Parthenogenesis is a form of asexual reproduction whereby females can produce viable eggs without fertilization by males. It is an ability possessed by a wide variety of plant and animal species, including most non-vascular plants (liverworts, hornworts, and mosses), a succulent plant genus in South Africa, assorted invertebrates, especially certain arthropods (water fleas, daphnia, rotifers, aphids, some bees, some scorpions, and parasitic wasps), and a few vertebrates (some reptiles, fish, and in a few instances, birds and sharks). In general, parthenogenesis is rare -- most animals capable of asexual reproduction are very simple -- either sponges or cnidarians (jellyfish, coral, etc), too simple to have sexes.

孤雌生殖的过程不应该与雌雄同体的质量相混淆--雌雄同体的物种。 在大多数雌雄同体的物种中，生殖仍然是有性的，需要两个参与者。 孤雌生殖是复杂动物可以克隆自己的唯一方式。 在某些情况下，它可以导致后代在遗传上与父母不同，这取决于卵子是单倍体还是二倍体。 像任何其他形式的繁殖，孤雌生殖有其好处（繁殖不需要男性）和缺点（遗传多样性低，易受有害突变的影响而持续几代）。

许多能进行孤雌生殖的物种也能使用有性生殖手段。 这就通过重组来洗刷基因，使遗传多样性超过必要的阈值。 在一些爬行动物中，最明显的是新墨西哥鞭尾，完全通过孤雌生殖进行繁殖。 这些物种往往是多倍体的，即它们有两套以上的染色体，意味着它们的基因组是由同一属的两个或多个亲代蜥蜴物种组合而成。 物种间的染色体混合导致孤雌生殖的机制不明，但这就是观察到的。 多倍体发生在两个或多个物种的某些杂种中。

Although there are no known natural cases of mammal parthenogenesis, it has been induced artificially in rabbits (Gregory Pincus, 1936) mice (Tokyo University of Agriculture, 2004), and monkeys. Induced parthenogenesis in mice and monkeys often results in abnormal development, because the mother's chromosomes are imprinted in the offspring's genome twice, and many mammals genomes are completely dependent on a mix of genes from both sexes for smooth development. As a result, due to ethical reasons, human live births from parthenogenesis are unlikely to be pursued, though the process can be used to create embryos for experimentation. The South Korean scientist Hwang Woo-Suk achieved this in 2007 while attempting to be the first to clone a human. He was not successful in the cloning, but did produce viable human embryos made via artificial parthenogenesis.