Establishment of equilibrium for the dominant lethal gene for Manx taillessness in cats.

An account is given of a model by which the dominant gene for Manx taillessness in cats is maintained at a stable equilibrium value in cat populations in spite of the homozygous condition being lethal. The model assumes that M-carrying sperm have a selective advantage during fertilization, and that M-carrying chromatids are selectively retained at the second maturation division. Estimates of fertilization parameters differed significantly from the value 0.5, which is the expected value if selective fertilization is absent.