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Biological Interaction

Biological interaction

Biological interactions result from the fact that organisms in an ecosystem interact with each other, in the natural world, no organism is an autonomous entity isolated from its surroundings. It is part of its environment, rich in living and non living elements all of which interact with each other in some fashion. An organism's interactions with its environment are fundamental to the survival of that organism and the functioning of the ecosystem as a whole. In ecology, biological interactions are the relationships between two species in an ecosystem. These relationships can be categorized into many different classes of interactions based either on the effects or on the mechanism of the interaction. The interactions between two species vary greatly in these aspects as well as in duration and strength. Species may meet once in a generation (e.g. pollination) or live completely within another (e.g. endosymbiosis). Effects may range from one species eating the other (predation), to both living together with mutual benefit (mutualism). The interactions between two species need not be through direct contact. Due to the connected nature of ecosystems, species may affect each other through intermediaries such as shared resources or common enemies.

Interactions categorized by effect

Terms which explicitly indicate the quality of benefit or harm experienced by participants in an interaction are listed below:
- Neutralism is a lack of interaction. Since all species sharing an environment interact in some way, a complete lack of interaction is rarely seen in nature. However, the term can also signify a relationship in which each species derives neither benefit nor detriment to any measurable degree.
- Mutualism benefits both populations. It is often non obligatory or temporary.
- Synnecrosis is detrimental to both species. It is a rare and necessarily short-lived condition as evolution selects against it.
- Amensalism is detrimental to one species and neutral to the other.
- Commensalism benefits one organism and the other organism is neither benefited nor harmed.
- Predation is an interaction between organisms in which one organism captures biomass from another. It is often used as a synonym for carnivory but formally also includes herbivory, parasitism, and parasitoidism. It is important to note that these interactions are not always static. In many cases, two species will interact differently under different conditions. This is particularly true in, but not limited to, cases where species have multiple, drastically different life stages.

Interactions classified by mechanism


- Symbiosis is an obligatory relationship between two populations. Partners in a symbiotic relation ship are constantly in contact with each other. Often one lives inside the other. It often implies mutualism, but most formal definitions also include other types of relationships like parasitism and commensalism.
- Competition is an association between two species in which both need some limited environmental factor for growth. Category:Ecology

Organism

In biology and ecology, an organism (in Greek organon = instrument) is a complex adaptive system of organs that influence each other in such a way that they function as a more or less stable whole and have properties of life. The origin of life and the relationships between its major lineages are controversial. Two main grades may be distinguished, the prokaryotes and eukaryotes. The prokaryotes are generally considered to represent two separate domains, called the Bacteria and Archaea, which are not closer to one another than to the eukaryotes. The gap between prokaryotes and eukaryotes is widely considered a major missing link in evolutionary history. Two eukaryotic organelles, namely mitochondria and chloroplasts, are generally considered to be derived from endosymbiotic bacteria. The phrase complex organism describes any organism with more than one cell.

Organizational terminology

Biological Organization

Viruses

Viruses are not typically considered to be organisms because they are not capable of independent reproduction or metabolism. However, according to the United States Code, they are considered to be microorganisms in the sense of biological weaponry and malicious use. This controversy is problematic, though, since some parasites and endosymbionts are incapable of independent life either. Although viruses do have enzymes and molecules characteristic of living organisms, they are incapable of surviving outside a host cell and most of their metabolic processes require a host and its 'genetic machinery'. The origin of such parasites is uncertain, but it appears most likely that they are derived from their host.

Life span

One of the basic parameters of organism is its life span. Some animals live as short as one day, while some plants can live thousands of years. Aging is important when determining life span of most organisms, bacterium, a virus or even a prion.

See also


- superorganism

External links


- [http://news.bbc.co.uk/1/hi/sci/tech/944790.stm BBCNews: 27 September, 2000, When slime is not so thick] Citat: "...It means that some of the lowliest creatures in the plant and animal kingdoms, such as slime and amoeba, may not be as primitive as once thought...."
  - [http://www.spaceref.com/news/viewpr.html?pid=4742 SpaceRef.com, July 29, 1997: Scientists Discover Methane Ice Worms On Gulf Of Mexico Sea Floor]
    - [http://www.science.psu.edu/iceworms/iceworms.html The Eberly College of Science: Methane Ice Worms discovered on Gulf of Mexico Sea Floor] download Publication quality photos
  - [http://www.sb-roscoff.fr/Ecophy/PDF/00-Fisher-NatWis.pdf Artikel, 2000: Methane Ice Worms: Hesiocaeca methanicola. Colonizing Fossil Fuel Reserves]
  - [http://www.spaceref.com/news/viewnews.html?id=339 SpaceRef.com, May 04, 2001: Redefining "Life as We Know it"] Hesiocaeca methanicola In 1997, Charles Fisher, professor of biology at Penn State, discovered this remarkable creature living on mounds of methane ice under half a mile of ocean on the floor of the Gulf of Mexico.
- [http://news.bbc.co.uk/1/hi/sci/tech/2585235.stm BBCNews, 18 December, 2002, 'Space bugs' grown in lab] Citat: "...Bacillus simplex and Staphylococcus pasteuri...Engyodontium album...The strains cultured by Dr Wainwright seemed to be resistant to the effects of UV - one quality required for survival in space...."
- [http://news.bbc.co.uk/1/hi/sci/tech/3003946.stm BBCNews, 19 June, 2003, Ancient organism challenges cell evolution] Citat: "..."It appears that this organelle has been conserved in evolution from prokaryotes to eukaryotes, since it is present in both,"..."
- [http://www.anselm.edu/homepage/jpitocch/genbios/bi04syllabsu03.html Interactive Syllabus for General Biology - BI 04, Saint Anselm College, Summer 2003]
- [http://www.personal.psu.edu/users/j/s/jsf165/Bio110.html Jacob Feldman: Stramenopila]
- [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Root NCBI Taxonomy entry: root] (rich)
- [http://www.anselm.edu/homepage/jpitocch/genbios/surveybi04.html Saint Anselm College: Survey of representatives of the major Kingdoms] Citat: "...Number of kingdoms has not been resolved...Bacteria present a problem with their diversity...Protista present a problem with their diversity...",
- [http://www.species2000.org/ Species 2000 Indexing the world's known species]. Species 2000 has the objective of enumerating all known species of plants, animals, fungi and microbes on Earth as the baseline dataset for studies of global biodiversity. It will also provide a simple access point enabling users to link from here to other data systems for all groups of organisms, using direct species-links.
- [http://www.abc.net.au/science/news/enviro/EnviroRepublish_828525.htm The largest organism in the world may be a fungus carpeting nearly 10 square kilometers of an Oregon forest, and may be as old as 8500 years.]
- [http://tolweb.org/tree/phylogeny.html The Tree of Life]. zh-min-nan:Seng-bu̍t ko:생물 ja:生物 th:สิ่งมีชีวิต

