Narrator: This is Science Today. Evolutionary biologists have wondered for years just why sexual reproduction is more common than asexual reproduction - especially since asexual populations have the advantage of producing more offspring. Now, researchers at the University of California, Santa Barbara, have demonstrated for the first time that the accumulation of beneficial mutations is faster in sexual populations. Biologist Marlene Zuk, of the University of California, Riverside, has also done work in this field and says that's because sexual reproduction provides more variation in offspring.
Zuk: You make fewer of them and they're not as much like you, but what if they're better? Let's say that you're in a population where there's some disease that's attacking everybody. Well, parasites are doing this because they're able to exploit some aspect of your genotype. Let's say they can do better to attach to your intestinal lining. Well, if you have a bunch of offspring that vary in the quality of their intestinal lining, then maybe one of them is going to be able to resist the pathogen.
Narrator: For Science Today, I'm Larissa Branin.