This article is about the biological phenomenon, for other uses see Symbiosis (disambiguation)

The term symbiosis (from the Greek: σύν syn "with"; and βίωσις biosis "living") commonly describes close and often long-term interactions between different biological species. The term was first used in 1879 by the German mycologist Heinrich Anton de Bary, who defined it as "the living together of unlike organisms."^[1][2] The definition of symbiosis is in, and the term has been applied to a wide range of biological interactions. The symbiotic relationship may be categorized as being mutualistic, parasitic, or commensal in nature.^[3][4] Others define it more narrowly, as only those relationships from which both organisms benefit, in which case it would be synonymous with mutualism.^[1][5][6]

Symbiotic relationships include those associations in which one organism lives on another (ectosymbiosis, such as mistletoe), or where one partner lives inside the other (endosymbiosis, such as lactobacilli and other bacteria in humans or zooxanthelles in corals). Symbiotic relationships may be either obligate, i.e., necessary for the survival of at least one of the organisms involved, or facultative, where the relationship is beneficial but not essential for survival of the organisms.^[7][8]

Contents 1 Commensalism 2 Parasitism 3 Symbiosis and evolution 3.1 Symbiogenesis 3.2 Co-evolution 4 Notes 5 See also 6 References 7 External links

[edit] Commensalism

Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped. It is derived from the English word commensal, meaning "sharing food" and used of human social interaction. The word derives from the medieval Latin word, formed from com- and mensa, meaning "sharing a table".^[9][10]

Commensal relationships may involve one organism using another for transportation (phoresy) or for housing (inquilinism), or it may also involve one organism using something another created, after its death (metabiosis). Examples of metabiosis are hermit crabs using gastropod shells to protect their bodies and spiders building their webs on plants.

[edit] Parasitism

A parasitic relationship is one in which one member of the association benefits while the other is harmed.^[11] Parasitic symbioses take many forms, from endoparasites that live within the host's body to ectoparasites that live on its surface. In addition, parasites may be necrotrophic, which is to say they kill their host, or biotrophic, meaning they rely on their host's surviving. Biotrophic parasitism is an extremely successful mode of life. Depending on the definition used, as many as half of all animals have at least one parasitic phase in their life cycles, and it is also frequent in plants and fungi. Moreover, almost all free-living animals are host to one or more parasite taxa. An example of a biotrophic relationship would be a tick feeding on the blood of its host.

[edit] Symbiosis and evolution

While historically, symbiosis has received less attention than other interactions such as predation or competition,^[12] it is increasingly recognised as an important selective force behind evolution,^[7][13] with many species having a long history of interdependent co-evolution.^[14] In fact, the evolution of all eukaryotes (plants, animals, fungi, and protists) is believed under the endosymbiotic theory to have resulted from a symbiosis between various sorts of bacteria.^[7][15][16]

[edit] Symbiogenesis

The biologist Lynn Margulis, famous for her work on endosymbiosis, contends that symbiosis is a major driving force behind evolution. She considers Darwin's notion of evolution, driven by competition, as incomplete and claims that evolution is strongly based on co-operation, interaction, and mutual dependence among organisms. According to Margulis and Dorion Sagan, "Life did not take over the globe by combat, but by networking."^[17]

[edit] Co-evolution

Symbiosis played a major role in the co-evolution of flowering plants and the animals that pollinate them. Many plants that are pollinated by insects, bats, or birds have highly specialized flowers modified to promote pollination by a specific pollinator that is also correspondingly adapted. The first flowering plants in the fossil record had relatively simple flowers. Adaptive speciation quickly gave rise to many diverse groups of plants, and, at the same time, corresponding speciation occurred in certain insect groups. Some groups of plants developed nectar and large sticky pollen, while insects evolved more specialized morphologies to access and collect these rich food sources. In some taxa of plants and insects the relationship has become dependent,^[18] where the plant species can only be pollinated by one species of insect.^[19]

[edit] Notes

[edit] See also

• aposymbiotic
• aquaponics
• decompiculture
• list of symbiotic organisms
• list of symbiotic relationships
• multigenomic organism

