Food web: Difference between revisions

Browse history interactively

← Previous edit Next edit →

Content deleted Content added

VisualWikitext

Inline

Revision as of 08:46, 28 April 2011

haha lol n00b

@@ Line 1: / Line 1: @@
+haha lol n00b
-[[Image:FoodWeb.jpg|thumb|right|280px|<center>A [[freshwater]] [[Aquatic ecosystem|aquatic]] and [[Ecoregion#Terrestrial|terrestrial]] food web.</center>]]
-[[Image:Food chain.jpg|thumb|140px|Example of a ''food chain'' in a Swedish lake. [[Osprey]] feed on [[northern pike]], which in turn feed on [[perch]] which eat [[Common Bleak|bleak]] that feed on freshwater [[shrimp]]. Although not shown, [[primary producers]] of this food chain are probably [[autotrophy|autotrophic]] [[phytoplankton]].]]
-'''Food chains''' and '''food webs''' are representations of the [[prey|predator-prey]] relationships between [[species]] within an [[ecosystem]] or [[habitat]].
-Many [[chain]] and web models can be applicable depending on habitat or [[Environment (biophysical)|environmental]] factors. Every known food chain has a base made of [[autotroph]]s, organisms able to manufacture their own food (e.g. [[plant]]s, [[chemotroph]]s).
-==Organisms represented in food chains==
-In nearly all food chains, [[solar energy]] is input into the system as [[light]] and heat, utilized by autotrophs (i.e., producers) in a process called [[photosynthesis]]. Carbon dioxide is reduced (gains electrons) by being combined with water (a source of hydrogen atoms), producing glucose.  [[Water splitting]] produces hydrogen, but is a nonspontaneous ([[endergonic reaction|endergonic]]) reaction requiring energy from the sun.  Carbon dioxide and water, both stable, oxidized compounds, are low in energy, but glucose, a high-energy compound and good [[electron donor]], is capable of storing the solar energy.<ref>{{cite book | last= Smith| first= Gilbert M.| title= A Textbook of General Botany| year= 2007| publisher= READ BOOKS| page= 145| url= http://books.google.com/?id=jmQUgBUaB_wC&pg=PA145&dq=%22The+available+energy+content+of+carbon+dioxide+and+that+of+water+are+relatively+low#v=onepage&q=%22The%20available%20energy%20content%20of%20carbon%20dioxide%20and%20that%20of%20water%20are%20relatively%20low| isbn= 9781406773156}}</ref>  This energy is expended for cellular processes, growth, and development. The plant sugars are [[polymerization|polymerized]] for storage as long-chain [[carbohydrate]]s, including other sugars, starch, and cellulose.
-Glucose is also used to make [[fat]]s and [[protein]]s.<ref name="macronutrients">{{cite book | last= Beckett| first= Brian S.| title= Illustrated Human and Social Biology| year= 1981| publisher= Oxford University Press| page= 38| url= http://books.google.com/?id=-mYIPXC0gEgC&pg=PA38&dq=photosynthesis+carbohydrates+fats+proteins#v=onepage&q=photosynthesis%20carbohydrates%20fats%20proteins| isbn= 9780199140657}}</ref>  Proteins can be made using [[nitrate]]s, [[sulfate]]s, and [[phosphate]]s in the soil.<ref>{{cite book | last= Smith| first= Gilbert M.| title= A Textbook of General Botany| year= 2007| publisher= READ BOOKS| page= 148| url= http://books.google.com/?id=jmQUgBUaB_wC&pg=PA148&dq=proteins+nitrates+sulphates&q=proteins%20nitrates%20sulphates| isbn= 9781406773156}}</ref>  When autotrophs are eaten by [[heterotroph]]s, i.e., consumers such as animals, the [[carbohydrate]]s, [[fat]]s, and [[protein]]s contained in them become energy sources for the heterotrophs.<ref name="macronutrients"/>
-==Chemoautotrophy==
-An important exception is [[lithotroph]]y, the utilization of inorganic compounds, especially [[mineral]]s such as [[sulfur]] or [[iron]], for energy. In some lithotrophs, minerals are used simply to power processes for making organic compounds from inorganic carbon sources.
