Evolution or mutation?

Question

I'm a little confused when it comes to the theory of evolution. I was always under the impression that evolution occured because of mutations that were allowed to be reproduced. That the mutation somehow made that specific species stronger. My boyfriend seems to think that evolution is somehow geneticaly encoded from previously generions. For example, the giraffe "grew" a long neck so it could reach leaves that no other animal could get to.

Answer 1

You both have minor flaws in your concepts.  Your boyfriend's concept of preconceived genetic encoding towards future adaptation to an environment is very much like Lamarck's belief that animals can "will" their evolution, where as in actual fact evolution acts upon variance within a population.  For instance two of the tallest giraffes, being the most successful in the African acacia tree environment because they are able to acquire the most food and as-of-such they should find a greater reproductive success within their group.  If they both had unique height genes then their offspring have a good chance of being as tall or even taller.  This is NOT mutation however, simply the selection of the fittest genes within a gene pool of great variance.  Your boyfriend is close to this, however without specifying that selection occurs because of individual fitness and natural selection upon the groups variance he leaves himself open to being interpreted as being a Lamarkian, which is incorrect.  As for your beliefs, mutation does occur as a part of evolution, but its effects on change within a population are actually quite small.  Most mutations are either detrimental or neutral and consequently are either discarded via the mutation killing its new host prior to the host finding reproductive success, or if the mutation is neutral then it can be carried within the population's genepool for many generations although with absolutely no morphological expression.  The few mutations that do find success may spread throughout a species rapidly, and if their is no geneflow between that group and it's neighbours of the same species then speciation may occur and seperate these two populations into seperate species.  This form of evolutionary change and/or speciation, however, is actually the exception, rather then the norm.  Most evolutionary change comes about because of gene flow and/or genetic drift.  So you too have some concepts correct, but not the whole picture.

PS if you need any clarification or would like me to go into further detail then please write me!

Answer 2

There are several mechanisms that cause evolution.  Mutation is one of them.  There is also gene flow and genetic drift.

Answer 3

Your boyfriend is referring to Lamarck, who did put forth that idea.  He was onto something, but had no knowledge of genetics.  The theory of survival of the fittest would say instead that those animals with the longest necks were best able to survive in their environment, more likely to reproduce, and more likely to have offsprings with long necks.  

Check out this exact reference to Lamarck and Darwin and giraffes.  Actually, giraffes can definitely eat grass if necessary, and the whole debate is frought with uncertainty.

Doesn't invalidate the theory, though, and any change would have to be through mutation.

http://www.natureinstitute.org/pub/ic/ic...

Answer 4

Your theory is correct not his.  The giraffe with the naturally longer neck from birth reproduced making the majority of his offspring have longer necks and so on.

Answer 5

Mutation is a fundamental method of creating changes in genes.  Without that all animals would be the same and would never change.  The diversity of genes means that some will produce better solutions to different problems.  The animal with the greatest collection of beneficial genes will evolve by a process of natural selection.  If that selection allows that particular animal to survive then it occupies a particular niche and becomes better and better at exploiting that niche.   Animals occasionally change niches and the environment also changes.  Both keep driving many animals to adapt to new niches.  The giraffe will keep getting taller because they are in a niche that relies on eating the highest branches.

Answer 6

Your boyfriend is almost talking about the Lamarckian system of evolution, which has been discounted.  But in a sense, you're both right.  Evolution does occur because of mutations, as you said.  The mutations that help out the species are the ones that are passed on.  So some giraffe ancestor had a mutation that made its neck grow longer.  That longer neck allowed it to get to higher leaves, which meant good eating.  It had lots of successful offspring with the same mutation, allowing it to spread.  Gradually, over time, the mutations that led to a long, long neck survived, while ones encouraging a shorter neck didn't.  That's how evolution works.

Answer 7

Genetics and evolution have been enemies from the beginning of both concepts. Gregor Mendel, the father of genetics, and Charles Darwin, the father of modern evolution, were contemporaries. At the same time that Darwin was claiming that creatures could change into other creatures, Mendel was showing that even individual characteristics remain constant. While Darwin’s ideas were based on erroneous and untested ideas about inheritance, Mendel’s conclusions were based on careful experimentation. Only by ignoring the total implications of modern genetics has it been possible to maintain the fiction of evolution.

To help us develop a new biology based on creation rather than evolution, let us sample some of the evidence from genetics, arranged under the four sources of variation: environment, recombination, mutation, and creation.

