Ecology

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Ecology
.

Ecology (from

Ancient Greek οἶκος (oîkos)  'house' and -λογία (-logía)  'study of')[A] is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history
.

Ecology is a branch of biology, and is the study of abundance, biomass, and distribution of organisms in the context of the environment. It encompasses life processes, interactions, and adaptations; movement of materials and energy through living communities; successional development of ecosystems; cooperation, competition, and predation within and between species; and patterns of biodiversity and its effect on ecosystem processes.

Ecology has practical applications in fields such as conservation biology, wetland management, natural resource management, and human ecology.

The term ecology (German: Ökologie) was coined in 1866 by the German scientist Ernst Haeckel. The science of ecology as we know it today began with a group of American botanists in the 1890s.[1] Evolutionary concepts relating to adaptation and natural selection are cornerstones of modern ecological theory.

water filtration, soil formation, erosion
control, flood protection, and many other natural features of scientific, historical, economic, or intrinsic value.

Levels, scope, and scale of organization

Ecosystems vary from tiny to vast. A single tree is of little consequence to the classification of a forest ecosystem, but is critically relevant to organisms living in and on it.[2] Several generations of an aphid population can exist over the lifespan of a single leaf. Each of those aphids, in turn, supports diverse bacterial communities.[3] The nature of connections in ecological communities cannot be explained by knowing the details of each species in isolation, because the emergent pattern is neither revealed nor predicted until the ecosystem is studied as an integrated whole.[4]

The main subdisciplines of ecology,

community) ecology and ecosystem ecology, differ in their contrasting paradigms. The former focuses on organisms' distribution and abundance, while the latter focuses on materials and energy fluxes.[5]

Hierarchy

System behaviors must first be arrayed into different levels of the organization. Behaviors corresponding to higher levels occur at slow rates. Conversely, lower organizational levels exhibit rapid rates. For example, individual tree leaves respond rapidly to momentary changes in light intensity, CO2 concentration, and the like. The growth of the tree responds more slowly and integrates these short-term changes.

O'Neill et al. (1986)[6]: 76 

To structure the study of ecology into a conceptually manageable framework, the biological world is organized into a

non-linear behaviors; this means that "effect and cause are disproportionate, so that small changes to critical variables, such as the number of nitrogen fixers, can lead to disproportionate, perhaps irreversible, changes in the system properties."[9]
: 14 

Biodiversity

Biodiversity refers to the variety of life and its processes. It includes the variety of living organisms, the genetic differences among them, the communities and ecosystems in which they occur, and the ecological and evolutionary processes that keep them functioning, yet ever-changing and adapting.

Noss & Carpenter (1994)[10]: 5 

Biodiversity (an abbreviation of "biological diversity") describes the diversity of life from genes to ecosystems and spans every level of biological organization. The term has several interpretations, and there are many ways to index, measure, characterize, and represent its complex organization.[11][12][13] Biodiversity includes species diversity, ecosystem diversity, and genetic diversity and scientists are interested in the way that this diversity affects the complex ecological processes operating at and among these respective levels.[12][14][15]

Biodiversity plays an important role in

ecosystem services[18][19] and species migration (e.g., riverine fish runs and avian insect control) has been implicated as one mechanism by which those service losses are experienced.[20] An understanding of biodiversity has practical applications for species and ecosystem-level conservation planners as they make management recommendations to consulting firms, governments, and industry.[21]

Habitat

Biodiversity of a coral reef. Corals adapt to and modify their environment by forming calcium carbonate skeletons. This provides growing conditions for future generations and forms a habitat for many other species.[22]
Long-tailed broadbill building its nest

The habitat of a species describes the environment over which it occurs and the type of community that is formed.[23] More specifically, "habitats can be defined as regions in environmental space that are composed of multiple dimensions, each representing a biotic or abiotic environmental variable; that is, any component or characteristic of the environment related directly (e.g. forage biomass and quality) or indirectly (e.g. elevation) to the use of a location by the animal."[24]: 745 

Niche

Termite mounds with varied heights of chimneys regulate gas exchange, temperature and other environmental parameters that are needed to sustain the internal physiology of the entire colony.[25][26]

