Aussie Finch Forum

Thanks for everyone's input into this, it's greatly appreciated.
From what the current owner has told be, this is one of four birds that he bought from someone who had bought them from an Auction. Other than the birds being purchased in the same lot together, the origins of this Bengalese and the three others are unknown. However I am getting all four from him and if I get a pair out of them I will be using the mate from the same group just to stack my odds.

I still haven't had much more time to do much more research but one thing I do know is that as with other Mutations, just because it presents in one way overseas does not mean that a similar Australian mutation in Phenotype always has the same genetic inheritance.
This can go one of two ways, it can be a true Biological Mosaic that is an event of genetic mix that occurs at embryonic stage (I have limited understanding of this at the moment) and not a mutation as such (This may be similar for half-siders that also cant be bred true) or it is actually a Mutation that has traditional means of inheritance that can be explored.
I have to hope that this is something develop-able but I wont know unless i give it a go.

This a wikkipedia definition of Mosaic.
In genetics, a mosaic or mosaicism denotes the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.[1]

http://en.wikipedia.org/wiki/Mosaic_%28genetics%29

Thanks again, its a great help.

Paul

Aussie_Bengo wrote: This a wikkipedia definition of Mosaic.
In genetics, a mosaic or mosaicism denotes the presence of two or more populations of cells with different genotypes in one individual who has developed from a single fertilized egg.[1]

A mosaic canary is not an example of mosaicism in the above sense, it is just a colour variety name. While the first examples of mosaic canaries were female, males are just as common as females now the variety is established.

And Wiki, while useful, is somewhat limited in it's reliability. Glad you are getting all 4 birds from the guy. And putting them together is definately the way to begin. Then outcross the adults, while crossing the 1st generation young. Hope to read how things are going and see pics of the offspring in about 6 months time.
LML

First a small pedantic point:
Mammals have XY in males and XX in females, except for monotremes who have weird numbers of weird sex chromosomes (platypuses have ten).
Birds have ZZ in males and ZW in females.
Yes it is confusing.

Now, re: mosaic canaries, I looked into this a while ago and was left with the understanding that mosaic canaries have variable amounts of siskin features. I must admit I am still a bit confused about this, but think that dimorphic and mosaic red-factor canaries have variable expression of siskin genes in a mostly-canary bird. To my understanding, this mosaicism is not strictly and predictably heritable like the autosomal or sex-linked traits we are used to. A bit more like the half-siders than a normal mutation.
So more of a lucky dip than normal inheritance.

I welcome correction on this if anyone knows better.

So, your (beautiful) tricolour bengo may be challenging to reproduce.
Alternatively, the term "mosaic" might be applied here in reference to the pattern, rather than the genetics, in which case it may be a whole lot less complicated.

Good luck with breeding a few up to see!
And congrats on your prize-winning birds at the Manly show.

mm.

This post is going to be long and contain lots of genetics . No easy way around that to answer the original question or to clear up some misconceptions already spreading through this post. I apologise in advance to those who wish I hadn't joined in but I couldn't resist .

Firstly, as others have alluded too, there is a difference between a mosaic genetically and visually. A tortoiseshell cat is not a mosaic genetically, just visually. However, as that comparison has been made already....

A normal cat is cinnamon / brown / chocolate as the colour can be modified by a "density" gene (think sky blue / mauve / violet in budgies). Ginger is controlled by a co-dominant gene which is either ginger or not ginger and not ginger means blue which can also be changed to grey or black by the density gene. This ginger gene is sex linked.

As females in mammals are XX, in every cell one X is switched off. In the case of the tortoiseshell some cells have the non-ginger chromosome switched off, these cells will then be "blue" haired while in other cells the non-blue chromosome is switched off, these cells are therefore ginger haired.

Note there's no white yet - a true tortoiseshell is just blue and ginger. A tricolor, one with white as well, has a third set of genes at play which control in essence whether the pigment makes it into the hair at all. If the pigment isn't passed from the cells into the hair those hairs are white. This gene behaviour is universally known as pied or piebald and occurs in mammals and birds alike. This gene is usually autosomal ie not sex linked.

Note also, for a male cat to be tortoiseshell it must have what in humans is called Kleinfelter's Syndrome, ie it has the sex genotype XXY which is most likely the result of an error at egg creation when the splitting of the chromosomes goes wrong. It has one X switched off in each cell as that bit's still normal.

So, now to our bengos in question to determine if this bird is a mutation or a freak.....
- is it possible to have ginger and chocolate in the same bird?
- is the chocolate and ginger co-dominant?
- is the chocolate / ginger sex linked?

Remember, the black and ginger are variations of the same gene in cats, for the bengos to be true "tortoiseshell" this must also be the case in some way.

My understanding of bengo genetics is that there is a dominant colour - chocolate - and a recessive colour - fawn (ginger). There is a third colour - chestnut which is recessive to chocolate but dominant over fawn. All these colours are autosomal ie none are sex linked.

