Aussie Finch Forum

GregH wrote: Chimeric expression of sex-linked characteristics is common in mammals and I presume some of the variegation in birds might come into this category too. Does anyone know if this has been investigated?

My understanding of a "Chimera", in placental mammals, is two fertilised eggs that fuse in the uterus to produce a single individual with two separate sets of D.N.A. It has been documented in humans where a different DNA reading can be obtained from different body fluids on the same individual. Eg. saliva and blood. I find it difficult to relate this to birds, or any egg laying animal, where the fertilized egg or zygote cannot fuse with another outside of the mothers body.
In humans the person would never know that they were a chimera unless the DNA tests were done.
A woman in the States went through a lengthy court case to prove she was the mother of her child, when DNA tests said that she was not.
Pretty weird eh!

Strictly speaking chimeras do descend from the fusion of two separate germlines where as I was thinking about the mosaic expression you get from x-chromosome inactivation and wondered if it had an analogous situation in birds. Gynandromorphic (half sider) birds are considered true chimeras according to work published by Zhao et al 2010 in Nature. If you don't have access to Nature you can read a review in AAAS site. While everyone is fascinated by bilateral and obvious gynandromorphs in sexually dimorphic species such spectacular examples of avian chimeras are probably the minority of avian chimeras.

As for the creation of chimeras in other egg-laying animals it's understandably rare but for instance it's normal in deep-sea angler fish where the male seeks out a female, grafts itself to her side and atrophies to the point where it is little more than a pair of testis. There is a picture of Siamese swallows and robins floating around on the net and there are also lots of conjoined or two headed snakes around if you Google for them. THese animals are rare not only because the condition is rare but in the wild it would be fatal which explains why we don't see them.

Dredging up an old topic but thought you guys might be interested in this little one I've just produced, https://fbcdn-sphotos-f-a.akamaihd.net/ ... 0922_n.jpg
the parents of this bird are a pied split whitefaced cock and a cinnamon pearl pied split whitefaced hen, the baby seems to have cinnamon pearled patches on both wings, whether it is a chimera or due to x inactivation I'm not sure, but that combination (cinnamon and pearl are both sex linked mutations) should not be possible from this mating. Quite a unique little bird and will e interesting to see how it develops.

I use Curtin Uni cheap if U are a club member Pete
Brian

maz wrote:Dredging up an old topic but thought you guys might be interested in this little one I've just produced, https://fbcdn-sphotos-f-a.akamaihd.net/ ... 0922_n.jpg
the parents of this bird are a pied split whitefaced cock and a cinnamon pearl pied split whitefaced hen, the baby seems to have cinnamon pearled patches on both wings, whether it is a chimera or due to x inactivation I'm not sure, but that combination (cinnamon and pearl are both sex linked mutations) should not be possible from this mating. Quite a unique little bird and will e interesting to see how it develops.

Are both sex linked recessive? If so, who's to say your cock isn't split for both? Very well could be, that would explain it appearing unexpectedly.