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Author Topic:   What is the evolutionairy theory on the Giraffe?
redstang281
Inactive Member


Message 1 of 70 (739)
12-14-2001 7:52 AM


Just curious. How did the giraffe acquire his long neck?
Replies to this message:
 Message 2 by joz, posted 12-14-2001 9:24 AM redstang281 has responded

joz
Inactive Member


Message 2 of 70 (740)
12-14-2001 9:24 AM
Reply to: Message 1 by redstang281
12-14-2001 7:52 AM


quote:
Originally posted by redstang281:
Just curious. How did the giraffe acquire his long neck?

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

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....


This message is a reply to:
 Message 1 by redstang281, posted 12-14-2001 7:52 AM redstang281 has responded

Replies to this message:
 Message 3 by redstang281, posted 12-14-2001 10:30 AM joz has responded

redstang281
Inactive Member


Message 3 of 70 (748)
12-14-2001 10:30 AM
Reply to: Message 2 by joz
12-14-2001 9:24 AM


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

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....


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?)


This message is a reply to:
 Message 2 by joz, posted 12-14-2001 9:24 AM joz has responded

Replies to this message:
 Message 4 by joz, posted 12-14-2001 10:36 AM redstang281 has responded

joz
Inactive Member


Message 4 of 70 (750)
12-14-2001 10:36 AM
Reply to: Message 3 by redstang281
12-14-2001 10:30 AM


quote:
Originally posted by redstang281:
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?)

You seem to be neglecting the common mammalian trait of nurturing our young....


This message is a reply to:
 Message 3 by redstang281, posted 12-14-2001 10:30 AM redstang281 has responded

Replies to this message:
 Message 5 by redstang281, posted 12-14-2001 10:47 AM joz has responded

redstang281
Inactive Member


Message 5 of 70 (752)
12-14-2001 10:47 AM
Reply to: Message 4 by joz
12-14-2001 10:36 AM


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

Explain.


This message is a reply to:
 Message 4 by joz, posted 12-14-2001 10:36 AM joz has responded

Replies to this message:
 Message 6 by joz, posted 12-14-2001 10:52 AM redstang281 has responded
 Message 9 by mark24, posted 12-14-2001 11:39 AM redstang281 has not yet responded

joz
Inactive Member


Message 6 of 70 (754)
12-14-2001 10:52 AM
Reply to: Message 5 by redstang281
12-14-2001 10:47 AM


quote:
Originally posted by redstang281:
Explain.

Did you have a mother?


This message is a reply to:
 Message 5 by redstang281, posted 12-14-2001 10:47 AM redstang281 has responded

Replies to this message:
 Message 7 by redstang281, posted 12-14-2001 10:57 AM joz has responded

redstang281
Inactive Member


Message 7 of 70 (756)
12-14-2001 10:57 AM
Reply to: Message 6 by joz
12-14-2001 10:52 AM


quote:
Originally posted by joz:
Did you have a mother?


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.

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


This message is a reply to:
 Message 6 by joz, posted 12-14-2001 10:52 AM joz has responded

Replies to this message:
 Message 8 by joz, posted 12-14-2001 11:05 AM redstang281 has responded

joz
Inactive Member


Message 8 of 70 (758)
12-14-2001 11:05 AM
Reply to: Message 7 by redstang281
12-14-2001 10:57 AM


quote:
Originally posted by redstang281:
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.


Your mother took care of you I presume?

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

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

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


This message is a reply to:
 Message 7 by redstang281, posted 12-14-2001 10:57 AM redstang281 has responded

Replies to this message:
 Message 10 by nator, posted 12-14-2001 12:09 PM joz has not yet responded
 Message 11 by redstang281, posted 12-14-2001 12:12 PM joz has not yet responded

mark24
Member (Idle past 3361 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 9 of 70 (759)
12-14-2001 11:39 AM
Reply to: Message 5 by redstang281
12-14-2001 10:47 AM


The way evolution works is to offer up random mutations to non random natural selection.

This means that ANYTHING that would increase the survival of an individual, would mean a greater chance of surviving to mate & therefore pass on those genes.

In the case of a Giraffe, lets assume three scenarios ;

1/ A light drought. The young Giraffes would be able to survive on their mothers milk whilst the mother was able to obtain both food & water. If food is plentiful enough, & leaves remain on lower branches, then there’s no particular natural selection going on here. The shorter necked individuals get as much food as the longer necked examples. All the young Giraffes are amply fed by their mothers milk.

