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Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. [1] In vertebrates , the most common form of asexual reproduction is parthenogenesis , which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited.
[1] [2] [3] Sexual reproduction is widespread in eukaryotes, though a few eukaryotic species have secondarily lost the ability to reproduce sexually, such as Bdelloidea, and some plants and animals routinely reproduce asexually (by apomixis and parthenogenesis) without entirely having lost sex.
This diagram illustrates how sexual reproduction (top) might create new genotypes faster than asexual reproduction (bottom). The advantageous alleles A and B occur randomly. In sexual reproduction, the two alleles are combined rapidly. But in asexual reproduction, the two alleles must independently arise through clonal interference.
Eukaryotes may be either unicellular or multicellular. In comparison, prokaryotes are typically unicellular. Unicellular eukaryotes are sometimes called protists. Eukaryotes can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion (fertilization).
Parthenogenesis (/ ˌ p ɑːr θ ɪ n oʊ ˈ dʒ ɛ n ɪ s ɪ s,-θ ɪ n ə-/; [1] [2] from the Greek παρθένος, parthénos, 'virgin' + γένεσις, génesis, 'creation' [3]) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization.
There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically similar ...
Muller's ratchet relies on genetic drift, and turns faster in smaller populations because in such populations deleterious mutations have a better chance of fixation. Therefore, it sets the limits to the maximum size of asexual genomes and to the long-term evolutionary continuity of asexual lineages. [4]
Most commonly apparent in species that reproduce quickly and asexually, like bacteria, exponential growth is intuitive from the fact that each organism can divide and produce two copies of itself. Each descendent bacterium can itself divide, again doubling the population size (as displayed in the above graph). [2]