Natural environment

The natural environment comprises all living and non-living things that occur naturally on Earth. In its purest sense, it is thus an environment that is not the result of human activity or intervention. The natural environment may be contrasted to "the built environment." For some, there is a difficulty with the term "natural environment" in that nearly all environments have been directly or indirectly influenced by humans at some point in time. In order to address this concern, some level of human influence is thus allowable without the status of any particular landscape ceasing to be "natural." The term's meaning, however, is usually dependent more on context than a set definition. Many natural environments are the product of the interaction between nature and humans. For this reason, the term ecosystem has been used to describe an environment that contains nature, and includes people. It follows then that environmental problems are human or social problems. Some also consider it dangerously misleading to regard "environment" as separate from "people." It is the common understanding of natural environment that underlies environmentalism—a broad political, social, and philosophical movement that advocates various actions and policies in the interest of protecting what nature remains in the natural environment, or restoring or expanding the role of nature in this environment. While wilderness is increasingly rare, wild nature (e.g., unmanaged forests, uncultivated grasslands, wildlife, wildflowers) can be found in many locations previously inhabited by humans. Goals commonly expressed by environmentalists include: reduction and clean up of man-made pollution, with future goals of zero pollution; reducing societal consumption of non-renewable fuels, development of alternative, green, low carbon or renewable energy sources; conservation and sustainable use of scarce resources such as water, land and air; protection of representative or unique or pristine ecosystems; preservation and expansion of threatened or endangered species or ecosystems from extinction; the establishment of nature and biosphere reserves under various types of protection, and, most generally, the protection of biodiversity and ecosystems upon which all human and other life on earth depends. More recently, there has been a strong concern about climatic changes caused by anthroprogenic releases of greenhouse gases, most notably carbon dioxide, and their interactions with human uses and the natural environment. Efforts here have focused on the mitigition of greenhouse gases that are causing climatic changes (i.e., through the Climate Change Convention and the Kyoto Protocol), and ondeveloping adaptative strategies to assist species, ecosystems, humans, nations and regions in adjusting to these climatic changes.

See also


- Built environment
- Ecology
- The Gaia theory
- List of environment topics
- Natural capital
- Natural history
- Wildlife Category:Geography Category:Environment Category:Ecology

Pollination

pollinating a Sedum telephium]] Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (male gametes) to the plant carpel, the structure that contains the ovule (female gamete). The receptive part of the carpel is called a stigma in the flowers of angiosperms and a micropyle in gymnosperms. The study of pollination brings together many disciplines, such as botany, horticulture, entomology, and ecology. Pollination is important in horticulture because most plant fruits will not develop if the ovules are not fertilised.

Types of pollination

The process of pollination requires pollinators as agents that carry or move the pollen grains from the anther to the receptive part of the carpel. Methods of pollination, categorized by pollinator type, are: anther]
- Entomophily: pollination by insects
  - Bee pollination on Sunflower
  - Madagascar orchid requires a moth with a 30 cm (1 ft) long proboscis
  - Beetles pollinate cycads.
- Zoophily: pollination by animals such as birds or bats
  - Hummingbird
- Anemophily: pollination by wind
  - very common in grasses
  - Sweet chestnut and Tridax
  - Conifers
- Hydrophily: pollination by water
  - Mesophytes like Ribbonweed Some flowers are pollinated using buzz pollination.

Pollination in agriculture

Pollination management is a branch of horticulture that seeks to protect and enhance present pollinators and often involves the culture and addition of pollinators in monoculture situations, such as commercial fruit orchards. The largest managed pollination event in the world is in Californian almond orchards, where nearly half (about one million hives) of the US honeybees are trucked to the almond orchards each spring. New York's apple crop requires about 30,000 hives; Maine's blueberry crop uses about 50,000 hives each year. Bees are also brought to commercial plantings of cucumbers, squash, melons, strawberries, and many other crops. Honeybees are not the only managed pollinators: other species of bees are also raised as pollinators. The alfalfa leafcutter bee is an important pollinator for alfalfa seed in western United States and Canada. Bumblebees are increasingly raised and used extensively for greenhouse tomatoes and other crops. The ecological and financial importance of natural pollination by insects to agricultural crops, improving their quality and quantity, becomes more and more appreciated and has given rise to new financial opportunities. The vicinity of a forest or wild grasslands near agricultural crops, such as apples, almonds or coffee can improve their yield by about 20%. This may result in forest owners demanding payment for their part in the improved results. This is a simple example of the economic value of ecological services. Pollination also requires consideration of pollenizers. (The terms "pollinator" and "pollenizer" are often confused: a pollinator is the agent that moves the pollen, whether it be wind, bees, bats, moths, or birds; a pollenizer is the plant that provides the pollen.) Some plants are self-fertile or self-compatible and can pollinate themselves. Other plants have chemical or physical barriers to self-pollination and need to be cross-pollinated: with these self-infertile plants, not only pollinators must be considered but pollenizers as well. In pollination management, a good pollenizer is a plant that provides compatible, viable and plentiful pollen and blooms at the same time as the plant that is to be pollinated. Pollination can be cross-pollination with a pollinator and an external pollenizer, self-pollenization with a pollinator, or self-pollination without any pollinator:
- Cross-pollination (syngamy): pollen is delivered to a flower of a different plant. Plants adapted to outcross or cross-pollinise have taller stamens than carpels to better spread pollen to other flowers.
- Self-pollenization (autogamy): pollen moves to the female part of the same flower, or to another flower on the same individual plant. This is sometimes referred to as self-pollination, but this is not synonymous with autogamy. Clarity requires that the term "self-pollination" be restricted to those plants that accomplish pollination without an external pollinator (example: the stamens actually grow into contact with the pistil to transfer the pollen). Most peach varieties are autogamous, but not truly self-pollinated, as it is generally an insect pollinator that moves the pollen from anther to stigma. Plants adapted to self-fertilize have similar stamen and carpel length.
- Cleistogamy: pollination that occurs before the flower opens is always self-pollination. Some cleistogamous flowers never open, in contrast to chasmogamous flowers that open and are then pollinated. Cleistogamous flowers must of necessity be self-compatible or self-fertile plants. Other plants are self-incompatible. These are end points on a continuum, not absolute points. Hybridization is effective pollination between flowers of different species of the same genus, or even between flowers of different genera (as in the case of several orchids). Peaches are considered self-fertile because a commercial crop can be produced without cross-pollination, though cross-pollination usually gives a better crop. Apples are considered self-incompatible, because a commercial crop must be cross-pollinated. Remember that most fruits are grafted clones, genetically identical. An orchard block of apples of one variety is in effect all one plant. Growers now consider this a mistake. One means of correcting this mistake is to graft a limb of an appropriate pollenizer (generally a variety of crabapple) every six trees or so. To attract pollinators, some flowers, such as sunflower, when viewed under ultraviolet light (as they would be seen by honeybees), have a darker centre, where the pollen is located. There may also be patterns upon the petals. These are called nectar guides. Pollination of food crops has become an environmental issue, due to two cross trends. The trend to monoculture means that greater concentrations of pollinators are needed at bloom time than ever before, yet the area is forage poor or even deadly to bees for the rest of the season. The other trend is the decline of pollinator populations, due to pesticide misuse and overuse, new diseases and parasites of bees, [clearfelling|[clearcut logging]], decline of beekeeping, suburban development, removal of hedges and other habitat from farms, and public paranoia about bees. Widespread aerial spraying for mosquitoes due to West Nile fears is causing an acceleration of the loss of pollinators. The US solution to the pollinator shortage, so far, has been for commercial beekeepers to become pollination contractors and to migrate. Just as the combine harvesters follow the wheat harvest from Texas to Manitoba, beekeepers follow the bloom from south to north, to provide pollination for many different crops.

