A mutation is an alteration of a gene's DNA sequence. Mutations are usually bad news, but those rare changes that benefit an organism are the raw material of evolution.
DNA needs to be copied when cells divide, so that each new cell has a complete set of genetic instructions. The cellular process of copying DNA is full of mechanisms that check and double check the construction of a new DNA molecule. But when changes, or mistakes do occur, it is usually harmful or at best has no effect on the organism.
Very, very rarely a mutation results in a change that is advantageous to an organism; providing some characteristic that confers an edge to the organism, some type of survival advantage that ultimately results in the mutated organism leaving more offspring (copies of its genes) that do others in the population.
Mutations & Natural Selection
Natural selection is the mechanism of evolution, the process in nature by which only the organisms that are best adapted to their environment tend to survive and transmit their genetic characteristics to the next generation. Individuals less well adapted to their environment tend to be eliminated, where environment represents the combined biological and physical influences.
The meaningful difference between the organisms of a population is genetic; differences in the genome of one member of a population compared to the others. These differences arise through mutation.
The Power Is in Natural Selection over Time:Reproductive Isolation & Extinction
Over time, natural selection can even result in sub-populations within a species being so genetically different that they are no longer able to reproduce with each other. They become separate species (reproductive isolation). But natural selection does not always result in new forms or species. Natural selection may also result in the elimination of species from the environment (extinction).
Natural Selection Example:The Peppered Moth
The peppered moth (Biston betularia) is a temperate nocturnal moth species that provides a great example of natural selection.
The Peppered Moth Pre-industrial Revolution
In England, the common color of peppered moths was light gray (Biston betularia f. typica), prior to the industrial revolution. The moth’s light gray color closely matched the lichen-covered trees in their environment.
There was also a genetic color variant in the moth population that resulted in some, relatively rare, very dark colored moths (Biston betularia f. carbonaria). Their numbers remained low because when these dark moths landed on the light grey lichen-covered tress, they were easy targets for predators.
The Peppered Moth after the Advent of Industry
Early coal-based industry was extremely dirty, and around large cities, everything was essentially covered in soot. This high level of pollution killed the light gray lichens on trees and the bark became much darker in appearance.
When the light-colored peppered moths landed on the same trees they had always landed on, they were extremely visible against the dark bark, and easy targets for predators. The dark colored moth variant now had the advantage, being harder for predators to spot and more often living long enough to reproduce.
Over generations, the polluted environment continued to favor darker moths, and they progressively became more common. By the late 19th century, 98% of the moths near cities were black.
Biston betularia in an Era of Modern, Cleaner Industry
Modern air pollution controls have cleaned up the environment compared to the early days of the industrial revolution. The cleaner environment has allowed the lichens to grown back, and the trees have returned to a lighter in color. Now, natural selection favors lighter moth varieties so they have become the most common and the dark-colored variant is again rare.
More Information
For more information on evolution and general biology see the science website Science Prof Online.
Sources
Brown, Bryson (2007) Evolution: A Historical Perspective. Greenwood Press.
The copyright of the article DNA Gene Mutations & Evolution in Genetics & Evolution is owned by Tami Port. Permission to republish DNA Gene Mutations & Evolution in print or online must be granted by the author in writing.
The Peppered moth? Really? Do evolutionists still use that as a case for
evolution? Amazing! Both dark and light varieties of peppered moths
existed in Britain before, during, and after the Industrial Revolution.
Therefore, the Industrial Revolution did not cause any new varieties to
evolve through mutation. The proposed explanation for the alleged change in
the ratio of light to dark moths was based on the effectiveness of the
moth’s camouflage when the moth landed on a tree trunk. But since peppered
moths don’t normally land on tree trunks (they rest on the undersides of
leaves), the hypothetical effectiveness of the camouflage is irrelevant. If
there was any change in the ratio of light to dark moths, it didn’t have
anything to do with camouflage and thus with adaptation to environmetal
change through mutation and natural selection. The idea that diet,
exercise, or the environment, can somehow change the DNA in the
reproductive cells so that the offspring are better adapted to the
environment is without scientific support. Adaptations are not acquired and
inherited. The genetic information is there to begin with. If a creature
already has the genetic potential to survive in its environment, it adapts
and survives. If it doesn’t have the genetic information to survive in that
environment, it migrates to an environment where it can survive, or it
dies. Often, it is the latter. That’s why there are so many extinct
species.