-In a few haha food chains, e.g., near [[hydrothermal vent]]s in the [[deep sea]], autotrophs are able to produce organic compounds without sunlight, through a process similar to photosynthesis called [[chemosynthesis]], using a carbon source such as carbon dioxide and a chemical energy sources such as [[hydrogen sulfide]], H<sub>2</sub>S, or molecular hydrogen, H<sub>2</sub>.
-Unlike water, the hydrogen compounds used in chemosynthesis are high in energy. Other lithotrophs are able to directly utilize inorganic substances, e.g., iron, hydrogen sulfide, elemental sulfur, or thiosulfate, for some or all of their energy needs.<ref>{{cite book | author= Jorge G. Ibanez| coauthors= Margarita Hernandez-Esparza, Carmen Doria-Serrano, Mono Mohan Singh| title= Environmental Chemistry: Fundamentals| year= 2007| publisher= Springer| page= 156| url= http://books.google.com/?id=6sPU95tqqn4C&pg=PA156&dq=sulfur+oxidizers+%22elemental+sulfur%22&q=sulfur%20oxidizers%20%22elemental%20sulfur%22| isbn= 9780387260617}}</ref><ref>{{cite book | last1= Lengeler| first1= Joseph W.| last2= Drews| first2= Gerhart| last3= Schlegel| first3= Hans Günter| title= Biology of the Prokaryotes| year= 1999| publisher= Georg Thieme Verlag| page= 249| url= http://books.google.com/?id=MiwpFtTdmjQC&pg=PA249&dq=sulfur+oxidizers+%22elemental+sulfur%22&q=sulfur%20oxidizers%20%22elemental%20sulfur%22| isbn= 9783131084118}}</ref><ref>{{cite book | last1= Reddy| first1= K. Ramesh| last2=DeLaune| first2= Ronald D.| title= Biogeochemistry of Wetlands: Science and Applications| year= 2008| publisher= CRC Press| page= 466 | url= http://books.google.com/?id=8yLE_tMMTl8C&pg=PA466&dq=sulfur+oxidizers+%22elemental+sulfur%22&q=sulfur%20oxidizers%20%22elemental%20sulfur%22| isbn= 9781566706780}}</ref><ref>{{cite book | last1= Canfield| first1= Donald E.| last2= Kristensen| first2= Erik| last3= Thamdrup| first3= Bo| title= Aquatic Geomicrobiology| year= 2005| publisher= Elsevier| page= 285| url= http://books.google.com/?id=yrJxfG0_WyYC&pg=PA285&dq=iron+oxidizer#v=onepage&q=iron%20oxidizer| isbn= 9780120261475}}</ref>
-==Involvement in the carbon cycle==
-Carbon dioxide is recycled in the [[carbon cycle]] as carbohydrates, fats, and proteins are oxidized ([[metabolism|burned]]) to produce carbon dioxide and water.  Oxygen released by photosynthesis is utilized in [[respiration]] as an [[electron acceptor]] to release chemical energy stored in organic compounds.
-Dead organisms are consumed by [[detritivore]]s, [[scavenger]]s, and [[decomposer]]s, including [[fungi]] and [[insect]]s, thus returning nutrients to the soil.
-==Food web==
-[[Image:EltonFW.jpg|center|thumb|500px|Victor Summerhayes and [[Charles Sutherland Elton|Charles Elton]]'s 1923 food web of Bear Island (''Arrows point to an organism being consumed by another organism'').]]
-Food chains are overly simplistic as representatives of the relationships of living organisms in nature. Most consumers feed on multiple species and in turn, are fed upon by multiple other species.
-For a snake, the prey might be a mouse, a lizard, or a frog, and the predator might be a bird of prey or a badger.  The relations of detritivores and [[parasitism|parasites]] are seldom adequately characterized in such chains as well.
-A food web is a series of related food chains displaying the movement of energy and matter through an ecosystem. The food web is divided into two broad categories: the grazing web, beginning with autotrophs, and the detrital web, beginning with organic debris.  There are many food chains contained in these food webs.