Bee pollination

Manitoba structure appears rough and globular to the left. The bee's stash of pollen is on its hindleg]] Bees travel from flower to flower, collecting nectar (later converted to honey), and in the process they pick up pollen grains. The bee collects the pollen by rubbing against the anthers. The pollen collects on the hind legs, in dense hairs referred to as a pollen basket. As the bee flies from flower to flower, the pollen grains are transferred onto the stigma of the female flower part. Nectar provides the energy for bee nutrition; pollen provides the protein. When bees are rearing large quantities of brood (beekeepers say hives are "building"), bees will deliberately gather pollen to meet the nutritional needs of the brood. A honeybee that is deliberately gathering pollen is up to ten times more efficient as a pollinator than one that is primarily gathering nectar and only unintentionally transferring pollen. Good pollination management seeks to have bees in a "building" state during the bloom period of the crop, thus requiring them to gather pollen, and making them more efficient pollinators. Thus the management techniques of a beekeeper providing pollination service are different from, and somewhat incompatible with, those of a beekeeper who is trying to produce honey.

Number of hives needed per acre (4,000 m2) of crop pollination

beekeeper]] :Apples: 1—2 :Blueberries: 4 :Cantaloupe: 2—4 :Cucumber 2—1 :Squash: 1 :Watermelon: 1—3 It is estimated that about one hive per acre will sufficiently pollinate watermelons. In the 1950s when the woods were full of wild bee trees, and beehives were normally kept on most South Carolina farms, a farmer who grew ten acres (40,000 m²) of watermelons would be a large grower and probably had all the pollination needed. But today's grower may grow 200 acres (800,000 m²), and, if lucky, there might be one bee tree left within range. The only option in the current economy is to bring beehives to the field during blossom time. Source: Delaplaine et al. 1994, Bee pollination of Georgia crop plants. CES Bulletin 1106

See also

Fruit tree pollination

Wiktionary Entries


- Cross-pollination
- Pollination

External links


- [http://www.beeculture.com/beeculture/book/index.html Insect Pollination Of Cultivated Crop Plants by S. E. McGregor USDA 1972] (needs updating but still valuable)
- [http://pollinator.com The Pollination Home page]
- [http://www.pulseplanet.com/archive/May98/1625.html Pulse of the Planet description of buzz pollination] Category:Biological reproduction Category:Ecology Category:Sexuality Category:Symbiosis Category:Pollination ja:受粉

Endosymbiosis

An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis (Greek: endo = inner and biosis = living). For instance, some nitrogen fixing bacteria (known as rhizobia) live in root nodules on legume roots, reef-building corals contain single-celled algae, and several insect species contain bacterial endosymbionts. Many other examples of endosymbiosis exist. Many instances of endosymbiosis are obligate, where neither the endosymbiont nor the host can survive without the other, such as gutless marine worms which get nutrition from their endosymbiotic bacteria. However, not all endosymbioses are obligate. Also, some endosymbioses can be harmful to either of the organisms involved. See symbiosis for further discussion of this issue. It is generally agreed that certain organelles of the eukaryotic cell, especially mitochondria and chloroplasts, originated as bacterial endosymbionts. This theory is known as the endosymbiotic theory, confirmed and popularized by Lynn Margulis.

The endosymbiont theory and mitochondria and chloroplasts

The endoymbiont theory explains the origins of organelles such as mitochondria and chloroplasts in eukaryotic cells. Lynn Margulis of the University of Massachusetts most forcefully defended the endosymbiont theory. The theory proposes that chloroplasts and mitochondria evolved from certain types of bacteria that prokaryotic cells engulfed through endophagocytosis. These cells and the bacteria trapped inside them entered an symbiotic relationship, a close association between different types of organisms over an extended time. However, more specifically, the relationship was endosymbiotic, meaning that one of the organisms (the bacteria) lived within the other (the prokaryotic cells). According to the endosymbiont theory, an anaerobic cell probably ingested an aerobic bacterium but failed to digest it. The aerobic bacterium flourished within the cell because the cell’s cytoplasm was abundant in half-digested food molecules. The bacterium digested these molecules with oxygen and gained great amounts of energy. Because the bacterium had so much energy, it probably leaked some of it as ATP into the cell’s cytoplasm. This benefited the anaerobic cell because it enabled it to digest food aerobically. Eventually, the aerobic bacterium could no longer live independently from the cell, and it therefore became a mitochondrion. The origin of the chloroplast is very similar to that of the mitochondrion. A cell must have captured a photosynthetic cyanobacterium and failed to digest it. The cyanobacterium thrived in the cell and eventually evolved into the first chloroplast. Other eukaryotic organelles may have also evolved through endosymbiosis. Scientists believe that cilia, flagella, centrioles, and microtubules may have come from a symbiosis between a spirilla-like bacterium and an early eukaryotic cell. There are several examples of evidence that support the endosymbiont theory. Mitochondria, chloroplasts, and centrioles contain their own small supply of DNA, which may be remnants of the DNA the organelles had when they were independent aerobic bacteria. In addition, there are organisms alive today, called living intermediates, that are in a similar endosymbiotic condition to the prokaryotic cells and the aerobic bacteria. Living intermediates show that the evolution proposed by the endosymbiont theory is possible. For example, the amoeba lacks mitochondria but has aerobic bacteria that carry out a similar role. A variety of corals, clams, snails, and one species of Paramecium permanently host algae in their cells. These modern organisms with endosymbiotic relationships with aerobic bacteria suggest that the endosymbiont theory, which explains the origin of mitochondria and chloroplasts, is accurate.