Definitions of niche date back to 1917.

hyperspace whose dimensions are defined as environmental variables and whose size is a function of the number of values that the environmental values may assume for which an organism has positive fitness."[30]
: 71 

Niche construction

Organisms are subject to environmental pressures, but they also modify their habitats. The

Ecosystem engineering is related to niche construction, but the former relates only to the physical modifications of the habitat whereas the latter also considers the evolutionary implications of physical changes to the environment and feedback on natural selection. Ecosystem engineers are defined as: "organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In so doing they modify, maintain and create habitats."[32]
: 373 

Biome

Biomes are larger units of organization that categorize regions of the Earth's ecosystems, mainly according to the structure and composition of vegetation.

hot desert, and polar desert.[34] Other researchers have recently categorized other biomes, such as the human and oceanic microbiomes. To a microbe, the human body is a habitat and a landscape.[35] Microbiomes were discovered largely through advances in molecular genetics, which have revealed a hidden richness of microbial diversity on the planet. The oceanic microbiome plays a significant role in the ecological biogeochemistry of the planet's oceans.[36]

Biosphere

The largest scale of ecological organization is the biosphere: the total sum of ecosystems on the planet.

feedback loop generated by the metabolism of living organisms that maintains the core temperature of the Earth and atmospheric conditions within a narrow self-regulating range of tolerance.[39]

Population ecology

Population ecology studies the dynamics of species populations and how these populations interact with the wider environment.[40] A population consists of individuals of the same species that live, interact, and migrate through the same niche and habitat.[41]

A primary law of population ecology is the Malthusian growth model[42] which states, "a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."[42]: 18  Simplified population models usually starts with four variables: death, birth, immigration, and emigration.

An example of an introductory population model describes a closed population, such as on an island, where immigration and emigration does not take place. Hypotheses are evaluated with reference to a null hypothesis which states that

random
processes create the observed data. In these island models, the rate of population change is described by:

where N is the total number of individuals in the population, b and d are the per capita rates of birth and death respectively, and r is the per capita rate of population change.[42][43]

Using these modeling techniques, Malthus' population principle of growth was later transformed into a model known as the

Pierre Verhulst
:

where N(t) is the number of individuals measured as biomass density as a function of time, t, r is the maximum per-capita rate of change commonly known as the intrinsic rate of growth, and is the crowding coefficient, which represents the reduction in population growth rate per individual added. The formula states that the rate of change in population size () will grow to approach equilibrium, where (), when the rates of increase and crowding are balanced, . A common, analogous model fixes the equilibrium, as K, which is known as the "carrying capacity."

Population ecology builds upon these introductory models to further understand demographic processes in real study populations. Commonly used types of data include life history, fecundity, and survivorship, and these are analyzed using mathematical techniques such as matrix algebra. The information is used for managing wildlife stocks and setting harvest quotas.[43][44] In cases where basic models are insufficient, ecologists may adopt different kinds of statistical methods, such as the Akaike information criterion,[45] or use models that can become mathematically complex as "several competing hypotheses are simultaneously confronted with the data."[46]

Metapopulations and migration

The concept of metapopulations was defined in 1969[47] as "a population of populations which go extinct locally and recolonize".[48]: 105  Metapopulation ecology is another statistical approach that is often used in conservation research.[49] Metapopulation models simplify the landscape into patches of varying levels of quality,[50] and metapopulations are linked by the migratory behaviours of organisms. Animal migration is set apart from other kinds of movement because it involves the seasonal departure and return of individuals from a habitat.[51] Migration is also a population-level phenomenon, as with the migration routes followed by plants as they occupied northern post-glacial environments. Plant ecologists use pollen records that accumulate and stratify in wetlands to reconstruct the timing of plant migration and dispersal relative to historic and contemporary climates. These migration routes involved an expansion of the range as plant populations expanded from one area to another. There is a larger taxonomy of movement, such as commuting, foraging, territorial behavior, stasis, and ranging. Dispersal is usually distinguished from migration because it involves the one-way permanent movement of individuals from their birth population into another population.[52][53]

Community ecology

community ecology
.

Community ecology examines how interactions among species and their environment affect the abundance, distribution and diversity of species within communities.

