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Summary Article: Reproduction
From The Encyclopedia of Applied Animal Behaviour & Welfare

Reproduction refers to the propagation of a new individual, and may arise sexually or asexually. While sexual reproduction involving the fusing of gametes from different individuals is the norm in the animal kingdom, sexual reproduction by hermaphrodite individuals (in which a single individual produces both the eggs and sperm of a mating) and asexual reproduction also occur in both invertebrates and vertebrates. For example, the mangrove killifish (Kryptolebias marmoratus) has a mixed mating strategy, with hermaphrodites engaging in both self-and cross-fertilization, while the female hammerhead shark (Sphyrna) may reproduce asexually through parthenogenesis. Some species can alternate between sexual and asexual reproduction (heterogamy) according to the prevailing conditions, in order to capitalize on the advantages associated with each strategy. Sexual reproduction has the advantage of allowing genetic mixing through the fusion of gametes produced by meiosis (even in the case of intra-individual sexual reproduction). This can facilitate adaptation in a changing environment and may result in change in the gene frequency within the population. By contrast, asexual reproduction facilitates rapid colonization of new areas, and may be a particularly successful strategy in stable environments.

see also: K and r selection

Fig. R.5. Venn diagram illustrating the possible relationship between different types of repetitive behaviour, as proposed by Mills and Luescher (2006) in Mason and Rushen (2006). See text for details of the various terms. Note: the relative areas of the ellipses do not represent the relative magnitudes of the respective sets.

Mills, Daniel S.
© CAB International 2010

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