In meiosis, then, an entire chromosome is pulled to a pole in anaphase, whereas in mitosis only a single chromatid is pulled to a pole. The chromosomes move to the poles in a random fashion, and some paternal and some maternal chromosomes move to each pole without regard to the movement of all other chromosomes. Both cells are diploid, although changes to the chromatids of the individual chromosomes will have occurred through crossing over. 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.