I hope you have read the articles i posted. I'm going to lay the foundation this one last time really carefully, note that i am not going to be making any creationist arguement, it's all scientific fact. I would be grateful if you read it all carefully. Thanks.
Ok, quoting from the evolution Happens link i put up:
1. Mutation: A mutation is any change in the DNA base sequence (genetic information) of a gene. However, only heritable mutations, those occurring in the gametes (reproductive cells) or the cell lineage contributing to the gametes, are involved in evolution. Such mutations, known as germinal mutations, can result from many factors, including natural background radiation, chemical mutagens and viral infection.
2. Natural Selection: The gene code being acted on by the environment in which the organism lives. An example - hairy dogs in a hot environment, dogs born with shorter hair at more of an advantage because don't get so hot, they can hunt for longer etc. Therefore increased 'fitness' - over time the environment weeds out the dogs with the longer hair, leaving a population of dogs with shorter hair. A technical definition is as follows: Natural selection is the process by which traits that provide a reproductive advantage tend to increase in frequency in a given population over time, while traits that leave individuals at a reproductive disadvantage tend to decrease in frequency over time. A reproductive advantage may arise from differences in survival, in fertility, in rate of development, in mating success or by some other aspect of the life cycle.
3. Genetic Drift: is the process by which the frequencies of existing genes in a population change over time due to chance. This happens due to the random nature of recombination - not all genes from the Father are passed to the offspring, neither are all the genes from the mother passed to the offspring. In large populations it pretty much evens itself out, however in small populations it can lead to loss of genes.
Again let me quote from the same site:
Now the reason why we need these genetic mutations is because they can add new base pairs and so eventually result in new genetic information that did not exist before, leading to the organism having new structures and new things (ie. the organism is becoming more complex).
If you look back up to the top you will see that mutation is one of the three mechanisms by which evolution occurs.
Lets have a closer look at the mechanism of mutation:
Let me quote from the link that i gave you:
1. Chemical Mutagens 2. Radiation 3. Sunlight 4. Spontaneous
So how can these mutations affect the genetic code?
1. Deletion (removal of a basepair)2. Addition (inserting a new basepair)
3. Exchange (changing a basepair to a different one) 4. Duplication (bases are duplicated).
This alteration of the genetic code is what can give rise to this new genetic information that had to be produced for the first simple creature to become more complex. Without mutation we could never have got evolution from the first simple organism to all the organisms on earth today.
However does natural selection require mutation to give these changes that we see in a population? No it does not - it is a separate evolutionary mechanism. It is the natural environment selecting genes from what is known as a gene pool. Let me quote a definition of a gene pool from biology online:
At this point is it important to stress that natural selection (though it is a mechanism of evolution) on it's own is not able to evolve a simple organism into all the complex organisms we have today. Because just like a deck of cards there are only ever going to be a certain number of combinations available unless you add new cards - the addition of this new information can only occur through mutation.
I hope what i have written is clear enough for you and maybe Jerry when he reads it. This is just what you would learn in a classroom - no arguements, just the scientific facts laid out for you.
Ok, quoting from the evolution Happens link i put up:
A quick definition of each of them for you:How does evolution occur? The three main mechanisms are mutation,
natural selection
and genetic drift.
1. Mutation: A mutation is any change in the DNA base sequence (genetic information) of a gene. However, only heritable mutations, those occurring in the gametes (reproductive cells) or the cell lineage contributing to the gametes, are involved in evolution. Such mutations, known as germinal mutations, can result from many factors, including natural background radiation, chemical mutagens and viral infection.
2. Natural Selection: The gene code being acted on by the environment in which the organism lives. An example - hairy dogs in a hot environment, dogs born with shorter hair at more of an advantage because don't get so hot, they can hunt for longer etc. Therefore increased 'fitness' - over time the environment weeds out the dogs with the longer hair, leaving a population of dogs with shorter hair. A technical definition is as follows: Natural selection is the process by which traits that provide a reproductive advantage tend to increase in frequency in a given population over time, while traits that leave individuals at a reproductive disadvantage tend to decrease in frequency over time. A reproductive advantage may arise from differences in survival, in fertility, in rate of development, in mating success or by some other aspect of the life cycle.
3. Genetic Drift: is the process by which the frequencies of existing genes in a population change over time due to chance. This happens due to the random nature of recombination - not all genes from the Father are passed to the offspring, neither are all the genes from the mother passed to the offspring. In large populations it pretty much evens itself out, however in small populations it can lead to loss of genes.
Again let me quote from the same site:
What exactly does the theory of evolution state? The theory of evolution states that:
All life forms (species) have developed from other species.
All living things are related to one another to varying degrees through common descent (share common ancestors).
All life on Earth has a common origin. In other words, that in the distant past, there once existed an original life form and that this life form gave rise to all subsequent life forms.
The process by which one species evolves into another involves random heritable genetic mutations (changes), some of which are more likely to spread and persist in a gene pool than others. Mutations that result in a survival advantage for organisms that possess them, are more likely to spread and persist than mutations that do not result in a survival advantage and/or that result in a survival disadvantage.
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Now the reason why we need these genetic mutations is because they can add new base pairs and so eventually result in new genetic information that did not exist before, leading to the organism having new structures and new things (ie. the organism is becoming more complex).
If you look back up to the top you will see that mutation is one of the three mechanisms by which evolution occurs.
Lets have a closer look at the mechanism of mutation:
Let me quote from the link that i gave you:
The following will cause mutations:A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene. A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed.
Once the gene has been damaged or changed, the mRNA transcribed from that gene will now carry an altered message.
The polypeptide (aminoacid chain) made by translating the altered mRNA will now contain a different sequence of amino acids. The function of the protein made by folding this polypeptide will probably be changed or lost. In this example, the enzyme that is catalyzing the production of flower color pigment has been altered in such a way it no longer catalyzes the production of the red pigment.
No product (red pigment) is produced by the altered protein.
In subtle or very obvious ways, the phenotype (physical makeup)of the organism carrying the mutation will be changed. In this case the flower, without the pigment is no longer red.
1. Chemical Mutagens 2. Radiation 3. Sunlight 4. Spontaneous
So how can these mutations affect the genetic code?
1. Deletion (removal of a basepair)2. Addition (inserting a new basepair)
3. Exchange (changing a basepair to a different one) 4. Duplication (bases are duplicated).
This alteration of the genetic code is what can give rise to this new genetic information that had to be produced for the first simple creature to become more complex. Without mutation we could never have got evolution from the first simple organism to all the organisms on earth today.
However does natural selection require mutation to give these changes that we see in a population? No it does not - it is a separate evolutionary mechanism. It is the natural environment selecting genes from what is known as a gene pool. Let me quote a definition of a gene pool from biology online:
You can think of it like a deck of cards - each card represents a gene and like there are different combinations of cards, so there can be different combinations of genes. However the number of genes is restricted - hence the term 'gene pool'. Natural selection acts on these genes leading to some genes being selected over others. Like the example of the hairy dogs - the gene pool changes to the combination where the gene coding for short hair is more prevalent.gene pool
The total sum of genetic information present in a population at anygiven moment.
The collective genomes of a species, the genetic diversity of a gene pool is determined by the variety of combinations of genes existing in the population.
At this point is it important to stress that natural selection (though it is a mechanism of evolution) on it's own is not able to evolve a simple organism into all the complex organisms we have today. Because just like a deck of cards there are only ever going to be a certain number of combinations available unless you add new cards - the addition of this new information can only occur through mutation.
I hope what i have written is clear enough for you and maybe Jerry when he reads it. This is just what you would learn in a classroom - no arguements, just the scientific facts laid out for you.