Fission (biology)
Fission, in biology, is the division of a single entity into two or more parts and the regeneration of those parts to separate entities resembling the original. The object experiencing fission is usually a cell, but the term may also refer to how organisms, bodies, populations, or species split into discrete parts.[1][2][3] The fission may be binary fission, in which a single organism produces two parts, or multiple fission, in which a single entity produces multiple parts.
"Binary fission" redirects here. For the binary fission of atomic nuclei, see Nuclear fission.Multiple fission[edit]
Fission of protists[edit]
Multiple fission at the cellular level occurs in many protistists, e.g. sporozoans and algae. The nucleus of the parent cell divides several times by amitosis, producing several nuclei. The cytoplasm then separates, creating multiple daughter cells.[16][17][18]
Some parasitic, single-celled organisms undergo a multiple fission-like process to produce numerous daughter cells from a single parent cell. Isolates of the human parasite Blastocystis hominis were observed to begin such a process within 4 to 6 days.[19] Cells of the fish parasite Trypanosoma borreli have also been observed participating in both binary and multiple fission.[20]
Plasmotomy[edit]
Some protozoans reproduce by yet another mechanism of fission called plasmotomy. In this type of fission, a multinucleate adult parent undergoes cytokinesis to form two multinucleate (or coenocytic) daughter cells. The daughter cells so produced undergo further mitosis.
Opalina and Pelomyxa reproduce in this way.
Population fission[edit]
Any splitting of a single population of individuals into discrete parts may be considered fission. A population may undergo fission process for a variety of reasons, including migration or geographic isolation. Since the fission leads to genetic variance in the newly isolated, smaller populations, population fission is a precursor to speciation.[28][29]