Johnson & Stinchcomb (2007)[54]: 250 

Community ecology is the study of the interactions among a collection of species that inhabit the same geographic area. Community ecologists study the determinants of patterns and processes for two or more interacting species. Research in community ecology might measure species diversity in grasslands in relation to soil fertility. It might also include the analysis of predator-prey dynamics, competition among similar plant species, or mutualistic interactions between crabs and corals.[54]: 250 

Ecosystem ecology

These ecosystems, as we may call them, are of the most various kinds and sizes. They form one category of the multitudinous physical systems of the universe, which range from the universe as a whole down to the atom.

Tansley (1935)[55]: 299 
White Mountains, New Hampshire (US) is an example of ecosystem ecology

The underlying concept of an ecosystem can be traced back to 1864 in the published work of

fungi and bacteria).[58]

Food webs

Generalized food web of waterbirds from Chesapeake Bay

A food web is the archetypal

herbivores, and the energy is transferred through a chain of organisms by consumption. The simplified linear feeding pathways that move from a basal trophic species to a top consumer is called the food chain. Food chains in an ecological community create a complex food web. Food webs are a type of concept map used to illustrate and study pathways of energy and material flows.[6][59][60]

Trophic levels

ecological relationships among creatures that are typical of a northern boreal terrestrial ecosystem. The trophic pyramid roughly represents the biomass (usually measured as total dry-weight) at each level. Plants generally have the greatest biomass. Names of trophic categories are shown to the right of the pyramid. Some ecosystems, such as many wetlands, do not organize as a strict pyramid, because aquatic plants are not as productive as long-lived terrestrial plants such as trees. Ecological trophic pyramids are typically one of three kinds: 1) pyramid of numbers, 2) pyramid of biomass, or 3) pyramid of energy.[40]
: 598 

A trophic level (from Greek troph, τροφή, trophē, meaning "food" or "feeding") is "a group of organisms acquiring a considerable majority of its energy from the lower adjacent level (according to

trophism among species. Biodiversity within ecosystems can be organized into trophic pyramids, in which the vertical dimension represents feeding relations that become further removed from the base of the food chain up toward top predators, and the horizontal dimension represents the abundance or biomass at each level.[62] When the relative abundance or biomass of each species is sorted into its respective trophic level, they naturally sort into a 'pyramid of numbers'.[63]

Species are broadly categorized as

carnivorous predators that feed exclusively on herbivores), and tertiary consumers (predators that feed on a mix of herbivores and predators).[64] Omnivores do not fit neatly into a functional category because they eat both plant and animal tissues. It has been suggested that omnivores have a greater functional influence as predators because compared to herbivores, they are relatively inefficient at grazing.[65]

Trophic levels are part of the

complex systems view of ecosystems.[66][67] Each trophic level contains unrelated species that are grouped together because they share common ecological functions, giving a macroscopic view of the system.[68] While the notion of trophic levels provides insight into energy flow and top-down control within food webs, it is troubled by the prevalence of omnivory in real ecosystems. This has led some ecologists to "reiterate that the notion that species clearly aggregate into discrete, homogeneous trophic levels is fiction."[69]: 815  Nonetheless, recent studies have shown that real trophic levels do exist, but "above the herbivore trophic level, food webs are better characterized as a tangled web of omnivores."[70]
: 612 

Keystone species

Sea otters, an example of a keystone species

A keystone species is a species that is connected to a disproportionately large number of other species in the

food-web. Keystone species have lower levels of biomass in the trophic pyramid relative to the importance of their role. The many connections that a keystone species holds means that it maintains the organization and structure of entire communities. The loss of a keystone species results in a range of dramatic cascading effects (termed trophic cascades) that alters trophic dynamics, other food web connections, and can cause the extinction of other species.[71][72] The term keystone species was coined by Robert Paine in 1969 and is a reference to the keystone architectural feature as the removal of a keystone species can result in a community collapse just as the removal of the keystone in an arch can result in the arch's loss of stability.[73]
sea urchins that feed on kelp. If sea otters are removed from the system, the urchins graze until the kelp beds disappear, and this has a dramatic effect on community structure.[74]

