Quizzes & Puzzles3 mins ago
Evolutionary Biology
Can anyone tell me if there is ananimal that's evolution in any way has been affected by humans? By this i mean, when the creature is born, something in it's genetic structure would not be the way it is if humans hadn't impacted on it in sime way. Viruses are an example that would fit this, but i'm wondering about more complex organisms.
The only example i've heard of is some type of wood pigeon which had previously foraged on the canopy, but due to human factors the fruits there no longer existed, so the bird was forced to forage lower down. Now, even when there is abundance above, the birds still tend to look on the ground. I'm not sure on the details of this case, and how it was tested to make sure it wasn't just learned behaviour.
The only example i've heard of is some type of wood pigeon which had previously foraged on the canopy, but due to human factors the fruits there no longer existed, so the bird was forced to forage lower down. Now, even when there is abundance above, the birds still tend to look on the ground. I'm not sure on the details of this case, and how it was tested to make sure it wasn't just learned behaviour.
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This one's debateable, but interesting nonetheless: http://en.wikipedia.org/wiki/Peppered_moth_evo lution
There must be several examples where humans have either deliberately or accidentally introduced species to another part of the world. Once that population is genetically isolated from its parent population it will evolve according to the selection pressures prevalent in its new location.
Rats and mice are frequent examples of this and are particularly isolated once introduced to island ecosystems. Some work has been carried out on rodents introduced accidentally to antarctic and sub-antarctic islands where the cold climate is the main selection factor. Some have evolved to be larger (less heat loss per gram) and others have fur modifications (greater insulation).
A reference to one such study can be seen here:
http://www.springerlink.com/content/g275481030 xh2457/
Rats and mice are frequent examples of this and are particularly isolated once introduced to island ecosystems. Some work has been carried out on rodents introduced accidentally to antarctic and sub-antarctic islands where the cold climate is the main selection factor. Some have evolved to be larger (less heat loss per gram) and others have fur modifications (greater insulation).
A reference to one such study can be seen here:
http://www.springerlink.com/content/g275481030 xh2457/
Seems we continue meeting on the subject of evolution drestie. I'm glad that you opened your post with the consideration of "debatable"... since numerous studies following Bernard Kettlewell's paper have found the speciation implied therein doesn't exist... This from Jonathan Wells, Phd., Department of Molecular Cell Biology, University of California Berkeley, California, USA : "The geographic distribution of melanic peppered moths did not fit the theory: the frequency of melanics was not as high as it should have been in some places, and higher than it should have been in others. Furthermore, melanism is not correlated with lichen cover; in the U.K., it declined before lichens returned to the trees, while in the U.S., it occurred despite the presence of lichens and declined without any perceptible changes in lichen cover. Finally, peppered moths do not normally rest on tree trunks: instead, they normally rest under horizontal branches high in the canopy, not where Kettlewell and his successors had carried out their experiments on selective predation.... this classical story of evolution by natural selection, as it continues to be retold in many textbooks, is seriously flawed. In particular, the illustrations which typically accompany the story (like the photographs in Figure 1) mislead students by portraying peppered moths on tree trunks where they do not normally rest. Unknown to Kettlewell, his experiments had less to do with natural selection than with unnatural selection, and the true causes of industrial melanism in peppered moths remain largely unknown." (Document dated 1999)...
Well a lot of animals have been deliberately bred by humans with great distinctions.
Horses for example from huge Shire's to tiny Shetland ponies - the evolution of the modern horse is entirely a human construct to the point that almost without exception racehorses trace their ancestry back to one of 3 horses, Herod, Eclipse or Matchem.
You'd certainly never have seen anything remotely like Red Rum wandering across the Russian Steps 50,000 years ago!
Horses for example from huge Shire's to tiny Shetland ponies - the evolution of the modern horse is entirely a human construct to the point that almost without exception racehorses trace their ancestry back to one of 3 horses, Herod, Eclipse or Matchem.
You'd certainly never have seen anything remotely like Red Rum wandering across the Russian Steps 50,000 years ago!
Most/all intensively farmed animals have been bred for certain characteristics that will make them easier to sell, such as chickens with unnaturally large breast areas: completely unnecessary for flight, but preferable when selling. This is true of modern day cows and pigs that you will see on farms.
