© by Wekrue WebDesign 2018

THE COLOUR INHERITANCE

OF GOULDIAN FINCHES

Why the Gouldian Finches die by the Black Spot?read more>
Read more articels about Gouldian Finches...

PART 1: HEAD/BEAK

Unique in birdlife is the fact that in Gouldian Finches displaying three completely discrete but naturally co-occurring genetically inherited phenotypes; red- (carotenoid), black- (melanin) and orange/ yellow- (carotinoid) headed Gouldian Finches. In nature, the black-headed Gouldian Finches are the most numerous (c.a. 3: 1 compared to the red-headed ones). The orange-headed on the other hand are very rare. It was reported that on 3,000 red- headed & black-headed Gouldian Finches only one yellow- (orange) headed occurs. In the captivity the numerical ratio of the head colour can be manipulated by controlling the mating. As unique as the fact of the three individual head colors is, so unique is also the behavior of the head colours to each other and the mode of inheritance.
We consider the black-headed  appeareance as the original form of the gouldian finches. This results in that any other head colour (red or yellow) is considered a mutation. The redhead factor is a naturally occurring mutation that causes a change in the structure of the head. The black eumelanin is displaced and the red (carotinoid) canthaxanthin is deposited in the head feathers. The factor that causes the formation of the black eumelanin in the head feathering is in an autosomal chromosome pair and each gouldian finch possess this factor pair. That means all black-headed, red-headed and also the orange-headed have this factor pair, which causes the formation of the black eumelanin in the head feathers. The yellow-headed appeareance is a typical Loss-of-function-mutation, because these birds are unable to produce from the of the nutrition ingested yellow carotinoids the red dyes. This fact was already reported in 1963 by O. Voelker. That's why yellow-coloured ones always show a yellow tipped beak, as this inability to form red dyes applies to the whole body.
The inheritance of the three morphs is as follows: Red head  = sex-linked dominant Black Head = sex-linked recessive Yellow (Orange) Head = autosomal                                                      recessive Extraordinary is the inheritance of the head colours because they are determined by two chromosomes. 1.The sex-linked chromosome which determined the feather structure and therewith as well the possibilities of the head colour. 2. The autosomal chromosome which determined the beak colour. If these two separate chromosomes come together, the head colour is determined. By mating is to consider that the feather structure of the black-headed is of a general type. The ornamental red-headed or orange-headed depends only from the beak colour of the black-headed. Including the beak colour, we have really to deal with 4 head colours: - Red Head - Black Head with R.T.B.                                 (=red tipped beak) - Black Head with Y.T.B.                                 (=yellow tipped beak) - Yellow (Orange) Head
Further reports about the characteristics of the individual head colours: RED-HEADED GOULDIAN FINCHES: - Red-headed males can be split (carrier) in   black-headed. - Red-headed females never can be split   (carrier) for the black-  headed. - Males can be double-factor (DF) or single-   factor (SF) red-head and always (SF as   well as DF) express the red colour. - Females can only be single-factor (SF)   and express the red colour.  - Red-headed females always only inherit   their own visible head color. - Red-headed females always show a lot of   black in their masks, even if they are not   black-headed but red-headed. - No male or female can ever be “split” for   the red-head colour.    (continue reading about the sex-linked   dominant inheritance…>) - Individual body colours affect the head   colour. The blue-gene (body) suppresses   the red and yellow colour. When the body   is of blue colour the red head occurs then   salmon pink to beige.
For further information click on the image:
BLACK-HEADED GOULDIAN FINCHES: - Males can be double-factor (DF) and   express only then the black   colour.                              - They also can be single-factor (SF). Then   they are visible a single-factor (SF) red-   head and “split” for black-head. - No female can ever be split for the black-   head colour.   - From mating a pure black-headed male   with a red-headed female we only will get   black-headed females. - Mating a red-headed male split (carrier)   for black-head with a red-head female will   get also black-headed females, among   other. - Individual body colours affect the head   colour. The yellow-gene (body)   suppresses the black colour of the head.   When the body is of yellow colour the   black head occurs then ash-grey to white. - Black-headed males can only be occurred   from two mating possibilities:       1. Black-headed  male x Black-headed           female       2. Red-headed male split (carrier) for           black-headed x black-headed female - It is claimed that the black-headed males   and also the red-headed, split (carrier) in   blackhead are the most vital and resilient.   Among other things, this concern fertility   and lifespan.
- The yellow (orange) head also requires at   least one red-head gene to be present in   order to express the yellow (orange)   colour. The yellow carotenoid lutein   epoxide can only be deposited where also   red carotinoid (canthaxanthin) is present.   Therefore a double- factor orange-headed   gouldian finch shows a pure black head.   The only thing that points to a genetic   yellow-(orange) headed gouldian finch   is a yellow tipped beak.   Easier explained: The yellow (orange)   head factor needs the red head factor   to be visible. But it is wrong to speak in   this case from "split (carrier) in a orange   (yellow) head", because this bird only   cannot express the yellow head colour   due to the lack of red gene. Both man and   woman can show this property. - Yellow-headed females always show a lot   of black in their masks, even if they are   not black-headed but yellow-headed.  - Individual body colours affect the head   colour. The blue-gene (body) suppresses   the red and yellow colour. When the body   is of blue colour the orange head occurs   then salmon pink to beige.
We have for the males 9 and for the females 6 inheritance combinations. If we multiply now the matings possibilities, we have a total of 54 possibilities to get three visible head colour.
YELLOW (ORANGE)-HEADED GOULDIAN FINCHES:
To start off the Gouldian Calculator, click on the image:
Furthermore, it has to be considered that In addition to the 3 pure inheritance  (red, black yellow), where there is no split (carrier) property, there are still 6 more split (carrier) combinations: 1. A Red Head Male and Female can be     split (carrier) for a Yellow Head. 2. A Red Head Male can be split (carrier)     for a Black Head, a Red Head Female     never can be split for a Black Head. 3. A Red Head Male can be split (carrier)     for a Black Head and  at the same time     split (carrier) for Yellow Head.     (a Red Head Female can be only split     for a Yellow Head [see 1.] ) 4. A Yellow Head Male can be split     (carrier) for a Black Head, a Yellow     Head Female never can be split for a     Black Head 5. A Black Head Male and a Black Head     Female can be genetically a Yellow     Head (not to be confused with the     split (carrier) property for a Yellow     Head. 6. A Black Head Male and a Black Head     Female can be split (carrier) for a     Yellow Head.