Complexity

Complexity is understood as a large computational effort needed to assemble numerous interacting parts. Global patterns of biological diversity are complex. This

ecotones spanning landscapes. Complexity stems from the interplay among levels of biological organization as energy, and matter is integrated into larger units that superimpose onto the smaller parts.[75]: 209  Small scale patterns do not necessarily explain larger ones, as in Aristotle's expression "the sum is greater than the parts".[76][77][E] "Complexity in ecology is of at least six distinct types: spatial, temporal, structural, process, behavioral, and geometric."[78]: 3  From these principles, ecologists have identified emergent and self-organizing phenomena that operate at different environmental scales of influence, ranging from molecular to planetary, and these require different explanations at each integrative level.[39][79]

Holism

Holism is a critical part of the theory of ecology. Holism addresses the biological organization of life that self-organizes into layers of emergent whole systems that function according to non-reducible properties. This means that higher-order patterns of a whole functional system, such as an ecosystem, cannot be predicted or understood by a simple summation of the parts.[80] "New properties emerge because the components interact, not because the basic nature of the components is changed."[40]: 8 

Relation to evolution

Ecology and evolutionary biology are sister disciplines.

populations, and inheritance thread equally into both. In this framework, the analytical tools of ecologists and evolutionists overlap as they study life through phylogenetics or Linnaean taxonomy.[81] There is no sharp boundary separating ecology from evolution, and they differ more in their areas of applied focus. Both explain properties and processes across different spatial or temporal scales of organization.[82][39] Ecologists study the abiotic and biotic factors that influence evolutionary processes,[83][84] and evolution can be rapid, occurring on ecological timescales as short as one generation.[85]

Behavioural ecology

chameleons (Bradypodion spp.). Chameleons change their skin colour to match their background as a behavioural defence mechanism and also use colour to communicate with other members of their species, such as dominant (left) versus submissive (right) patterns shown in the three species (A-C) above.[86]

All organisms have behaviours. Even plants express complex behaviour, including memory and communication.

weevils, the mating dance of a salamander, or social gatherings of amoeba.[88][89][90][91][92]

Adaptation is the central unifying concept in behavioural ecology.[93] Behaviours can be recorded as traits and inherited in much the same way that eye and hair colour can. Behaviours can evolve by means of natural selection as adaptive traits conferring functional utilities that increases reproductive fitness.[94][95]

Cognitive ecology

Cognitive ecology integrates theory and observations from evolutionary ecology and cognitive science, to understand the effect of animal interaction with their habitat on their cognitive systems.[96] "Until recently, however, cognitive scientists have not paid sufficient attention to the fundamental fact that cognitive traits evolved under particular natural settings. With consideration of the selection pressure on cognition, cognitive ecology can contribute intellectual coherence to the multidisciplinary study of cognition."[97][98]

Social ecology

Social-ecological behaviours are notable in the

eusocialism has evolved. Social behaviours include reciprocally beneficial behaviours among kin and nest mates[90][95][99] and evolve from kin and group selection. Kin selection explains altruism through genetic relationships, whereby an altruistic behaviour leading to death is rewarded by the survival of genetic copies distributed among surviving relatives. The social insects, including ants, bees, and wasps are most famously studied for this type of relationship because the male drones are clones that share the same genetic make-up as every other male in the colony.[95] In contrast, group selectionists find examples of altruism among non-genetic relatives and explain this through selection acting on the group; whereby, it becomes selectively advantageous for groups if their members express altruistic behaviours to one another. Groups with predominantly altruistic members survive better than groups with predominantly selfish members.[95][100]

Coevolution

Bumblebees and the flowers they pollinate have coevolved so that both have become dependent on each other for survival.
Parasitism: A harvestman arachnid being parasitized by mites. The harvestman is being consumed, while the mites benefit from traveling on and feeding off of their host.

