The food web (or food cycle ) is the natural interconnection of the food chain and graphical representation (usually images) of what-eat-what in the ecological community. Another name for the food web is the consumer resource system . Ecologists can broadly categorize all life forms into one of two categories called trophic levels: 1) autotrophs, and 2) heterotrophs. To maintain their body, grow, develop, and reproduce, autotrophs produce organic materials from inorganic substances, including minerals and gases such as carbon dioxide. These chemical reactions require energy, which mainly comes from the Sun and most by photosynthesis, although very small amounts come from hydrothermal vents and hot springs. There is a gradient between trophic levels running from complete autotrophs that obtain the only source of carbon from the atmosphere, to mixotrophs (like carnivorous plants) which are autotrophic organisms that partially obtain organic matter from sources other than the atmosphere, and complete heterotrophs that must feed to obtain material organic. The linkage in the food network illustrates the feeding path, such as where heterotrophs obtain organic material by feeding on autotroph and other heterotrophs. The food web is a simplified illustration of the various feeding methods that connect an ecosystem into an integrated exchange system. There are different types of eating relationships that can be roughly divided into herbivores, carnivores, scavenging and parasitism. Some organic ingredients eaten by heterotrophs, such as sugars, provide energy. Autotrophs and heterotrophs come in a variety of sizes, from microscopic to many tons - from cyanobacteria to giant redwoods, and from viruses and bdellovibrio to blue whales.
Charles Elton pioneered the concept of the food cycle, food chain, and food size in his 1927 "Ecological Animal"; Elton's 'food cycle' is replaced by 'food web' in the next ecological text. Elton organized the species into a functional group, which became the basis for classical and historic papers Raymond Lindeman in 1942 on tropical dynamics. Lindeman emphasized the importance of the role of decomposer organisms in the trophic classification system. The notion of the food web has a historical footing in Charles Darwin's writings and terminology, including the "entangled bank," "the web of life," "complicated network of relationships," and refers to the act of decomposing earthworms he speaks of "the continuing movement of earth particles". Even earlier, in 1768 John Bruckner described nature as "a continuous web of life".
The food web is a limited representation of real ecosystems because they have to collect many species into tropical species, which are groups of functional species that have the same predators and prey in the food web. Ecologists use this simplification in quantitative (or mathematical) models of the dynamics of natural resource systems or consumers. By using this model they can measure and test common patterns in real food web network structures. Ecologists have identified non-random properties in the food topographic structure. The published examples used in the meta analysis are variable quality with negligence. However, the number of empirical studies on the web community is on the rise and mathematical treatment of the food web using network theory has identified a common pattern for all. Legal scaling, for example, predicts the relationship between the predator topology of the web food predator and the level of species richness.
Video Food web
Food network taxonomy
Links in the food network map the eating connections (who eat who) in the ecological community. Food cycles are obsolete terms that are identical to the food network. Ecologists can broadly categorize all life forms into one of two trophic, autotroph and heterotrophic layers. Autotrophs produce more biomass energy, either chemically without solar energy or by capturing solar energy in photosynthesis, than they use during metabolic respiration. Heterotrophs consume rather than produce biomass energy because they metabolize, grow, and add to secondary production levels. A food web describes a collection of heterotrophic polyphagus consumers that make networks and cycles of energy and nutrient flow from self-feeding autotrophic bases.
The basal or basal species in the food web is a species that is without prey and can include autotrophs or saprophytic detritivores (ie community decomposers, biofilms, and periphytes). Web feeding connections are called trophic links. The number of trophic links per consumer is the size of the food web connection. Food chains nest within the network of food trophic networks. The food chain is a linear (noncyclic) feeding route that tracks monophagous consumers from basic species to top consumers, who are usually larger carnivorous predators.
The link is connected to the knot in the food web, which is a collection of biological taxa called tropical species. Tropical species are functional groups that have the same predators and prey in the food web. Common examples of nodes collected in food webs may include parasites, microbes, decomposers, saprotrophs, consumers, or predators, each containing many species on the web that can connect with other tropical species.
Trophic level
The food web has a trophic level and position. Basal species, like plants, form the first level and are a resource-limited resource that does not feed other living things on the web. Basal species may be autotrophs or detritivores, including "decaying organic matter and associated microorganisms that we define as detritus, microorganic materials and related microorganisms (MIP), and vascular plant material." Most autotrophs capture solar energy in chlorophyll, but some autotrophs (chemolithotrophs) derive energy by chemical oxidation of inorganic compounds and can grow in dark environments, such as Thiobacillus sulfur bacteria, which live in hot spaces. sulfur springs. The upper level has a top (or peak) predator that does not kill other species directly for its food source needs. The intermediate level is filled with omnivores that eat more than one trophic level and cause energy to flow through a number of food paths ranging from basal species.
