Mcnugget or the omelette - a profound evolutionary dilemma (Jul/31/2007 )

Despite this interesting discussion, I guess the 'chicken' humans eat allday, are still the same species as the wild type (i.e. Gallus gallus from Asia), but several domesticated races/breeds according the human needs (egg production, flesh content etc, loss of colouration) were developed, long time by breed-selection. But I guess that all these races (e.g., ornamental, flesh or fight races) are still interbreedable with the the original form somewhere in the Asian forests (apart from possibility that perhaps the courting abilites a bred-away in the domesticated races, which makes breeding difficult or impossible). Finally I guess that the genetic diversity of these breeds is very low, only one or a few ancestors. This is expressed e.g. in high susceptibility for diseases, but uniformly high egg/flsh production as the farmers like it.
And there is the opportunity of hybridisation (not canary + condor)...but not so common in vertebrate breeding. But it increases the possibilities of discussion.
Keep on writing for the next 10, a real virtual carrot.

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And all the while I thought that dpo and I were having a profound philosophical discussion on macroevolution, a contentious topic that’s got the creationists up in arms. Perhaps you can weigh in on one detail dpo (is this an acronym of sorts i.e. days post-onoculation ) raised that I am not so convinced about. Did it only take one mutation in the gamete of the red jungle fowl to cause the emergence of the animal that McDonald’s and the Colonel have been making millions from (after globalization that is)?

almost there,

casandra

PS I thought you upped and ran away yesterday. I almost sounded the amber alert.

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Hey dpo,

Did I hit the nail with the acronym? Here we were yesterday trying to compete with Fred for the top 20 posters, contributing your franc and my loonie, squeezing our brains to come up with unassailable/irrefutable arguments (con and pro pre-chicken) only to be nicely told by our resident entomologist Dr. hobglobin that the chicken keeping us entertained in this thread is the same species as the original wildtype one from Asia which man, as usual, only tamed and honed according to his specifications. Still got some francs left ?


definitely there and with 2,950 reasons for not yet retiring from this forum,

casandra

PS
But he can't take away the candor from us (or is it the connary?)!!!

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Congratulations with your 50th Post !!

I was kinda figuring you wouldn't be able to wait and would post two posts in a row, just a little tease

You're right, I'm a little baffled by hobglobin's response, although he doesn't answer the question actually. I agree that there's limited variability between the common household chicken and the one living in the Asian forests, but somewhere between the big dinosaurs and the Asian chicken, some (or only one?) mutation(s) must have occurred. Ah well, we weren't there when the mutations happened and I don't think there are fossils for each and every mutation. So I think we will have to stick with a philosophical approach.

As for the acronym, I just use it when I sign up to message boards because it's still available most of the time, no mysterious explanations here, although ...
And as for the francs, I still have some left, but they're actually not worth anything anymore as we pay in Euro's now...

I still need about 20 more posts to get up to your level, but one day, read my lips, one day I will succeed!

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Sorry guys, but 0ne mutation=one new species is not neccesarily true. Not always darwin theory works like that. First the gene has a tendency(?) to mantein the order and "protect" the function of it so many of the mutations are silent, so you will need an accumulation of mutations in order to make the leap to make another being, then need the physical separation of both until they can't mate and then you maybe will have a new species. In other words you have the pre chicken that has a number of mutations that passes to the offspring and that offspring will mate with the prechicken with old gene sequence and wtih the new gene sequence. They will mate until something take thems appart (for example the formation of a new valley) and they can't mate anymore so you have pre chickens with pre chickens, new chickens with new chickens and the hybrid of both, so lets thinks that the hybrid were all eaten by some Hommo sapiens so now you have the pre chicken in one part of the valley and the new chickens in the mountains, so the pre chicken can't fly and go where the new chickens are and viceversa so they stop to mate. After many generations of no mating and with all the hybrid gone(eaten) then there will be mutations that will create the mecanism to stop the mating of the prechicken with the new chicken and thats how you have now the new specie, the CHICKEN.

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Hi merlav,

I like your scenario...the only thing missing is "why did the chicken cross the road?" (the answers are in the chit chat's humour sense thread ). However I found this article entitled "Protochicken" which was very informative and shows that hobglobin is probably right (I hate it when that happens ). But there could be a loophole....what is a subspecies, anyway? DPO any thoughts, barring semantics that is?

"Every breed of domestic chicken that ever lived can be traced to a single subspecies of red junglefowl native to Thailand, according to mitochondrial DNA evidence discovered by Japanese researchers.....