-In a grazing web, energy and nutrients move from plants to the herbivores consuming them to the carnivores or omnivores preying upon the herbivores.  In a detrital web, plant and animal matter is broken down by decomposers, e.g., bacteria and fungi, and moves to detritivores and then carnivores.<ref>{{cite book | last1= Gönenç| first1= I. Ethem| last2= Koutitonsky| first2= Vladimir G.| last3= Rashleigh| first3= Brenda| title= Assessment of the Fate and Effects of Toxic Agents on Water Resources| year= 2007| publisher= Springer| page= 279| url= http://books.google.com/?id=nBQYnbsUrBQC&pg=PA278&dq=Water+Resources+grazing+detrital+web&cd=1#v=onepage&q=Water%20Resources%20grazing%20detrital%20web| isbn= 9781402055270}}</ref>
-There are often relationships between the detrital web and the grazing web.  Mushrooms produced by decomposers in the detrital web become a food source for deer, squirrels, and mice in the grazing web.  [[Earthworm]]s eaten by robins are detritivores consuming decaying leaves.<ref>{{cite book | author= Gil Nonato C. Santos| coauthors= Alfonso C. Danac, Jorge P. Ocampo | title= E-Biology II| year= 2003| publisher= Rex Book Store| page= 58| url= http://books.google.com/?id=L9TwLvnIvnkC&pg=PA58&dq=grazing+web+detrital+web#v=onepage&q=grazing%20web%20detrital%20web| isbn= 9789712335631}}</ref>
-==Flow of food chains==
-{{See also|Trophic level}}
-[[Food energy]] flows from one organism to the next and to the next and so on, with some energy being lost at each level.  Organisms in a food chain are grouped into [[trophic level]]s, based on how many links they are removed from the primary producers. In trophic levels there may be one species or a group of species with the same predators and prey.<ref>{{cite book | author= Jerry Bobrow, Ph.D.| coauthors= Stephen Fisher| title= CliffsNotes CSET: Multiple Subjects| year= 2009| edition= 2nd| publisher= John Wiley and Sons| page= 283| url= http://books.google.com/?id=BAaYNjlrJDcC&pg=PR1&dq=%22are+presumed+to+share+both+predators+and+prey%22#v=snippet&q=%22presumed%20to%20share%20both%20predators%20and%20prey%22| isbn= 9780470455463}}</ref>
-Autotrophs such as plants or [[phytoplankton]] are in the first trophic level; they are at the base of the food chain. Herbivores (primary consumers) are in the second trophic level.  Carnivores (secondary consumers) are in the third.  Omnivores are found in the second and third levels.  Predators preying upon other predators are tertiary consumers or secondary carnivores, and they are found in the fourth trophic level.<ref name="trophic">{{cite book | last1= Fallaria| first1= Rebecca R.| last2= Apolinario| first2= Nenita A.| last3= Ronquillo| first3= Jesse D.| title= Science Spectrum| year= 2004| edition= 6th| publisher= Rex Book Store| page= 59| url= http://books.google.com/?id=L9TwLvnIvnkC&pg=PA59&dq=decomposers+of+the+available+materials+function+as+herbivores+or+carnivores&q=decomposers%20of%20the%20available%20materials%20function%20as%20herbivores%20or%20carnivores| isbn= 9789712335631}}</ref>
-Food chain length is another way of describing food webs as a measure of the number of species encountered as energy or nutrients move from the plants to top predators.<ref name="Post93">{{cite journal|last=Post|first=D. M.|title= The long and short of food-chain length|year=1993|journal = Trends in Ecology and Evolution|volume=17|issue=6| pages=269–277|doi=10.1016/S0169-5347(02)02455-2}}</ref>{{Rp|269}}</blockquote> There are different ways of calculating food chain length depending on what parameters of the food web dynamic are being considered: connectance, energy, or interaction.<ref name="Post93" /> In a simple predator-prey example, a deer is one step removed from the plants it eats (chain length = 1) and a wolf that eats the deer is two steps removed (chain length = 2). The relative amount or strength of influence that these parameters have on the food web address questions about:
-*the identity or existence of a few dominant species (called strong interactors or keystone species)
-*the total number of species and food-chain length (including many weak interactors) and