Environment

This refers to all of the external factors which influence a creature during its lifetime. For example, one person may have darker skin than another simply because she is exposed to more sunshine. Or another may have larger muscles because he exercises more. Such environmentally-caused variations generally have no importance to the history of life, because they cease to exist when their owners die; they are not passed on. In the middle 1800s, some scientists believed that variations caused by the environment could be inherited. Charles Darwin accepted this fallacy, and it no doubt made it easier for him to believe that one creature could change into another. He thus explained the origin of the giraffe’s long neck in part through ‘the inherited effects of the increased use of parts’.1 In seasons of limited food supply, Darwin reasoned, giraffes would stretch their necks for the high leaves, supposedly resulting in longer necks being passed on to their offspring.

Recombination

This involves shuffling the genes and is the reason that children resemble their parents very closely but are not exactly like either one. The discovery of the principles of recombination was Gregor Mendel’s great contribution to the science of genetics. Mendel showed that while traits might be hidden for a generation they were not usually lost, and when new traits appeared it was because their genetic factors had been there all along. Recombination makes it possible for there to be limited variation within the created kinds. But it is limited because virtually all of the variations are produced by a reshuffling of the genes that are already there.

For example, from 1800, plant breeders sought to increase the sugar content of the sugar beet. And they were very successful. Over some 75 years of selective breeding it was possible to increase the sugar content from 6% to 17%. But there the improvement stopped, and further selection did not increase the sugar content. Why? Because all of the genes for sugar production had been gathered into a single variety and no further increase was possible.

Among the creatures Darwin observed on the Galápagos islands were a group of land birds, the finches. In this single group, we can see wide variation in appearance and in life-style. Darwin provided what I believe to be an essentially correct interpretation of how the finches came to be the way they are. A few individuals were probably blown to the islands from the South American mainland, and today’s finches are descendants of those pioneers. However, while Darwin saw the finches as an example of evolution, we can now recognize them merely as the result of recombination within a single created kind. The pioneer finches brought with them enough genetic variability to be sorted out into the varieties we see today.

2. Mutation

Now to consider the third source of variation, mutation. Mutations are mistakes in the genetic copying process. Each living cell has intricate molecular machinery designed for accurately copying DNA, the genetic molecule. But as in other copying processes mistakes do occur, although not very often. Once in every 10,000–100,000 copies, a gene will contain a mistake. The cell has machinery for correcting these mistakes, but some mutations still slip through. What kinds of changes are produced by mutations? Some have no effect at all, or produce so small a change that they have no appreciable effect on the creature. But many mutations have a significant effect on their owners.Based on the creation model, what kind of effect would we expect from random mutations, from genetic mistakes? We would expect virtually all of those which make a difference to be harmful, to make the creatures that possess them less successful than before. And this prediction is borne out most convincingly. Some examples help to illustrate this.

Geneticists began breeding the fruit fly, Drosophila melanogaster, soon after the turn of the century, and since 1910 when the first mutation was reported, some 3,000 mutations have been identified.3 All of the mutations are harmful or harmless; none of them produce a more successful fruit fly—exactly as predicted by the creation model.

Is there, then, no such thing as a beneficial mutation? Yes, there is. A beneficial mutation is simply one that makes it possible for its possessors to contribute more offspring to future generations than do those creatures that lack the mutation.

Darwin called attention to wingless beetles on the island of Madeira. For a beetle living on a windy island, wings can be a definite disadvantage, because creatures in flight are more likely to be blown into the sea. Mutations producing the loss of flight could be helpful. The sightless cave fish would be similar. Eyes are quite vulnerable to injury, and a creature that lives in pitch dark would benefit from mutations that would replace the eye with scar-like tissue, reducing that vulnerability. In the world of light, having no eyes would be a terrible handicap, but is no disadvantage in a dark cave. While these mutations produce a drastic and beneficial change, it is important to notice that they always involve loss of information and never gain. One never observes the reverse occurring, namely wings or eyes being produced on creatures which never had the information to produce them.

Natural selection is the obvious fact that some varieties of creatures are going to be more successful than others, and so they will contribute more offspring to future generations. A favourite example of natural section is the peppered moth of England, Biston betularia. As far as anyone knows, this moth has always existed in two basic varieties, speckled and solid black. In pre-industrial England, many of the tree trunks were light in colour. This provided a camouflage for the speckled variety, and the birds tended to prey more heavily on the black variety. Moth collections showed many more speckled than black ones. When the Industrial Age came to England, pollution darkened the tree trunks, so the black variety was hidden, and the speckled variety was conspicuous. Soon there were many more black moths than speckled [Ed. note: see Goodbye, peppered moths for more information].

As populations encounter changing environments, such as that described above or as the result of migration into a new area, natural selection favours the combinations of traits which will make the creature more successful in its new environment. This might be considered as the positive role of natural selection. The negative role of natural selection is seen in eliminating or minimizing harmful mutations when they occur.

Answer 8

Evolution occurs from random mutations.  Like for the giraffe...it didn't just grow and strech it's neck. A random mutation caused it to grow slight longer.  And each generation the giraffe's neck got longer, and that's why it looks the way it is today.