It might have all been a reaction to parasites, one theory holds.
See, the bad thing about reproduction sans sex is you make clones, and clones, and more clones. Every organism has the same DNA, other than mutations that occur over time. If a parasite figures out how to exploit a vulnerability, the entire species can be doomed.
But with good ol' sex comes unique combinations of DNA and genetically unique individuals. A parasite may kill many, but it's likely that some organisms won't be vulnerable and the species will live on.
All this has been modeled before. But the true test for any theory is what actually happens in nature.
So for 10 years, scientists studied Potamopyrgus antipodarum, a New Zealand freshwater snail that comes in a sexual and an asexual version. They counted the snails and the number of parasite infections for each variety.
Clones that were plentiful at the beginning of the study became more susceptible to parasites over time. As parasite infections increased, the once plentiful clones dwindled dramatically in number, the scientists write in the July issue of the journal American Naturalist. Some clonal types disappeared entirely.
Meanwhile, sexual snail populations remained more stable over time. This, the authors say, is exactly the pattern predicted by the parasite hypothesis.
"The rise and fall of these female-only lineages was surprisingly fast and consistent with the prediction of the parasite hypothesis for sex," said study team member Jukka Jokela of the Swiss Federal Institute of Aquatic Science and Technology. "These results suggest that sexual reproduction provides an evolutionary advantage in parasite rich environments."
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- DeliaTheArtist
- added this
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Neat.
So the next time you want to get some I might suggest "If we don't have sex the parasites win."
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- theultimateend
- 5 months ago
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Ha!
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well i was invited out for clubbing tonight, i guess now i'll have something interesting to say...
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- RaceBannon
- 5 months ago
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Corals can be both gonochoristic (unisexual) and hermaphroditic, each of which can reproduce sexually and asexually.
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This is just a very short term evolutionary influence. It's rather fatuous to attribute such a major aspect of reproduction to ONE single influence like that, and a rather speculative one at that. Basically anything at all that is detrimental to a species continued survival in its current form is an evolutionary influence and would have contributed to the change to sexual reproduction.
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- ozoneocean
- 5 months ago
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So Bill Clinton has way too many of these parasites in theory.
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- Crenshaw_Brothers
- 5 months ago
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...for many women...sex produces couch ridden parasites called boyfriends. I learned this from a pair-of-sites.
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don't let the bed bugs bite :D