I seem to recall hearing a similar thing about wheat, or at least some species of wheat. Where it has actually become dependent on human interaction for propogation. I think the plants were cross polenated with other species and selectively bred until the seeds (the part that is used to make flour, etc) became so large, that they can no longer disperse with the plants actions alone. Without human action (continually harvesting the wheat and re-seeding some of the seeds) this species would become extinct. So not only have humans created species, but allow unviable species to survive.
I seem to recall hearing a similar thing about wheat, or at least some species of wheat. Where it has actually become dependent on human interaction for propogation. I think the plants were cross polenated with other species and selectively bred until the seeds (the part that is used to make flour, etc) became so large, that they can no longer disperse with the plants actions alone. Without human action (continually harvesting the wheat and re-seeding some of the seeds) this species would become extinct. So not only have humans created species, but allow unviable species to survive.
Clanad, Jonathon Wells is hardly an impartial scientist. He himself has stated that he studied Biology "to destroy Darwinism", and is a member of the Discovery Institute, an organisation dedicated to spreading creatonism/ID at the expense of evolutionary theory.His work on this area was based around reviews of researchers in the field, and his conclusions are based more upon selective quotation and biased editorialising than objective review.. The principals who he quoted have since rejected his comments on their behalf. Majerus, the most respected researcher in this field has commented himself the following;
"To end, may I put on record to you, that my view is that the rise and fall of the carbonaria form of the peppered moth has resulted from changes in the environments in which this moth lives. These changes have come about as a result on changes in pollution levels which have altered the relative crysis of the forms of this moth. The main, if not the only selective factor that has lead to changes in the frequencies of the forms over time is differential bird predation. The case of melanism in the peppered moth IS ONE OF THE BEST EXAMPLES OF EVOLUTION IN ACTION BY DARWIN'S PROCESS OF NATURAL SELECTION that we have. In general it is based on good science and it is sound."
(Majerus email to Don Frack, posted March 30, 1999. Capitalization original.
Wells assertion that peppered moths do not rest on tree trunks is plain wrong. Peppered moths have been observed resting on ALL parts of a tree, although with a preference toward the trunk/branch intersection.
"To end, may I put on record to you, that my view is that the rise and fall of the carbonaria form of the peppered moth has resulted from changes in the environments in which this moth lives. These changes have come about as a result on changes in pollution levels which have altered the relative crysis of the forms of this moth. The main, if not the only selective factor that has lead to changes in the frequencies of the forms over time is differential bird predation. The case of melanism in the peppered moth IS ONE OF THE BEST EXAMPLES OF EVOLUTION IN ACTION BY DARWIN'S PROCESS OF NATURAL SELECTION that we have. In general it is based on good science and it is sound."
(Majerus email to Don Frack, posted March 30, 1999. Capitalization original.
Wells assertion that peppered moths do not rest on tree trunks is plain wrong. Peppered moths have been observed resting on ALL parts of a tree, although with a preference toward the trunk/branch intersection.
Be that as it may, Lazy Gun, there are many other credentialed scientists that have found fault with the premise re: The Peppered Moth... (I was unaware of Wells predisposition, by the way). Good examples would be Fine Tuning the Peppered Moth Paradigm, by Bruce S. Grant, Department of Biology, College of William & Mary, Williamsburg, VA, Craig Holdrege (1999). "The Case of the Peppered Moth Illusion," Whole Earth (Spring 2000 Issue), Judith Hooper (2002), Of Moths and Men, Jerry A. Coyne, Not Black and White in Nature, Vol. 396, Nov. 5, 1998, pp 35-36, ad infinitum. I realize full well that with just a little effort, you will be able to provide your own list in support of your position. I respect that and am simply engaging in drestie's prescient observation. I wouldn't be quite so hasty in dismissing Mr. Wells writings base solely on his perceived predjudice... to do so will eliminate just about all opponents, one or the other...in my opinion...
Apparently so, Jake, according to the research I did on him.
Clanad is right enough when he says that you do have some scientists arguing against the orginal theory, but those experts in the field who have reproduced Kettlewells original work, and have themselves spent many years studying the Peppered Moth are all broadly in agreement with the original premise.
Based upon what little I know about the subject, the objections to the original work seem to be largely based around a strong desire to debunk the work, rather than just an impartial review of the science.
