The effects of evolution on Genetic Diversity

[shekenahglory]

Hey everyone, this is my first post here, and its some thoughts I had on this subject, and a hypothesis, I just wanted to post it to see what others might have to contribute to the discussion....

 

I posted a longer version on another science discussion website, but it was quite long, so I trimmed it a bit. - its still long!

 

Hypothesis

The health, robustness, adaptability, ability, and vitality of the population (macrobiological scale) of living organisms on the planet is in a decreasing trend.

 

Now, I know that the historical evidence of the fossil record contradicts this, but please get to the bottom of the post before you dismiss it

 

Definitions: I had wrote the definitions of health, robustness, adaptability, ability, and vitality, but I guess you can just look them up and figure out how to apply them

 

I dont know a the best way one would go about quantifying these things, but as I was looking into it, the concept of genetic diversity seems very important. It probably doesnt encompass every factor, but its importance for robustness and vitality of individual species is well documented.

 

http://en.wikipedia.org/wiki/Genetic_diversity

 

I looked at the different mechanisms of evolution, and classified many of them according to their impact on genetic diversity. These classifications are my assumptions according to how well I understand them, and those assumptions may well be wrong, and if so I would appreciate someone enlightening me. Also, I'm sure its an incomplete list, but these seem to be the major drivers as far as they are known so far. Additions to any group are welcome. The classifications are based on whether the mechanism BY ITSELF adds to genetic diversity of the original + new population, is neutral, or contributes to a loss of genetic diversity. I understand that these mechanisms are all working together at the same time, which is generally understood to lead to increased genetic diversity across the biological population.

 

Processes that increase genetic diversity:

mutation (there must be more, what else?)

 

Neutral processes:

genetic transfer between populations

genetic recombination

gene swapping (bacteria)

 

Processes that decrease genetic diversity :

genetic drift

natural selection

disruptive selection

stabilizing selection

directional selection

adaptive radiation

population bottlenecks

the founder effect

 

Perhaps the thoughts can be boiled down to this, it looks to me like the mechanisms that decrease diversity are greater in strength than those that increase diversity. It seems like, and I'm bet it could be calculated some how, that the rates of removal of diversity can be demonstrated to occur faster than the rate of increasing diversity. As for increasing diversity, The fossil record is only acceptable as circumstantial evidence in this case, as it seems to be showing a trend of increase in diversity, but its just a history book - and if we are reading it accurately, we should be able to observe and document the rates at which natural mechanisms are able to increase genetic diversity.

 

Why the hypothesis is needed: Its possible that mechanisms that tend to increase genetic diversity within a population are not sufficient to stabilize or overcome the known mechanisms that tend to decrease genetic diversity with in population. In order for the overall process of evolution to have brought us from simple organisms to the complexity represented today, the natural methods of increasing and sustaining genetic diversity must have been successful to this point, or to some point of peak macrobiological genetic diversity in the past. The historical evidence suggests this to be true. To validate that the processes identified to be at work today are sufficient to generate increased genetic diversity would validate the historical evidence. If it cant be demonstrated, its possible that 1) there are natural mechanisms that contribute to genetic diversity that have not yet been identified. 2) there were in the past processes that contributed to genetic diversity in the past that are not occurring now. (I cant think of any accepted historical evidence to support this) 3) The processes collectively known as evolution is insufficient to account for the macrobiological genetic diversity that currently exists (historical evidence contradicts this)

[dr.syntax]

But surely your list of processes that increase genetic diversity would have to include sexual reproduction. If I am wrong please explain how. ...Dr.Syntax

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Merged post follows:

Consecutive posts merged

Hey everyone, this is my first post here, and its some thoughts I had on this subject, and a hypothesis, I just wanted to post it to see what others might have to contribute to the discussion....

 

I posted a longer version on another science discussion website, but it was quite long, so I trimmed it a bit. - its still long!

 

Hypothesis

The health, robustness, adaptability, ability, and vitality of the population (macrobiological scale) of living organisms on the planet is in a decreasing trend.

 

Now, I know that the historical evidence of the fossil record contradicts this, but please get to the bottom of the post before you dismiss it

 

Definitions: I had wrote the definitions of health, robustness, adaptability, ability, and vitality, but I guess you can just look them up and figure out how to apply them

 

I dont know a the best way one would go about quantifying these things, but as I was looking into it, the concept of genetic diversity seems very important. It probably doesnt encompass every factor, but its importance for robustness and vitality of individual species is well documented.

 

http://en.wikipedia.org/wiki/Genetic_diversity

 

I looked at the different mechanisms of evolution, and classified many of them according to their impact on genetic diversity. These classifications are my assumptions according to how well I understand them, and those assumptions may well be wrong, and if so I would appreciate someone enlightening me. Also, I'm sure its an incomplete list, but these seem to be the major drivers as far as they are known so far. Additions to any group are welcome. The classifications are based on whether the mechanism BY ITSELF adds to genetic diversity of the original + new population, is neutral, or contributes to a loss of genetic diversity. I understand that these mechanisms are all working together at the same time, which is generally understood to lead to increased genetic diversity across the biological population.