Jun 12, 2008 5:08 PM
Tami Port :
Yes. I and scientists much wiser, textbooks and university biology programs
still use this example, because it’s an elegant illustration of how natural
selection works. I am afraid that you may be misunderstanding what the
Peppered moth example illustrates. No new species of Peppered moth evolved.
And yes, there were light and dark variants before, during and after the
industrial revolution. That fact in no way detracts from the example. The
proportion of dark and lighter Peppered moth color variants in the
population shifted under the selective pressure of predation. That’s the
point…natural selection.
Nor is this example about environment
changing a single organism's DNA. The inheritance of acquired
characteristics (Lamarckianism...what your statement about diet and
exercise changing DNA implies) is an antiquated hypothesis that, as you
mention, is without scientific merit. Lamarckianism is not, in any way,
similar evolution via natural selection.
With respect to your
comment on where Peppered moths do and do not land, the text book examples
do often oversimplify this point. I’d recommend that you see Bird Predation
Theory (BPT) and Bernard Kettlewell’s experiments for clarification on why
oversimplifying this example doesn’t invalidate the theory of natural
selection as a mechanism for evolutionary change. And Peppered moths are
certainly not the only example. Over substantial periods of time, natural
selection has the power to make populations (like the Galapagos finches for
example) so different that selection can ultimately result in distinct
species.
Jan 5, 2009 11:59 AM
Guest :
Is this realy Natural selection or just adaptation. i f you think about it
they might seem similar but they are very different; how so? Fisrt of
natural selection means that you need a new piece of DNA, which could
explain how evolution works, but as some know it is impossible without
human intervention, to add on new genetic material; this is where adapation
differs. It suggests that an already exsisting form of DNA is modified so
that it's host is better adapted to it's environment. So then my question
to you is, how did evolution occur?
Jan 6, 2009 1:26 PM
Tami Port :
Regarding the January 5th comment... I am afraid that your
understanding of genetics is flawed. Natural selection does not require a
'new' piece of DNA, merely genetic variability which comes about through
mutation and sexual reproduction (shuffling of the genes); and unless you
are talking about artificial selection (such as dog breeding), human
intervention is not required at all. Evolution is the process of biological
change which occurs when some individuals in a genetically variable
population are better suited to survive and reproduce in their environment
than are others in that same population. In the peppered moth example,
there was genetic variation in color of the moths. Those moths that were
best camouflaged were more prone to survive and successfully reproduce,
leaving more offspring like themselves (more of their genes) in the next
generation. Moths of a color variation less camouflaged and more
conspicuous were less likely to survive and reproduce, leaving less of
their genes in the nexst generation. There are many good books on evolution
and natural selection, including "Evolution 101" by Randy &
Janice Moore, but any solid general biology textbook, such as Campbell
& Reece's "Biology" can provide a straightforward
explanation.
Mar 10, 2009 9:36 PM
Guest :
natural selection is not a kind of mutation.it is an evolution created
because of the morphology.psycology and the behaviour of the individu. the
better the individu can adapt with the new environment the more success the
individu can survive.
Mar 23, 2009 10:07 PM
Guest :
The theory of natural selection being the tool of the evolutionary process
sounds good until you consider the overall evolutionary process. Quote:
"Natural selection does not require a 'new' piece of DNA, merely
genetic variability which comes about through mutation and sexual
reproduction" The first form of life had no genetic material from
which to have any variability-thus it would have required a 'new' piece of
DNA unless I'm misunderstanding things and it is possible to find thousands
of 'variations' of deoxyribonucleic acid in the ocean or wherever it might
survive; in addition, these variations need a method of reproduction in
their current state. Also, has the theory of natural selection ever been
observed? The moth example is only a start of the theory which then
reverted back so it doesn't really work. What species has ever been
observed to mutate to the point that it couldn't mutate with its ancestors
but was still capable of mutating with others that had also mutated (with
or without human intervention)?
