Are there evolutionary reasons for reproduction?

Just in case the other attempts didn't sink in: Some organisms yes, not all. Imagine a group of organisms that each ejects 10 seeds measuring 1mm each once per year into a calm area of water. Those seeds combine with each other, more or less by chance, and that is germination with sex.You seem to think this is a perfectly fine situation, yes?Now imagine one organism that came along that produced 1000 seeds measuring 0.0001mm each once per year into said water.One might see that such an organism might have an advantage: They get lots more chances of germination. 100 times more chances in fact.But there is a slight disadvantage: By stripping down the seed, it means that small seeds cannot germinate with other small seeds and rely on all the mechanics in the big seeds to do the work.Agree?So 'small' needs to germinate 'large'.Yes?We have two 'types' but only one of them recently evolved, the other evolved at a different time - we have the original and the evolved?Do you agree that a large seed didn't have to evolve at the same time as the small seed? That the large seed was the original and is only called large relative to the new smaller seed? Do you agree that even though the small seed needs the large seed that doesn't mean the two had to evolve at the same time since the large doesn't necessarily need the small seed (at least initially)? It seems like a roadblock until you dig a little deeper and you realize that it isn't actually a problem.The stumbling block I think you've encountered in your head might be that female gametes now often require male gametes. But the state of affairs you are used to is not necessarily the state of affairs originally.Think about it like this: After a while the watery environment we described is suddenly filled with lots of 'spare' male gametes that never fertilize. So the female gametes may begin to specialise in capturing the male gametes which may be a better strategy than being ok at both female-female fertilization and male-female. It is almost a biological law that becoming more specialised at one thing makes you less good at other things (it is the principle upon which some vaccinations are made). So it isn't a surprise to learn that many eggs are now so specialized in sperm fertilization techniques that they are very poor at female-female fertilization (although in cases where it is still in principle possible, it occasionally still occurs).Many insect eggs will hatch as one sex unless they are specifically fertilized. It is a necessary logic that if males evolve - the thing that isn't male is female. So, even though males may require females to reproduction - they are already in the population. Any mutation which created something that was unable to reproduce with anything around it would obviously die without reproducing and that's no way to evolve a new trait - you are quite right in that.But a mutation which changes the way one goes about reproducing with the things that are commonly around may be successful. And smaller more plentiful gametes is one such thing one can do and biologists call things that use the small plentiful gamete strategy: Male.Those that don't...are called female. The population evolved as female, and males came along to take advantage of that resource. That shouldn't be controversial - the only question is, how did that happen. And that's a different question than the one at hand.Edited by Modulous, : now with 100% more words!

No specific organism - lets call it hypothetia {a hypothetical organism}. It directly addresses it. When you have time, re-read my post. Hypothetia that produce smaller seeds are called 'male'. The original organisms that produce the larger seeds are called 'female'. We have just devised a way for male and female things to come into being at the same time, without the need for both of them to simultaneously evolve. That is the primal state of the hypothetia population. It is from this state we think about how to evolve sex and sex differentiation. Except I specifically pointed out that both sexes are not required in hypothetia. The females can reproduce without males since that is how they started in their primal state. The only new thing that was introduced was that males existed that NEED females. The females did not start off needing the males. Actually I was being even more specific than that. I was pointing out that the more specialised an organism becomes to a specific environment, the worse it does in other environments. Aphids beg to differ (though they don't generally don't bother actually laying the eggs, and they incubate them internally). If you ever get the youngest pacified, consider reading about Parthenogenesis

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Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occurs without fertilization by a male. In plants, parthenogenesis means development of an embryo from an unfertilized egg cell, and is a component process of apomixis. The offspring produced by parthenogenesis are always female in species that use the XY sex-determination system, and male in those that use the ZW sex-determination system.

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Parthenogenesis occurs naturally in some invertebrate animal species (e.g. water fleas, aphids, nematodes, some bees, some Phasmida, some scorpion species, and parasitic wasps), and vertebrates (e.g. some reptiles, fish, and very rarely birds and sharks) and this type of reproduction has been induced artificially in other species.

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Added by edit:Don't take my word for it, go look up the evolution of anisogamy yourself: Cooperation and the evolution of anisogamyGametic conflict versus contact in the evolution of anisogamyThe quick and the dead? Sperm competition and sexual conflict in sea.Selection for high gamete encounter rates explains the evolution of anisogamy using plausible assumptions about size relationships of swimming speed and duration.Naturally, reality is much messier than hypothetia - but if you can't get your head around her...you won't have a chance with the real deal.Edited by Modulous, : No reason given.Edited by Modulous, : No reason given.