Clanad is right enough when he says that you do have some scientists arguing against the orginal theory, but those experts in the field who have reproduced Kettlewells original work, and have themselves spent many years studying the Peppered Moth are all broadly in agreement with the original premise.
Based upon what little I know about the subject, the objections to the original work seem to be largely based around a strong desire to debunk the work, rather than just an impartial review of the science.
On the original question there are lots of examples where man has altered the genetic make-up of an animal. You could divide the effects into two, deliberate and accidental:
Deliberate: all farm animals are bred as jake has said (horses, cows, etc.); Sheep have been cloned (through genetic engineering) fruit flies and other lab studies have deliberately altered genes and behaviour, Dogs and cats are bred for characteristics such as size or temperament.
Accidental: Peppered moth, peregrine falcons, pigeons, gulls, rats, etc. in other words animals that have adapted to town life have adapted their behaviour in response to environmental changes. Unfortunately, accidental changes often lead to extinction or depletion of the stock of the animal in question or a competitor, e.g. effect of red squirrel population in uk from introduction of grey squirrel.
According to Steve Jones, Wolves would have originally been tolerated by early man if they offered some benefit like protection from some other predator or they could have led humans to a food source. The more social of the wolves may have even been fed scraps or orphan pups taken in. This was the start of the domestication of the dog. Domesticated dogs have been far more successful than their wild cousins.
Deliberate: all farm animals are bred as jake has said (horses, cows, etc.); Sheep have been cloned (through genetic engineering) fruit flies and other lab studies have deliberately altered genes and behaviour, Dogs and cats are bred for characteristics such as size or temperament.
Accidental: Peppered moth, peregrine falcons, pigeons, gulls, rats, etc. in other words animals that have adapted to town life have adapted their behaviour in response to environmental changes. Unfortunately, accidental changes often lead to extinction or depletion of the stock of the animal in question or a competitor, e.g. effect of red squirrel population in uk from introduction of grey squirrel.
According to Steve Jones, Wolves would have originally been tolerated by early man if they offered some benefit like protection from some other predator or they could have led humans to a food source. The more social of the wolves may have even been fed scraps or orphan pups taken in. This was the start of the domestication of the dog. Domesticated dogs have been far more successful than their wild cousins.
The reason you can dismiss Wells is because of his stated views on many a topic:
He is unsure of the age of the earth (he thinks it might be 4.5 billion years old but the more evidence he sees the less he's sure)
He is dismissive of the link between HIV and Aids (A position he shares with his hero Philip E Johnson, he of the wedge strategy of toppling evolution because of its godless naturalist philosophy. A quote from Johnson: "This isn't really, and never has been a debate about science. It's about religion and philosophy." )
He is or was a moonie with a mission:
He urges US government to eliminate research funding for evolutionary biology.
"Father's words, my studies, and my prayers convinced me that I should devote my life to destroying Darwinism, just as many of my fellow Unificationists had already devoted their lives to destroying Marxism. When Father chose me (along with about a dozen other seminary graduates) to enter a Ph.D. program in 1978, I welcomed the opportunity to prepare myself for battle."
He champions irreducible complexity which has no basis in science and no evidence in support and about 6 (six) dubious peer reviws yet denies evolution which has 150 years peer reviewed evidence based on a few selective and dishonest misquotes of other peoples work.
Try and provide an anti-evolution argument that has been advanced by someone who doesn't oppose it on religious grounds.
He is unsure of the age of the earth (he thinks it might be 4.5 billion years old but the more evidence he sees the less he's sure)
He is dismissive of the link between HIV and Aids (A position he shares with his hero Philip E Johnson, he of the wedge strategy of toppling evolution because of its godless naturalist philosophy. A quote from Johnson: "This isn't really, and never has been a debate about science. It's about religion and philosophy." )
He is or was a moonie with a mission:
He urges US government to eliminate research funding for evolutionary biology.
"Father's words, my studies, and my prayers convinced me that I should devote my life to destroying Darwinism, just as many of my fellow Unificationists had already devoted their lives to destroying Marxism. When Father chose me (along with about a dozen other seminary graduates) to enter a Ph.D. program in 1978, I welcomed the opportunity to prepare myself for battle."
He champions irreducible complexity which has no basis in science and no evidence in support and about 6 (six) dubious peer reviws yet denies evolution which has 150 years peer reviewed evidence based on a few selective and dishonest misquotes of other peoples work.
