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.
It must be penis envy - for it IS a black dildo! ;^)
Is the Paint Drying channel not coming in clearly? ;^)
Did we all eat a bunch of bad turkey or WHAT???
how is dildo as opposed to penis any different? This must be such a very fine distinction that only a highly honed and sophisticated mind like that of the darwin-central crowd can graspNooooooo comment.
Oh and BTW, there is no comparison to what your site did toward DLR and anything that has happened on the FR.Oh, I disagree entirely! In the eyes of the frevolutionists, they were being persecuted because Jim Robinson was nuking the rude members, and disagreeing with the rest. This caused them to run away howling and shrieking to their own forum, where they could exercise much more freedom to lick their imagined wounds and hurl insults at Jim. Lo and behold, in comes someone who disagrees with them. He doesn't immediately shake hands with those who have stabbed him in the back multiple times on FR, and therefore he is trolling for a fight, and is nuked basically for no other reason than because he disagreed. They'll try to say he wasn't playing by the rules, but that's all make-believe.
For example, they have a specific injunction against promoting ID/creationism where FR does not prohibit promoting evolution.
Witnessing is prohibited, yet FR doesn't mention not promoting atheism.
The prohibition of not promoting the agenda of the left is actually funny considering the support the ACLU enjoys from the evos.
The prohibition against spam regurgitation (dumping tracts into threads) does not have an equivalent here because there is no prohibition against someone posting *scientific* evidence in the form of research papers to support their belief about the correctness of evolution.
I find it amusing that they so freely admit that if you post anything that violates their restrictive posting guidelines, you are a goner, but whine when over here about how JR runs HIS site when some of them get the axe for violating HIS less restrictive posting guidelines.
They just want to control BOTH websites and are pretty peeved that they haven't accomplished that here yet.
I guess that's where the Free of Free Republic comes in.
And here I thought only two year olds were so obsessed with potty talk.
That's funny. I hear a sizzling noise.
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