Bacterial endosymbionts in marine oligochaetes

Some marine oligochaetes (e.g Olavius or Inanidrillus) have obligate extracellular endosymbionts that fill the entire body of their host. These marine worms are nutritionally dependent on their symbiotic chemoautotrophic bacteria lacking any digestive or excretory system (no gut, mouth or nephridia).

Bacterial endosymbionts in other marine invertebrates

Extracellular endosymbionts are also represented in all 5 extant classes of Echinodermata (Crinoidea, Ophiuroidea, Asteroidea, Echinoidea, and Holothuroidea). Little is known of the nature of the association (mode of infection, transmission, metabolic requirements, etc.) but phylogenetic analysis indicates that these symbionts belong to the alpha group of the class Proteobacteria, relating them to Rhizobium and Thiobacillus. Other studies indicate that these subcuticular bacteria may be both abundant within their hosts and widely distributed among the Echinoderms in general.

Symbiodinium dinoflagellate endosymbionts in marine metazoa and protists

Dinoflagellate endosymbionts of the genus Symbiodinium, commonly known as zooxanthellae, are found in corals, mollusks (esp. giant clams, the Tridacna), sponges, and foraminifera. These endosymbionts drive the amazing formation of coral reefs by capturing sunlight and providing their hosts with energy for carbonate deposition. Previously thought to be a single species, molecular phylogenetic evidence over the past couple decades has shown there to be great diversity in Symbiodinium. In some cases there is specificity between host and Symbiodinium clade. More often, however, there is a ecological distribution of Symbiodinium, the symbionts switching between hosts with apparent ease. When reefs become environmentally stressed, this distribution of symbionts is related to the observed pattern of coral bleaching and recovery. Thus the distribution of Symbiodinium on coral reefs and its role in coral bleaching presents one of the most complex and interesting current problems in reef ecology.

Bacterial obligate endosymbionts in insects

Among bacterial endosymbionts of insects, the best studied are the pea aphid Acyrthosiphon pisum and its endosymbiont Buchnera sp. APS, and the tsetse fly Glossina morsitans morsitans and its endosymbiont Wigglesworthia glossinidia brevipalpis. As with endosymbiosis in other insects, the symbiosis is obligate in that neither the bacteria nor the insect is viable without the other. Scientists have been unable to cultivate the bacteria in lab conditions outside of the insect. With special nutritionally-enhanced diets, the insects can survive, but are unhealthy, and at best survive only a few generations. The endosymbionts live in specialized insect cells called bacteriocytes (also called mycetocytes), and are maternally-transmitted, i.e. the mother transmits her endosymbionts to her offspring. In some cases, the bacteria are transmitted in the egg, as in Buchnera; in others like Wigglesworthia, they are transmitted via milk to the developing insect embryo. The bacteria are thought to help the host by either synthesizing nutrients that the host cannot make itself, or by metabolizing insect waste products into safer forms. For example, the primary role of Buchnera is thought to be to synthesize essential amino acids that the aphid cannot acquire from its natural diet of plant sap. The evidence is (1) when aphids' endosymbionts are killed using antibiotics, they appear healthier when their plant sap diet is supplemented with the appropriate amino acids, and (2) after the Buchnera genome was sequenced, analysis uncovered a large number of genes that likely code for amino acid biosynthesis genes; most bacteria that live inside other organisms do not have such genes, so their existence in Buchnera is noteworthy. Similarly, the primary role of Wigglesworthia is probably to synthesize vitamins that the tsetse fly does not get from the blood that it eats. The benefit for the bacteria is that it is protected from the environment outside the insect cell, and presumably receives nutrients from the insect. Genome sequencing reveals that obligate bacterial endosymbionts of insects have among the smallest of known bacterial genomes and have lost many genes that are commonly found in other bacteria. Presumably these genes are not needed in the environment of the host insect cell. (A complementary theory as to why the bacteria may have lost genes, Muller's ratchet, is that since the endosymbionts are maternally transmitted and have no opportunity to exchange genes with other bacteria, it is more difficult to keep good genes in all individuals in a population of these endosymbionts.) Research in which a parallel phylogeny of bacteria and insects was inferred supports the belief that the obligate endosymbionts are transferred only vertically (i.e. from the mother), and not horizontally (i.e. by escaping the host and entering a new host). Attacking obligate bacterial endosymbionts may present a way to control their insect hosts, many of which are pests or carriers of human disease. For example aphids are crop pests and the tsetse fly carries the organism (trypanosome protozoa) that causes African sleeping sickness. Other motivations for their study is to understand symbiosis, and to understand how bacteria with severely depleted genomes are able to survive, thus improving our knowledge of genetics and molecular biology.

References

Obligate bacterial endosymbiosis in marine oligochaetes:


- Endosymbiotic sulphate-reducing and sulphide-oxidizing bacteria in an oligochaete worm. Dubilier N., Mülders C.,Ferdelman T., De Beer D.,Pernthaler A.,Klein M., Wagner M., Erseus C., Thiermann F., Krieger J., Giere O & Amann R. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11357130

Bacterial endosymbionts in echinoderms:


- Subcuticular bacteria from the brittle star Ophiactis balli (Echinodermata: Ophiuroidea) represent a new lineage of extracellular marine symbionts in the alpha subdivision of the class Proteobacteria. Burnett, W J and J D McKenzie http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=168468&rendertype=abstract

Symbiodinium dinoflagellate endosymbionts in marine metazoa and protists


- Excellent review paper covering the role of Symbiodinium in reef ecology and the current state of research: [http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.ecolsys.34.011802.132417?cookieSet=1 FLEXIBILITY AND SPECIFICITY IN CORAL-ALGAL SYMBIOSIS: Diversity, Ecology, and Biogeography of Symbiodinium. Andrew C. Baker, Annual Review of Ecology, Evolution, and Systematics 2003 34, 661-689]

