What is the evolutionairy theory on the Giraffe?

Just curious. How did the giraffe acquire his long neck?

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Originally posted by joz:
Um... Because being able to reach higher up the tree is an advantage when you eat leaves maybe?

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Thus those with longer necks would tend not to starve to death and therefore pass a genetic tendency for long necks down to their offspring...those with short necks would starve and not pass on their genes....

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So if the ones with short necks would starve, then how did baby giraffe's survive long enough to grow long necks(so that they could survive long enough to pass on genes?)

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Originally posted by joz:
You seem to be neglecting the common mammalian trait of nurturing our young....

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Explain.

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Originally posted by joz:
Did you have a mother?

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I want to know in what way the giraffe took care of the baby giraffe to help him survive and eat the leafs on the top of the tree that only the full grown giraffe could reach.I think I know what you are going to say, but I want you to say it, not me.

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[This message has been edited by redstang281, 12-14-2001]

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Originally posted by joz:
Your mother took care of you I presume?

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If so then she was displaying the shared mammalian trait of nurturing your offspring...

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Oh and you know what giraffes are mammals as well....

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The mechanism by which the help is given is immaterial it is sufficient that the help is given...

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I thank Mark for giving me a real answer. The giraffe baby would suck the mother's milk until it is big enough to reach the tree branches.So you are saying that the environment presents a need that must be forfilled in order for a species to survive? Which would mean in this case the environment presented the giraffe with vegetation above his head and the giraffe had to develop a longer neck to reach the vegetation or else it would die out?

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Originally posted by mark24:
Sorry redstang, not sure if this was aimed at me or Joz. But anyway.....

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No. The environment is able to throw all sorts of things at the Giraffe, famine & drought among them. ANYTHING that gives a survival advantage to an individual will allow that individual to compete better for food, mates etc & pass those traits on. If the're good enough, they'll become the norm, given enough generations.

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I see what you're getting at re. HAVING to get long necks or die. If they couldn't get access to as much food as they do, then they would either be unsuitable for the habitat that they live in & become extinct there, or live where there is less competition for food. The fact it has a long neck, ALLOWS it to exist in habitats of drought & famine, enhancing the geographical diversity of that species, thus contributing directly to the success of that species.

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The question then arises, what happens to species like antelopes that don't have long necks. Surely they would die too? No. They have adaptions to the environment unique to themselves (incidentally there are species of long necked antelope, though not approaching that of Giraffes). this could be a different diet, a migratory habit etc.

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Incidentally, in the examples I gave, I tried to show how natural selection would work when a long neck was compared to purely a food variable. It also has the advantage of spying predators from far enough away that they don't become a threat. Thus "long necked" young are more likely to survive even when food is plentiful. Its entirely possible that the driving environmental factor behind long-neckedness was predator evasion. & that as a side advantage, they were able to get to higher branches.

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I must commend you on how well your informantion has been thought out.So this would mean that the during the time the giraffe was evolving it had a survival advantage over the antelope. So therefor, antelope wouldn't have been able to survive as well as the giraffe in certain environments. Why didn't the antelope evolve the longer neck so it could have a survival advantage as well?

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Originally posted by Mister Pamboli:
Well the answer has already been given in part - antelope and other animals under the same pressures developed other means of survival. The giraffes neck is only one of many solutions.

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Oh, I understand that it's one of the many solutions to survival. But if gives them a survival advantage then why didn't all animals develope it so they could all have better means of surviving? [b] [QUOTE]Bear in mind that if all grazing animals developed long necks there would be more competition for the treetop treats and this would be yet another selective pressure. Some antelope do have quite long necks and others can stand quite elegantly on their hind legs to graze from trees.
[/b][/QUOTE]But if they have a long neck that shouldn't limit them to only eating vegitation from the top. It should only give them a greater range to select from. A giraffe does have to drink water on the ground, so he is capable of lowering his neck. So if vegitation wasn't left at the top from other long neck animals eating it, then he could certainly eat near the middle or the bottom. [b] [QUOTE]BTW, were I a literal creationist, I would need to ask myself - if one was to design an animal which has to survive on a boat for 40 days, would one give it 2-metre legs and a 3-metre neck? I suspect not.[/b][/QUOTE]I disregard this only to keep the focus on the post to my original question.

