Asexual to sexual reproduction? How?

This post has been pretty well covered, but I would just like to add to the responses of two of the questions.

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If sexual reproduction is "better", then why is the most effecient reproducing organism bacterium?

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Don't you think it's kind of odd that an organism wasting energy on supporting a sexual reproductive system would be able to survive?

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Size places many interesting constraints on physiology. What is most "efficient" for a bacteria is not necessarily more "efficient" for an elephant. Also, accept for a second that it is more beneficial to be a bigger bacteria. Sexual selection may be more costly than asexual selection, but it allows for bigger sizes to be attained. If the advantage to being bigger outways the disadvantages of sexual reproduction, then we will see sexual reproduction evolve as a result of natural selection, even though it is not neccessarily beneficial in itself to be a sexual reproducer.As an additional point, let me grimace and invoke Dawkins. If selection happens on a genetic level and not an individual level, then we must ask a new question. Is it advantageous for a gene to propogate through sexual reproduction? If it is, as some previous messages on this thread have suggested, then natural selection would favor sexual genes over asexual genes, regardless of the cost to an individual. (Note- my feelings about this argument are mixed, but its out there.)

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What kind of staggering odds would it be for a population of asexual organisms to evolve two separate, but compatible sexes, simultaneously in order to create the sex glands perfectly operable in a male, and also simultaneously evolve a female partner for the male with all of her sex organs in perfect operation?

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Consider that male and female were not initially present. There was no gender, each organism just had a single sex organ that allowed for gene transfer. This isn't so hard to believe, or all that improbable. Every barnacle comes equipped with male and female organs, and procreates through mutual penetration. And flowers have a pistol and stamen, the male and female reproductive components.Later, the organs differentiated into male and female components. How this differentiation happens is I think a much more challenging and interesting question, in particular why this differentiation had been selected for.

PaulK,My understanding is that current theory says something very similar to what you say, except that it is more male biased. Males began producing more reproductive partners, and eventually began this arms race towards who could produce the greatest number of sperm. Of course, this meant reducing the size of the sperm, because with smaller sperm, there is less of an energy investment, and more total sperm. Since sperm became so small, females needed to compensate by making their eggs larger, so that a combination of egg and sperm would be big enough and have enough energy to produce a viable offspring. Thus, big egg, small numerous sperm.Personally, I don't like this argument. But under your argument, it is still unclear where and how a difference in sexes becomes able to genetically propogate in a stable pattern into future generations, since you allow for the population to change and correct itself if the proportion of males and females becomes imbalanced.

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I have asked the question why nature would have selected sex over asexual reproduction.

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Let me emphasize Wounded King's point- the majority of life on earth is asexual. In sheer numbers and total mass, bacteria rule the world. A very small percentage of the world procreates through sex, it just happens to be the proportion we see on a regular basis.A better question is why nature selected sexual reproduction for the big organisms that we see day to day. Perhaps it is that at large sizes, sexual reproduction is less costly, more efficient, or a natural consequence of other features structural features. Think of what it would take for a bear to split into two in the same way that an amoeba splits into two when it reproduces.

Great post L-man, I for one didn't really know this back ground, it was nice to have an "expert" come in and relay the true account.One question- I know you hadn't studied this, but what is the sequence of events for plant sexuality?

What is the date of the sources you are quoting? Research in hot fields like sexual reproduction evolve rapidly and new explanations can arise in as little as 5 to 10 years. I mean, Lithoid-Man offered a very good explanation of sex, and I bet his research was performed after that book.Also, statements like this:

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You only have to think of sex to see how absurd it is.

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lead me to believe that you think the pure existence of sex is absurd, rather than the origination of sex being absurd. This sort of concern is outside the scop of this thread, but even more importantly, if sex is so absurd, why was it "designed"? The absurdity of sex is evidence against a designer if anything.Now, I'm not familiar with this literature, but statements like

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Evolution of many aspects of reproduction requires more theoretical studies, while the existing data are insufficient to choose among the currently competing hypotheses.

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indicates that there are "currently competing hypotheses," or possible explanations out there. There is simply not enough data to choose a correct one yet. This does not say sexual reproduction is incompatible with evolution. It only says the mechanism of sexual reprduction is currently unknown, but compatible explanations exist. Which doesn't say anything new, this is why we still do science, because we don't know everything yet. And this is making your whole argument sound like an irreducible complexity argument.

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Lastly, I would ask the evolutionists this question which a friend of mine posed to an evolutionist: The human female reproductive mechanism uses scent. The mechanism gives a scent that only attracts the sperm cells that it was designed to attract. How could this mechanism evolve step-by-step?

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Sounds to me a lot like the way a flower attracts a pollinator. I think Chiroptera's explanation of a positive feedback loop fits the bill pretty well.