Parthenogenesis is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete without combining with another gamete. In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Some key points about parthenogenesis are:

• Parthenogenesis is sometimes considered to be an asexual form of reproduction, but it may be more accurately described as an “incomplete form of sexual reproduction” since offspring of parthenogenic species develop from gametes.

• Parthenogenesis can operate on either a haploid or a diploid cell.

• Parthenogenic species may be obligate (incapable of sexual reproduction) or facultative (capable of switching between parthenogenesis and sexual reproduction depending upon environmental conditions) .

• More than 2,000 species are thought to reproduce parthenogenically.

• Parthenogenesis is important for various reasons, such as helping in determining the sex of an individual in honey bees, wasps, etc., supporting the chromosomal theory of inheritance, eliminating variations from populations, being the simplest, most stable and easy process of reproduction, causing polyploidy in organisms, and helping in the development.

Parthenogenesis may also be achieved through an artificial process as described below under the discussion of mammals.