Reproduction through mitosis, creating a new, genetically identical individual. Humans and most of the animals and plants that humans think about reproduce sexually. Many plants and 'lower animals' reproduce both sexually and asexually; there are some single-celled organisms that reproduce only through asexual means.
Asexual reproduction tends to be fast, convenient (no need to go hunting for a mate), and a good way to pump out a stable, healthy population. Of course, if the environment is undergoing change, sexual reproduction can be an important aid to adaptation. Asexual reproduction is essentially producing clones, with almost no variations between individuals (what variation there is, is due to mutation).
Types of asexual reproduction include:
- plants. (AKA vegetative reproduction):
- Rhizomes: stems running underground that can produce new, individually viable offshoots.
- Runners or Stolons: the same as rhizomes, but above the ground.
- Tubers: modified rhizomes, in which all the offshoots are clumped together in one large lump. Think potato.
- Bulbs: In some plant species the above-ground portion of the plant dies off during the winter, leaving an underground bulb. A bulb is a short stem surrounded by fleshy leaves for storing nutrients. Produces only one 'offspring'.
- Corms: The same as a bulb, but with thin, papery leaves, instead of fleshy storage leaves.
- Plantlets: (AKA turions) miniature plants that form on the margin of the leaves; these drop off and grow into mature plants.
- Cuttings: A stem is taken from a plant and replanted to grow on its own. This may require humans to artificially add enzymes that encourage rooting.
- Grafting: A plant is grown; some part of this plant is cut off, and a piece of another plant (this piece is called a scion) is attached in it's place. If done correctly, the scion will grow, taking nutrients from the root system of the host plant, and producing the fruit or flower of the plant that the scion was taken from. Plants such as seedless grapes and navel oranges can only reproduce by these human-aided, artificial means.
- Apomixis: A seed is produced that can develop without ever being fertilized
- Fission: Straight-out mitosis. The parent cell splits in two. This works only with single-celled organisms. The Ameba is an example.
- Sporulation: Some single-celled animals can 'hibernate', excreting a hard shell, while inside the nucleus divides into hundreds of fragments (AKA spores). When environmental conditions become favourable, the outer shell disintegrates, releasing the spores. The Ameba is an example.
- Budding: The offspring develop as a small bud connected to the animal. Examples are the Sea anemone, Tapeworm, and Coral.
- Fragmentation / Autotomy: Some animals can either be broken, or break themselves, into multiple pieces, each of which can grow into a entire creature. The Sea star and Hydra are well known for this ability.
- Parthenogenesis: The female produces viable eggs without ever being fertilized. Occurs in a few types of insects, reptiles, and fish.