Try and provide an anti-evolution argument that has been advanced by someone who doesn't oppose it on religious grounds.
Several dissenting views re the Peppered Moth have been suggested Clanad. Bear in mind I am not an expert, just an interested reader.
1. Original work showed peppered moths resting on tree trunk, and the natural selection agent was birds picking off those moths that hadnt changed colour. Dissenting view.... peppered moths dont rest on tree trunk. Follow up research... Peppered Moths rest on all parts of the tree, although with a preference for the juncture of trunk and branch.
2.Industrial pollutants acted as a mutagen on individual eggs/plasm. Reseach has disproven this.
3. Peppered moths were glued to the tree trunk, skewing the results and invalidation the original work with suggestions of fakery to validate evolutionary theory... It has often been pointed out that dead moths were indeed glued to tree bark, but this was purely so that photographic evidence of both the camofluage effect and also birds taking the moths could be collected. It does not invalidate the overwhelming weight of evidence collected by both the original researcher and subsequent researchers.
Have I missed any?
1. Original work showed peppered moths resting on tree trunk, and the natural selection agent was birds picking off those moths that hadnt changed colour. Dissenting view.... peppered moths dont rest on tree trunk. Follow up research... Peppered Moths rest on all parts of the tree, although with a preference for the juncture of trunk and branch.
2.Industrial pollutants acted as a mutagen on individual eggs/plasm. Reseach has disproven this.
3. Peppered moths were glued to the tree trunk, skewing the results and invalidation the original work with suggestions of fakery to validate evolutionary theory... It has often been pointed out that dead moths were indeed glued to tree bark, but this was purely so that photographic evidence of both the camofluage effect and also birds taking the moths could be collected. It does not invalidate the overwhelming weight of evidence collected by both the original researcher and subsequent researchers.
Have I missed any?
Not bad, LazyGun... with the considered exception of factual information askew from current findings... From New Republic magazine dated March 1999: Background:
According to the standard account, only one version of Biston betularia existed before the mid-19th century: a white variety, peppered with black spots. During the Industrial Revolution its numbers plummeted because it became easy prey for birds as it rested on the pollution-blackened trunks of trees.
In its place a mutant, pitch-black form of the peppered moth began to thrive, as it could rest on tree trunks without fear of being eaten. Precisely as predicted by Darwin's theory of natural selection, this "fitter" mutant moth rapidly outnumbered the white version, reaching 100 per cent levels in some industrial areas.
During the Fifties, however, naturalists discovered a resurgence of the white variety, prompting the belief that Darwin had struck again through the Clean Air Acts, which had led to the return of unpolluted trees. These allowed the white moths to regain their Darwinian ascendancy, while the numbers of the now all-too-visible black variety fell.
Scientists are beginning to concede that the white variety flourished again well before the return of pollution-free trees, while the black type continued to thrive in areas unaffected by industry. Experiments have also shown that neither moth chooses resting places best suited to its camouflage. Most damning of all, despite 40 years of effort, scientists have seen only two moths resting on tree trunks - the key element of the standard story and Kettlewell's experiments.
Contd.
According to the standard account, only one version of Biston betularia existed before the mid-19th century: a white variety, peppered with black spots. During the Industrial Revolution its numbers plummeted because it became easy prey for birds as it rested on the pollution-blackened trunks of trees.
In its place a mutant, pitch-black form of the peppered moth began to thrive, as it could rest on tree trunks without fear of being eaten. Precisely as predicted by Darwin's theory of natural selection, this "fitter" mutant moth rapidly outnumbered the white version, reaching 100 per cent levels in some industrial areas.
During the Fifties, however, naturalists discovered a resurgence of the white variety, prompting the belief that Darwin had struck again through the Clean Air Acts, which had led to the return of unpolluted trees. These allowed the white moths to regain their Darwinian ascendancy, while the numbers of the now all-too-visible black variety fell.
Scientists are beginning to concede that the white variety flourished again well before the return of pollution-free trees, while the black type continued to thrive in areas unaffected by industry. Experiments have also shown that neither moth chooses resting places best suited to its camouflage. Most damning of all, despite 40 years of effort, scientists have seen only two moths resting on tree trunks - the key element of the standard story and Kettlewell's experiments.