[edit] References

• Ahmadjian, Vernon; Paracer, Surindar (2000), Symbiosis: an introduction to biological associations, Oxford [Oxfordshire]: Oxford University Press, ISBN 0-195-11806-5 
• Burgess, Jeremy (1994), Forum: What's in it for me, New Scientist, http://media.newscientist.com/article/mg14119115.200-forum-whats-in-it-for-me--jeremy-burgess-examines-therole-of-cooperation-within-natures-competitive-ways-.html 
• Boucher, Douglas H (1988), The Biology of Mutualism: Ecology and Evolution, New York: Oxford University Press, ISBN 0195053923 
• Cordes, E.E.; Arthur, M.A.; Shea, K.; Arvidson, R.S.; Fisher, C.R. (2005), "Modeling the mutualistic interactions between tubeworms and microbial consortia", PLoS Biol 3 (3): 1–10, doi:10.1371/journal.pbio.0030077 
• Brinkman, F.S.L.; Blanchard, J.L.; Cherkasov, A.; Av-gay, Y.; Brunham, R.C.; Fernandez, R.C.; Finlay, B.B.; Otto, S.P.; Ouellette, B.F.F.; Keeling, P.J.; Others, (2002), "Evidence That Plant-Like Genes in Chlamydia Species Reflect an Ancestral Relationship between Chlamydiaceae, Cyanobacteria, and the Chloroplast", Genome Research 12 (8): 1159–1167, doi:10.1101/gr.341802, PMID 12176923, http://www.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=5449063, retrieved 2007-09-30 
• Danforth, B.N.; Ascher, J. (1997), "Flowers and Insect Evolution", Science 99: 42, doi:10.1126/science.283.5399.143a, http://www.sciencemag.org/cgi/reprint/283/5399/143a.pdf, retrieved 2007-09-25 
• Douglas, A. E. (1994), Symbiotic interactions, Oxford [Oxfordshire]: Oxford University Press, ISBN 0-19-854294-1 
• Facey, Douglas E.; Helfman, Gene S.; Collette, Bruce B. (1997), The diversity of fishes, Oxford: Blackwell Science, ISBN 0-86542-256-7 
• Golding, RS; Gupta (1995), "Protein-based phylogenies support a chimeric origin for the eukaryotic genome", Mol. Biol. Evol. 12 (1): 1–6, PMID 7877484 
• Harrison, Rhett (2002), "Balanced mutual use (symbiosis)", Quarterly journal Biohistory 10 (2), https://www.brh.co.jp/en/experience/journal/32/ss_3.html, retrieved 2007-09-23 
• Harrison, Maria J. (2005), "Signaling in the arbuscular mycorrhizal symbiosis", Annu. Rev. Microbiol. 59: 19–42, doi:10.1146/annurev.micro.58.030603.123749, PMID 16153162 
• Lee, J. (2003), "Amphiprion percula" (On-line), Animal Diversity Web, http://animaldiversity.ummz.umich.edu/site/accounts/information/Amphiprion_percula.html, retrieved 2007-09-29 
• Isaac, Susan (1992), Fungal-plant interactions, London: Chapman & Hall, ISBN 0-412-36470-0 
• Isaak, Mark (2004), CB630: Evolution of obligate mutualism, TalkOrigins Archive, http://www.talkorigins.org/indexcc/CB/CB630.html, retrieved 2007-09-25 
• Moran, N.A. (2006), "Symbiosis", Current Biology 16 (20): 866–871, doi:10.1016/j.cub.2006.09.019, http://linkinghub.elsevier.com/retrieve/pii/S0960982206022123, retrieved 2007-09-23 
• Nardon, P.; Charles, H. (2002), "Morphological aspects of symbiosis", Symbiosis: Mechanisms and Systems. Dordercht/boson/London, Kluwer Academic Publishers 4: 15–44, doi:10.1007/0-306-48173-1_2 
• Powell, Jerry (1992), "Interrelationships of yuccas and yucca moths", Trends in Ecology and Evolution 7: 10–15, doi:10.1016/0169-5347(92)90191-D 
• Nair, S. (2005), "Bacterial Associations: Antagonism to Symbiosis", in Ramaiah, N, Marine Microbiology: Facets & Opportunities;, National Institute of Oceanography, Goa, pp. 83–89, http://drs.nio.org/drs/handle/2264/74, retrieved 2007-10-12 
• Roughgarden, J. (1975), "Evolution of Marine Symbiosis--A Simple Cost-Benefit Model", Ecology 56 (5): 1201–1208, doi:10.1046/j.1420-9101.2000.00157.x, http://links.jstor.org/sici?sici=0012-9658(197522)56%3A5%3C1201%3AEOMSSC%3E2.0.CO%3B2-R, retrieved 2007-09-25 
• Saffo, M.B. (1993), "Coming to terms with a field: Words and concepts in symbiosis", Symbiosis. 14 (1-3), http://www.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=3004656, retrieved 2007-10-05 
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• Sagan, Dorion; Margulis, Lynn (1997), Microcosmos: Four Billion Years of Evolution from Our Microbial Ancestors, Berkeley: University of California Press, ISBN 0-520-21064-6 
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• Toller, W. W.; Rowan, R.; Knowlton, N. (2001), "Repopulation of Zooxanthellae in the Caribbean Corals Montastraea annularis and M. faveolata following Experimental and Disease-Associated Bleaching", The Biological Bulletin 201 (3): 360–373, doi:10.2307/1543614, PMID 11751248, http://www.biolbull.org/cgi/content/full/201/3/360 
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