Obligate bacterial endosymbionts in insects:


- PLOS Biology Primer- Endosymbiosis: lessons in conflict resolution http://www.plosbiology.org/plosonline/?request=get-document&doi=10.1371/journal.pbio.0020068
- A general review of bacterial endosymbionts in insects. P. Baumann, N. A. Moran and L. Baumann, Bacteriocyte-associated endosymbionts of insects in M. Dworkin, ed., The prokaryotes, Springer, New York, 2000. http://link.springer.de/link/service/books/10125/
- An excellent review of insect endosymbionts that focuses on genetic issues. Jennifer J. Wernegreen (2002), Genome evolution in bacterial endosymbionts of insects, Nature Reviews Genetics, 3, pp. 850-861. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12415315&dopt=Abstract
- A review article on aphids and their bacterial endosymbionts. A. E. Douglas (1998), Nutritional interactions in insect-microbial symbioses: Aphids and Their Symbiotic Bacteria Buchnera, Annual Reviews of Entomology, 43, pp. 17-37.
- Describes possible methods to control the human pathogen causing African sleeping sickness, which is transmitted by tsetse flies. Focuses on methods using the primary and secondary endosymbionts of the tsetse fly. Serap Aksoy, Ian Maudlin, Colin Dale, Alan S. Robinsonand and Scott L. O’Neill (2001), Prospects for control of African trypanosomiasis by tsetse vector, TRENDS in Parasitology, 17 (1), pp. 29-35. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11137738&dopt=Abstract
- Announces and analyzes the full genome sequence of Buchnera sp. APS, the endosymbiont of the pea aphid, and the first endosymbiont to have its genome sequenced. S. Shigenobu, H. Watanabe, M. Hattori, Y. Sakaki and H. Ishikawa (2000), Genome sequence of the endocellular bacterial symbiont of aphids Buchnera sp. APS, Nature, 407, pp. 81-86. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10993077&dopt=Abstract
- An article that discusses one theory on how obligate endosymbionts may have their genomes degraded, in a freely-available journal. Nancy A. Moran (1996), Accelerated evolution and Muller’s ratchet in endosymbiotic bacteria, Proceedings of the National Academy of Sciences of the USA, 93, pp. 2873-2878. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8610134&dopt=Abstract Category:Symbiosis

Mutualism

For another use of the term see Mutualism (economic theory). In biology, mutualism is an interaction between two species in which both species derive benefit. Mutualisms can be lifelong interactions involving close physical and biochemical contact (known as symbiosis) such as those between trees and mycorrhizal fungi; they can also be briefer, non-symbiotic interactions, such as those between flowering plants and pollinators. Mutualisms may also be obligatory or non-obligatory (facultative). For example, bacteria known as rhizobia can reproduce either in the soil or in (usually) mutualistic symbiosis with legume plants. Mycorrhizal fungi, on the other hand, can be totally dependent on their plant hosts. Microbes often band together for mutual benefit in biofilms to break down solid food sources as in rusticles. Category:Ecology Category:Symbiosis

Neutralism

Neutralism describes the relationship (or lack thereof) between two species which do not interact with or affect each other. It is used in ecology to describe biological interactions when the population density of one species has absolutely no effect whatsoever on the other. Neutralism is extremely unlikely and impossible to prove. When dealing with the complex networks of interactions presented by ecosystems, one cannot assert positively that there is absolutely no interaction between two species. If two species do not interact directly, links can be found through other species and shared resources. Since true neutralism is rare or nonexistent, its usage is often extended to situations where interactions are merely insignificant or negligible. ----- In Esperanto culture, neutralism was a political bourgeois tendence that sought neutrality and pacifism among countries and the ideologies of the 1930s. Neutralists grouped in Universala Esperanto-Asocio. Its theory was rejected by laborist Esperantism, that advocated class struggle. Category: ecology

Synnecrosis

Synnecrosis (syn·ne·cro·sis) (sin²[schwa]-kro¢sis) [syn- + necro- + -sis] is an interaction between individuals or populations so mutually detrimental that it results in death, as in the case of some parasitic relationships. Category:Ecology

Commensalism

In ecology, commensalism is an interaction between two living organisms, where one creature benefits and the other is neither harmed nor helped. As with all ecological interactions, commensalisms vary in strength and duration from intimate, long-lived symbioses to brief, weak interactions through intermediaries. The term commensalism derives from the Latin com mensa, meaning sharing a table. Originally it was used to describe the use of waste food by second animals, like the carcass eaters who follow hunting animals, but wait until they have finished their meal. Other forms of commensalism include:
- Phoresy: Using a second organism for transportation. Examples are the remora on a shark, or mites on dung bugs. Both temporary and permanent phoresy exist.
- Inquilism: Using a second organism for housing. Examples are epiphytic plants (such as many orchids) which grow on trees, or birds that live in holes in trees.
- Metabiosis: A more indirect dependency, in which the second organism uses something the first created, however after the death of the first. An example are the hermit crabs who use gastropod shells to protect their bodies. The question of whether the relationship between humans and some types of our gut flora is commensal or mutualistic is still unanswered. Some biologists argue that any close interaction between two organisms is unlikely to be completely neutral for either party, and that relationships identified as commensal are likely mutualistic or parasitic in a subtle way that has not been detected. Category:Symbiosis Category:Ecology

Biomass

Biomass is organic non-fossil material, collectively. In other words, biomass comprises the mass of all biological organisms, dead or alive, excluding biological mass that has been transformed by geological processes into substances such as coal or petroleum. The most successful animal of the earth, in terms of biomass, is the Antarctic krill, Euphausia superba, with a biomass of probably over 500 million tonnes, roughly twice the total biomass of humans. The entire earth contains about 75 billion tons of biomass. Humans comprise about 250 million tonnes (0.33%), domesticated animals about 700 million (1.0%), and crops about 2 billion tons or 2.7% of the Earth's biomass. In many ways biomass can be considered as a form of stored solar energy. The energy of the sun is 'captured' through the process of photosynthesis in growing plants. Biomass is sometimes burned as fuel for cooking and to produce electricity and heat. This is called Biofuel. Biomass used as fuel often consists of underutilized types, like chaff and animal waste. This is often considered a type of alternative energy, although it is a polluting one. Paradoxically, in some industrialized countries like Germany, food is cheaper than fuel compared by price per joule. Central heating units supplied by food grade wheat or maize are available. Biomass is also the dried organic mass of an ecosystem. As the trophic level increases, the biomass of each trophic level decreases. That is, producers ( grass, trees, scrubs, etc.) will have a much higher biomass than animals that consume the producers (deer, zebras, insects, etc.). The level with the least biomass will be the highest predators in the food chain (foxes, eagles, etc.)

