Asexual reproduction  is a type of "Asexual meiosis or mitosis" by which offspring arise from a single organism, and inherit the genes of that parent only; it does not involve the fusion of gametesand almost never changes the number of chromosomes.
Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many plants and fungi sometimes reproduce asexually. While all prokaryotes reproduce without the formation and fusion of gametes, mechanisms for lateral gene transfer such as conjugationtransformation and transduction can be likened to sexual reproduction in the sense of genetic recombination in meiosis. It is not entirely understood why the ability to reproduce sexually is so common among them.
Current hypotheses  suggest that asexual reproduction may have short term benefits when rapid population growth is important or in stable environments, while sexual reproduction offers a net advantage by allowing more rapid generation of genetic diversity, allowing adaptation to changing environments. Developmental constraints  may underlie why few animals have relinquished sexual reproduction completely in their life-cycles.
Another constraint on switching from sexual to asexual reproduction would Asexual meiosis or mitosis the concomitant loss of meiosis and the protective recombinational repair of DNA damage afforded as one function of meiosis.
An important form of fission is binary fission, where the parent organism is replaced by two daughter organisms, because it literally divides in two.
Only prokaryotes the archaea and the bacteria reproduce asexually through binary fission. Eukaryotes such as protists and unicellular fungi may reproduce in a functionally similar manner by Asexual meiosis or mitosis ; most of these are also capable of sexual reproduction.
Multiple fission at the cellular level occurs in many protistse. The nucleus of the parent cell divides several times by mitosisproducing several nuclei.