Contd.
Contd
According to Michael Majerus, a Cambridge University expert on the moth, Dr. Kettlewell tried to confirm the standard story simply by pinning dead moths on to parts of the trees where they could be seen easily by birds. Dr. Majerus said: "He stuck them on low branches because he wanted to sit in his hide and watch them being eaten. They actually seem to rest in the shadows under branches, which makes even the black ones difficult to spot by birds."(Emphasis added)
Scientists are now beginning to doubt even the basic presumption that birds were responsible for the changing fortunes of the different types of Biston. According to Prof Jerry Coyne, an expert on evolution at the University of Chicago, when Dr Kettlewell could not get the moths he needed naturally, he bred them in his laboratory.
Prof Coyne said: "That could affect their vigour, so the level of bird predation he saw was just due to the fact that his moths were raised in the lab. In one case, Kettlewell actually used to warm them up on the bonnet of his car."
Prof Coyne insisted, however, that the moths are almost certainly an example of natural selection: "I'm certainly not saying Darwin is wrong. The real cause is probably connected with pollution - but beyond that I wouldn't want to go." He said, however, that Dr Kettlewell's widely-quoted experiments are essentially useless. "There is a lot of wishful thinking and design flaws in them, and they wouldn't get published today."
So, it would appear that your argument isn't with religious zealots but with well credentialed scientists arriving at their postions from observation and testing... rather vigorous scientific endeavours, no?
According to Michael Majerus, a Cambridge University expert on the moth, Dr. Kettlewell tried to confirm the standard story simply by pinning dead moths on to parts of the trees where they could be seen easily by birds. Dr. Majerus said: "He stuck them on low branches because he wanted to sit in his hide and watch them being eaten. They actually seem to rest in the shadows under branches, which makes even the black ones difficult to spot by birds."(Emphasis added)
Scientists are now beginning to doubt even the basic presumption that birds were responsible for the changing fortunes of the different types of Biston. According to Prof Jerry Coyne, an expert on evolution at the University of Chicago, when Dr Kettlewell could not get the moths he needed naturally, he bred them in his laboratory.
Prof Coyne said: "That could affect their vigour, so the level of bird predation he saw was just due to the fact that his moths were raised in the lab. In one case, Kettlewell actually used to warm them up on the bonnet of his car."
Prof Coyne insisted, however, that the moths are almost certainly an example of natural selection: "I'm certainly not saying Darwin is wrong. The real cause is probably connected with pollution - but beyond that I wouldn't want to go." He said, however, that Dr Kettlewell's widely-quoted experiments are essentially useless. "There is a lot of wishful thinking and design flaws in them, and they wouldn't get published today."
So, it would appear that your argument isn't with religious zealots but with well credentialed scientists arriving at their postions from observation and testing... rather vigorous scientific endeavours, no?
You know, dawkins, I've been aware for a long time, probably since our first encounter, that you are an atheist, by your own claim. However, we've engaged in numerous debates (usually without adequate resolution) but I've always respected your position and ability to intelligently express your views. I've never let your beliefs color the central theme of our discussion(s). You, on the other hand are clearly stating that if anyone, including well established scientists (of whom there are thousands), takes a position and expounds on that position, it must be disregarded, even derided due only to the fact that the expounder of those views is religious. I find that narrow minded and bordering dangerously on bigotry... traits I wouldn't like to attribute to anyone with whom I have a philosophical or knowledge based debate... but I am troubled by your position as stated... Wells views are experientially based regardless of his motivations. All scientists and investigators are motivated... possibly predjudiced, in one way or another, no?
Sorry Clanad!
I am not going to even try to enter into the evolution/religion debate... still trying to solidify my own opinions. But I love reading all these discussions, as long as they stay civil and informative :)
I know I should probably start my own thread, but I would be very interested to hear from all of you about how you deal with your personal religious beliefs if they do not fit in with your scientific knowledge. I personally struggle with this on a daily basis.
I am not going to even try to enter into the evolution/religion debate... still trying to solidify my own opinions. But I love reading all these discussions, as long as they stay civil and informative :)
I know I should probably start my own thread, but I would be very interested to hear from all of you about how you deal with your personal religious beliefs if they do not fit in with your scientific knowledge. I personally struggle with this on a daily basis.
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