Types of high volume industrial biomass on Earth

Certain types of biomass have attracted research and industrial attention. Many of these are considered to be potentially useful for energy or for the production of bio-based products. Most of these are available in very large quanities and have low market value.
- Dried distiller's grain
- Jatropha
- Manure
- Meat and bone meal
- Miscanthus
- Peat
- Plate waste
- Landscaping waste
- Maize
- Rice hulls
- Silage
- Stover
- Maiden Grass
- Switchgrass
- Whey
- Sugarcane bagasse

See also


- Biosphere
- Bioalcohol
- Biofuel
- Biodiesel
- By-product
- Gasohol
- Green power
- Thermal depolymerization
- Wood gas
- Corn kernels

External links


- [http://feedstockreview.ornl.gov/pdf/billion_ton_vision.pdf "Biomass as Feedstock for a Bioenergy and Bioproducts Industry"], a 2005 joint study sponsored by the United States Department of Energy and Department of Agriculture
- [http://www.cus.net/renewableenergy/subcats/biomass/biomass.html Biomass]
- [http://www.aboutbioenergy.info Educational Web Site for Biomass and Bioenergy] This educational web site created by [http://www.iea-bioenergy-task29.hr/ IEA Bioenergy Task 29] has the aim to inform you about the oldest source of energy used by humans. Category:Fuels Category:Ecology Category:Renewable energy Category:Materials ja:バイオマス

Carnivore

A carnivore is an animal that eats a diet consisting solely of meat, whether it comes from live animals or dead (scavenging). The word also refers to the mammals of the Order Carnivora, many (but not all) of which fit the first definition. Bears are an example of members of Carnivora that are not true carnivores. Carnivores that eat primarily (or only) insects are called insectivores.

Animals that are obligate carnivores

insectivore]] An obligate or true carnivore is an animal that subsists on a diet consisting only of meat. They may consume other products presented to them, especially animal products like cheese and bone marrow, or sweet sugary substances like honey and syrup, but, as these products are not essential, they do not need to consume these on a regular basis. True carnivores lack the physiology required for the digestion of vegetable matter. Domesticated carnivores are often recommended to have vegetable supplements (or such containing processed pet foods) as meats designed for human consumption may be lacking in vital nutrients.
- Felines, ranging from domestic cats to lions, tigers, and other large predators.
- Some canines, such the Grey wolf but not the Red wolf or coyote. Domestic dogs are broadly considered carnivorous but the classification is often debated.
- Hyenas
- Some mustelids
- Polar Bears
- Birds of prey, including hawks, eagles, falcons and owls
- Scavenger birds, like vultures
- Several species of waterfowl including gulls, penguins, pelicans and storks stork
- Anurans
- Snakes
- Crocodilians
- Sharks and many other species of fish
- Toothed whales
- Octopuses and squid
- Spiders
- Mantophasmatodea, Reduviidae and other insects There are also several species of carnivorous plants, though most are primarily insectivorous, some digest nematodes and other small invertebrates. Many dinosaurs were obligate carnivores, namely most –if not all– theropods, like Tyrannosaurus rex. Sauropods and ornithischians were herbivorous.

Words with same roots "eater of flesh" but different meaning


- Sarcophagus

See also


- Cannibalism
- Insectivore
- Sarcophagus
- Carnivorous plant

Compare and contrast


- Herbivore
- Omnivore Category:Eating behaviors ms:Maging ja:肉食動物 simple:Carnivore

Parasitism

: For parasitism as a social offense, see Parasitism (social offense). Parasitism (Greek: παρασσυτισμός) is an interaction between two organisms, in which one organism (the parasite) benefits and the other (the host) is harmed. Parasitism can be considered a special case of predation since in both interactions one species acquires biomass directly from another. In cases where the parasite is specific to a single host, the interaction is symbiotic. Parasites that live inside the body of the host are called endoparasites (e.g., hookworms that live in the host gut) and those that live on the outside are called ectoparasites (e.g., mosquitos). A parasite that kills its host is called a parasitoid. Some parasites are social parasites, taking advantage of interactions between members of a social host species such as ants or termites to their detriment. Kleptoparasitism involves the parasite stealing food that the host has caught or otherwise prepared. It is important to note that "benefit" and "harm" in the definition of parasitism apply to lineages, not individuals. Thus, if an organism becomes physically stronger as a result of infection but loses reproductive capabilities (as results from some flatworm infections of snails), that organism is harmed in an evolutionary sense and is thus parasitized. Many endoparasites acquire hosts by passive mechanisms, such as the nematode Ascaris lumbricoides, an endoparasite of the human intestine. A. lumbricoides produces large numbers of eggs which are passed from the host's digestive tract into the external environment, relying on other humans to inadvertently ingest them in places without good sanitation. Ectoparasites, on the other hand, often have elaborate mechanisms and strategies for finding hosts. Some aquatic leeches, for example, locate hosts by sensing movement and then confirm their identity through skin temperature and chemical cues before attaching. The hosts of parasites often evolve elaborate defensive mechanisms as well. Plants often produce toxins, for example, which deter both parasitic fungi and bacteria as well as herbivores. Vertebrate immune systems can target most parasites through contact with bodily fluids. Many parasites, particularly microorganisms, evolve adaptations to a particular host species; in such specific interactions the two species generally coevolve into a relatively stable relationship that does not kill the host quickly or at all (since this would be detrimental for the parasite as well; but see parasitoid). Sometimes, the study of parasite taxonomy can elucidate how their hosts are similar or related. For instance, there has been a dispute about whether Phoenicopteriformes (flamingos) are more closely related to Ciconiiformes (storks and related groups) or to Anseriformes (waterfowl and allies). Flamingos share parasites with ducks and geese, so these groups are thought to be more closely related to one another than either is to storks. Category:Symbiosis Category:Ecology Category:Parasitology

