Could there be an evolution with asexual reproduction?

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AM I a monkey
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Could there be an evolution with asexual reproduction?

Post by AM I a monkey » Thu Feb 02, 2006 5:33 am

Asexual reproduction produces an exact replica of the parent due to the lack of genetic recombination. From an evolutionary standpoint, I could argue that asexual reproduction is inferior because it stifles the potential for change. It is apparent from the fossil record that asexual reproduction was the first form by which living organisms reproduced on the early earth. Many simple organisms, such as bacteria, and simple animals, such as protists and worms still reproduce asexually, but sexual reproduction is, by far, the most widely used method by which species maintain their presence on our planet. My question is how sexual reproduction arose in the first place and how it is maintained given the obvious advantages of asexual reproduction?
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Post by MrMistery » Thu Feb 02, 2006 7:34 pm

About how it is maintained: the organisms that reproduce sexually will have more chances to adapt to their environment and thus will have more chances to survive
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Post by AstusAleator » Thu Feb 02, 2006 7:34 pm

Bacteria undergo conjugation, which is essentially a sharing of genetic information. In this way, they can achieve genetic diversity in their populations, and have a higher survivability.
It could be that the process of conjugation eventually lead to an early form of sexual reproduction, though this is just my speculation, not based on any recent research.
I think that in higher organisms, such as amphibians and reptiles, asexual reproduction can be seen as evolutionarily inferior, as it would rely solely on random mutations to adapt to the environment, as opposed to genes that are currently in the genome but passive or recessive.

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Post by MrMistery » Thu Feb 02, 2006 7:36 pm

I am sorry, are we discussing advantages of sexual or asexual reproduction?
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Post by AstusAleator » Thu Feb 02, 2006 10:44 pm

Both I guess, hehe. Don't try to read my statements as sequential. They're seperate. I'm saying that asexual reproduction in bacteria is very fit due to conjugation, but that asexual reproduction in larger organisms is not evolutionary advantageous.
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Post by delgrodel » Sat Feb 11, 2006 11:13 am

Hehe,

In discussing the advantages of sex, one must keep in mind the host of disadvantages that comes with it. For one, large amounts of energy are required to maintain the sex organs. Studies have shown that Drosophila with sex organs removed tend to live significantly longer than their sexually active counterparters (controlled for STDs, I assume!). Of course, the actual practice of sexual intercourse itself tends to be quite dangerous. Just think of the diseases that can be passed around this way! Also, remember that sex isn't confined to humans alone. Flies and lizards have sex too! Many animals have elaborate mating rituals that require great input of energy and often make these animals easy pickings for predators. When you say that diversity is main benefit conveyed by sex, you should keep in mind that the first sexual organisms were single celled organisms with evolutionary time scales multitudes faster than our own. The rate of mutation in bacterial colonies comes from the fact that they can rapidly replicate without the need for sexual intercourse. Were bacteria hindered by something as time consuming as sex, they lose a large part of the reason they have been so successful. Put this aside the fact that there are organisms that are sexual but produce exact clones of themselves then you might be tempted to ask why there was ever sex in the first place :)

One theory is that sex appeared and simply couldn't disappear afterwards. Just look around you. Do you think you can tell your best friend to ditch his girlfriend by telling him of the evolutionary disadvantages of sex? What it boils down to is that the first sexual organisms simply had to do what they were "programmed" to, and apparently the force of selection wasn't strong enough to dictate otherwise.

Please keep these points in mind when disucssing something as obviously advantageous as sex :)

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Post by flint » Sun Feb 12, 2006 4:49 pm

Asexual reproduction is great as long as the environment remains stable. BUT what happens when there is a change in the environment? Asexual populations can pretty much only keep making the same individuals who are suited for the environment before it changed because everyone is essentially the same. Sexual reproduction is much better at adapting to new challenges set before them because there is a wide range of different individuals and some of them might be well adapted to the new changes in the environment. I dont know how sexual reproduction would have evolved though, but there could certaintly be evolution in asexual reproduction due to mutations alone (they provide enough variation).

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Post by David George » Thu Mar 02, 2006 7:57 am

The way in which sexual reproduction is better is because there are greater chances of mixing of genes.The organisms have greater chances of evolution.For the environment if humans reproduce asexually the population might explode even if environmental factors prevent birth of offsprings.That is why very few macro organisms reproduce asexually.
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Post by AstusAleator » Fri Mar 03, 2006 11:38 am

If you think of plants, asexual reproduction is essentially a fall-back plan for many families. If a plant can't cross pollinate with another plant, it will self pollinate. If it can't produce a flower this season, it will invest in its roots which can reproduce it if it dies.
Asexual reproduction is highly successful with micro-organisms. But, as I said before, congjugation and other processes keep the genome heterogeneous. That, and the rapid rate at which they are capable of reproducing, allows mutations to sustain the diversity of the genome.

Larger organisms can't carry it out quite as successfully as they reproduce slower, and tend to make exact clones with no swapping of genes.
What did the parasitic Candiru fish say when it finally found a host? - - "Urethra!!"

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