-*how community structure, function and stability is determined.<ref name="Worm03">{{cite journal|last1=Worm|first1=B.|last2=Duffy|first2=J.E.|title= Biodiversity, productivity and stability in real food webs|year=2003|journal = Trends in Ecology and Evolution|volume=18|issue=12| pages=628–632|doi=10.1016/j.tree.2003.09.003}}</ref>
-==Entropic losses in the chain==
-{{See also|Ecological efficiency}}
-It is the case that the [[biomass]] of each [[trophic level]] decreases from the base of the chain to the top. This is because energy is lost to the environment with each transfer as [[entropy]] increases.  About eighty to ninety percent of the energy is expended for the organism’s life processes or is lost as heat or waste. Only about ten to twenty percent of the organism’s energy is generally passed to the next organism.<ref name="entropy">{{cite book | last= Spellman| first= Frank R.| title= The Science of Water: Concepts and Applications| year= 2008| publisher= CRC Press| page= 165| url= http://books.google.com/?id=Grivqd7tLuAC&pg=PA165&dq=%22is+lost+as+heat+and+wastes%22&cd=2#v=onepage&q=%22is%20lost%20as%20heat%20and%20wastes%22| isbn= 9781420055443}}</ref>  The amount can be less than one percent in animals consuming less digestible plants, and it can be as high as forty percent in [[zooplankton]] consuming [[phytoplankton]].<ref>{{cite book | last= Kent| first= Michael| title= Advanced Biology| year= 2000| publisher= Oxford University Press US| page= 511| url= http://books.google.com/?id=8aw4ZWLABQkC&pg=PA511&dq=%22trophic+efficiency+of+less+than+1%25%22&cd=1#v=onepage&q=%22trophic%20efficiency%20of%20less%20than%201%25%22| isbn= 9780199141951}}</ref>  Graphic representations of the biomass or productivity at each tropic level are called [[ecological pyramid]]s or trophic pyramids.  The transfer of energy from primary producers to top consumers can also be characterized by energy flow diagrams.<ref>{{cite book | last= Kent| first= Michael| title= Advanced Biology| year= 2000| publisher= Oxford University Press US| page= 510| url= http://books.google.com/?id=8aw4ZWLABQkC&pg=PA510&dq=%22by+an+energy+flow+diagram%22&cd=1#v=onepage&q=%22by%20an%20energy%20flow%20diagram%22| isbn= 9780199141951}}</ref>
-== Pyramids ==
-{{See also|Ecological pyramid}}
-In a pyramid of numbers, the number of consumers at each level decreases significantly, so that a single [[top consumer]], (e.g., a [[polar bear]] or a human), will be supported by a million separate producers.<ref>{{cite book | last= Merchant| first= Carolyn| title= The Columbia Guide to American Environmental History| year= 2005| publisher= Columbia University Press| page= 169| url= http://books.google.com/?id=bcdo0qlS0awC&pg=PA169&dq=pyramid+of+numbers+trophic+levels+phytoplankton#v=onepage&q=pyramid%20of%20numbers%20trophic%20levels%20phytoplankton| isbn= 9780231112338}}</ref>
-There is usually a maximum of four or five links in a food chain, although food chains in [[aquatic ecosystems]] are frequently longer than those on land.<ref name="entropy"/><ref>{{cite book | author= Gil Nonato C. Santos| coauthors= Alfonso C. Danac, Jorge P. Ocampo | title= E-Biology II| year= 2003| publisher= Rex Book Store| page= 60| url= http://books.google.com/?id=L9TwLvnIvnkC&pg=PA60&dq=Eventually+all+energy+flowing+through+the+trophic+levels+is+dissipated+as+heat#v=onepage&q=Eventually%20all%20energy%20flowing%20through%20the%20trophic%20levels%20is%20dissipated%20as%20heat| isbn= 9789712335631}}</ref>  Eventually, all the energy in a food chain is lost as heat.<ref name="entropy"/><ref name="trophic"/>
-Some producers, especially phytoplankton, are able to reproduce quickly enough to support a larger biomass of grazers. This is called an inverted pyramid, caused by a longer lifespan and slower growth rate in the consumers than in the organisms being consumed,<ref>{{cite book | last= Spellman| first= Frank R.| title= The Science of Water: Concepts and Applications| year= 2008| publisher= CRC Press| page= 167| url= http://books.google.com/?id=Grivqd7tLuAC&pg=PA167&dq=However,+biomass+pyramids+can+sometimes+be+inverted.&cd=1#v=onepage&q=However%2C%20biomass%20pyramids%20can%20sometimes%20be%20inverted.