The movie “Jurassic Park” featured a scene where the hero discovers dinosaur eggs and realizes that some of the previously all-male population of animals have become females. Is this possible in real life? It turns out that it is, sort of. In fact, one species of reptile has done away with males altogether.
The existence of the phenomena, known as parthenogenesis, was first discovered in the 1700s by Swiss scientist Charles Bonnet, who was studying aphids at the time. Since then, several other species have been found to be able to produce young without the help of a male. Most, but not all, are insects.
Sharks are sometimes known to produce young without the presence of a male. In December 2001, a shark pup was born to one of three female hammerhead sharks in an enclosed tank with no male present. The pup’s DNA was analyzed in 2007 and it was found that its mother was its only parent. Again, in 2008, a blacktip shark who died was found to have been pregnant. She had been in captivity for eight years and had never been in the presence of a male. For some reason, all shark pups born to virgin females are female.
Komodo dragons are also known to produce young through parthenogenesis. In fact, two different cases were discovered in England in 2006. Since Komodo dragons are a species with a WZ chromosome makeup, all of their offspring are male. This would enable an isolated female to repopulate her environment by mating with her own offspring.
Honeybees practice an interesting form of parthenogenesis. Queen bees mate only once in their lifetimes. Progeny born as a result of mating are females. But they also produce offspring from otherwise unfertilized eggs. These bees become male drones. . This brings the concept of gender selection to a whole new level.
The lizard called the New Mexico whiptail has taken parthenogenesis to the extreme. There are no male whiptails. It is interesting, though, that the female members still practice mating behaviors, with some females known to mount ovulating companions in the same way a male might. When two whiptails are placed together, they synchronize their ovulation cycles so that only one is producing eggs at any given time.
There’s more information on this amazing phenomena here