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.
I am not saying that it was. My problem is that in a complicated system (which I believed was designed with the ability to adapt) there is no reason to believe that the creature is not doing what it was programmed to do. Of ocurse the initial program is largely unknown so we are left with a mystery but we should not assume that the organism is somehow turning an accident into something beneficial. Someone designed a program that played checkers (for example) and his program did better than he planned by manipulating the inteligent input naturally. That is what I believe that "evolution" does in most cases.
I'm ready to play ball when you are. Over the past few years, your side has demonstrated a contempt for reason, disgust for logic and traded an upturned nose for an intelligent response. You (pl) are immune to logic but can't abide ridicule. You hypocritically demand I address the topic (as if it were worthy) yet let your own RWP slide with an infantile
Oh well, lead a horse to water...
What about the bad mutations? Who caused those? Mutations, both good and bad, are the result of the same process. Why discard the bad as due to "nature" and ascribe the good to God? Could some of the bad ones be due to God presenting a "challenge" to an individual?
Control over life sciences is where the fundamental revolution will occur, not control over the economy, control over politics, control over society, control over nuclear fission.
--Aldous Huxley
Nah, just too dumb to know what the quotes meant. As some wag put it, there's no reason to attribute bad intent when simple stupidity will suffice.
So you're saying your side won't debate unless there's a large sum of money involved.
One of us is willing to remove all suspicion that this is other than an intellectual contest. Why isn't the other? Possibly because that isn't what they had in mind?
Be my guest. I'll await your reasoned, logical, intelligent rebuttal to the article above. Or your reasoned, logical, intelligent assent to its methods and conclusions - either way.
I recall watching a very interesting program on genetics several years ago. It discussed a mechanism which I believe was called the "homeo-box".
The homeo-box was a genetic sequence which appears in all higher animals and which appears to have a role in eliminating viability of some very dramatic genetic abnormalities during gestation.
An example of an organism without the homeo-box was, I believe, one of many types of flies. Flies are sometimes born with extra sets of legs or with legs growing out of parts of the body where they don't belong. I think that the legs can even be quite functional but probably don't lend much to the success of the fly.
Organisms with the homeo-box do not exhibit this type of genetic abnormality. The research seemed to indicate that the function of the homeo-box sequence was to accomplish some sort of accounting of early fetal development and to initiate a spontaneous abortion if the accounting indicated that a severe problem had been detected.
Another aspect of genetic variability which I think is not sufficiently appreciated is that the typical genome appears to contain a high percentage of unexpressed genes.
I would not be surprised if it is found or has been found that this unexpressed genetic material is the storehouse of past genetic mutations which have been preserved in an inactivated state. The evolutionary value of having a ready supply of previously successful but abandoned mutations could be quite high.
The posted article discusses coloration as a heritable trait. Millions of years of evolution could favor a plant which is able to readily mutate its color as a response to environmental stress. The typical pollenator may have a tendency to sample unrecognized plants in an attempt to profit early from the introduction of a new plant into the area. Plants which have an inbred system for being able to change colors may outproduce those which are rigidly programmed to be a fixed color.
Long periods of time could pass during which the survival value of readily being able to change color would be of no value. When a drought or similar stressful time appears, those plants which tend to "experiment" randomly with alternate colors can find themselves outproducing those which don't.
I find myself rather amazed by those who believe that they are successfully attacking "Darwinism" by suggesting that his initial explanations are incomplete or inexact.
To me, this would be similar to suggesting that there is no legitimacy to our understanding of the periodic table of the elements because high-speed semiconductors are not predictable from the most obvious chemical combinations.
I am a Christian so I believe in a battle between the forces of good and evil (which all of nature attests to). What God is or is not doing directly, I don't know.
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