Skip to comments.Evolution moves more quickly than scientists thought
Posted on 11/19/2006 1:00:27 PM PST by DaveLoneRanger
ST. LOUIS - Evolution happens. But it can also stop and turn on a dime.
A new study of lizards in the Bahamas shows that the natural selection pressures that drive evolution can flip-flop faster than previously thought - even in months.
"Darwin was right about so many things," said Jonathan Losos, a former Washington University biologist who led the study. "In this case he was wrong. He thought that evolution must occur slowly and gradually."
The lizards and their changing leg lengths are yet another case of evolution occurring in real time. From finches that evolve longer beaks in a few years to bacteria that adapt to strange feeding regimens in days, evolution, as a science, has leapt out of musty museums and into the field.
Scientists say that, from a political perspective, the cases offer a vivid reminder of the continuous process that some people imagine proceeding only in fossilized fits and starts: First monkey, then man.
But for the scientists themselves, the cases show that evolutionary biology has, well, evolved into a predictive, experimental science like any other.
Losos had the perfect Petri dishes: 12 tiny islands in the Bahamas with small populations of insect-eating Anolis sagrei, six-inch long lizards that normally live on the ground but can adapt to life in trees.
On six of the islands, Losos introduced a predator, a large curly-tailed lizard that can gobble up the lizards. He theorized that at first, the fastest prey would survive as they ran for the trees. Natural selection would reward long legs. Then, as the little lizards adapted to life in trees, nimble twig maneuvers and shorter legs would be rewarded.
At the start of the experiment, the scientists, using dental floss nooses on the ends of 10-foot poles, caught all lizards and carefully measured their hind-limbs. After the first six months, their predictions held up. The average leg length of survivors was 2 percent longer than those that were killed. After a year, leg length was 3 percent shorter. The changes were small in absolute terms but statistically very large, said R. Brian Langerhans, a graduate student with Losos.
The study appeared Friday in the journal Science. Losos did the research while at Washington University, but left for Harvard University in June.
The lizard study echoes one of the classic cases of evolution-in-action: Darwin's finches on the Galapagos Islands. For more than 30 years, Princeton University biologists Peter and Rosemary Grant have measured changes in the finches' beaks. After extended droughts, small seeds became more scarce. In a few years, the finches evolved longer beaks to crack the larger, tough seeds that remained. Then as more plentiful times returned, the bird beaks got smaller again.
At Michigan State University, Richard Lenski is studying evolution in test tubes. For almost 20 years, he has reared 12 colonies of E. coli. They have divided more than 30,000 times - which, in terms of human generations, is longer than Homo sapiens has been around. Lenski has challenged the bacteria with strange feeding patterns - feeding them sugars, then starving them.
The colonies all adapted, quickly. But they used different genetic tricks to get there. Their DNA is now remarkably different: an example of parallel evolution.
It's difficult to know how an organism will adapt, and also how subtle environmental changes will kick evolution off in a striking new direction, said Ken Petron, a University of Cincinnati ecologist who worked with the Grants on their finches.
For example, on one trip to the Galapagos during a time of seed scarcity, the Grants expected to find the trend toward larger beaks. But a new, larger finch had colonized the island and was eating the larger seeds, Petron said. It was no longer an advantage for the smaller finches to grow larger beaks.
"It's very difficult to predict the outcome of evolution before it happens," he said.
But if biologists can get better at predicting evolution, it could have applications for areas in which humans are altering the environment and causing evolutionary pressures themselves, Langerhans said. Stanford University ecologist Stephen Palumbi has estimated a $50 billion "evolution bill" associated with the antibiotic and pesticide resistance that bacteria, weeds and insects have evolved in medicine and agriculture.
Had the experiment continued, Losos expected the lizard legs to get even shorter with successive generations. But two hurricanes in quick succession submerged the little islands. "All the living lizards were washed away. Bummer," Losos said.
Some eggs survived, however, and hatchling populations are growing. Losos plans to start the experiment over.
More lies from a drunken poster. We do not use such pix on our site (no matter how much you might fantasize about it), and DLR was warned to abide by posting rules. He was given the same chances as everyone else there, but he ignored them. Oh well, the other two creationists posting there have not had the same problem. Go figure. Of course, like I said, you are a liar. But, hey, what can we expect of someone who stalks a sweet littly lady across forums?
So basically you type your lies with one hand...
Okay, you've just called hundreds of thousands of biologists "liars." Would you care to back up your claim, or will you run, cowardly, like you did from your other unsupportable claim up thread?
Well, thanks for the advice. I am curious, what university did Moses attend? Oops! My mistake, you were referring to the authors! I expect they have attended all of them; omnipresence and all, dontcha know...
Backing up my claim:
Another reference: The Holy Bible
No no. That is you on your meds. Don't mistake me for taking the same treatment as you.
This thread is an embarrassment with two posterd acknowledging dishonesty without a scintilla of shame.
We will leave it with you. Thanks.
We will leave it with you. Thanks.
I agree completely with your post #512....you nailed it...
*Heck!* Even LC is more specific ! *Gosh!*
BTW, Newton wasn't a liar, though his mechanics were shown to be incorrect. Even Aristotle was no lier, though spilling a lot of claims which were shown to be false later.
The reason: Up to their best knowledge, they told the truth. That's the difference to your posts
Central Archivist/Junior, for somebody who has been throwing around the label "liar", you certainly exposed yourself as fitting the bill completely. Your disavowal in post #541 is the height of being disingenuous.
You can argue for your belief in evolution. However, to use an image of a dildo on a debate opponent, man.. don't you guys have any pride?? That is so eighth grade. For a bunch of "scientists", your credibility is sinking into the gutter, along with your website.
I felt a little sympathy for your cohort earlier this month, but I'm seeing what Jim Robinson saw, when he started cutting you folks down to size.
Appreciate the little revelation there. It sure cuts into anyone's credibility to be caught red handed like that. Just to let you know that people are out there seeing it.
You have demonstrably put forth a complete and utter falsehood regarding your treatment of me on your forum.
You really are a drama queen.
But the BIG LIE calls God a liar. Sounds like you sign on to the BIG LIE and therefore you are calling God a liar. You can call me a liar all you want but if you say God is a liar you will have to answer to Him, not me.
It's a dildo dipwit. Well, I can see where you might have made the mistake, having never seen the real thing before.
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