Symbiosis

Symbiosis (pl. symbioses) (from the Greek words syn = con/plus and biono = living) is an interaction between two organisms living together in more or less intimate association or even the merging of two dissimilar organisms. The term host is usually used for the larger (macro) of the two members of a symbiosis. The smaller (micro) member is called the symbiont (plural: symbionts), or alternately, symbiote (plural: symbiotes). When a microscopic symbiont lives inside the cells of a host, it is referred to as an endosymbiont. The various forms of symbiosis include: -
- parasitism, in which the association is disadvantageous or destructive to one of the organisms and beneficial to the other (+ -)
- mutualism, in which the association is advantageous to both (+ +)
- commensalism, in which one member of the association benefits while the other is not affected (+ 0)
- amensalism, in which the association is disadvantageous to one member while the other is not affected (- 0) In some cases, the term symbiosis is used only if the association is obligatory and benefits both organisms. Symbiosis as defined in this article does not restrict the term to only the mutually beneficial interactions. Symbiosis may be divided into two distinct categories: ectosymbiosis and endosymbiosis. In ectosymbiosis, the symbiont lives on the body surface of the host, including the inner surface of the digestive tract or the ducts of exocrine glands. In endosymbiosis, the symbiont lives either in the intracellular space of the host or extracellularly. An example of mutual symbiosis is the relationship between clownfish of the genus Amphiprion (family, Pomacentridae) that dwell among the tentacles of tropical sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the anemone fish from its predators (a special mucus on the anemone fish protects it from the stinging tentacles). sea anemone.]] Another example is the goby fish, which sometimes lives together with a shrimp. The shrimp digs and cleans up a burrow in the sand in which both the shrimp and the goby fish live. The shrimp is almost blind leaving it vulnerable to predators when above ground. In case of danger the goby fish touches the shrimp with its tail to warn it of imminent danger. When that happens both the shrimp and goby fish quickly retract into the burrow. A famous land version of symbiosis is the relationship of the Egyptian Plover bird and the crocodile. In this relationship, the bird is well known for preying on parasites that feed on crocodiles which are potentially harmful for the animal. To that end, the crocodile openly invites the bird to hunt on his body, even going so far as to open the jaws to allow the bird enter the mouth safely to hunt. For the bird's part, this relationship not only is a ready source of food, but a safe one considering that few predator species would dare strike at the bird at such close proximity to its host. The biologist Lynn Margulis, famous for the 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 evolution is strongly based on co-operation, interaction, and mutual dependence among organisms. According to Margulis and Sagan (1986), "Life did not take over the globe by combat, but by networking". As in humans, organisms that cooperate with others of their own or different species often outcompete those that don't. However, mutualism, parasitism, and commensalism are often not discrete categories of interactions and should rather be perceived as a continuum of interaction ranging from parasitism to mutualism. In fact, the direction of a symbiotic interaction can change during the lifetime of the symbionts due to developmental changes as well as changes in the biotic/abiotic environment in which the interaction occurs.

See also


- List of symbiotic relationships

References


- Lynn Margulis and Dorion Sagan, Microcosmos: Four Billion Years of Evolution from Our Microbial Ancestors. Summit Books, New York, 1986. ISBN 0520210646
- Jan Sapp Evolution by Association, Oxford University Press, 1994. ISBN 0195088212 Category:Ecology
- ja:共生

Competition

Competition is the act of striving against another force for the purpose of achieving dominance or attaining a reward or goal, or out of a biological imperative such as survival. Competition is a term widely used in several fields, including biochemistry, ecology, economics, business, politics, and sports. Competition may be between two or more forces, life forms, agents, systems, individuals, or groups, depending on the context in which the term is used. Competition may yield various results to the participants, including both intrinsic and extrinsic rewards. Some, such as survival advantages, including favorable territory, are intrinsic biological factors that occur as a result of ecological competition between organisms. Others, such as business dominance and political power, involve competition between humans. In addition, extrinsic symbols, such as trophies, plaques, ribbons, prizes, or laudations, may be given to the winner(s). Such symbolic rewards are commonly used wherever the rewards inherent in the competition are primarily intrinsic, such as at human sporting and academic competitions. In general, the rewards range widely but usually help reinforce the advantage that one participant has over the other participant(s).

Sizes and levels of competition

Competition may also exist at different sizes; some competitions may be between two members of a species, while other competitions can involve entire species. In an example in economics, a competition between two local stores would be considered small compared to competition between several mega-giants. As a result, the consequences of the competition would also vary- the larger the competition, the larger the effect. In addition, the level of competition can also vary. At some levels, competition can be informal and be more for pride or fun. However, other competitions can be extreme and bitter; for example, some human wars have erupted because of the intense competition between two nations or nationalities.

Consequences of competition

nationalities Competition can result in both beneficial and detrimental results. For example, inter-species competition, including between humans, is the driving force of adaptation and ultimately, evolution. Social darwinists claim that competition also serves as a mechanism for determining the best-suited group, politically, economically, and ecologically, however this belief is very questionable. However, competition can also have negative consequences, particularly on the human species. Potential detrimental effects include the injury of other organisms and the drain of valuable resources and energy for competition. In addition, human competition may also require large amounts of money (such as in political elections, international sports competitions, and advertising wars) and can also lead to the compromising of ethical standards in order to gain an advantage in the competition. For example, several athletes have been caught using banned steroids in professional sports in order to boost their own chances of success or victory. Finally, competitive striving can also be harmful for the participants. Examples include athletes that injure themselves because they exceed the physical tolerances of their bodies, and companies that pursue unprofitable paths while engaging in competitive rivalries.