Ecological interactions can be classified broadly into a

mineral nutrients.[104]

Biogeography

Biogeography is the comparative study of the geographic distribution of organisms and the corresponding evolution of their traits in space and time.

global warming.[110][111]

r/K selection theory

r/K selection theory

population density. For example, when an island is first colonized, density of individuals is low. The initial increase in population size is not limited by competition, leaving an abundance of available resources for rapid population growth. These early phases of population growth experience density-independent forces of natural selection, which is called r-selection. As the population becomes more crowded, it approaches the island's carrying capacity, thus forcing individuals to compete more heavily for fewer available resources. Under crowded conditions, the population experiences density-dependent forces of natural selection, called K-selection.[112] In the r/K-selection model, the first variable r is the intrinsic rate of natural increase in population size and the second variable K is the carrying capacity of a population.[29]

Molecular ecology

The relationship between ecology and genetic inheritance predates modern techniques for molecular analysis. Molecular ecological research became more feasible with the development of rapid and accessible genetic technologies, such as the

Molecular Ecology in 1992.[113] Molecular ecology uses analytical techniques to study genes in an evolutionary and ecological context. In 1994, John Avise played a leading role in this area of science with the publication of his book, Molecular Markers, Natural History and Evolution.[114]

Human ecology

A dual discipline

Only within the moment of time represented by the present century has one species man acquired significant power to alter the nature of his world.

Rachel Carson, "Silent Spring"[115]

Ecology is both a biological science and a human science.

interdisciplinary investigation into the ecology of our species. "Human ecology may be defined: (1) from a bioecological standpoint as the study of man as the ecological dominant in plant and animal communities and systems; (2) from a bioecological standpoint as simply another animal affecting and being affected by his physical environment; and (3) as a human being, somehow different from animal life in general, interacting with physical and modified environments in a distinctive and creative way. A truly interdisciplinary human ecology will most likely address itself to all three."[116]: 3  The term was formally introduced in 1921, but many sociologists, geographers, psychologists, and other disciplines were interested in human relations to natural systems centuries prior, especially in the late 19th century.[116][117]

Restoration Ecology

Ecology is an employed science of restoration, repairing disturbed sites through human intervention, in natural resource management, and in environmental impact assessments. Edward O. Wilson predicted in 1992 that the 21st century "will be the era of restoration in ecology".[119]

Relation to the environment

The environment of ecosystems includes both physical parameters and biotic attributes. It is dynamically interlinked and contains

conspecifics) and other species that share a habitat.[122]

Disturbance and resilience

A disturbance is any process that changes or removes biomass from a community, such as a fire, flood, drought, or predation.[123] Disturbances are both the cause and product of natural fluctuations within an ecological community.[124][123][125][126] Biodiversity can protect ecosystems from disturbances.[126]

Metabolism and the early atmosphere

Metabolism – the rate at which energy and material resources are taken up from the environment, transformed within an organism, and allocated to maintenance, growth and reproduction – is a fundamental physiological trait.

Ernest et al.[127]: 991 

The Earth was formed approximately 4.5 billion years ago.[128] As it cooled and a crust and oceans formed, its atmosphere transformed from being dominated by hydrogen to one composed mostly of methane and ammonia. Over the next billion years, the metabolic activity of life transformed the atmosphere into a mixture of carbon dioxide, nitrogen, and water vapor. These gases changed the way that light from the sun hit the Earth's surface and greenhouse effects trapped heat. There were untapped sources of free energy within the mixture of reducing and oxidizing gasses that set the stage for primitive ecosystems to evolve and, in turn, the atmosphere also evolved.[129]

The leaf is the primary site of photosynthesis in many higher plants.

Throughout history, the Earth's atmosphere and

Great Oxidation) did not begin until approximately 2.4–2.3 billion years ago, but photosynthetic processes started 0.3–1 billion years prior.[130][131]

Radiation: heat, temperature and light

The biology of life operates within a certain range of temperatures. Heat is a form of energy that regulates temperature. Heat affects growth rates, activity, behaviour, and

autotrophs. Autotrophs—responsible for primary production—assimilate light energy which becomes metabolically stored as potential energy in the form of biochemical enthalpic bonds.[83][84][132]

Physical environments

Water

Wetland conditions such as shallow water, high plant productivity, and anaerobic substrates provide a suitable environment for important physical, biological, and chemical processes. Because of these processes, wetlands play a vital role in global nutrient and element cycles.