Biologists have pondered the origins of the domestic chicken for many decades. Paleontologists first fixed the original date of chicken domestication some 4,000 years ago at a site in Pakistan. However, subsequent discoveries of chicken bones at Neolithic sites at the mouth of the Yellow River in China push the date back to about 7,500 years ago. However, the red junglefowl was not native to that arid region of China, suggesting an older heritage in a more tropical area.

The new findings by the Japanese researchers suggest that domestication took place more than 8,000 years ago in what is now Thailand and Vietnam, the region in which this red junglefowl is found today. Moreover, this data indicates that the chicken is a notable exception to the general rule that the domestication of a species results in the extinction of its wild ancestor, the researchers note."

The complete study can be reviewed in the Proceedings of the National Academy of Science, v.91, pp. 12505-12509, 12/20/94, Fumihito et al.

I guess the chicken is not what Gould had in mind when he was formulating his punctuated equilibia theory .

Perhaps we can go back to a more philosophical discussion, is evolution progressive i.e. from simple to the most complex?

up to 51,

casandra

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The Protochicken article doesn't really give any answer to your first question: how many mutations are required to make a new species. The only conclusion I could find is that most chickens as we now them today are alike.
So I'm still quite confident with my one (well, maybe two) mutations to create a new species. And I'm not alone with this!

I found this article about the flower colour of monkeyflowers (http://www.innovations-report.com/html/reports/life_sciences/report-23323.html):

Major mutations, not many small changes, might lead way to new species

Hummingbirds visited nearly 70 times more often after scientists altered the color of a kind of monkeyflower from pink – beloved by bees but virtually ignored by hummingbirds – to a hummer-attractive yellow-orange.
Researchers writing in the Nov. 13 issue of Nature say perhaps it was a major change or two, such as petal color, that first forged the fork in the evolutionary road that led to today’s species of monkeyflowers that are attractive to and pollinated by hummingbirds and separate species of monkeyflowers that are pollinated by bees.
"It could be that the first adaptations require a few big changes, sort of like taking a watch that has stopped ticking and banging it a few times before making the small tweaks to restore its optimal performance," says Douglas Schemske,

The original research can be found in Bradshaw and Schemske, Nature 426:176-178.

So the banging of the watch is like punctuated equilibrium, but the small tweaks are the gradual evolution, so I think both are important.

Regarding your last question, I don't think evolution is necessarily progressive. Evolution 'provides' the best organism for the current situation and in some points (although I don't know of any examples yet, I'll think about) this may lead to an organism which is less complex. To the observer it may look like the complexity is increasing, but this is because you rarely see all stages of the evolutionary process and if you can't compare the true ancestor to the result, it's hard to analyze the difference in complexity.

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historically speaking eggs have been around much longer than chickens (not a very precise question).
the humming bird thing is a beautiful example of parralel complementary evolution - sensitivity to colour on one hand and production of precise colours on the other
so who came first the farmer, the chicken or the egg

dom

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It sure doesn't, I only quoted it to demonstrate we're probably chasing ghosts (and increasing our posts )since our original premise is that the chicken we're laboring about is a new species (when it's not) so we're in fact just begging the question.



But aren't most major mutations deleterious? That the emergence of new species or splitting of ancestry is influenced more by ecologic/environmental pressure? Besides there's also a controversy even among the evolutionists..the direct line of causality from microevolution to macroevolution, whether they are mutually reducible to each other or independent of each other.

Or the banging of the watch could have resulted in its complete wreckage and loss of functionality...it can go either way you know . This is an argument for design.



You're right..."best" is once again a matter of semantics. And we have the fossil records for comparison...now if we can just fill in the gaps.

casandra
PS If we keep this up dpo I can already read your lips.

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indeed, the vast majority of major mutations will be deleterious, but once in a while, it's possible that one confers an advantage. But that's why I prefer the gradual evolution above the punctuated equilibrium.

I agree that the watch allegory may not be the best way to put it, as it immediately brings the watchmaker into play, but I think this is also just a story about how most major mutations are deleterious (I would never recommend to bang your watch against the wall if you want a better one ). The fossils are indeed a good help, but these can only tell us that much. Changes in coat colour, changes in mating behaviour, ... all of these may have played an important role in the establishment of the species as we know them today, but we will never be able to know them (unless we clone all the animals from blood remaining in mosquito's trapped in amber, oh no, wait that's been done before )

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