These females are able to produce offspring by laying unfertilized eggs. This is uncommon in the animal kingdom, but not completely unheard of. There are 80 known species of unisexual animals, including species of fish, amphibians, and other reptiles. The most commonly-known are the whiptail lizards. There are 12 species of whiptail lizards in south-western North America. Out of those, 7 are unisexual (all female) and they reproduce through parthenogenesis (self-cloning, essentially). Scientists have hypothesized for years that these unisexual species came about from inter-species mating from different species of whiptails. Usually when two animals from different species produce a hybrid, the hybrid turns out to be sterile. Sometimes, the hybridization induces a mutation that allows for females to reproduce with parthenogenesis. Recently, scientists were able to create their own species of all-female, self-cloning lizards in a laboratory by making a hybrid between two already existing species. This confirms the suspicion that the 7 unisexual lizards species came about through hybridization.