(the video just to prove that that budgie is real)

Probably one of the strangest color mutations I've ever seen. Not normal, I'm sure of that. Some of them have almost perfectly even halves, like the budgie I just showed, while others may have a section of their body a different color, like this one.



To this day, we still have no idea how this occurs. Some people say it's chimerism, where two non-identical twins morph into one.

What are your thoughts on this?

Ive seen something like this before...
turned out someone had messed with the photo!

That video is very cool.

Twinzy is real but it's an aberration not an inheritable mutation. It just so happens that I've written a lengthy article on the tricolor cockatiel with much discussion of halfsiders, chimeras, and genetic mosaics. It's actually more likely that he's a mosaic than a chimera, since chimerism tends to express itself differently than this. Go here to get the full scoop: http://www.littlefeatheredbuddies.com/i ... color.html

This happens with people too! I once saw a medical show about a woman who had her children taken from her because they thought she had somehow kidnapped them (obviously other issues going on here too, but I digress)... their DNA didn't lineup with hers. Turns out her ovaries and who knows what else belonged to a fraternal twin that wasn't fully absorbed or whatever. So her children's DNA matched up with their father(s), but not hers.

Honestly, sometimes real life really is stranger than fiction.

There have been at least two cases in humans like that. In one case, I think the family was tested because somebody needed a kidney transplant or something like that, and they were looking for a donor within the family. The results said that the woman was not the mother of her children, although they were related to her brother and their father was really the father. In another case, a woman (who was pregnant at the time) was in danger of being prosecuted for welfare fraud because the test results said her children were not her children - and when the new baby was born the tests said that one wasn't her child either, even though there were witnesses to the birth!! Both cases were solved when some clever person started running more DNA tests and found that different body parts gave different results, and when they tested the right parts the mothers were a match for their children.

Yes! The second case is the one I was thinking of. At some point they actually took her children from her, IIRC, due to her DNA not matching, even with the newborn. Crazy stuff.

You know, I'm wondering if some of these occurances in birds could possibly be bilateral gynadromorphism, where one chromosome gets lost, and the organism ends up having both male and female traits. It's more likely to happen with gender dimorphic birds like cardinals, chickens, or eclectus parrots, but I was thinking more on the lines of inherited sex-based mutations. Granted, I have no idea how budgie color mutations work, and I'm still trying to figure it out with cockatiels.

I have a bit of a better idea of it though.

But just to throw a crazy and unlikely situation as an example out there, let's say Shodu and Buster lay a clutch, and to the whole community's confusion and excitement, one of the babies is a half-sider, with one half being grey, and one half being cinnamon. Because Cinnamon is one of the sex-linked recessive traits, and only found visible in their female chicks, and the grey chicks are males (with the possibility of an exception, according to Carolyn Still waiting to see that actually happen), would that make the chick a gynadromorph?

Here's an example of what gynadromorphism looks like in birds. Grey cardinals are female while red ones are male.

Some halfsiders are gynandromorphs, and if Buster and Shodu threw a cinnamon-normal halfsider chick it could be one. But it could also happen with a chick who wasn't a gynandromorph. If they had a son who was split cinnamon and the normal gene was damaged on one side of the body, that could let the cinnamon "shine through" on that side since the normal gene wouldn't be there to override it. Not having a normal gene in the other chromosome to oppose it is the reason that girls are visual for sex-linked mutations with only one copy of the gene.

Theoretically B&S could have a daughter who was all girl but was halfsider normal/cinnamon. But the events that could make this happen are a lot lower probability than having a gynandromorph or a non-gynandromorph halfsider boy so I won't go into detail lol.

I get the impression that most gynandromorphy isn't caused by losing one chromosome. Rather it's caused by an abnormal cell division that makes the individual end up with too many sex chromosomes in parts of the body, for example being XXY instead of XY. In birds, males are XX and females are XY. The XY part of the body would be normal female and the XXY part would have male characteristics although it's genetically not a normal male due to that Y chromosome in the mix.

I'm not sure offhand what would happen if a hen lost the Y chromosome in part of the body so that these cells were just plain X. The Y is thought to basically be an empty "place holder" chromosome with few or no genes on it, so I'm not sure that losing it would make any difference. Without actually looking it up, I would guess that there are some genes on the X chromosome that trigger male characteristics when two copies are present but not when there's only one. So if a male lost one of his X chromosomes in part of the body it might trigger a female appearance in that area.