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Proc. Natl. Acad. Sci. USA
Vol. 94, pp. 7761-7767, July 1997
Colloquium Paper
Incipient species formation in salamanders of the Ensatina complex
David B. Wake*
ABSTRACT
The Ensatina eschscholtzii complex of plethodontid salamanders, a well-known "ring species," is thought to illustrate stages in the speciation process. Early research, based on morphology and coloration, has been extended by the incorporation of studies of protein variation and mitochondrial DNA sequences. The new data show that the complex includes a number of geographically and genetically distinct components that are at or near the species level. The complex is old and apparently has undergone instances of range contraction, isolation, differentiation, and then expansion and secondary contact. While the hypothesis that speciation is retarded by gene flow around the ring is not supported by molecular data, the general biogeographical hypothesis is supported. There is evidence of a north to south range expansion along two axes, with secondary contact and completion of the ring in southern California. Current research targets regions once thought to show primary intergradation, but which molecular markers reveal to be zones of secondary contact. Here emphasis is on the subspecies E. e. xanthoptica, which is involved in four distinct secondary contacts in central California. There is evidence of renewed genetic interactions upon recontact, with greater genetic differentiation within xanthoptica than between it and some of the interacting populations. The complex presents a full array of intermediate conditions between well-marked species and geographically variable populations. Geographically differentiated segments represent a diversity of depths of time of isolation and admixture, reflecting the complicated geomorphological history of California. Ensatina illustrates the continuing difficulty in making taxonomic assignments in complexes studied during species formation.
Originally posted by x0846
Don't evolutionists believe that the evolution of a particular species evolves into a more proficient, adaptable, smarter, … species?
Why then did whatever evolve into a 'man'? Why doesn't he have a hairy body to protect him from the elements? Why would something evolve into a 'man' when a man is so fragile? Why didn't something evolve into more than man?
How has man evolved in say the last 5000-10000 years? Why don't we have wings? Wings would make getting around a lot easier so where are our wings? Why no gills so we could use the water like a fish? Why does man have such an advanced brain? What made evolution make a certain species into a man?
Do you have anything to show why evolutionists think something evolved into a man and why?
X0846
So a bird, the ostrich, evolved into grounded bird, why didn’t the ostrich evolve into a flying bird instead of a running bird? After all it is a bird and don’t birds fly.
Animals evolve differently based on enviroment and location. Perhaps the ostrich evolved non-flying as a result of its envirormental location. Over time it got larger and was unable to fly. Following your logic, all birds would have evolved the same, all flying, all the same size, all the same color. Penguines dont fly but they swim, why? Maybe its easier to "fly" through the water and catch fish. I know what your gonna say next, there are flying birds in the penguines habitat, yes, but there arent NEAR as many.
[edit on 21-8-2007 by coop039]
Originally posted by ModernDystopia
Originally posted by x0846
X0846
Chimps, our closest relatives, do not have a developed enough neocortex to construct a fire to cook, stay warm, etc. Humans do. We don't NEED a full body of fur to keep warm because our brains have allowed us to "discover" fire. Is it safe to assume that our early bipedal ancestors were very hairy, and eventually lost hair over-time? Absolutely.
There's no reason to say that we have more advanced brains than say a dolphin, as we know so little about the species. For example, a dolphin has almost twice as many neocortex folds in its brain than humans, and the amount of folding in a mammal's brain is significant in regards to its evolution and brain power. Does this mean dolphin's are smarter than humans? Perhaps in certain aspects. In fact, the only thing that keeps mammals like dolphins from speaking is the fact that the human brain is divided into two halves, called lateralization. We are the only mammal that exhibits this.
As to why we don't have wings. Whatever species we evolved from (NOT chimps, rather a very close ancestor of chimps) didn't have wings.
Take a look at the ostrich. They are birds, have wings, but don't fly. Instead, through evolution, the wings became used for balance while running. It would not be useful for such a large bird to exert so much energy to fly when it could use its long legs to run, and thus travel, much faster.
Also, ask yourself why you get goosebumps when you get cold. That's the erector pili. Animals activate this during times of cold to make their hair/fur thicken, thus making them warmer. Sometimes we get goosebumps when we are frightened. Why? Because animals, when threatened, also active their erector pili to bulk up their fur to give the appearance of being large and menacing. Or even ask yourself the obvious question - why do we have a tail bone?
All of these characteristics (tails, full bodies of hair, etc) existed in our ancestors. Through the process of evolution, we lost these characteristics simply because they are not useful anymore.
[edit on 17-8-2007 by ModernDystopia]
Originally posted by runetang
1 thing I disagree with. You imply that early humans, our ancestors, had actual tails which came from their tail bone. I do not believe this is true nor that you could prove that it is true.
It's a theory, but IMO, I don't think early humans had a tail considering how small the tail is on certain primates already.
Don't evolutionists believe that the evolution of a particular species evolves into a more proficient, adaptable, smarter, … species?
Originally posted by x0846
So, because a man learned to build a fire does that make him better equipped to deal with the elements?
Yes
No, of course it doesn’t, dump yourself in the middle of a winter wilderness in all your nakedness and let’s see if you survive with your brain and get a fire going before you freeze to death. I’ll bet your dead within one 24 hour period.
Humans today do not have the survival skills that they did thousands of years ago.
Your dolphins which you say don’t speak, what don’t they speak the English lingo so they couldn’t possible communicate. Their communication system is much more advanced than ours, their able to navigate the oceans like we navigate highways but we need signs to tell us where we’re going only they don’t have maps and signs telling them where to go and yet they navigate the oceans of the world.
Most marine life does have a remarkable ability to navigate the oceans, not just dolphins. The navigation abilities of most land animals are not as advanced. Perhaps this is because marine life has had a much longer time to evolve, or the ability to navigate the oceans was a stronger survival benefit compared to the ability to navigate on land.
The ostrich didn’t fly because of its size well weren’t their other ‘birds’ that were much larger than an ostrich and they flew.
The ostrich doesn't fly because it took a different evolutionary path. Each mutation that gave the ostrich its attributes happened to aid in its survival without giving it the ability to fly.
Goosebumps, that’s a real good piece of evidence of evolution. Then you say animals use a chemical reaction which causes bodily change, if we evolved from the animal why did we bring goose bumps with us and not move away from this animal trait?
The same reason we still have a tail bone. Evolution takes millions of years. You don't gain or lose a trait completely overnight.
Why do we have a tail bone? Why don’t we have a tail? Certainly a tail would be a huge benefit so why would evolution do away with such a vital asset?
Because it no longer provided a significant survival advantage.
Why did we loose those characteristics when they obviously would be useful to us?
When a characteristic no longer provides a significant survival advantage, the species begins to lose it.
Why did evolution produce the most evil species on the planet? Animals kill for food what does the evolved man kill another man for? Certainly not food.
Are you suggesting that instead God is the one that created humans as the most evil species on the planet?