The giraffe...

[petrushka.googol]

The giraffe presents an evolutionary conundrum.

 

It's long neck is both an advantage and a disadvantage.

 

It enables it to eat leaves at a height but makes eating from shrubs impossible.

 

Also it's legs are rather "rickety" and it can't run very fast since it's heart cannot pump blood to the top of it's head under these conditions.

 

Where does it fit into the evolutionary jigsaw?

 

And why do we not have another variant of this animal in the wild? (unless you consider animals like the alpaca etc.)?

 

Please advise.

[delboy]

Evolution doesn't produce ideals, it's more about what's possible. If a giraffe can eek out a living with the advantages it has, then it is a success for the moment. There must be enough of an advantage of being able to eat the highest vegetation to outweigh any disadvantages.

 

There are probably no other similar animals around for exactly the reasons you give. It's perhaps not ideal in many respects.

 

Also - giraffes in Denmark need to evolve stronger migratory habits if they are to survive (not sure if this news has spread across the pond yet).

[Phi for All]

The giraffe presents an evolutionary conundrum.

 

It's long neck is both an advantage and a disadvantage.

 

Isn't this the way of all adaptations? The size of the great white shark keeps it from going into tight areas, the fleetness of the cheetah limits its stamina so it can't run far, the flight capability of birds steals most of their physical resources and leaves them disproportionately disadvantaged in areas other than flight.

 

The giraffe is pretty intimidating due to its height, and a herd of them probably doesn't need to run all that often. They seem like they might be so successful at that tree-top eating niche that no other species has been able to evolve to compete. We used to have more long-necked creatures.

 

I wonder also if perhaps the trees where giraffes live need them to prune the tops so the trees can broaden out to provide more shade and environments for other creatures. Lots of plants and creatures co-evolve successfully.

[ydoaPs]

The giraffe presents an evolutionary conundrum.

 

It's long neck is both an advantage and a disadvantage.

 

It enables it to eat leaves at a height but makes eating from shrubs impossible.

 

Also it's legs are rather "rickety" and it can't run very fast since it's heart cannot pump blood to the top of it's head under these conditions.

 

Where does it fit into the evolutionary jigsaw?

 

And why do we not have another variant of this animal in the wild? (unless you consider animals like the alpaca etc.)?

 

Please advise.

The mammal presents an evolutionary conundrum.

 

Its lungs both an advantage and a disadvantage.

 

It enables it to breath above the water but makes breathing below the water impossible.

 

Also, its arms aren't very good for flying at all.

 

Where does it fit into the evolutionary jigsaw?

[Greg H.]

The giraffe presents an evolutionary conundrum.

 

It's long neck is both an advantage and a disadvantage.

 

It enables it to eat leaves at a height but makes eating from shrubs impossible.

 

Also it's legs are rather "rickety" and it can't run very fast since it's heart cannot pump blood to the top of it's head under these conditions.

 

Where does it fit into the evolutionary jigsaw?

 

And why do we not have another variant of this animal in the wild? (unless you consider animals like the alpaca etc.)?

 

Please advise.

Define "very fast". A giraffe can sprint at roughly 35 mph (60 or so km/h) - that's a hell of a lot faster than I can run. But in terms of animals, it is, admittedly, not that rapid.

 

Also, as giraffes can drink water from the ground (and lay down to sleep), they would have no issues eating close to the ground shrubbery, if they really needed to. The fact that the routinely do not eat such shrubs in no way implies that their consumption is any way impossible.

[John Cuthber]

This

http://www.123rf.com/photo_1364035_a-giraffe-feeding-on-the-grass-in-wildlife-park-in-england.html

suggests that they are able to eat grass.

 

Isn't this

"And why do we not have another variant of this animal in the wild? (unless you consider animals like the alpaca etc.)?"

a bit like saying "Why don't we have another variant on the shark (unless you consider dogfish and killer whales etc)"?

[Phi for All]

Isn't this

"And why do we not have another variant of this animal in the wild? (unless you consider animals like the alpaca etc.)?"

a bit like saying "Why don't we have another variant on the shark (unless you consider dogfish and killer whales etc)"?

 

I took this to mean, "Why don't we have creatures with giraffe-like treetop-eating capabilities everywhere there are tall trees?"

 

I wasn't really considering animals like the alpaca. They only aspire to be ruminants. As for treetop dining, meh.

[overtone]

One of the spots in the "evolutionary jigsaw" that giraffes fit well is as counterevidence to any hypothesis of intelligent design - the nerve routing and blood supply of the giraffe neck is a kludge, obviously a result of incremental changes in the basic setup of a much shorter neck.

 

As far as physiologically similar animals, there are fossils of tall herbivores with long necks all over the place, some dating back to dinosaur times, others of quite recent extinction, many of the recent ones very closely related to modern giraffes (http://en.wikipedia.org/wiki/Camelid). We live with a recently occurring and perhaps temporary dearth of them at the moment, is all - maybe a consequence of the shrinkage of savannah climate regions in the current interstade and glacial epoch generally, maybe not.

[petrushka.googol]

The mammal presents an evolutionary conundrum.

