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 Post subject: Gallus giganteus
PostPosted: Wed May 01, 2013 12:39 am 
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Showy Hen
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Hi George,

george wrote:
The fact that the two traits, when combined in the one individual, produce such a neat, functional comb is convincing and sits very well with the Gallus giganteus hypothesis (i.e. more or less flightless, knob-combed, hard-feathered, extinct wild ancestor of the Malay/Oriental).


The two traits arise from two separate genes on two different chromosomes, they are not related to each other. Whether either trait originated from wild, domesticated Oriental or European fowl is another matter.

Current scientific opinion does not seem to support the Gallus giganteus theory and I have to say I am not convinced this species existed.

Cheers

Oak


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PostPosted: Wed May 01, 2013 12:05 pm 
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The position of a gene on a chromosome has little to do with how they interact phenotypically, which is what I am concerned with here, not whether the two are linked. And again, little to do with the origins of each.

The truth is that the ultimate origins of either gene will probably never be proven. Likewise, it is very difficult to identify an extinct wild ancestor for a hybrid domestic animal, hence no scientific evidence thus far for or against G. giganteus, although there have been no rigorous test for the hypothesis. All the major gamefowl authorities which treat both Bankiva and Oriental type fowl consider that they have distinctly different ancestors. Like you, I am not convinced the species existed, as there is no conclusive evidence, but I think it is a very plausible hypothesis.

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PostPosted: Wed May 01, 2013 7:54 pm 
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Hi George,

I think we both agree that walnut comb cannot really be taken as evidence for the origin of either comb type.

george wrote:
The truth is that the ultimate origins of either gene will probably never be proven.


I wouldn't be so absolute. There have been studies on both comb types. I don't want to get too bogged down in genetics but two findings of the following paper were:

1. Rose comb was first caused by an inversion event (a piece of DNA got knocked out flipped around and put back in) on the wild type chromosome. The wild type being straight combed.

2. A second Rose comb allele is present in some European breeds. The second mutation occurred in the reproductive cells of a bird that was heterozygous for the original Rose comb allele and the wild type allele.

http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002775#pgen.1002775-Hillel1

george wrote:
Likewise, it is very difficult to identify an extinct wild ancestor for a hybrid domestic animal, hence no scientific evidence thus far for or against G. giganteus, although there have been no rigorous test for the hypothesis.


I take finding 1. as evidence against Gallus giganteus.

I have no reason for mentioning finding 2. as it doesn't prove anything, I just find it interesting.

Regards

Oak


Last edited by Oak on Wed May 01, 2013 8:10 pm, edited 1 time in total.

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PostPosted: Wed May 01, 2013 8:06 pm 
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Thanks for posting the link to PLOS, interesting article and great to see the pictures of the phenotypes (not that all the variation is due to R1, R2 and r but an interesting set of combs all the same).


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PostPosted: Fri May 03, 2013 1:31 pm 
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Interesting article Oak, thanks for posting. The second rose-comb allele is interesting, I assume it is probably of European origin?

The first rose-comb allele, as the authors state, "probably occurred early in the process of chicken domestication, as it is widespread among chicken populations originating in both Asia and Europe, separated for hundreds of years." As Asia was the center of domestication, it is likely rose-comb originated in Asia.

I don't find point 1. as evidence for or against G. giganteus. Hypothetically speaking, G. giganteus would have evolved from a common ancestor which possessed a 'wild-type' single comb. Obviously it took two mutations (Pea and Rose) to achieve the knob-comb, and these mutation events wouldn't have occurred at the same time. Let's say, for arguments sake, the Pea-comb mutation occurred first, and selection favored this in the ancestral population at that time (for whatever reason). Then another mutation arose, Rose-comb, which proved a further adaptation and improved fitness in that habitat, leading to walnut/knob-combed species of jungle fowl (i.e. G. giganteus). The possession of the rose allele must have provided a strong enough fitness gain to negate the adverse effects on male fertility, though possibly there was some rose-comb heterozygosity as seen in some domestic breeds today. At the same time other adaptive changes were producing the typical Oriental features we see today.

Of course this is all hypothetical, based on my reasoning and the poultry literature, and as yet there is no empirical support. Though I find the idea fascinating and worthy of investigation, but I'm stuck on how this hypothesis could be accurately tested.

This has become an interesting discussion, but a little off topic. Maybe a mod can split it off as a new topic?

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PostPosted: Fri May 03, 2013 6:56 pm 
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Hi George,

I agree, this probably should be split off into a Gallus giganteus thread.

The second Rosecomb allele arose from a mutation of the first and it is probably of European origin given the breeds it was found in.