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[This message has been edited by Percipient, 12-15-2001]

In order for the giraffe to aquire his long neck the long neck gene would have to be passed down to the younger generations. Which would mean that the gene could only come from giraffe's who have longer necks. So therefor in order for all giraffe's to have longer necks there would have to be a period of time in which no short neck giraffe's could survive to pass along their shork neck gene's. This would mean the short neck giraffe's would have to die out of starvation from loss of leaves on a lower vegation level. But how could a period of time like this exist if other lower animals with the same diet as the giraffe were able to survive?

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[This message has been edited by redstang281, 12-14-2001]

Would the giraffe's evolving long neck have any positive side effects on the environment?

How did the animal the okapi evolve?

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Originally posted by mark24:
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To point out the obvious ; If there was a foliage eater that was less adapted to its diet than the Giraffe & had the same geographical range or less, & also possessed no other adaptations to its habitat, then the Giraffe out-competed it long ago, & no such organism is alive today.

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The okapi is alive today. He is a foliage eater - the same diet as the giraffe. He is infact a close relative to the giraffe. This shows that he was able to survive without evolving a longer neck. Thus the question remains why did the giraffe evole a long neck?

[QUOTE]Originally posted by Percipient:
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Redstang writes:
How did the animal the okapi evolve?[/QUOTE]

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I would like to thank Mark for his very well thought out descriptions of possible evolutionary scenarios for the giraffe. If he wants to also tackle the okapi I think that would be great, but what your series of questions indicates to me is that you're seeking questions for which we do not have answers.
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He definatly did put a lot of thought into it. [b] [QUOTE] If we find answers to all your questions it only means you're asking the wrong questions. The toilers in the field of science are pondering plenty of unsolved mysteries, and there are tons of questions for which we have no answers. What would it mean if you asked some of these questions, such as does Higg's Boson exist, or is string theory correct, or how did life originate? When we said we didn't know, do you believe it would then be valid to conclude this was evidence of the divine at work? If so, then welcome to the world of Intelligent Design.
[/b][/QUOTE]Are my questions not welcomed?

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Originally posted by Percipient:
You're questions are very welcome. I was just wondering where you were going with them. If not toward ID, then just forget I said anything.

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There is one more thing I'd like to add. This is not in any way a criticism of Mark's scenarios, just a clarification. The scenarios are only applications of the evolutionary framework to the available evidence and are not evidence themselves. One of the giraffe scenarios may be true, or perhaps it happened some other way. For instance, one possibility Mark doesn't mention when contrasting giraffe and impala development is that their common ancestor may have become separated into populations in different geographical regions before being reunited on the savannah of modern day Africa. And adding that scenario probably still doesn't cover all the bases, because in general in any field as study as you expand the details in the scenarios the necessity for subdividing them arises.

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--Percy

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So in order for the okapi and giraffe to evolve then they must have been geographically seperated?

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Originally posted by mark24:
As Percy states, its not a requirement. It would depend on levels of competition. This allows for more than one organism occupying the same ecological niche.

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Okapi are rainforest dwellers & Giraffe live on woody savannah. So they are geographically separated.

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A VERY long neck in a rainforest isn't a survival advantage.

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Why? [b] [QUOTE] If the Okapi & Giraffe are related, doesn't this imply common descent?
[/b][/QUOTE]I was speaking from an evolutionist pov.As I asked earlier, is it possible that the giraffe's long neck helps the environment in anyway, or no?

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Originally posted by mark24:
2/ Yes & no, depending on whether your a tree, having your seeds dispersed in Giraffe dung, or an insect sitting on a high leaf about to be eaten.

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Which would help to keep insects from becoming over populated.Why did just the giraffe's neck grow and not his whole body? Why did he become misproportioned?