Posted on 11/13/2003 10:23:32 AM PST by PatrickHenry
EAST LANSING, Mich. – For more than a century, scientists have concluded that a species evolves or adapts by going through an infinite number of small genetic changes over a long period of time.
However, a team of researchers, including a Michigan State University plant biologist, has provided new evidence that an alternate theory is actually at work, one in which the process begins with several large mutations before settling down into a series of smaller ones.
The research is published in the Nov. 12 issue of the journal Nature.
“The question is asked, ‘If a population finds itself in some maladaptive state, due perhaps to a change in climate, how will it adapt?’” said Douglas Schemske, MSU Hannah Professor of Plant Biology and a member of the research team. “The evidence that has come to light recently – both in plants and other organisms – is that the initial changes are bigger than we might have expected.”
To study the question, Schemske and his colleagues used a common plant called the monkeyflower, changing its genetic make up in a rather dramatic way to see if it would attract new pollinators – hummingbirds instead of bees or vice versa.
By moving a small piece of the genome between two different species of the plants – the pink-flowered M. lewisii and the red-flowered M. cardinalis – the researchers created different colored flowers that attracted new pollinators.
“We discovered that moving this single genetic region caused a dramatic increase in visitation by a ‘new’ pollinator,” Schemske said. “Specifically, the orange flowers produced on the previously pink flowered and bee-pollinated M. lewisii were regularly visited by hummingbirds but shunned by bees.
“Also, the pink flowers of the previously hummingbird-pollinated M. cardinalis were attractive to both bees and hummingbirds,” he said.
Schemske and H.D. “Toby” Bradshaw, a professor of biology at the University of Washington and the lead author of the paper that appeared in Nature, said altering the genetic region responsible for the flowers’ color is much like what could happen during a naturally occurring mutation.
“Perhaps a single mutation having to do with color changed the pollinator milieu back when there was only a single species,” Bradshaw said. “That one big evolutionary step may then have been followed by many smaller steps triggered by pollinator preferences that led ultimately to different species.”
Schemske compared the process to the repairing of a finely tuned watch.
“In our model, the first adaptive adjustments might require big changes, similar to banging the broken watch a few times before making the final small tweaks to restore its optimal performance,” he said.
The plants used in the work were produced in a campus greenhouse and then transported to an area near the Yosemite National Park where natural populations of both species occur.
“This was a rather unique aspect of the work,” Schemske said, “in that it combined molecular genetic techniques and ecological observations to elucidate the process of adaptation in natural populations.”
The work was supported by a grant from the National Science Foundation.
Another service of Darwin Centraltm. Our motto: "Defrauding the world for 150 years"
You've got hopes...
I'll give it a go (I like banging my head against a wall!). You, me, and everyone else are similar to our parents but not exact copies. We take genes from each plus have some that are random and unique to ourselves. This is happening all the time and the unique changes can be good or bad. These changes aren't made by someone or something, they're the result of the complex process during fertilization. Some of the unique changes are bad enough that you miscarry. Some are good and the result is that you have superior intelligence or are more athletic than others, etc. Presumably, this would allow you to propagate your genes further.
I have a problem with the popular accounts of evolution. They describe it in a way that gives the appearance of active guidance or intent. There is no intent in evolution. The random, unique changes are both good and bad. I also think there's a tendency to dismiss the magnitude of genetic errors in early pregnancy. We see the billions of people around us and think that pregnancies work all the time. In reality, something like 20-30% of pregnancies fail after being detected (ie. after implantation) and these were strong embryos with fairly small genetic errors. The total failure rate from the moment of fertilization is much higher. I'd bet that the total failure rate from fertilization to viability is over 50%. Mutations occur all the time.
Once you realize that mutations are happening all the time it's easy see how evolution occurs. I guess my main question to people who claim that evolution is a "fairy tale" is this: do you deny the documented mutations that occur in early pregnancy? If you do, then you're a flake. If you don't, then why is it so difficult that smaller mutations are occuring all the time?
I do not question mutations at all. I do question the assertion that beneficial mutations are not directed by the same being who created life to begin with.
Didn't one of his buds on another thread say that FR censors the truth and that anyone who tells the truth will be banned? Gore must have been too truthful to last on FR.
-------------------------------------------------------------------------------- To: Right Wing Professor "My mind is made up, don't bother me with science" Thanks for the confession. Your honesty is refreshing in these kind of debates. 16 posted on 11/13/2003 11:03 AM PST by Raymond Hendrix -------------------------------------------------------------------
At our last precinct caucus we had a highschool student attend his first one. When asked why he chose to caucus as a Republican instead of a Dem, he said, "When the students are smarter than the teachers and the Democrats run the schools, it's time to get active in the other party."
The issue was whether speciation occurs gradually, or by a single major change followed by a set of smaller changes. Where the plant originally came from, while relevant to evolution as a whiole, is not germane here. Mutation accounts for the variation; natural selection accounts for its becoming dominant in the population.
If a the original "watch" came from the intervention of an intelligent being then why would you attribute later variation or improvement on a random or un-directed mutation? You are just stating a belief without a foundation.
Whether or not the original plant was made by an intelligent being, we have in this present instance a case where a change in a single allele caused a gross change in the organism, which closely resmbles the change required to generate one known species from another. This argues that there is no necessity to assume intervention by an intelligent being in the present instance
------------------------------------------------------ To: Raymond Hendrix Neener neener neeener. 30 posted on 11/13/2003 1:45 PM CST by Right Wing Professor ------------------------------------------------------------
See what I mean?
But the case under discussion is a beneficial mutation, at least for plants in regions where hummingbirds are the dominant pollinator. I've read the entire paper, and I don't see where divine intervention was involved.
It must be true, though, because a bunch of nobodys named Steve believe it.
Yes, if you mean that you lack a sense of humor.
Did you read the paper?
And on another subject, where's the debater you promised me?
...says the fellow who has absolutely nothing to offer on the particular topic at hand, but plenty to say about the people who do.
How about just addressing the data, man? Or is meta-commentary the best we can expect?
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