Asexual reproduction has been documented in all kingdoms of life. Any organism produced asexually is genetically identical to its parent. Parthenogenesis is the development of an adult organism from an unfertilized egg. It differs from asexual reproduction per se in that it involves at least one gamete. Sexual reproduction increases genetic variability through crossing over, independent assortment, and random fertilization.
Genetic variability provides the raw material for natural selection and thus, evolution.