Tuesday, August 4, 2009

Evolution Of Sex

Despite its central role in biology, sex is a bit of an evolutionary mystery. Reproducing without sex—like microbes, some plants and even a few reptiles—would seem like a better way to go. Every individual in an asexual species has the ability to reproduce on its own. But in sexual species, two individuals have to combine in order to reproduce one offspring. That gives each generation of asexuals twice the reproductive capacity of sexuals. Why then is sex the dominant strategy when the do-it-yourself approach is so much more efficient? asexual organisms from getting too plentiful. When an asexual creature reproduces, it makes clones—exact genetic copies of itself. Since each clone has the same genes, each has the same genetic vulnerabilities to parasites. If a parasite emerges that can exploit those vulnerabilities, it can wipe out the whole population. On the other hand, sexual offspring are genetically unique, often with different parasite vulnerabilities. So a parasite that can destroy some can't necessarily destroy all. That, in theory, should help sexual populations maintain stability, while asexual populations fa

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