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RRWick
May 14th 2007, 07:22 PM
I was going to post this question in the Noah's Ark thread, but I thought it needed a thread of its own.

If all land animal species on the planet descended from 2 ancestors that lived 4500 years ago (or however long ago the flood supposedly happened), how has so much genetic variation arisen since?

With diploid species like us (and most animals), each individual has two copies of each gene. So if there are two animals of a species, there could only be 4 different versions of each gene, at most.

Populations descended from only 2 ancestors are very inbred; they have very low genetic variation, which is to say that there aren't very many versions of each gene. But this isn't what we see in the natural world. There is enormous genetic variation in most species. We don't see 4 versions of each gene, but countless versions.

New functional versions of genes are created all the time in nature through mutation (and propagated through natural selection), but not nearly at the rate necessary to create the genetic variation we see in 4500 years. How could two tigers have given rise to populations of Bengal tigers, Indochinese tigers, Siberian tigers, Sumatran tigers, and more, all in a few hundred generations?

NHL Fever
May 15th 2007, 05:15 AM
I think you're taking about 7000 year creation or something. There is a range of opinions among Christians about how long creation took, and by what route. I think the simplest answer to your question is that it took a lot longer than 4500 years.

Jemma Ash
May 15th 2007, 08:20 AM
Genesis 7:2-3 "Take with you seven of every kind of clean animal, every kind of unclean animal, a male and its mate, and also seven of every kind of bird, male and female, to keep their various species alive throughout the earth." (NIV)

Genesis 7:14 "They had with them every wild animal according to its kind, all livestock according to their kinds, every creature that moved along the ground according to its kind, everything with wings."

Therefore, (correct me if i am wrong please), there were seven of every animal not just two. Kind and species may be different in this context. Using your example of tigers, surely a Bengal and a siberian tiger are two KINDS of tigers therefore they were not mutated versions of 1 type of tiger...I did basic genetics in high school biology and what you said about the 4 different versions of each gene is not quite right i don't think...when those "4 different versions" mix then you would end up with 8 and when those 8 interbred you would end up with...etc...

i hope this helps.

DSK
May 15th 2007, 11:09 AM
I was going to post this question in the Noah's Ark thread, but I thought it needed a thread of its own.

If all land animal species on the planet descended from 2 ancestors that lived 4500 years ago (or however long ago the flood supposedly happened), how has so much genetic variation arisen since?

With diploid species like us (and most animals), each individual has two copies of each gene. So if there are two animals of a species, there could only be 4 different versions of each gene, at most.

Populations descended from only 2 ancestors are very inbred; they have very low genetic variation, which is to say that there aren't very many versions of each gene. But this isn't what we see in the natural world. There is enormous genetic variation in most species. We don't see 4 versions of each gene, but countless versions.

New functional versions of genes are created all the time in nature through mutation (and propagated through natural selection), but not nearly at the rate necessary to create the genetic variation we see in 4500 years. How could two tigers have given rise to populations of Bengal tigers, Indochinese tigers, Siberian tigers, Sumatran tigers, and more, all in a few hundred generations?

Variation among species isn't evolution. There are hundreds of types of dogs, but they are still dogs. A dog has never become anything other than a dog, no matter how much time is allowed. Variations among species is often called micro-evolution, which does occur. The change of one species into an entirely different species such as a dog evolving into a horse would be macro-evolution, and this has never happened. Not one species has ever crossed the species gene barrier to become a new or different sort of species.
_____________________________________________

Concerning mutations

"Mutational changes: Occasionally changes in offspring occur because of a mutational defect. Such alterations always weaken the individual that has them. A mutational change is not a normal variational reshuffling of the DNA code, but an actual change in one tiny item in the code information. The result is that the perfection of the code has been damaged. The resultant offspring are weaker and they are more likely to die off.