 

Processes that increase genetic diversity:

mutation (there must be more, what else?)

 

Neutral processes:

genetic transfer between populations

genetic recombination

gene swapping (bacteria)

 

Processes that decrease genetic diversity :

genetic drift

natural selection

disruptive selection

stabilizing selection

directional selection

adaptive radiation

population bottlenecks

the founder effect

 

Perhaps the thoughts can be boiled down to this, it looks to me like the mechanisms that decrease diversity are greater in strength than those that increase diversity. It seems like, and I'm bet it could be calculated some how, that the rates of removal of diversity can be demonstrated to occur faster than the rate of increasing diversity. As for increasing diversity, The fossil record is only acceptable as circumstantial evidence in this case, as it seems to be showing a trend of increase in diversity, but its just a history book - and if we are reading it accurately, we should be able to observe and document the rates at which natural mechanisms are able to increase genetic diversity.

 

Why the hypothesis is needed: Its possible that mechanisms that tend to increase genetic diversity within a population are not sufficient to stabilize or overcome the known mechanisms that tend to decrease genetic diversity with in population. In order for the overall process of evolution to have brought us from simple organisms to the complexity represented today, the natural methods of increasing and sustaining genetic diversity must have been successful to this point, or to some point of peak macrobiological genetic diversity in the past. The historical evidence suggests this to be true. To validate that the processes identified to be at work today are sufficient to generate increased genetic diversity would validate the historical evidence. If it cant be demonstrated, its possible that 1) there are natural mechanisms that contribute to genetic diversity that have not yet been identified. 2) there were in the past processes that contributed to genetic diversity in the past that are not occurring now. (I cant think of any accepted historical evidence to support this) 3) The processes collectively known as evolution is insufficient to account for the macrobiological genetic diversity that currently exists (historical evidence contradicts this)

 

Every process you listed as neutral in fact increases genetic diversity. I don`t like being hard on people but where did you get this information ? Is some creationist literature your source ? Whatever, ...Dr.Syntax

[Mokele]

Yes, natural selection and many other processes reduce genetic diversity.

 

But remember, there's a constantly influx of mutations, and it's *way* more than most people realize. On average, every human has 5 mutations that affect final protein structure, and many, many more that are neutral or that have unknown effects.

 

In the face of such a huge mutation influx, methods to weed out undesirable mutations are absolutely necessary.

[shekenahglory]

I am realizing that I probably dont have the time right now to thoroughly respond to posts, so I probably shouldnt have posted it in the first place. Anyways, all this "research" more or less came from wikipedia, accept for the classifications, which I did myself based on what I was understanding of the processes. I do want to note that I believe most people make the mistake of considering natural selection to be a process that adds to genetic diversity, but it seems pretty clear that by itself it does not. The other negative mechanisms most people dont even think much about, but they are quite dramatic in their ability to cause change.

 

As for the neutral processes, after looking into it more I think gene swapping and gene transfer between populations are the same thing actually, and that they only occur in single celled (or simple at least) organisms. I placed them as neutral because even though the recipient population experiences increased genetic diversity, the diversity already existed within the donor population, so there is no net increase. Unless within the transfer process some other mechanism occurs, such as mutation....I dont know if it does or not.

 

furthermore I am thinking that genetic recombination and mutation are not adequate groupings for my breakdown. it seems like genetic recomination is a larger process of chromosomal reproduction and repair, within which there may be mechanisms of mutation that cause an increase of genetic diversity through copying errors, or something else. Also, mutation is perhaps too generic, if I had time I would like to look into the actual process of reproduction and especially the points at which the DNA is replicated for the purpose of reproduction, and identify the points at which "copying errors", mutations, or some other mechanism that might increase genetic diversity might occur. For that reason, I wouldn't classify sexual reproduction here either, as that is also a more complex process within which mutations or other mechanisms are expected to occur.

 

Mokele (what does that name mean?), I am curious to know more about the constant infux of mutations, and rates and mechanisms of such things, and where you get such a statistic as that, and why its relevant, all written in an easy to understand form It seems Wikipedia isnt very user friendly as a method to educate oneself on mutations, as its very sparse in the information present, and also presents it in a way that requires a firm understanding of genetics and cellular biology.

[Mokele]

Google scholar (go to google, click "more" on the top left, select "scholar") will let you search scientific articles. Many will require you to purchase access or to get them via a university, but some are free, and the abstracts of all are free. Just go there and search for "mutation rate".

 

Sorry I can't be more help, I'm pretty much overwhelmed with teaching responsibilities at the moment.