In biology,
polyspermy describes an
egg that has been
fertilized by more than one
sperm.
Diploid organisms normally contain two copies of each
chromosome, one from each parent. The cell resulting from polyspermy, on the other hand, contains three or more copies of each chromosome—one from the egg and one each from multiple sperm. Usually, the result is an inviable
zygote. This may occur because sperm are too efficient at reaching and fertilizing eggs due to the selective pressures of
sperm competition. Such a situation is often deleterious to the female: in other words, the
male-male competition among sperm spills over to create
sexual conflict.