Comment by GuiA | Hacker News Reader

Comment by GuiA | Hacker News Reader

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> I wonder what's the evolutionary reason for this not happening in more species.

There's rarely an "evolutionary reason" for a trait not developing. Wings would certainly be a net benefit to mice survival-wise; but unless there's a strong evolutionary pressure for such a trait to develop, it's unlikely to appear.

It's the same for asexual reproduction: unless there's a strong advantage for a species to reproduce asexually, it's likely not going to appear.

In other words, evolutionary selection is really about the strict minimum needed for a species' population to thrive; evolution selects, but it doesn't optimize.

You also have to account for things that are hard to predict: even though on paper it seems like asexual reproduction would lead to a higher chance of propagating genes, perhaps in reality the lack of diversity in the resulting offspring would be negative to the species' survival (or while it sounds like mice developing wings would be an advantage, in reality the energy needed to develop wings would make it a survival disadvantage).

An interesting case were these rules are "suspended" are in closed ecosystems where certain species have no predators and plenty of sustenance; e.g. paradise birds in pacific islands, which can develop completely superfluous feather patterns and attributes at no evolutionary "cost".

>>unless there's a strong advantage for a species to reproduce asexually, it's likely not going to appear.

I was under the (perhaps wrong) impression that asexual reproduction predated sexual reproduction in the history of life (prokaryotes predating eukaryote?) so I always thought that organisms "lost" the trait of asexual reproduction somewhere down the line. Probably an assumption without basis.

>>perhaps in reality the lack of diversity in the resulting offspring would be negative to the species' survival.

Yes. I imagine the answer would be something like that, but the question of what is the exact reason still stands.

Like i said I haven't the foggiest idea of the subject matter but always liked to think and speculate about it. Origin and Nature of Life, Physical nature of consciousness and Neuroscience in general are all topics I find fascinating. If anybody know any popular science books they can recommend on any of these topics, it would be great.

Dawkins' books, especially the earlier ones (e.g. Blind Watchmaker), are quite a good and gentle introduction.

Yes, you are right that life originally started as asexual reproduction and sexual reproduction appeared later; my answer was more about the likelihood of a species that already reproduces sexually moving towards asexual reproduction.

Regarding the question of why the asexual->sexual shift happened in the first place, the wikipedia article on asexual reproduction has this to say:

Current hypotheses [2] suggest that asexual reproduction may have short term benefits when rapid population growth is important or in stable environments, while sexual reproduction offers a net advantage by allowing more rapid generation of genetic diversity, allowing adaptation to changing environments.

>> Yes, you are right that life originally started as asexual reproduction and sexual reproduction appeared later

No, that's a hot research topic.

E.g. a popular hypothesis is than in an RNA world very early and simple organisms had inefficient metabolism and error-prone genetic copy. They didn't have enough energy to sustain a backup of their genetic information, RNA is not very stable, etc. So the only way to keep functioning was to constantly mate with other organisms and exchange good replacements for broken genes.

Thanks for your replies (Need to think more about them) and book recommendation.

These topics are truly fascinating. Many seem to consider them 'soft' compared to Physics, but in some ways, I find some of the questions involved at least as deep and fundamental (or even more) as those currently being asked in the Physics discipline.

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