Posted on 02/14/2006 11:21:06 AM PST by PatrickHenry
Modern genetics has uncovered new species evolving in situations that would even impress Darwin.
The current journal Nature features two different cases — involving palm trees and lake fish — in which genetics have shown single species splitting into two new species while living side by side.
The most common sort of evolution is thought to happen when different groups of the same species are separated by some physical barrier, and then adapt to different environments without any chance of interbreeding.
Eventually the populations diverge and adapt to differing lifestyles so much they can't successfully interbreed. That's what biologists call allopatric speciation.
But the two new cases are strong candidates for the more subtle "sympatric" speciation, in which something as simple as flowering at a different time of year or preferring a different type of food can eventually lead individuals of the same species living side-by-side to evolve away from each other and create new and different species.
That appears to be what happened with the two palm tree species on small, 6.9 million-year-old Lord Howe Island, a volcano poking out of the Pacific Ocean some 400 miles off the coast of Australia.
"Flowering time has been the main driver of sympatric speciation," said Vincent Savolainen, Botanist for the Royal Botanic Gardens, Kew, in the U.K.
Savolainen and his colleagues studied the two species of Howea palm trees on Lord Howe Island and have concluded the trees diverged to take advantage of different kinds of soils.
Howea forsteriana, the thatch palm, prefers alkaline soils. Howea belmoreana, the curly palm, prefers neutral or acidic soils.
But it was probably when the two palms started flowering at different times that they really made the break.
Today, the two species open their flowers six weeks apart. That makes it virtually impossible for them to interbreed and much easier for the species to drift apart.
Based on genetic evidence, the two trees diverged from a common ancestor just one million years ago, said Savolainen. Since then the two palms have become visibly different, as well, with the flowers of the thatch palm's flowers containing many spikes and its leaves straight and leaflets drooping.
The curly palm's flowers have only one spike and the leaves are curved, with leaflets aimed upward.
A similar thing happened with the two species of Midas cichlid fish living in a small isolated crater lake in Central America.
"Crater Lake Apoyo in Nicaragua provides an exceptionally clear situation for testing sympatric speciation," reports Marta Barluenga and colleagues at the University of Konstanz, Germany.
The lake is less then three miles wide, deep, only 23,000 years old, and hasn't any place for fish to hide from each other.
As in the case of the palm trees, the genes of the distinctly different-looking fish indicate they diverged from a common ancestor just 10,000 years ago. What seems to have separated the cichlids into two species, however, is food.
Stomach contents of fish show that one species prefers foods found in the open upper waters, while the other species dines on the bottom waters.
Their jaws have even adapted to the different eating preferences, increasing the visible difference between the species.
The discovery in Lake Apoyo is particularly important because there are many cichlid fish in African lakes that are suspected of evolving sympatrically, but are much harder to study, wrote Barluenga.
"We've always said cichlid fish must be this way," said Carol Tang, a research associate and associate director of public programs at the California Academy of Sciences.
But, she said, it has taken the latest genetics, combined with good old-fashioned field exploration, to really prove the case.
"I am impressed," said biologist David Wake of the University of California at Berkeley.
Previous work on cichlid fishes in African lakes hadn't made as solid a case for sympatric speciation, partially because many African lakes are more complicated places where fish have a harder time avoiding interbreeding before they become truly new species, he said.
"This is not an issue here where there is clear evidence of 'biological species' that differ in ecology," he said.
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Glad to see more pro-evolution freepers. Add me to the list please.
But palm fish are still palm fish!
Heehee...
On the other hand, for both the palm and the fish the writer says this all happened a long time ago and nobody was around to see it, but, we are to accept that it did.
It's a "by faith alone" sort of thing.
I started thinking of fresh, steamed fish served wrapped in a banana leaf. Definitely time for lunch.
""But it's still a palm, it's still a fish! When a fish gives birth to a palm, get back to me.""
Dang right. Their still makin' babies "after they're kind." When them palm trees start dropping fish, then come see me.
/idiocy
Great article and keep up the great work. It's people like you who are making a difference on this db in explaining the process of science.
Evolution will morph into whatever it needs to be to accommodate visible phenomena. I always thought that real science made hypothesis and tested them in a way that would prove or disprove them.
Another example where conclusions about observations are colored by the observer's assumptions and speculations. Does this even qualify as "science"?
Then you would be incorrect. Science does not deal with proof.
What do you mean "pro-evolution"?
So if the attractive women who work in the ad agency 2 floors below mine wont accept my request for a date, is it because I'm more evolved or because they are more evolved?
:-)
I didn't even know fish had hands...
There is no theory of evolution. Just a list of animals Chuck Norris allows to live.
"Then you would be incorrect. Science does not deal with proof."
LUCKY THING FOR THE THEORY OF EVOLUTION!!
You just like to think of it as "faith" so that you can continue in your belief that your completely faith-based world view is equally valid.... IE. that science and religion are on equal standing and are equally factual.
I had a great Jesuit college religion professor who used to stress. "Religion contains TRUTHS .... not facts". If your looking for moral direction, personal clarity or purpose...go with religion. If you want facts - go with science. Religion provides the framework structure, science provides the bricks.
LOL!
That would be cool!
By pro-evolution, I mean people who do not reflexively mock evolution because they think it is nihilist. I don't think that being religious means being against science, and I don't think it's right to mock people and their beliefs because they don't fit with your own. If people want to put full faith in creationism or ID, then that's fine by me. But I've never been treated worse by freepers than when I claimed that evolution makes perfect sense and that I thought people who disavowed it didn't fully understand the theory.
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