Cronk & Fennessy (2001)[133]: 29 

Diffusion of carbon dioxide and oxygen is approximately 10,000 times slower in water than in air. When soils are flooded, they quickly lose oxygen, becoming

brackish, or oceanic environments.[133] The physiology of fish is adapted to compensate for environmental salt levels through osmoregulation. Their gills form electrochemical gradients that mediate salt excretion in salt water and uptake in fresh water.[134]

Gravity

The shape and energy of the land are significantly affected by gravitational forces. These govern many of the geophysical properties and distributions of biomes across the Earth. On the organismal scale, gravitational forces provide directional cues for plant and fungal growth (gravitropism), orientation cues for animal migrations, and influence the biomechanics and size of animals.[83] Ecological traits, such as allocation of biomass in trees during growth are subject to mechanical failure as gravitational forces influence the position and structure of branches and leaves.[135] The cardiovascular systems of animals are functionally adapted to overcome the pressure and gravitational forces that change according to the features of organisms (e.g., height, size, shape), their behaviour (e.g., diving, running, flying), and the habitat occupied (e.g., water, hot deserts, cold tundra).[136]

Pressure

Climatic and

seals are adapted to deal with changes in sound due to water pressure differences.[142]

Wind and turbulence

The architecture of the inflorescence in grasses is subject to the physical pressures of wind and shaped by the forces of natural selection facilitating wind-pollination (anemophily).[143][144]

thermally layered zones, affecting how fish, algae, and other parts of the aquatic ecosystem are structured.[145][146]

Wind speed and turbulence influence

xeric ecosystems to intermix with sister lineages that are segregated to the interior mountain systems.[148][149]

Fire

Forest fires modify the land by leaving behind an environmental mosaic that diversifies the landscape into different seral stages and habitats of varied quality (left). Some species are adapted to forest fires, such as pine trees that open their cones only after fire exposure (right).

Plants convert carbon dioxide into biomass and emit oxygen into the atmosphere. By approximately 350 million years ago (the end of the

Devonian period), photosynthesis had brought the concentration of atmospheric oxygen above 17%, which allowed combustion to occur.[150] Fire releases CO2 and converts fuel into ash and tar. Fire is a significant ecological parameter that raises many issues pertaining to its control and suppression.[151] While the issue of fire in relation to ecology and plants has been recognized for a long time,[152] Charles Cooper brought attention to the issue of forest fires in relation to the ecology of forest fire suppression and management in the 1960s.[153][154]

Soils

Soil is the living top layer of mineral and organic dirt that covers the surface of the planet. It is the chief organizing centre of most ecosystem functions, and it is of critical importance in agricultural science and ecology. The

microorganisms are influenced by and are fed back into the trophic dynamics of the ecosystem.[157][158]

Biogeochemistry and climate

Ecologists study nutrient budgets to understand how these materials are regulated, flow, and

recycled through the environment.[83][84][132] This research has led to an understanding that there is global feedback between ecosystems and the physical parameters of this planet, including minerals, soil, pH, ions, water, and atmospheric gases. Six major elements (hydrogen, carbon, nitrogen, oxygen, sulfur, and phosphorus; H, C, N, O, S, and P) form the constitution of all biological macromolecules and feed into the Earth's geochemical processes. From the smallest scale of biology, the combined effect of billions of ecological processes amplify and regulate the biogeochemical cycles of the Earth.[159]

History

Early beginnings

By ecology, we mean the whole science of the relations of the organism to the environment including, in the broad sense, all the "conditions of existence". Thus, the theory of evolution explains the housekeeping relations of organisms mechanistically as the necessary consequences of effectual causes; and so forms the monistic groundwork of ecology.