| isbn= 9781420055443}}</ref> with phytoplankton living just a few days, compared to several weeks for the zooplankton eating the phytoplankton and years for fish eating the zooplankton.  A pyramid of energy, reflecting the energy or kilojoules in each level, is representative of the true relationships of the phytoplankton, zooplankton, and fish, showing phytoplankton as the largest section, then zooplankton as a smaller section, and fish as the smallest section.<ref>{{cite book | last= Kent| first= Michael | title= Advanced Biology| year= 2000| publisher= Oxford University Press US| page= 509| url= http://books.google.com/?id=8aw4ZWLABQkC&pg=PA509&dq=%22pyramid+of+energy%22+advanced+biology&cd=1#v=onepage&q=| isbn= 9780199141951}}</ref>
-== History of food webs ==
-Food webs serve as a framework to help ecologists organize the complex network of interactions among species observed in nature. The earliest description of a food chain was given by the [[medieval]] [[Afro-Arab]] biologist [[Al-Jahiz]] (781-868).<ref>Frank N. Egerton, "A History of the Ecological Sciences, Part 6: Arabic Language Science - Origins and Zoological", ''Bulletin of the Ecological Society of America'', April 2002: 142-146 [143]</ref>{{Verify source|date=September 2010}} Perhaps the earliest graphical depiction of a food web was by [[Lorenzo Camerano]] in 1880, followed independently by those of Pierce and colleagues in 1912 and [[Victor Ernest Shelford|Victor Shelford]] in 1913.<ref>Egerton FN (2007) [http://www.esajournals.org/doi/full/10.1890/0012-9623(2007)88%5B50%3AUFCAFW%5D2.0.CO%3B2 Understanding food chains and food webs], 1700-1970. ''Bulletin of the Ecological Society of America'' 88:50-69.</ref><ref>Shelford, V (1913) [http://books.google.com/books?id=99UGAAAAYAAJ&dq=victor+shelford+an  imal+communities&printsec=frontcover&source=bl&ots=XT6Rz02AEZ&sig=hOm3G1CE5r4PYmq2kuR0VNKrxjU&hl=en&ei=mRvzSrCjG4aSMc_-kOgF&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAoQ6AEwAQ#v=onepage&q=&f=false Animal Communities in Temperate America as Illustrated in the Chicago Region]. University of Chicago Press.</ref> Two food webs about [[herring]] were produced by Victor Summerhayes and [[Charles Sutherland Elton|Charles Elton]]<ref>Summerhayes VS, Elton CS (1923) Contributions to the Ecology of Spitsbergen and Bear Island.  ''Journal of Ecology'', 11, 214-286.</ref> and [[Alister Hardy]]<ref>Hardy, AC (1924) The herring in relation to its animate environment. Part 1. The food and feeding habits of the herring with special reference to the east coast of England. ''Fisheries Investigation London Series II'', 7(3): 1–53.</ref> in 1923 and 1924.  After Charles Elton's use of food webs in his 1927 synthesis,<ref>Elton CS (1927) Animal Ecology. Republished 2001. University of Chicago Press.</ref> they became a central concept in the field of [[ecology]]. The utilization of the common currency of energy flow along links in a flow was emphasized in [[Raymond Lindeman]]'s work,<ref>Lindeman RL (1942) The trophic-dynamic aspect of ecology. ''Ecology'' 23:399-418.</ref> initiating the extensive analysis of energy and material flows that are a core activity of [[ecosystem ecology]].
-Interest in food webs increased after Robert Paine's experimental and descriptive study of intertidal shores<ref>Paine RT (1966) Food web complexity and species diversity. ''The American Naturalist'' 100:65-75.</ref> suggesting that food web complexity was key to maintaining species diversity and ecological stability. Many theoretical ecologists, including [[Robert May, Baron May of Oxford|Sir Robert May]]<ref>May RM (1973) Stability and Complexity in Model Ecosystems. Princeton University Press.</ref> and Stuart Pimm,<ref>Pimm SL (1982) Food Webs, Chapman and Hall.</ref> were prompted by this discovery and others to examine the mathematical properties of food webs. According to their analyses, complex food webs should be highly unstable. The apparent paradox between the complexity of food webs observed in nature and the mathematical fragility of food web models is currently an area of intensive study and debate. The paradox may be due partially to conceptual differences between persistence of a food web and equilibrial [[stability]] of a food web.