Apr 15, 2009 12:42 PM
Guest :
Dear Guest, You are a complete moron. Do your research. Your argument
is full of theories, and faulty ideas that fail to hold any ground. Stop
pretending to know anything about natural selection. You dont... It is very
frustrating, and somewhat entertaining to read what you have written, and
seem to stand by so strongly, and I realize that with someone as hard
headed, small minded, and un-intelligent as you and your ideas have proven
to be, the attempt of talking to you has not, and will never have any
effect. Don't be offended though. Please.. One who cannot correctly spell
the words "individual" and "behavior" should not be
expected to understand something as mildy complex as the method of natural
selection.
Apr 15, 2009 1:17 PM
Tami Port :
Guest who left a comment on April 15... Well done! You have great
talent at personal attack, but what exactly is your argument here? You make
no points of your own regarding natural selection, genetics, evolution,
science in general or even what exactly your point is. You do make a solid
argument for using spell check.
May 20, 2009 1:29 PM
Guest :
The peppered moth is a good, simple example of how selection works and how
something's ability to thrive is directly affected by it's ability to make
the best use of its environment. The case in point is selection not
mutation. An example of mutation would be this (this is not a real fact
about grey moths): the grey moth is allergic to grey trees by its very
nature, it cannot land on them. But in one generation and one family, a
mutation occurs, and suddenly the moth can land on grey trees as it has an
increased chemical that "cures" its allergy. Said moth breeds
passing on genes.
Aug 6, 2009 9:33 PM
Guest :
Natural selection is not evolution. Evolution supposedly comes about as a
result of a mutation of genes. The problem is this: I've researched this
and have never, ever been able to find one single example of a mutation
that resulted in a new specie. Everything I've found indicates that
everything results in a negative effect on the specie or as the author
said, at best no effect. Why is it scientists have never found one single
example? It's because it has never happened. I'm sorry, but the theory of
evolution doesn't work. Back to the drawing board, scientists. Oh, one
other point: most of science says that all these non-existent specie
changing mutations are caused randomly. (No God) ejkrigbaum
Oct 9, 2009 7:44 PM
Guest :
but do these examples, like rats and moths, apply to macroevolution? how
can we use this to explain mass-scale, limb-growing, completely changing to
look like something totally different evolution? it seems to me that in
order for, say, a species that lives in the water will never be able to
survive out of water, no matter how much time lapses, and won't ever form a
new subspecies that can. Where do these genetic variances occur and how? no
one's genes will just randomly sprout a new strand of DNA allowing for a
completely new feature or characteristic, right?
Nov 4, 2009 3:30 PM
Guest :
k this is to the guest who is trying to reinvent the wheel or something when a gene is mutated (randomly or by an environmental factor like the
sun) that benefits the organism, it will give that organism the upper hand
over other organisms. With this mutated gene being hereditary, it will then
pass it on to its offspring who will in turn pass it on. Since the mutation
gives this organism a higher survival rate, this organism may become a
species growing much more numerous. So, that is the basics of evolution. Natural Selection is what happens during evolution. The organisms that
have their beneficial mutations survive and reproduce more so than the
previous organisms and thus stay alive as a species longer. and their
are tones of examples of good mutations, look at the swine flu, people are
scared that if it MUTATES it will become immune to the vaccination. Search
up beneficial mutation or "beneficial mutation examples". And
stop trying to act like you know so much more than scientists who spend
their whole life doing research in their fields. If the theory of evolution
was so easily disproved in a paragraph written by a nobody (you) than i
think you would be saying it on CNN or a university
May 8, 2008
