Neat
article on the introgression of an allele for switching the red seeds of rice to white from the
japonica to the
indica subspecies. Basically the mutant arose in the
japonica subspecies, "jumped" to the
indica, and fixed. You can read the paper for why people prefer white to red varieties, but the important point that the authors offer is that a) rice is highly inbred and b) there are fertility barriers between the two varieties. That implies that the selective advantage was so great that people worked hard to hybridize the two even though it was something of an unnatural act.
Labels: Population genetics