always so much to learn with these birds!

flap wrote:This is where I get confused. If there is a RH split to YH, say it is Rr and a YH being rr, the only combinations I can see are Rr (RH split to YH) or rr (YH). Where would the BH gene come into it?

BH is sex linked, so a RH cock can be split for YH and carry the BH gene but not show it until he breeds and then the BH gene will be passed to some of his daughters who will be BH.

Sometime I feel so inadequate... I think it will take me some time to get my head around this one. Primarily because I have a fundamental assumption that the bird can only have two colour traits, but from the above posts, they can have 3, some genetic, some sex-linked. But I still don't get it... I just don't have a scientific mind... Genetics for dummies anyone?

There is also a Reverse Genetics article in the May 2010 newsletter.

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Thanks BB will check that out, it was before i joined AFF. Though I wonder whether I will be even more bamboozled?

If you go to one part of the article it mentions the colour of the wanted bird, explains how and why this colour is inherited in an easy to understand way and tells you exactly what colour bird is required to get the coloured bird you want.

An important point in understanding Gouldian head colour genetics is that there are TWO DIFFERENT sets of genes/chromosomes involved.

One set is the sex-determining chromosomes which provide TWO genes or factors for males (RR, Rr, or rr), BUT only one gene or factor for females (R or r) - where R is the dominant red gene for head colour, and r is the recessive black gene.

A different set of chromosomes (not the sex chromosomes) provide for inheritance of yellow head. BOTH males and females can be YY, Yy, or yy - where Y is the dominant NO-yellow, and y is the recessive yellow.

The Yellow head is only expressed in birds with yy on the second set of chromosomes - NOT in split yellows (Yy) or YY.

In females with R, and yy the head is yellow. In females with r, and yy the head is black but the beak has a yellow tip.

In males with RR or Rr, and yy the head is yellow. In males with rr, and yy the head is black but the beak has a yellow tip.

OK let me see if I have got this. all the gouldians have the sex linked R gene. Unlike humans who have two sets of chromosomes, cocks ahve two sets, females only one. so RH and BH will be determined by the combinations or expression of genes.
With the YH they still have the R gene which determines sex, but the colour is inherited via the autosomal recessive gene. This will only be expressed by yy and the presence of an R gene. if r is present instead then they will be BH. Am I getting warmer?
The bit I am still not clear is YY. I understand it isn't yellow and it isn't split. is it just to represent head colour in general because R only relates to sex?

flap wrote:OK let me see if I have got this. all the gouldians have the sex linked R gene. Unlike humans who have two sets of chromosomes, cocks ahve two sets, females only one. so RH and BH will be determined by the combinations or expression of genes.
With the YH they still have the R gene which determines sex, but the colour is inherited via the autosomal recessive gene. This will only be expressed by yy and the presence of an R gene. if r is present instead then they will be BH. Am I getting warmer?
The bit I am still not clear is YY. I understand it isn't yellow and it isn't split. is it just to represent head colour in general because R only relates to sex?

Comments on last paragraph:
YY indicates that the bird (male or female) is carrying NO genes for yellow head. Yy indicates one gene for yellowhead (a split). yy indicates two genes for yellow head. Y is dominant over y. Y and y genes are NOT carried on the sex chromosomes - they are carried on a seperate set of chromosomes. From memory birds have a total of about 40 sets of chromosomes carrying all inherited attributes.

Many characters are inherited from the sex chromosomes (BUT NOT the yellow head). For example the sex chromosomes in Gouldians determine sex, red/black head, and the dominant yellowback colours.

I love genetics and have been round budgie genetics which is way complicated all my life. And I'm still trying to get Gouldian Genetics. So take it slow like I am having to do and put all these useful sites under favourites so you can check.
LML