Survival of the fittest: Organisms are damaged by mutations or otherwise tend to be culled out. Evolutionists call that culling out process "survival of the fittest." But all that actually occurred was that misfits produced by mutations or accidents are eliminated, thus returning the species closer to its pure pattern. "Survival of the fittest" accomplishes the opposite of evolution! The hardships of life cull out the weakened forms of each species, and thus keep each species very stable. There is nothing in this process that has anything to do with evolution—the evolving of one species into another." - http://evolution-facts.org/Evolution-handbook/E-H-9a.htm

Of other interest

Why Long Ages cannot Produce Evolutionary Change - see article at the following link - http://evolution-facts.org/Evolution-handbook/E-H-5a.htm

For an entire listing of article go to the following link - http://evolution-facts.org/Handbook%20TOC.htm

TEITZY
May 15th 2007, 01:31 PM
I was going to post this question in the Noah's Ark thread, but I thought it needed a thread of its own.

If all land animal species on the planet descended from 2 ancestors that lived 4500 years ago (or however long ago the flood supposedly happened), how has so much genetic variation arisen since?

With diploid species like us (and most animals), each individual has two copies of each gene. So if there are two animals of a species, there could only be 4 different versions of each gene, at most.

Populations descended from only 2 ancestors are very inbred; they have very low genetic variation, which is to say that there aren't very many versions of each gene. But this isn't what we see in the natural world. There is enormous genetic variation in most species. We don't see 4 versions of each gene, but countless versions.

New functional versions of genes are created all the time in nature through mutation (and propagated through natural selection), but not nearly at the rate necessary to create the genetic variation we see in 4500 years. How could two tigers have given rise to populations of Bengal tigers, Indochinese tigers, Siberian tigers, Sumatran tigers, and more, all in a few hundred generations?

But many organisms (including humans) are heterozygous and carry several different types (alleles) of a particular gene so the possible combinations or generic variations (especially where both parents are heterozygous for the same gene) can be enormous. Also in some cases combinations of alleles cause an intermediate effect (eg. the combination of a gene for long fur with a gene for short fur produces offspring with medium length fur).

In the Creation model we would predict a high level heterozygosity in the original kind which would decrease as populations spread out or became isolated from one another.

Cheers
Leigh

RRWick
May 15th 2007, 08:51 PM
Let me word my question differently:

There would be a whole lot of inbreeding after Noah's ark; it would be inevitable. So how come we don't see the evidence of this inbreeding in the genetics of animals today? Being only a few hundred generations away from only 2 ancestors would result in some very clear genetic characteristics.

Did God manipulate the animals’ DNA generations after the flood to inject more genetic diversity into the populations? That's the only explanation I can think of...

TEITZY
May 15th 2007, 11:12 PM
Let me word my question differently:

There would be a whole lot of inbreeding after Noah's ark; it would be inevitable. So how come we don't see the evidence of this inbreeding in the genetics of animals today? Being only a few hundred generations away from only 2 ancestors would result in some very clear genetic characteristics.

Did God manipulate the animals’ DNA generations after the flood to inject more genetic diversity into the populations? That's the only explanation I can think of...

Well firstly, God brought the animals to Noah so I'm sure he would have brought ones with the most genetic diversity to go on the ark.

By "very clear genetic characteristics" I assume you mean diversity within created kinds. I think we do see that in many animals like dogs for instance. Lion and tigers are categorized as separate species by man but we know they can breed together and produce viable offspring which is strong evidence that they both originally came from the same cat-like animal that came off the Ark. We have also actually observed speciation taking place in many animal populations and that shows that genetic diversity within populations can happen quite quickly. What we don't see is any evidence of reptiles changing into birds or monkeys changing into men. As Creationists point out, the diversity we see within species or populations is actually the result of a net loss of genetic information whereas for evolution to work (even on the micro scale), there must be a net increase in new genetic information.

Evolutionists like to refer to natural selection or variation within species as 'micro-evolution' but this is actually deceptive terminology, since micro-evolution implies that a species is incrementally becoming more genetically diverse, whereas the fact is it is actually less genetically diverse than its parents.

Cheers
Leigh

RRWick
May 16th 2007, 12:45 AM
the diversity we see within species or populations is actually the result of a net loss of genetic information

I don't understand what you are talking about here. Could you explain?

TEITZY
May 16th 2007, 01:48 AM
I don't understand what you are talking about here. Could you explain?

Well offspring do not inherit ALL the genetic information of their parents so some of that information is lost and therefore they are less genetically diverse or more specified in their genetic traits. So certain features will be lost while others will become dominant within that population. The only way to regain this lost information is to interbreed with the parent or another individual from the parent population that carries the lost gene/s.