-[[Image:Pryosome oil spill.jpg|right|250px|thumb|Food web impact from the bottom up: [[Pyrosome]] found floating dead in an oil slick after the 2010 Gulf of Mexico disaster.]]
-Current research points to important roles of non-random structure in the connections within the food web that develop as food webs assemble over long periods of time, of patterns in the strengths of interactions among species within the food web, of variable strengths of species interactions as species abundances change, and of spatial variation in the environment creating food webs of different structures that are connected by movement of individuals and materials, in the creation and persistence of complex food webs.<ref>Polis GA, Winemiller KO (1996) Food Webs: Integration of Patterns and Dynamics. Chapman & Hall.</ref>
-== See also ==
-{{Portal box|Environment|Ecology|Earth sciences|Biology|Sustainable development}}
-{{Refbegin|2}}
-* [[Antipredator adaptation]]s
-* [[Apex predator]]
-* [[Balance of Nature]]
-* [[Biodiversity]]
-* [[Biogeochemical cycle]]
-* [[Consumer-resource systems]]
-* [[Ecological network]]
-* [[Food systems]]
-* [[Ecology of the San Francisco Estuary#Food web|Food web of the San Francisco Estuary]]
-* [[Microbial food web]]
-* [[Natural environment]]
-* [[List of feeding behaviours]]
-* [[Soil food web]]
-* [[Kelp forest#Trophic ecology|Trophic ecology of kelp forests]]
-* [[Lentic ecosystem#Trophic relationships|Trophic relationships in lakes]]
-* [[Lotic ecosystem#Trophic relationships|Trophic relationships in rivers]]
-{{Refend}}
-{{br}}
-==Notes==
-{{Reflist|2}}
-{{feeding}}
-{{modelling ecosystems|state=expanded}}
-{{DEFAULTSORT:Food Chain}}
-[[Category:Trophic ecology]]
-[[af:Voedselketting]]
-[[ar:سلسلة غذائية]]
-[[zh-min-nan:Chia̍h-mi̍h báng]]
-[[bg:Хранителна верига]]
-[[ca:Xarxa tròfica]]
-[[cs:Potravní řetězec]]
-[[cy:Cadwyn fwyd]]
-[[da:Fødekæde]]
-[[de:Nahrungskette]]
-[[et:Toitumisahel]]
-[[el:Τροφική αλυσίδα]]
-[[es:Cadena trófica]]
-[[eo:Nutroĉeno]]
-[[eu:Kate trofiko]]
-[[fa:زنجیره غذایی]]
-[[fr:Réseau trophique]]
-[[gl:Cadea trófica]]
-[[ko:먹이사슬]]
-[[hi:खाद्य श्रृंखला]]
-[[hr:Hranidbeni lanac]]
-[[io:Nutriva kateno]]
-[[id:Rantai makanan]]
-[[it:Catena alimentare]]
-[[he:מארג מזון]]
-[[sw:Mtando chakula]]
-[[ht:Rezo alimantè]]
-[[lt:Mitybos grandinė]]
-[[hu:Tápláléklánc]]
-[[mk:Ланец на исхрана]]
-[[nl:Voedselketen]]
-[[ja:食物連鎖]]
-[[no:Næringskjede]]
-[[nn:Næringskjede]]
-[[pl:Łańcuch pokarmowy]]
-[[pt:Cadeia alimentar]]
-[[ro:Lanț trofic]]
-[[ru:Пищевая цепь]]
-[[scn:Catina alimintari]]
-[[simple:Food chain]]
-[[sk:Potravinový reťazec]]
-[[sl:Prehranjevalna veriga]]
-[[sr:Ланац исхране]]
-[[fi:Ravintoketju]]
-[[sv:Näringskedja]]
-[[ta:உணவுச் சங்கிலி]]
-[[tr:Besin zinciri]]
-[[uk:Харчовий ланцюжок]]
-[[ur:غذائی زنجیر]]
-[[vi:Chuỗi thức ăn]]
-[[zh:食物鏈]]