In the simplest scheme, the first trophic level (level 1) is the plant, then the herbivore (level 2), and then the carnivore (level 3). The trophic level is equal to one more than the length of the chain, which is the number of links that connect to the base. The base of the food chain (producer or primary detritivora) is set to zero. Ecologists identify feeding relationships and organize species into tropical species through extensive intestinal content analysis of different species. This technique has been enhanced through the use of stable isotopes to track the flow of better energy over the web. It has been thought that omnivory is rare, but recent evidence suggests otherwise. This awareness has made the tropic classification more complex.
tropical dynamics
The trophic level concept was introduced in a historic paper on tropical dynamics in 1942 by Raymond L. Lindeman. The basis of tropical dynamics is the transfer of energy from one part of the ecosystem to another. The trophic dynamic concept has functioned as a useful quantitative heuristic, but has several major limitations including the precision by which an organism can be allocated to certain trophic levels. Omnivores, for example, are not limited to one level. Nevertheless, recent research has found that discrete trophic levels do exist, but "above the trophic level of herbivores, food webs are better characterized as tangled omnivorous webs."
The central question in the tropical dynamic literature is the nature of control and regulation of resources and production. Ecologists use a simplified trophic model food chain model (producer, carnivore, decomposer). Using this model, ecologists have tested various types of ecological control mechanisms. For example, herbivores generally have abundant vegetative resources, meaning that their populations are largely controlled or regulated by predators. This is known as a top-down hypothesis or 'green-world' hypothesis. As an alternative to the top-down hypothesis, not all plant material can be eaten and the nutritional or antiherbivorous qualities of the plant (structural and chemical) indicate a form of regulation or under-control. Recent studies have concluded that "top-down" and "bottom-up" forces can affect community structures and the strength of their influence depends on the environmental context. This intricate multitrophic interaction involves more than two trophic levels in a food web.
Another example of multi-trophic interaction is a trophic cascade, in which predators help to increase plant growth and prevent overgrazing by suppressing herbivores. Links on the food web illustrate a direct link between trophic species, but there are also indirect effects that can alter abundance, distribution, or biomass at the trophic level. For example, herbivorous feeding predators indirectly affect control and regulation of primary production in plants. Although predators do not eat plants directly, they regulate herbivorous populations that are directly associated with trophism plants. The net effect of a direct and indirect relationship is called a trophic cascade. Tropical cascades are separated into species-level cascades, where only a small part of the web-food dynamics are affected by population changes, and community-level cascades, where population changes have dramatic effects on entire food-webs, such as the distribution of plant biomass.
Energy flow and biomass
Food webs describe the flow of energy through trophic links. The flow of energy is directed, as opposed to the cyclic stream of material through the food web system. The flow of energy "usually includes production, consumption, assimilation, non-assimilation (feces), and respiration (maintenance costs)." In a very general sense, the energy flow (E) can be defined as the amount of metabolic (P) and respiration (R) production, so E = P R.
Biomass represents stored energy. However, the concentration and quality of nutrients and energy varies. Many plant fibers, for example, can not be digested by many herbivores that leave the grazer community food network more nutrient than the detrital food network in which bacteria can access and release nutrient and energy stores. "Organisms typically extract energy in the form of carbohydrates, lipids, and proteins.This polymer has a dual role as energy supply and building blocks, the part that serves as an energy supply to produce nutrients (and carbon dioxide, water, and heat.) Therefore excretion nutrients are the basis for metabolism. "The units in the energy flow network are usually mass or energy per m 2 per unit of time.The different consumers will have different assimilation efficiency of metabolism in their diet.Each trophic level converting energy into biomass The energy flow diagram illustrates the rate and efficiency of transfer from one trophic level to another and rises through the hierarchy.
This is the case that the biomass of each trophic level decreases from the base of the chain to the apex. This is because energy is lost to the environment with each transfer as an increase in entropy. About eighty to ninety percent of energy is spent on living organisms or lost as heat or waste. Only about ten to twenty percent of the organism's energy is generally passed on to the next organism. The amount could be less than one percent in animals that consume undigested plants, and that could be as high as forty percent in zooplankton taking phytoplankton. Graphic representation of biomass or productivity at any tropical level is called an ecological pyramid or a trophic pyramid. Energy transfers from major producers to top consumers can also be characterized by energy flow diagrams.