If we use brown (B) and blue (b) eye colour as an example. Brown is the dominant gene while blue is recessive. So a brown eyed person will either be BB or Bb whereas a blue eyed person will be bb. So if you have two brown eyed parents who also carry the recessive blue eyed gene (both parents are Bb) then on average (using a punnet square) they will produce the following offspring:

...B...b
B BB Bb
b Bb bb

So on average 3 out of 4 children will have brown eyes while one will have blue. Now the BB child has lost the gene for blue eye colour and if he/she breeds with another brown eyed individual who is also BB then none of their offspring will carry the blue gene either. If they breed with another brown eyed individual who is Bb you end up with:

...B...B
B BB BB
b Bb Bb

So all children will have brown eyes while 50% have totally lost the recessive blue eye gene. Carry this on for several generations and you can see how the gene for blue eyes can be completely lost.

I hope this makes things a bit clearer:)

Cheers
Leigh

RRWick
May 16th 2007, 04:17 PM
Carry this on for several generations and you can see how the gene for blue eyes can be completely lost.

That is assuming that the blue eyed individuals don't breed. If eye color has no effect on reproduction, then the gene frequencies won't change, and the blue eye gene will not be lost (because the bb individuals will breed as much as the BB individuals).

If, on the other hand, being blue eyed somehow prevents you from reproducing (or even just lowers your chances of it), then the BB and Bb individuals will reproduce more, the frequency of the blue eye gene will drop, and the gene could be lost from the gene pool through the process you described.

I'm still not sure what you're getting at though. Is your claim that genetic diversity can only be reduced through the above process (natural selection), but it cannot be increased? If so, then (to get back to the original topic of this thread) how was genetic diversity increased after the flood?

TEITZY
May 17th 2007, 01:17 AM
That is assuming that the blue eyed individuals don't breed. If eye color has no effect on reproduction, then the gene frequencies won't change, and the blue eye gene will not be lost (because the bb individuals will breed as much as the BB individuals).

If, on the other hand, being blue eyed somehow prevents you from reproducing (or even just lowers your chances of it), then the BB and Bb individuals will reproduce more, the frequency of the blue eye gene will drop, and the gene could be lost from the gene pool through the process you described.

I meant the blue eyed gene would be lost from that particular population if it remained isolated from other individuals with blue eyes. Of course the opposite could happen very quickly too where you have 2 or more blue eyed individuals being isolated from brown eyed individuals. So I'm not saying all the alleles for certain genes will disappear altogether, but rather that as breeding occurs and populations spread out and become isolated from one another, that different groups will carry with them different alleles that will cause one group to differ (genetically and phenotypically) from another. In extreme cases this isolation can result in an inability to interbreed with the original parent population or other daughter populations (eg.speciation).


I'm still not sure what you're getting at though. Is your claim that genetic diversity can only be reduced through the above process (natural selection), but it cannot be increased? If so, then (to get back to the original topic of this thread) how was genetic diversity increased after the flood?

I think I need to define what I mean by "genetic diversity". By genetic diversity I am referring to the amount of genetic information in a population. So the parent population would be the most genetically diverse having a larger number of heterozygous genes while daughter populations would be less genetically diverse and less heterozygous.

So within the individuals that came off the ark there would have been great potential for variation and we would also expect there to be a relatively low level of mutations which would allow for close breeding without the often detrimental side effects we see today when close relatives breed.

So as animals began to spread out and encountered differing environments, natural selection would cull out those individuals not ideally suited to the enviornment and this results in a loss of genetic information from that particular group (eg. the gene for short fur may be lost in a cold climate while the long fur gene becomes dominant). Of course this tends to make groups highly specialized as only favourable genetic traits are kept while unfavourable ones are sifted out. This specialization may result in individuals from daughter populations looking (outwardly) quite different from the typical parent individual but the difference in outward appearance is actually caused by a net loss in genetic information or diversity.

So after the flood we had an increase in genetic specificity but a decrease in genetic diversity within populations. The only way to increase genetic diversity (regain lost genetic information) would be for one daughter population to interbreed with other daughter populations or the original parent population.

Cheers
Leigh