Ernst Haeckel (1866)[160]: 140  [B]

Ecology has a complex origin.[161] Ancient Greek philosophers such as Hippocrates and Aristotle recorded observations on natural history. However, they saw species as unchanging, while varieties were seen as aberrations. Modern ecology sees varieties as the real phenomena, leading to adaptation by natural selection.[40][162][163] Ecological concepts such as a balance and regulation in nature can be traced to Herodotus (died c. 425 BC), who described mutualism in his observation of "natural dentistry". Basking Nile crocodiles, he noted, opened their mouths to give sandpipers safe access to pluck leeches out, giving nutrition to the sandpiper and oral hygiene for the crocodile.[161] Aristotle and his student Theophrastus observed plant and animal migrations, biogeography, physiology, and their behavior, giving an early analogue to the concept of an ecological niche.[164][165]

Nowhere can one see more clearly illustrated what may be called the sensibility of such an organic complex, – expressed by the fact that whatever affects any species belonging to it, must speedily have its influence of some sort upon the whole assemblage. He will thus be made to see the impossibility of studying any form completely, out of relation to the other forms, – the necessity for taking a comprehensive survey of the whole as a condition to a satisfactory understanding of any part.

Stephen Forbes (1887)[166]

Ernst Haeckel (left) and Eugenius Warming (right), two founders of ecology

Ecological concepts such as food chains, population regulation, and productivity were developed in the 1700s, through the works of microscopist Antonie van Leeuwenhoek (1632–1723) and botanist Richard Bradley (1688?–1732).[40] Biogeographer Alexander von Humboldt (1769–1859) recognized ecological gradients, where species are replaced or altered in form along environmental gradients. Humboldt drew inspiration from Isaac Newton, as he developed a form of "terrestrial physics".[167][168][169] Natural historians, such as Humboldt, James Hutton, and Jean-Baptiste Lamarck laid the foundations of ecology.[170] The term "ecology" (German: Oekologie, Ökologie) was coined by Ernst Haeckel in his book Generelle Morphologie der Organismen (1866).[171] Haeckel was a zoologist, artist, writer, and later in life a professor of comparative anatomy.[160][172]

Linnaeus founded an early branch of ecology that he called the economy of nature.

The Origin of Species.[160] Linnaeus was the first to frame the balance of nature as a testable hypothesis.[174]

The layout of the first ecological experiment, carried out in a grass garden at Woburn Abbey in 1816, was noted by Charles Darwin in The Origin of Species. The experiment studied the performance of different mixtures of species planted in different kinds of soils.[175][176]

Since 1900

Modern ecology first attracted substantial scientific attention toward the end of the 19th century.

oekology" in the U.S. as early as 1892.[177] In the early 20th century, ecology transitioned from description to a more analytical form of scientific natural history.[167][170][178] Frederic Clements published the first American ecology book, Research Methods in Ecology in 1905,[179] presenting the idea of plant communities as a superorganism. This launched a debate between ecological holism and individualism that lasted until the 1970s.[180]

In 1942,

Robert MacArthur advanced mathematical theory, predictions, and tests in ecology in the 1950s.[170][181][182]

Ecology surged in popular and scientific interest during the 1960–1970s environmental movement.[170] In 1962, marine biologist and ecologist Rachel Carson's book Silent Spring helped to mobilize the environmental movement by alerting the public to toxic pesticides, such as DDT (C14H9Cl5), bioaccumulating in the environment. Since then, ecologists have worked to bridge their understanding of the degradation of the planet's ecosystems with environmental politics, law, restoration, and natural resources management.[21][170][184][185]

See also

Lists

Notes

  • ^
    This is a copy of Haeckel's original definition (Original: Haeckel, E. (1866) Generelle Morphologie der Organismen. Allgemeine Grundzige der organischen Formen- Wissenschaft, mechanisch begriindet durch die von Charles Darwin reformirte Descendenz-Theorie. 2 vols. Reimer, Berlin.) translated and quoted from Stauffer (1957).
  • ^
    Foster & Clark (2008) note how Smut's holism contrasts starkly against his racial political views as the father of apartheid.
  • ^
    First introduced in MacArthur & Wilson's (1967) book of notable mention in the history and theoretical science of ecology, The Theory of Island Biogeography.
  • ^
    Aristotle wrote about this concept in Metaphysics (Quoted from The Internet Classics Archive translation by W. D. Ross. Book VIII, Part 6): "To return to the difficulty which has been stated with respect both to definitions and to numbers, what is the cause of their unity? In the case of all things which have several parts and in which the totality is not, as it were, a mere heap, but the whole is something besides the parts, there is a cause; for even in bodies contact is the cause of unity in some cases and in others viscosity or some other such quality."
  • References

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