Food chain
The common metric used to measure the food web's trophic structure is the length of the food chain. The length of the food chain is another way of describing the food web as a measure of the number of species encountered as energy or nutrients that move from the plant to the top predator. There are various ways to calculate the length of a food chain depending on the parameters of the food web dynamics being considered: connection, energy, or interaction. In its simplest form, the length of the chain is the number of links between the trophic consumer and the web base. The average chain length of the entire web is the arithmetic average of the length of all the chains in the food web.
In a simple predator-prey example, the deer is a step removed from the plant it eats (long chain = 1) and the wolves that eat the deer are two steps removed from the plant (long chain = 2). The relative amount or power of influence this parameter has on the food web address question about:
- the identity or existence of some dominant species (called strong interactor or keystone species)
- total number of species and length of the food chain (including many weak interactions) and
- how the structure, function, and stability of the community are determined.
Ecological pyramid
In the pyramid of numbers, the number of consumers at each level decreases significantly, so that one top consumer, (eg, polar or human bears), will be supported by a large number of separate manufacturers. There is usually a maximum of four or five links in the food chain, although the food chain in aquatic ecosystems is often longer than inland. Finally, all the energy in the food chain is dispersed as heat.
The ecological pyramid puts the major producers at the base. They can describe the various numerical properties of the ecosystem, including the number of individuals per unit area, biomass (g/m 2 ), and energy (k cal m -2 yr -1 ). The pyramid setting that emerges from the trophic level with the amount of energy transfer decreases as the species becomes further removed from the source of production is one of several repetitive patterns among the planetary ecosystems. \ The size of each level in the pyramid generally represents biomass, which can be measured as the dry weight of an organism. Autotrophs may have the highest proportion of global biomass, but they are greatly rivaled or surpassed by microbes.
The structure of the pyramid can vary between ecosystems and across time. In some cases the biomass pyramid can be reversed. These patterns are often identified in aquatic ecosystems and coral reefs. The pattern of biomass inversion is associated with different sizes of manufacturers. Aquatic communities are often dominated by smaller producers of consumers with high growth rates. Aquatic producers, such as planktonic algae or aquatic plants, do not have a large accumulation of secondary growth such as those in woody trees from terrestrial ecosystems. However, they are able to reproduce fast enough to support larger grazer biomass. It reverses the pyramid. Primary consumers have longer life spans and slower growth rates that accumulate more biomass than the producers they consume. Phytoplankton live only a few days, while zooplankton eat phytoplankton live for several weeks and fish eat zooplankton alive for several years in a row. Water predators also tend to have lower mortality rates than smaller consumers, which contribute to the reversed pyramid pattern. Population structure, migration rates, and environmental protection for prey are other possible causes for pyramids with reverse biomass. The pyramid of energy, however, will always have an upright pyramid shape if all food sources of energy are included and this is determined by the second law of thermodynamics.
Maps Food web
The flux and recycling materials
Many elements and minerals of the Earth (or mineral nutrients) are contained within the tissues and diet of organisms. Therefore, the mineral and nutrient cycles trace the energy path of the food web. Ecologists use stoichiometry to analyze the ratio of the major elements found in all organisms: carbon (C), nitrogen (N), phosphorus (P). There is a big transitional difference between many terrestrial and aquatic systems because the C: P and C: N ratios are much higher in terrestrial systems while the N: P ratio equals between the two systems. Mineral nutrients are the material resources the organism needs for growth, development, and vitality. The food network illustrates the path of the mineral nutrition cycle as it flows through the organism. Most primary production in an ecosystem is not consumed, but recycled by the detritus back into useful nutrients. Many of the Earth's microorganisms are involved in mineral formation in a process called biomineralization. Bacteria that live in detrital sediments create and cycle nutrients and biominerals. Food web models and nutrition cycles have traditionally been treated separately, but there is a strong functional relationship between the two in terms of stability, flux, sources, sinks, and recycling of mineral nutrients.
Various kinds of food network
The food web should be collected and illustrate only a small part of the complexity of the real ecosystem. For example, the number of species on the planet is likely in the general order of 10 7 , over 95% of these species consist of microbes and invertebrates, and relatively few have been named or classified by taxonomy. It is explicitly understood that the 'careless' natural system and the trophic position of the food web simplify the complexity of real systems that sometimes overemphasize many rare interactions. Most studies focus on the greater influence in which most energy transfers occur. "This neglect and problem causes concern, but on this evidence does not present an insurmountable difficulty."