I think that the nature of the Rosecomb gene works against your theory. The gene can still be summed up as a simple chromsome inversion of the straight comb gene (with one extra mutation in some cases). I would expect a trait from another distinct species to have far more differences due to subsequent mutations (perhaps more correctly called substitutions) over tens or hundreds of thousands of years. However, I am not an evolutionary geneticist so I won't push the point. In any case, the authors of the study saw no reason suggest that the Rosecomb gene is older than domestic chickens or that the gene originated from another species. In fact, the Rosecomb gene:

Quote:
... represents a new example of how structural rearrangements have contributed to rapid phenotypic evolution observed in domestic animals


Cheers

Oak


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 8:17 am 
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Hi All
I have split these posts as requested from the history of OEG thread.
Can you let me know if I have missed a couple?

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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 8:58 am 
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Oak wrote:
I would expect a trait from another distinct species to have far more differences due to subsequent mutations (perhaps more correctly called substitutions) over tens or hundreds of thousands of years


Could it just be that jungle fowl were domesticated 2 times resulting in 1 bigger strain which lead to 'Gallus giganteus' and a smaller strain which went on to become everyday farm chooks?
Like the Aurochs (wild cattle) which was domesticated twice resulting in Taurine (European types) and then Zebu (eastern types with the hump and saggy skin)


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 10:30 am 
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Hi redjohanna and RyaRod,

redjohanna wrote:
Can you let me know if I have missed a couple?


I think you got them all.

RyaRod wrote:
Could it just be that jungle fowl were domesticated 2 times resulting in 1 bigger strain which lead to 'Gallus giganteus' and a smaller strain which went on to become everyday farm chooks?


Perhaps, but Bankiva gamefowl would need a place in the theory too. At the moment, I find this idea more likely than a wild population of Malay Game.

Cheers


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 12:00 pm 
on the subject of combs. I feel one of those species jungle fowl is a triple comb but it looks single. in my breeding os birds I have had birds with a single blade and no pints that are triple and others with perfect single blade with 4 points and also triple combed. to the average person the 4 pointed comb looks single and the single blade, no points an oddity. also it has been documented of fertile offspring of pheasants crossed to domestic chickens and I feel this can give rise to many reasons for comb types.


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 10:58 pm 
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Hi George and Oak,
William J.Plant has written about evolution of the domestic chicken and something that stands out to me is that he states 'The Malay's bones are not only filled with marrow, but are stayed inside, with the well-known spongy reinforcement.'
This is a vast genetic difference to any of the bankiva type birds. this is not a result of human domestication or breeding.
Whether gallus giganteus is the correct name for malay may not be known for many years.


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 11:11 pm 
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[quoteOak wrote:]Perhaps, but Bankiva gamefowl would need a place in the theory too. At the moment, I find this idea more likely than a wild population of Malay Game.

without the fact there is a wild population of malay game in existence today is not an excuse to say they are a result of human domestication and breeding. how long before our future ancestors only see rhino in zoos and wildlife parks? it may happen in our life time. thanks to our records they wont say they are a result of human domestication and breeding. the malay wild population may have been domesticated prior to written recordings or may be recorded, only we have not found or deciphered these records yet.


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 Post subject: Re: Gallus giganteus
PostPosted: Sat May 04, 2013 11:37 pm 
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Hi ruff and hensbyshenhouse,

hensbyshenhouse,

I'm actually reading "The origin evolution history and distrubution of domestic fowl part 3 the Gallus species by W.J. Plant" at the moment.

I'll let you know what I think when I'm through, there's a fair bit of Finsterbusch quoted in there as well. I have read the parts that cover the lines of reasoning in your posts, but I want to read the whole thing before coming to an opinion.

Regards

Oak


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 Post subject: Re: Gallus giganteus
PostPosted: Sun May 05, 2013 1:22 pm 
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A wild population of heavy Malay types birds would most likely fail in the wild as they wouldn't stand much of a chance against predators (taking into account that peafowl are a major part of the diet of leopards and tigers in some places), a slower heavy bird won't be able to fly or run fast enough to get away from larger predators and smaller predators (5-20kg) could still easily kill one.
Having said all of the above it could still be possible that these Malay type birds are from an island without large mammalian predators (that's how birds like Moas and Dodos got to their size.


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 Post subject: Re: Gallus giganteus
PostPosted: Sun May 05, 2013 2:07 pm 
a wild population could have been possible on an isolated island like madagasca. here as you know the Do Do lived and became extinct as a result of humans killing them and the animals like cats and rats being introduced. humans could even polluted the line by introducing their own breeds like they are doing all over the world with commercial strains and Europeans have done with their breeds like the oeg being introduced to change the fighting styles of birds.


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