Competition in different fields

Economics and business competition

Seen as the pillar of capitalism in that it may stimulate innovation, encourage efficiency, or drive down prices, competition is touted as the foundation upon which capitalism is justified. According to microeconomic theory, no system of resource allocation is more efficient than pure competition. Competition, according to the theory, causes commercial firms to develop new products, services, and technologies. This gives consumers greater selection and better products. The greater selection typically causes lower prices for the products compared to what the price would be if there was no competition (monopoly) or little competition (oligopoly). However, competition may also lead to wasted (duplicated) effort and to increased costs (and prices) in some circumstances. Similarly, the psychological effects of competition may result in harm as well as good. Three levels of economic competition have been classified. The most narrow form is direct competition (also called category competition or brand competition), where products that perform the same function compete against each other. For example, a brand of pick-up trucks competes with several different brands of pick-up trucks. Sometimes two companies are rivals and one adds new products to their line so that each company distributes the same thing and they compete. The next form is substitute competition, where products that are close substitutes for one another compete. For example, butter competes with margarine, mayonnaise, and other various sauces and spreads. The broadest form of competition is typically called budget competition. Included in this category is anything that the consumer might want to spend their available money on. For example, a family that has $20,000 available may choose to spend it on many different items, which can all be seen as competing with each other for the family's available money. Competition does not necessarily have to be between companies. For example, business writers sometimes refer to "internal competition". This is competition within companies. The idea was first introduced by Alfred Sloan at General Motors in the 1920s. Sloan deliberately created areas of overlap between divisions of the company so that each division would be competing with the other divisions. For example, the Chevy division would compete with the Pontiac division for some market segments. Also, in 1931, Proctor and Gamble initiated a deliberate system of internal brand versus brand rivalry. The company was organized around different brands, with each brand allocated resources, including a dedicated group of employees willing to champion the brand. Each brand manager was given responsibility for the success or failure of the brand and was compensated accordingly. This form of competition thus pitted a brand against another brand. Finally, most businesses also encourage competition between individual employees. An example of this is a contest between sales representatives. The sales representative with the highest sales (or the best improvement in sales) over the a period of time would gain benefits from the employer. It should also be noted that business and economical competition in most countries is often limited or restricted. Competition often is subject to legal restrictions, which usually provide for fair and equal business competition. Such laws may include the banning of monopolies and price gouging. Depending on the respective economic policy, the pure competition is to a greater or lesser extent regulated by competition policy and competition law. Competition between countries is quite subtle to detect, but is quite evident in the World economy, where countries like the US, Japan, the European Union and the East Asian Tigers each try to outdo the other in the quest for economic supremacy in the global market, harkening to the concept of Kiasuism.Such competition is evident by the policies undertaken by these countries to educate the future workforce. For example, East Asian economies like Singapore, Japan and South Korea tend to emphasize education by allocating a large portion of the budget to this sector, and by implementing programmes such as gifted education, which some detractors criticise as indicative of academic elitism.

Competition in biology and ecology

Competition is also present in biology, and more specifically, ecology. Competition between members of a species is the driving force of evolution and natural selection- the competition for resources, such as food, water, territory, and sunlight, results in the ultimate survival and dominance of the variation of the species best suited for survival. According to Darwin's Theory of Evolution, this intraspecies competition results in the organisms best suited for survival producing the most offspring. As a result, the species would evolve over time and adapt to the environment in which the organisms lived. Competition is also present between species. First, a limited amount of resources are available, and several species may depend on these resources. Thus, each of the species competes with the others to gain the resources. As a result, several species less suited to compete for the resources may either adapt or die out. In addition, competition is also prominent in predator-prey relationships. Both the predator and prey are competing against one another for survival; the predator is seeking food, and the prey is seeking to survive.

Competition in politics

Competition is also found in politics. In democracies, an election is a competition for an elected office. In other words, two or more candidates strive and compete against one another to attain a position of power. The winner gains the seat of the elected office for a set amount of time, when another election is usually held to determine the next holder of the office. In addition, there is inevitable competition inside a government. Because several offices are appointed, potential candidates compete against the others in order to gain the particular office. Departments may also compete for a limited amount of resources, such as for funding. Finally, where there are party systems, elected leaders of different parties will ultimately compete against the other party for laws, funding, and power. Finally, competition is also imminent between governments. Each country or nationality struggles for world dominance, power, or military strength. For example, the United States competed against the Soviet Union in the Cold War for world power, and the two also struggled over the different types of government (in this case, representative democracy and communism). The result of this type of competition often leads to worldwide tensions and may sometimes erupt into warfare.

Sports competition

While some sports, such as fishing, have been viewed as primarily recreational, most sports are considered competitive. The majority involve the competition between two or more persons, (or animals and/or mechanical devices typically controlled by humans as in horse racing or auto racing). For example, in a game of basketball, two teams compete against one another to determine who can score the most points. While there is no set reward for the winning team, many players gain an internal sense of pride. In addition, extrinsic rewards may also be given. Athletes, besides competing against other humans, also compete against nature in sports such as kayaking or mountain climbing, where the goal is to reach a destination, with only natural barriers impeding the process. While professional sports have been usually viewed as intense and extremely competitive, recreational sports, which are often less intense, are considered a healthy option for the competitive urges in humans. Sport provides a relatively safe venue for converting unbridled competition into harmless competition, because sports competition is not unrestrained. On the contrary, the competitions are governed by codified rules ageed upon by the participants. Violating these rules is considered to be unfair competition. Sports, in addition, is also considered artificial and not natural competition; for example, competing for control of a ball or defending territory on a playing field is not an innate biologal factor in humans. Athletes in sports like gymnastics and competitive diving actually compete against a conceptual ideal of a perfect performance, which incorporates measurable criteria and standards that are translated into numerical ratings and scores. Sports competition is generally broken down into three categories: individual sports, such as archery, dual sports, such as doubles tennis, or team sports competition, such as soccer. While most sports competitions are recreation, there exists several major and minor professional sports leagues throughout the world, and the Olympic Games, held every four years, is a pinnacle of sports competition.

Competition in education

Competition is also very evident in education. On a global scale, national education systems, intending to bring out the best in the next generation, encourage competitiveness among students by scholarships. Countries like Singapore and the United Kingdom have a gifted education programme which caters to gifted students, prompting charges of academic elitism. Upon receipt of their academic results, students tend to compare their grades to see who is better. For severe cases, the pressure to perform in some countries is so high that it results in stigmatisation of intellectually deficient students or even suicide as consequence of failing the exams, Japan being a prime example (see Education in Japan). This resulted in critical revaluation of examinations as a whole by educationists (see Exam). Competitions also make up a large proponent of extracurricular activities that students partake in. Such competitions include TVO's broadcasted Reach for the Top competition, FIRST Robotics and the University of Toronto Space Design Contest.

The study of competition

Competition has been studied in several fields, including psychology, sociology, and anthropology. Social psychologists, for instance, study the nature of competition. They investigate the natural urge of competition and its circumstances. They also study group dynamics to detect how competition emerges and what its effects are. Sociologists, meanwhile, study the effects of competition on society as a whole. In addition, anthropologists study the history and prehistory of competition in various cultures. They also investigate how competition manifested itself in various cultural settings in the past, and how competition has developed over time.

Competitiveness

Many philosophers and psychologists have identified a trait in most living organisms that drive the particular organism to compete. This trait, called competitiveness, is viewed as an innate biological trait that coexists along with the urge for survival. Competitiveness, or the inclination to compete, though, has become synonymous with aggressiveness and ambitiousness in the English language.

See also


- Biological interaction
- Competitor analysis
- Cooperative
- Co-operation
- Ecological model of competition
- Microeconomics
- Perfect competition
- Planned economy
- Monopolistic competition
- Imperfect competition
- Perverse competition
- "Winning isn't everything; it's the only thing." Category:Ecology ja:競技

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