I can't comment on the Siskin theory in canaries but it sounds reasonable. However, based on the expectation that colour is autosomal then it is not possible for a mosaic colour to exist by switching chromosomes on and off as in the cats. Thus, the bird above must be pied, that bit's easy as pied is dominant to all colours. It must also have some cells which show the chocolate pigment and some cells which show the ginger pigment. This cannot be explained by X chromosomes switching on and off as the colour isn't on an X chromosome in the first place. It must therefore be a true mosaic in the genetic sense of the word and either contain cells from two different gametes, ie one egg fertilised by two sperm (as oppsed to one sperm fertilising two eggs) or two embryos encased in one shell that then merged - an absorbed twin if you like (the latter is the more likely). It is therefore a true random event and cannot be reproduced at will, as indicated by the European breeders.

So, where to from here to see what happens next with colour inheritance?
- sex of the bird is unimportant, as the colour inheritance is not sex linked.
- do not pair it with a pied, as pied can be dominant or recessive you don't want to be confusing that issue. No pied offspring will probably mean that it is recessive pied, if so next generation put one of the non-pied young with a recessive pied just to make sure.
- in the first pairing do not pair it with chocolate, for that's dominant over ginger nor chestnut for the same reason. After that work backwards up the dominance tree.

Have fun? What's the turnaround time for bengo generations - weeks like zebbies or years like most other finches?

Thanks again everyone, I appreciate all the good responses.

To start with I'll make a statement to help our discussion about the current standard Bengalese Colours that is a bit of a less common or known opinion, however for interest sake my view is shared by the likes of Dr Terry Martin and also the Late Mark Shipway (former QLD Bengalese Breeders Society President). As discussed, generally the inheritance hierarchy for the three common Bengalese colours is Chocolate, dominant to Chestnut, dominant to Ginger Autosomal Recessive. Now to try and help our more informed members I'll explain a bit further on my view. Bengo feather colour is made from Eumelanin (black) and Phaomelenin (Ginger) and the combination creates essentially a Brown wild type bird like many other white based Finches. I'll draw direct comparison to the Zebra finch here that uses these two pigments as well but obviously in different patterns and arrangements. A Ginger Bengalese is alike to the Isabel Zebra Finch and I'll go so far as to say that the Ginger Bengalese is an Isabel by definition where all Black Eumelanin pigment has diluted away to 0% and what is left is only the Red/Brown Phaomelanin. The Chestnut Bengalese is therefore alike to the Carabel Zebra Finch or could be called a Partial (Par) Isabel. It is not my intention to go off topic other than to further state that the Chocolate, Chestnut ad Ginger Colours are believed to be an allelic series or variations of Phaomelanin (Black) dilution. To follow this view you cannot have a Chocolate Bengalese that is split for both Chestnut and Ginger, only one or the other.
I hope that helps somewhat.
Can the Tortiseshell Cat be reproduced or is it too a random event?

One of the reasons that Bengalese Breeding can be rewarding is that you can safely breed them after 6 months however there are many cases of them breeding soon after their 3 month maturation. This then helps the pace of any project that you may have for selectively breeding these guys.

Cheers.

Aussie_Bengo wrote:Thanks again everyone, I appreciate all the good responses.
SNIP

Can the Tortiseshell Cat be reproduced or is it too a random event?

Yes easy to reproduce, on average 50% of female offspring will be torties, balance will be colour of father (ie red or black). Sons will be 50% red and 50% black.

However pattern on every animal is different due to randomized switching of X chromosomes which happens very early in the embryo development.

Love all this genetics. Really makes me concentrate. Didn't know that about the Tortoiseshell Tom. So the puss my friends had back in the late 80's was as rare as they thought.
LML

Hi all,

mattymeischke wrote: Now, re: mosaic canaries, I looked into this a while ago and was left with the understanding that mosaic canaries have variable amounts of siskin features. I must admit I am still a bit confused about this, but think that dimorphic and mosaic red-factor canaries have variable expression of siskin genes in a mostly-canary bird.

It is not variable, mosaic canaries have inherited the dimorphic pattern from the red siskin = More lipochrome on the male, less on the female.

The pattern basically restricts where lipochrome will occur on the body and it does this in two consistent patterns depending on the bird's sex.

mattymeischke wrote:Now, re: mosaic canaries,....To my understanding, this mosaicism is not strictly and predictably heritable like the autosomal or sex-linked traits we are used to. A bit more like the half-siders than a normal mutation.
So more of a lucky dip than normal inheritance.

I welcome correction on this if anyone knows better.

Mosaic canary male x Mosaic canary female = 100% Mosaic canary males and females.


Red

Hi Peoples,

This is a great thread looking back. Thanks again for everyone's input.
Sorry for the gap on the update here but I must inform you that unfortunately after he picked it up for me this bird perished under my friends care so no such luck in messing around with this one (this time).

However I did plenty of research at the time and most of the feedback I received is similar to that of members posts above in that this kind of mutation or mosaic is much like that of the half siders in birds that are completely random. I hunted around on an old Bengalese Yahoo mail list group from 2000 that the BBS had going and Tri-Colours come up in there a few times. It seems they have always popped up from time to time but were also believed to be a sport that cant be reproduced.

I looked down the path of the tortoiseshell cat possibility by firstly trying to establish if such a mutation was possible with birds since the said mutation is associated with mammals. I asked the question of a poultry forum because it seems to me that the poultry fancy has roots in developing colour mutations in birds that span many years.
http://www.the-coop.org/forums/ubbthrea ... Post110243

So it would appear that the Bengalese Tri Colour is more likely a trophy bird more than anything else. Even still I'll keep my eye out for them.

Thanks again