Convergent evolution

[Moontanman]

Examples of convergent evolution are the similar shapes of Earthworms, worm snakes, Caecilians, worm lizards, glass lizards, amphiumas, real snakes, eels, sirens. The long slender legless or almost legless shape has been repeated many times. How many different examples of convergent evolution can be found?

BTW convergent evolution is an important example of why evolution is false according to creationists.

[Ganoderma]

although they appear different, those designs are all incredibly different and varied. for example worms have hairs which help to move. caecilians have a hard head and push out their skin/scales and use their spine and head like an arrow to push forward. snakes use belly scales to move back and forth, eels swim....

they are all legless (although some some snakes have leg remnants - boids-), but its like saying a dogs and elephants are the same guess we can split hairs anyway up the chain though eh?

one interesting example is ergoline alkaloids found in fungi (where lsd gets is origin). it is also found in some plants (convolvulaceae). it was theorized to be as said above. 2 groups, in this case in different kingdoms, managed to get the same chemicals. later on, ie now, it is found that they live in harmony together and the fungi seems to develop the chemicals and the plant accumulates them. i thought this was interesting how science is showing symbiotic relation ships in weird new ways.

i think one of the coolest things though would be 2 eyes.

the problem with evolution and creationism theories are, they can both argue their point, and there is no way to either prove or disprove either one. "god made it that way" or "nature made it that"...i gave up as it seems god and nature are one in the same...helps me think less lol.

[C1ay]

Originally Posted by Ganoderma

i gave up as it seems god and nature are one in the same...

Ahh, a pantheist among us

[Moontanman]

Originally Posted by Ganoderma

although they appear different, those designs are all incredibly different and varied. for example worms have hairs which help to move. caecilians have a hard head and push out their skin/scales and use their spine and head like an arrow to push forward. snakes use belly scales to move back and forth, eels swim....

they are all legless (although some some snakes have leg remnants - boids-), but its like saying a dogs and elephants are the same guess we can split hairs anyway up the chain though eh?

one interesting example is ergoline alkaloids found in fungi (where lsd gets is origin). it is also found in some plants (convolvulaceae). it was theorized to be as said above. 2 groups, in this case in different kingdoms, managed to get the same chemicals. later on, ie now, it is found that they live in harmony together and the fungi seems to develop the chemicals and the plant accumulates them. i thought this was interesting how science is showing symbiotic relation ships in weird new ways.

i think one of the coolest things though would be 2 eyes.

the problem with evolution and creationism theories are, they can both argue their point, and there is no way to either prove or disprove either one. "god made it that way" or "nature made it that"...i gave up as it seems god and nature are one in the same...helps me think less lol.

I think you are missing the big picture here. yes in close up detail all these animals are quite different, but Caecilians move across the surface with serpentine movements just like a snake, eels move across land the same way, as do sirens, amphiumas, even some worms do this. They all swim the same way, the ones that live under ground move in very similar ways, worm snakes and worm lizards look so much like worms, right down to the segmented rings on their bodies that are often mistaken for worms, only their dry bodies and dry habitats give them away. All these animals exploit the long worm like shape in similar ways to similar ends. Such similarities show up in four footed creatures as well, although horses, dogs and elephants are far more closely related than a snake and glass lizard much less a snake and an eel. Convergent evolution occurs all around us at the visual level. These animals have all evolved similar body plans under similar stresses and natural selection. There are other basic groups of similar body plans in animals that are far removed from each other in evolutionary terms. I was hoping for more examples but i will give another good one. Ichthyosaurs, sharks, and dolphins come to mind.

[Getting A Life]

Form depicts function. They (worm shaped organisms) move like that because they are made like that. I could walk on my hands with enough practise, but the way I am shaped, it conserves much energy to walk on my feet.

Form depicts function.

An example is the femur/metatarsal ratio in quadropeds. The higher the ratio the (potentially) faster an animal is. We can predict the speed of an extinct organism fairly accurately through examining this ratio and if the foot is plantigrade, digitigrade or centigrade. Applying the same ratio to extant species gives the expected results. Higher femur/metatarsal ratio = faster animal.

Whereas, if you examine the wide leg stance of reptiles leg bones compared to mammals you will almost immediately understand why they undulate their bodies side to side in a 'waddle' as they walk like they do.

The remnants of limbs are known as vestigial structures. Found in dolphins, whales, snakes...

[Moontanman]

No getalife, snakes do not move in a serpentine motion because they are legless. They are legless because natural selection favored that shape due to environmental pressures. the serpentine motion started before the loss of legs. It can bee seen today in some lizard species that are beginning to loose their legs because they don't need legs due to using their bodies in the serpentine motion being more efficient in their natural environment.

The form of the long legless body has evolved many times in many totally different animals due to natural selection. mammals seem to have missed the boat on this body from unless you count ferrets, the little snaky bastards are as close being snakes as any mammal I know of.

The pressures of natural selection have driven evolution to repeat many body forms over the last 500,000,000 years. You could walk on your hands and if the hand walking made you more likely to have offspring at some point, thousands if not millions of generations hence, your descendants just might walk on their hands naturally but not because you can hand walk but because natural selection favored you because you could.

[Getting A Life]

I am not saying they move that way because they are legless. I am saying they move that way because that is the most efficient way of moving without legs. Rolling would not work as too many obstacles would get in their path.

Form depicts function, right from a molecular level.

[Moontanman]

So are you saying there is no convergent evolution?

[freeztar]

I don't think he's saying that. In fact, it seems you are both on the same page as far as homoplasy is concerned, just coming at it from different angles.

Form does depict function (most of the time anyway), but that is a direct result of convergent evolution acting on species with unrelated ancestors adapting through natural selection to the same, or similar, environments.

Bats, birds, and pterodactyls all have wings, though they are only distantly related on a cladogram. They evolved wings separately, but for similar "reasons".

[Moontanman]

Earthworm



Worm caecilian



Worm Lizard



Worm Snake





Kid snake