There are different types or categories of food networks:
- source Web - one or more nodes, all of its predators, all of the food the predator eats, and so on.
- Webink - one or more nodes, all their prey, all the food eaten by this prey, and so on.
- Community (or connection) web - a group of nodes and all connections from who eats whom.
- Web energy flow - measurable energy flux between nodes along the link between resources and consumers.
- Paleoecological Web - the web that reconstructs the ecosystem of the fossil record.
- Functional Web - emphasizes the functional meaning of certain connections that have strong interaction strength and greater influence on community organizations, more than the flow path of energy. Functional nets have compartments, which are subgroups in larger networks where there are different densities and interaction strengths. The functional network emphasizes that "the importance of every citizen in maintaining community integrity is reflected in its influence on the growth rates of other populations."
In this category, food webs can be organized further according to the various types of ecosystems under investigation. For example, human food networks, agricultural food nets, detrital food webs, seafood webs, aquatic food webs, soil food webs, arctic food networks (or poles), terrestrial food webs, and microbial food webs. This characterization is derived from the concept of ecosystem, which assumes that the phenomenon being studied (interaction and feedback) is sufficient to explain patterns within boundaries, such as the edge of the forest, the island, the shoreline, or some other physical characteristic that is spoken.
Web detrital
In the detrital net, plants and animals are broken down by decomposers, for example, bacteria and fungi, and move to the detritivora and then the carnivores. There is often a link between the web of detrital and the web grazing. Mushrooms produced by decomposers on the web are a source of food for deer, squirrels, and mice in grazing nets. Earthworms devoured by robins are detritivors that feed on decaying leaves.
"Detritus can be broadly defined as any form of nonliving organic matter, including various types of plant tissues (eg leaf litter, dead wood, water macrophytes, algae), animal tissues (carcasses), dead microbes, faeces (manure, ), fecal pellets, guano, frass), as well as products secreted, excreted or excreted from the organism (eg extra-cellular polymers, nectar, root exudate and leachate, dissolved organic matter, extra-cellular matrix, mucus). this form of detritus, in terms of origin, size and chemical composition, varies throughout the ecosystem. "
Quantitative food web
Ecologists collect data on trophic levels and food webs for statistical models and calculate mathematical parameters, as used in other types of network analyzes (eg, graph theory), to study emerging patterns and properties shared among ecosystems. There are various ecological dimensions that can be mapped to create more complicated food webs, including: species composition (species species), richness (number of species), biomass (dry weight of plants and animals), productivity (energy conversion rates and nutrients into growth) , and stability (food webs from time to time). A food web diagram illustrating species composition shows how changes in one species can directly and indirectly affect many other species. Microcosm studies are used to simplify food web research into semi-isolated units such as small springs, decaying logs, and laboratory experiments using organisms that multiply rapidly, such as feeding daphnia in algae that grow under controlled environments in water jars.
While the complexity of real-food network connections is difficult to grasp, ecologists have found an invaluable mathematical model in the network of tools to gain insight into the structure, stability, and laws of web food behavior relative to observable results. "The food web theory is centered around the idea of ​​connection." Quantitative formula simplifies the complexity of food web structures. The number of trophic links (t L ), for example, is changed to a connection value:
- ,
where S (S-1)/2 is the maximum number of binary connections between species S. "Connectance (C) is a fraction of all possible link realizations (L/S 2 ) and represents the size standard web food complexity... "The distance (d) between each pair of species in a web is averaged to calculate the average distance between all nodes in a web (D) and multiplied by the total number of links (L) density (LD), which is influenced by a scale-dependent variable such as species richness.. These formulas are the basis for comparing and investigating the nature of non-random patterns in the web's food web structure among different ecosystem types.
The legal scale, complexity, choas, and patterned correlations are common features associated with the food web structure.
Complexity and stability
The food web is very complex. Complexity is a measure of the increase in the number of permutations and it is also a metaphorical term that conveys mental persistence or limits about unlimited algorithmic possibilities. In food web terminology, complexity is the product of the number of species and connections. The connection is "a fraction of all possible links realized in the network". These concepts are derived and stimulated through suggestions that complexity leads to stability in food webs, such as increasing the number of trophic levels in more species rich ecosystems. This hypothesis is challenged through mathematical models that show otherwise, but subsequent research shows that the premise applies in real systems.