2/ A medium drought. The longer necked examples are able to get the upper leaves when the lower leaves are gone. They are still able to produce milk for their offspring, who survive. The shorter necked examples can’t get adequate food for both themselves & their young, their milk dries up & the young die. However, they, along with weaned adolescents are able to feed themselves. There is adequate lower level foliage.

In this scenario, although the short necked adults survived, their young did not. As a result ALL surviving young had the “long necked” gene. As a result, there is a greater percentage of individuals with the “long necked” gene at the end of the year.

3/ A hard drought. No Giraffes are able to sustain milk for their young & all young die. The short necked Giraffes aren’t able to feed themselves either, & die, along with the adolescents. Only the long necked adults survive, by virtue of their long necks & greater ability to feed themselves. This year has been a waste as far as offspring goes, but next year sees a reduced population entirely armed with the magic survival gene “long neck”. All offspring from now on will have the gene & what began as a mutation in an individual, has now entered the general population.

------------------
Occam's razor is not for shaving with.


This message is a reply to:
 Message 5 by redstang281, posted 12-14-2001 10:47 AM redstang281 has not yet responded

  
nator
Member (Idle past 336 days)
Posts: 12961
From: Ann Arbor
Joined: 12-09-2001


Message 10 of 70 (761)
12-14-2001 12:09 PM
Reply to: Message 8 by joz
12-14-2001 11:05 AM


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

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

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

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


I can answer yout question with one word, actually.

Milk.


This message is a reply to:
 Message 8 by joz, posted 12-14-2001 11:05 AM joz has not yet responded

  
redstang281
Inactive Member


Message 11 of 70 (762)
12-14-2001 12:12 PM
Reply to: Message 8 by joz
12-14-2001 11:05 AM


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

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

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

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


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?


This message is a reply to:
 Message 8 by joz, posted 12-14-2001 11:05 AM joz has not yet responded

Replies to this message:
 Message 12 by mark24, posted 12-14-2001 12:38 PM redstang281 has responded

mark24
Member (Idle past 3361 days)
Posts: 3857
From: UK
Joined: 12-01-2001


Message 12 of 70 (763)
12-14-2001 12:38 PM
Reply to: Message 11 by redstang281
12-14-2001 12:12 PM


quote:
Originally posted by redstang281:
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?

Sorry redstang, not sure if this was aimed at me or Joz. But anyway.....

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.

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.

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.

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.

------------------
Occam's razor is not for shaving with.


This message is a reply to:
 Message 11 by redstang281, posted 12-14-2001 12:12 PM redstang281 has responded

Replies to this message:
 Message 13 by redstang281, posted 12-14-2001 2:23 PM mark24 has not yet responded

  
redstang281
Inactive Member


Message 13 of 70 (764)
12-14-2001 2:23 PM
Reply to: Message 12 by mark24
12-14-2001 12:38 PM


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

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.

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.

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.

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.


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?


This message is a reply to:
 Message 12 by mark24, posted 12-14-2001 12:38 PM mark24 has not yet responded

Replies to this message:
 Message 14 by Mister Pamboli, posted 12-14-2001 3:15 PM redstang281 has responded

Mister Pamboli
Member (Idle past 5743 days)
Posts: 634
From: Washington, USA
Joined: 12-10-2001


Message 14 of 70 (769)
12-14-2001 3:15 PM
Reply to: Message 13 by redstang281
12-14-2001 2:23 PM


quote:
Originally posted by redstang281:

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?


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.

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.

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.


This message is a reply to:
 Message 13 by redstang281, posted 12-14-2001 2:23 PM redstang281 has responded

Replies to this message:
 Message 15 by redstang281, posted 12-14-2001 3:30 PM Mister Pamboli has responded

redstang281
Inactive Member


Message 15 of 70 (770)
12-14-2001 3:30 PM
Reply to: Message 14 by Mister Pamboli
12-14-2001 3:15 PM


quote:
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.

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.

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


This message is a reply to:
 Message 14 by Mister Pamboli, posted 12-14-2001 3:15 PM Mister Pamboli has responded

Replies to this message:
 Message 16 by Mister Pamboli, posted 12-14-2001 4:38 PM redstang281 has not yet responded
 Message 17 by mark24, posted 12-14-2001 5:02 PM redstang281 has responded

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