 

Its lungs both an advantage and a disadvantage.

 

It enables it to breath above the water but makes breathing below the water impossible.

 

Also, its arms aren't very good for flying at all.

 

Where does it fit into the evolutionary jigsaw?

 

My analogy relates to terrestrial species. (not acquatic animals). Homo Sapiens also is adapted to a terrestrial habitat. Otherwise life would have originated on Atlantis....

[arc]

 

I wonder also if perhaps the trees where giraffes live need them to prune the tops so the trees can broaden out to provide more shade and environments for other creatures. Lots of plants and creatures co-evolve successfully.

 

Sure, after all those years of trying to outrun those damn ever lengthening necks you just finally give up, say uncle and accept your life as an umbrella for a bunch of noisy varmints.

Edited February 11, 2014 by arc

[Greg H.]

 

My analogy relates to terrestrial species. (not acquatic animals). Homo Sapiens also is adapted to a terrestrial habitat. Otherwise life would have originated on Atlantis....

And yet, your original conundrum is not really a conundrum at all, since they can reach things on the ground, if they need to. It's not easy for them, perhaps, but it's also no impossible. So where is this conundrum you speak of?

[Phi for All]

One of the spots in the "evolutionary jigsaw" that giraffes fit well is as counterevidence to any hypothesis of intelligent design - the nerve routing and blood supply of the giraffe neck is a kludge, obviously a result of incremental changes in the basic setup of a much shorter neck.

 

Agreed. I think the laryngeal nerve in the giraffe is one of the best pieces of supportive evidence for evolution there is. What intelligent designer would use fifteen feet for a one foot path?

 

 

Sure, after all those years of trying to outrun those damn ever lengthening necks you just finally give up, say uncle and accept your life as an umbrella for a bunch of noisy varmints.

 

In some way, I'm sure this adaptation is beneficial to the tree as well. And it's better to be an umbrella than a sippy-cup for Hawaiian honeycreeper finches. Some of the flowers they drink from have curved to match the honeycreeper's beaks (or did the beaks curve to match the flowers?).

[arc]

In some way, I'm sure this adaptation is beneficial to the tree as well. And it's better to be an umbrella than a sippy-cup for Hawaiian honeycreeper finches. Some of the flowers they drink from have curved to match the honeycreeper's beaks (or did the beaks curve to match the flowers?).

 

You are quite right Phi,

 

http://www.giraffeconservation.org/giraffe_facts.php?pgid=39

 

"Regardless of their size, giraffe are not as destructive as elephants when feeding, indeed one scientist, Robyn Pellew who studied giraffe in the Serengeti, demonstrated that when giraffe are not too numerous, their impact can actually stimulate shoot production in Acacia species, which soon declined when the browsing stimulus was withdrawn. There are, however, also some natural plant protection methods at work which ensure over-browsing does not happen, for example carnivorous ants that are symbiotic with some Acacia species reduce the amount of time that giraffe can spend browsing on any one plant. On a positive mutual note, giraffe can actively benefit some of their food sources: Acacia seed consumption by giraffe favours seed dispersal into non-shaded habitats and enhances the potential for seed germination through the beneficial effects of its digestive processes. Giraffe are also thought to play a role in pollination."

 

In some way, I'm sure this adaptation is beneficial to the tree as well. And it's better to be an umbrella than a sippy-cup for Hawaiian honeycreeper finches. Some of the flowers they drink from have curved to match the honeycreeper's beaks (or did the beaks curve to match the flowers?).

 

 

Specialization may be an Achilles heel in the evolutionary process. With an abundance of competition for both food and pollinators a match made in evolution would be beneficial in the short term. But off hand it would seem a high risk venture in the long run. Either species is now vulnerable from the others weaknesses and vulnerabilities whatever they may be, with the great panda immediately coming to mind.

 

 

 

It stands out to me that the best fit for a mechanism to the development of these continually longer cervices in giraffes would be the competition at the lower levels of the available vegetation.

 

http://www.giraffeconservation.org/giraffe_facts.php?pgid=51

 

The end of the Pliocene epoch (2.5-6 million years ago) saw a number of long necked giraffids evolve, but largely unsuccessfully with only 2 species surviving to this day.

 

• For a number of years there was discussion between some in the scientific community as to whether the West African and the Kordofan (sub)species of giraffe were in fact the same animal. DNA analysis can now confirm they are most certainly separate and indeed ongoing studies may well reveal they are actually separate ‘species’.
• In another case there was the suggestion that the Rothschild’s giraffe was in fact just a hybrid, but again genetic evidence has confirmed its place as an important (sub)species in its own right.
• A recent study of the Angolan giraffe in northern Namibia has suggested there is evidence that two neighbouring populations may well be separate (sub)species. And meanwhile the same science seems to have resolved a debate which sought to subdivide the South African giraffe into four separate (sub)species, and it is now widely accepted there is but one South African giraffe.

There may have been a very competitive period where an abundance of lower elevation foragers drove this species and its relatives into the higher branches. Could this forcing have even been primarily amongst the related species as their necks lengthened beyond the range of the competitors?