At different levels in the hierarchy of life, such as food chain stability, "the same overall structure is maintained regardless of ongoing flow and component changes." The farther the living systems (eg, ecosystems) shake from equilibrium, the greater the complexity. Complexity has many meanings in the life sciences and in public spaces that confuse its application as an appropriate term for analytical purposes in science. The complexity in life sciences (or biocomplexity) is defined by "the attributes arising from the interaction of behavioral, biological, physical, and social interactions that affect, defend, or modify by living organisms, including humans."
Several concepts have emerged from studies of complexity in food tissues. Complexity describes many principles relating to self-organization, non-linearity, interaction, cybernetic feedback, discontinuity, appearance, and stability in the food web. Nestedness, for example, is defined as "the pattern of interactions in which specialists interact with species that form the perfect subset of species with which the generalists interact", "- that is, the most specialized diet species are part of the diet of the more common common species, and the dietary part from the next more general, and so on. "Until recently, there was the notion that food webs had small nesting structures, but empirical evidence suggests that many published webs have subwebs lodged in their assemblies.
The food web is a complex network. As a network, they exhibit similar structural and mathematical legal properties that have been used to describe other complex systems, such as small worlds and free-scale properties. The small world attribute refers to many loosely connected nodes, a non-random solid grouping of multiple nodes (ie, tropical or keystone species in ecology), and a small path length compared to the usual lattice. "Ecological networks, in particular mutualistic networks, are generally very heterogeneous, consisting of areas with rare links between species and different areas of closely related species.The areas with high link densities are often referred to as groups, hubs, compartments, cohesive subgroups, or modules... In the food web, especially in aquatic systems, nestedness appears to be related to body size because diet of smaller predators tends to be a nested subset of larger predators (Woodward & Warren 2007; YvonDurocher et al. 2008), and phylogenetic constraints, in which the corresponding taxa lodged on the basis of their general evolutionary history, is also evident (Cattin et al., 2004). "Compartments in food tissue are a subgroup of taxa where many strong interactions occur in subgroups and multiple interactions weakness occurs between subgroups.Theoretically, the compartment improves stability in the network, such as ja food ring. "
The food webs are also complex in how they change in scale, seasonally, and geographically. The components of the food web, including organisms and mineral nutrients, cross the ecosystem threshold. This has led to a concept or field of study known as cross-border subsidies. "This leads to anomalies, such as food web calculations that determine that an ecosystem can support one and a half of the upper carnivores, without specifying which ends." Nevertheless, significant differences in structure and function have been identified when comparing different types of ecological food webs, such as land and aquatic food webs.
History of food network
The food web serves as a framework to help ecologists manage complex interaction networks among species observed in nature and around the world. One of the earliest descriptions of the food chain is described by a medieval Arab-African scholar named Al-Jahiz: "All animals, in short, can not live without food, nor are hunted game hunts in turn." The early graphical depictions of the food network were by Lorenzo Camerano in 1880, followed independently by those of Pierce and colleagues in 1912 and Victor Shelford in 1913. Two food webs about herrings were produced by Victor Summerhayes and Charles Elton and Alister Hardy in 1923 and 1924. Charles Elton then pioneered the concept of food cycles, food chains, and food sizes in his 1927 book "Ecological Animal"; Elton's 'food cycle' is replaced by 'food web' in the next ecological text. After Charles Elton used the food network in his 1927 synthesis, they became a central concept in the field of ecology. Elton organized the species into functional groups, forming the basis for the trophic classification system in classical papers and Raymond Lindeman's landmark in 1942 on tropical dynamics. The idea of ​​the food web has a historical footing in Charles Darwin's writings and terminology, including "the entangled bank," "the web of life," "complicated network of relationships," and refers to the act of decomposing earthworms he speaks of "the continuing movement of earth particles". Even earlier, in 1768 John Bruckner described nature as "a continuous web of life".
Interest in the food web increased after Robert Paine's experimental and experimental research on intertidal shores showed that the complexity of the food web is key to maintaining species diversity and ecological stability. Many theoretical ecologists, including Sir Robert May and Stuart Pimm, are encouraged by this invention and others to test the mathematical nature of the food web.
See also
References
Further reading
- Cohen, Joel E. (1978). Food web and special room . Monographs in Population Biology. 11 . Princeton, NJ: Princeton University Press. pp.Ã, xv 1-190. ISBN 978-0-691-08202-8.
- "Aquatic Food Web". NOAA Educational Resources . National Oceanic and Atmospheric Administration.
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