asexual reproduction

Asexual reproduction is the simplest form of reproduction, occurring in many simple plants and animals. Binary fission, shown here occurring in an amoeba, is one of a number of asexual reproduction processes

Examples of asexual reproduction. Asexual reproduction is the simplest form of reproduction, occurring in many plants and simple animals. Strawberry plants can reproduce by sending out runners; onion plants form bulbs; and potato plants form tubers. Amoebas divide into two (binary fission) and hydra form new hydra by budding. The offspring are always genetically identical to the parent.

Reproduction that does not involve the manufacture and fusion of sex cells (gametes) from two parents. Asexual reproduction has advantages in that there is no need to search for a mate; every asexual organism can reproduce on its own. Asexual reproduction can therefore lead to a rapid population build-up. However, every new organism produced by asexual reproduction is genetically identical to the parent - a clone.

In evolutionary terms, the disadvantage of asexual reproduction arises from the fact that only identical individuals (clones) are produced - there is no variation. In agriculture and horticulture, where standardized production is needed, this is useful. Taking cuttings of a good variety of fruit tree is an example of artificial asexual reproduction. However, in the wild, an asexual population that cannot adapt to a changing environment or evolve defences against a new disease is at risk of extinction. Many asexually reproducing organisms are therefore capable of reproducing sexually as well.

Asexual reproduction is very common in micro-organisms. But there are also many plants that use it naturally. The blackberry or bramble spreads by allowing its stems to root where they touch the ground. However, the blackberry also reproduces sexually using its flowers.

Asexual processes include binary fission, in which the parent organism splits into two or more ‘daughter’ organisms, and budding, in which a new organism is formed initially as an outgrowth of the parent organism. Asexual reproduction by means of spores is common in ferns and mosses. Many plants reproduce asexually by means of runners, rhizomes, bulbs, and corms; see also vegetative reproduction.