Bickering genes shape evolution

摘要

Not all genes follow the rules of inheritance; now researchers are discovering how organisms adapt to the troublemakers. Reproduction is supposed to be an equal opportunity event. Consider humans: hi developing sperm, the sex chromosomes sort 50:50 such that half the sperm carry the male-defining Y chromosome and the rest sport an X. Only the randomness of fertilization leads to families of nine girls and no boys, for example. The same supposedly holds true for the rest of the genome. But in humans,flies, mice, and perhaps many other organisms, guerrilla warfare within the genome sometimes pits one element against another. This often takes on the appearance of a battle between the sexes, but it is really a fight between genes. In this struggle, typically one or more of the X chromosome's genes strike out against the Y's genes. Genes on other chromosomes also can get caught up in this struggle, causing an escalating arms race.