disadvantages to asexual reproduction

Genetics as it applies to evolution, molecular biology, and medical aspects.

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castinpetal
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disadvantages to asexual reproduction

Post by castinpetal » Tue Nov 22, 2005 3:33 am

:D help... some organisms reproduce asexually throughout their life cycle, what are some disadvantages to that regarding chromosomes?

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asexual reproduction

Post by lara » Tue Nov 22, 2005 11:40 am

genetic information is shared by the two gametes in sexual reproduction, variety is produced in the species. if one agrees with the theory of evolution, then this factor is a very good one, as variety ensures the death of species with a certain weak element, and the survival of species with an advantageous element. This will create a better species, who is better at surviving. On the other hand, asexual reproduction doesn't allow any type of genetic variation.Less genetic diversity gives the offspring a lesser chance of survival if the environment changes.

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Post by baikuza » Tue Nov 22, 2005 1:39 pm

asexual reproduction do not need two different individu. one of the disadventages is that the doughter cell do not to much different as the parent. when the gametes fertilized, there whould be new variation in the doughter cell genes, this should make the evolution velocity goes more rapidly than in asexual reproduction(even there should be evolution too). this implicates that the organsim who do not do this, sexual reproduction, or we can said organism who only can do asexual reproduction are commonly classified in the lower clasification(e.g, bacteria(monera), protozoa)

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Post by Terry K. » Tue Nov 29, 2005 11:22 pm

If you look at it from the standpoint of a statistician, it is easy to see why asexual reproduction proves to be the downfall of many microscopic organisms. Think about this ('put on thinking cap') the human chromosome possibilities are expressed as 2^23 (which is rediculously large), now take into effect the principles of crossing over (which adds another whole variable to the equation would sends the numbers into digits we can't even recognize normally), now add in mutations, yep, that's a lot of factors. Compare that to the simplicity of an organism of asexual origin with only mutation and adaptation to the equation, it is nowhere near the genotypic variation of a human (that of sexual reproduction of 2 individuals). Now if some disease were to come along that was hypothetically going to wipe out all life on Earth, which set of organisms would have a better probability to survive, of course those of sexual reproduction by 2 organisms, which is why asexual reproduction, although it is convenient for the organisms that practice it, it is nowhere near as immune to certain diseases and other mutations as is organisms of 2 organism sexual reproduction. Huh, "sigh of relief", glad I got that all out. Hope I helped you a little (joking because I wrote a short story)
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Post by canalon » Wed Nov 30, 2005 1:42 am

Terry K. wrote:If you look at it from the standpoint of a statistician, it is easy to see why asexual reproduction proves to be the downfall of many microscopic organisms. […]


Yes... but No!

Just look at the bacteria, they do not reproduce sexually, and yet thet survive pretty well since a few billions years, and they can still probably be considered as the most succesfull beings in our biosphere, occupying more diverse niche than any other life forms.
But they have a sort of sexuality, it is simply not related to reproduction.
So look at the bdelloïd rotifers, no sex since the last few million years (this is longer than the existance of man...) and still there.

Because mutations and genes can be acquired without sexual reproduction, and that in fact sexuality is a rather cumbersome and expensive way of reproducing the real mistery is why is sex so common and widespread. The best hypothesis suggest that it is because it is a good way to get rid of parasites from one generation to the other, but this is still hotly debated.
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Post by Terry K. » Wed Nov 30, 2005 2:57 pm

Yes, but the only reason for their survival is due to the fact that they were around for way longer then homo sapiens, so look at it this way:
1. Remove all predation from the area for the length of the expirement and supply the zebras involved in the expirement all the resources they could need for the length of the expirement
2. Take 20 male zebras and 20 female zebras and send them out into the wild tagged, and force them to mate with each other for every mating cycle for 50 years
3. 50 years later (zebras are so abundant it's rediculous) send in 20 male lions and 20 female lions and allow them to *attempt* to decline the population in any way possible
-My point is: no duh they are abundant b/c they were around for so long without being killed that it is nearly impossible to get rid of them entirely, but eventually, the populations will be regulated by the predation. This will eventually occur with the human to bacteria population. Whether it occurs before the end of the time of the Earth, I don't know, but there will be some advances on our part that will decline the ratio of human to bacterium. SO my overall point is that if we were alloted an infinite amount of time on this Earth, we will eventually kill the bacterium off because of bacterium division having flaws that make sexual reproduction by 2 individuals superior to that of the bacterium method of reproduction.
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Post by canalon » Wed Nov 30, 2005 3:39 pm

Terry K. wrote:Yes, but the only reason for their survival is due to the fact that they were around for way longer then homo sapiens, so look at it this way: [snip]


Arrghhh I can't believe what I read!
There is no way human beings are going to get rid of bacteria. In fact we will probably get rid of ourselves before we get rid of only a small portion of bacterial population. Bacteria are able to adapt to conditions taht no human will ever be able to adapt too. Like hot water vent at temperature over 100ºC, like radiation levels that kill everything else (Deinococcus radiodurans is able to grow in nuclear reactors...). Moreover many bacteria are necessary for us to survive, and axenic animals are usually rather unhealthy and need highly specialized diets to live correctly. And the efficacity of antibiotics is steadily declining because in less than 50 years of steady use bacteria devlopped and spread resistance mechanism to all known antibiotics.

And I will stress agin that reproduction and excahnge of genetic material do not need to be linked. And that sex is definitely not the only way to create diversity (recombination, mutations, and variations of their rates should be kept in mind).

And as for your Tiger/Lion gedankexperiment, let me tell you that the experiment has sadly been carried out many times, and usually the predator population won.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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Post by MrMistery » Wed Nov 30, 2005 7:01 pm

Plus if you kill bacteria, Patrick would be out of work ;)
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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Post by canalon » Wed Nov 30, 2005 7:13 pm

MrMistery wrote:Plus if you kill bacteria, Patrick would be out of work ;)


But that is definitely not something I fear would happen anytime soon...
Patrick

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any proof. (Ashley Montague)

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Post by Terry K. » Thu Dec 01, 2005 3:36 pm

lol, what's his job, because he's a great arguer, you should look into being a lawyer or a democrat if you lose your job, lol
Saying that any two humans are exactly alike is like saying republicans have morals

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Post by canalon » Thu Dec 01, 2005 3:40 pm

I am a researcher (post doctoral level), and working on antibiotic ressistance and evolution in bacteria. Currently in farms from the barn to the manure pit. This is often a smelly job...
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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