Parthenogenesis

Parthenogenesis is a rare (in animals, but many plants exhibit this behavior), asexual form of reproduction in which the females of a species give birth without copulating with males. Instead, because the eggs are already diploid, only the physical actions of sex need to be employed for the female to give birth. This, however, is done by another female, one who is not ovulating. So the non-ovulating female dry humps the other female, and the offspring is an exact genetic copy of the mother.

Maybe the most popular example is a few species of the whiptail lizard. Unlike other parthenogenetic animal populations, these species are composed entirely of females.