Ecology

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For other uses, see Ecology (disambiguation). Not to be confused with ethology, ethnology, etiology, or deep ecology.

Ecology
habitats, from terrestrial to aquatic ecosystems
.
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Ecology (from

physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. 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

basic and applied science, and human social interaction (human ecology
).

The word 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.

Ecosystems are dynamically interacting systems of organisms, the communities they make up, and the non-living (

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

Main article: Outline of ecology

The scope of ecology contains a wide array of interacting levels of organization spanning micro-level (e.g.,

phenomena. Ecosystems, for example, contain abiotic resources and interacting life forms (i.e., individual organisms that aggregate into populations which aggregate into distinct ecological communities). Because ecosystems are dynamic and do not necessarily follow a linear successional route, changes might occur quickly or slowly over thousands of years before specific forest successional stages are brought about by biological processes. An ecosystem's area can vary greatly, 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] Some ecological principles, however, do exhibit collective properties where the sum of the components explain the properties of the whole, such as birth rates of a population being equal to the sum of individual births over a designated time frame.[5]

The main subdisciplines of ecology,

community) ecology and ecosystem ecology, exhibit a difference not only in scale but also in two contrasting paradigms in the field. The former focuses on organisms' distribution and abundance, while the latter focuses on materials and energy fluxes.[6]

Hierarchy

See also:
Biological classification

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)[7]: 76 

The scale of ecological dynamics can operate like a closed system, such as aphids migrating on a single tree, while at the same time remaining open about broader scale influences, such as atmosphere or climate. Hence, ecologists classify

vegetation associations, climate, and soil types, and integrate this information to identify emergent patterns of uniform organization and processes that operate on local to regional, landscape
, and chronological scales.

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."[10]
: 14 

Biodiversity

Main article: 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)[11]: 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.

ecosystem services[19][20] 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.[21] 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.[22]

Habitat

Main article: 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.[23]
Long-tailed broadbill building its nest

The habitat of a species describes the environment over which a species is known to occur and the type of community that is formed as a result.

montane or alpine ecosystem. Habitat shifts provide important evidence of competition in nature where one population changes relative to the habitats that most other individuals of the species occupy. For example, one population of a species of tropical lizard (Tropidurus hispidus) has a flattened body relative to the main populations that live in open savanna. The population that lives in an isolated rock outcrop hides in crevasses where its flattened body offers a selective advantage. Habitat shifts also occur in the developmental life history of amphibians, and in insects that transition from aquatic to terrestrial habitats. Biotope and habitat are sometimes used interchangeably, but the former applies to a community's environment, whereas the latter applies to a species' environment.[24][26][27]

Niche

Main article: Ecological 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.[28][29]

Definitions of the 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."[34]
: 71 

traits and niche requirements.[35] Species have functional traits that are uniquely adapted to the ecological niche. A trait is a measurable property, phenotype, or characteristic of an organism that may influence its survival. Genes play an important role in the interplay of development and environmental expression of traits.[36] Resident species evolve traits that are fitted to the selection pressures of their local environment. This tends to afford them a competitive advantage and discourages similarly adapted species from having an overlapping geographic range. The competitive exclusion principle states that two species cannot coexist indefinitely by living off the same limiting resource; one will always out-compete the other. When similarly adapted species overlap geographically, closer inspection reveals subtle ecological differences in their habitat or dietary requirements.[37] Some models and empirical studies, however, suggest that disturbances can stabilize the co-evolution and shared niche occupancy of similar species inhabiting species-rich communities.[38] The habitat plus the niche is called the ecotope, which is defined as the full range of environmental and biological variables affecting an entire species.[24]

Niche construction

Main article: Niche construction
See also:
Ecosystem engineering

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

ecosystem engineering are 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 the feedback this causes on the process of 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."[40]
: 373 

The ecosystem engineering concept has stimulated a new appreciation for the influence that organisms have on the ecosystem and evolutionary process. The term "niche construction" is more often used in reference to the under-appreciated feedback mechanisms of natural selection imparting forces on the abiotic niche.

social insects, including ants, bees, wasps, and termites. There is an emergent homeostasis or homeorhesis in the structure of the nest that regulates, maintains and defends the physiology of the entire colony. Termite mounds, for example, maintain a constant internal temperature through the design of air-conditioning chimneys. The structure of the nests themselves is subject to the forces of natural selection. Moreover, a nest can survive over successive generations, so that progeny inherit both genetic material and a legacy niche that was constructed before their time.[5][28][29]

Biome

Main article: 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.[43] 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.[44] 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.[45]

Biosphere

Main article: Biosphere
See also:
Earth's spheres

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.[48]

Population ecology

Main article: Population ecology
See also: Lists of organisms by population

Population ecology studies the dynamics of species populations and how these populations interact with the wider environment.[5] A population consists of individuals of the same species that live, interact, and migrate through the same niche and habitat.[49]

A primary law of population ecology is the Malthusian growth model[50] which states, "a population will grow (or decline) exponentially as long as the environment experienced by all individuals in the population remains constant."[50]: 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.[50][51]

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.[51][52] In cases where basic models are insufficient, ecologists may adopt different kinds of statistical methods, such as the Akaike information criterion,[53] or use models that can become mathematically complex as "several competing hypotheses are simultaneously confronted with the data."[54]

Metapopulations and migration

Main article: Metapopulation
See also: Animal migration

The concept of metapopulations was defined in 1969[55] as "a population of populations which go extinct locally and recolonize".[56]: 105  Metapopulation ecology is another statistical approach that is often used in conservation research.[57] Metapopulation models simplify the landscape into patches of varying levels of quality,[58] 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.[59] 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.[60][61]

In metapopulation terminology, migrating individuals are classed as emigrants (when they leave a region) or immigrants (when they enter a region), and sites are classed either as sources or sinks. A site is a generic term that refers to places where ecologists sample populations, such as ponds or defined sampling areas in a forest. Source patches are productive sites that generate a seasonal supply of

field studies to explain metapopulation structure.[62][63]

Community ecology

community ecology
.
Main article:
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)[64]: 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.

Ecosystem ecology

Main article: 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)[65]: 299 

White Mountains, New Hampshire (US) is an example of ecosystem ecology

Ecosystems may be habitats within biomes that form an integrated whole and a dynamically responsive system having both physical and biological complexes. Ecosystem ecology is the science of determining the fluxes of materials (e.g. carbon, phosphorus) between different pools (e.g., tree biomass, soil organic material). Ecosystem ecologists attempt to determine the underlying causes of these fluxes. Research in ecosystem ecology might measure

fungi and bacteria),[66]

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

technoecosystems, which are affected by or primarily the result of human activity.[5]

Food webs

Main article: Food web
See also: Food chain
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 that is used to illustrate and study pathways of energy and material flows.[7][70][71]

Empirical measurements are generally restricted to a specific habitat, such as a cave or a pond, and principles gleaned from small-scale studies are extrapolated to larger systems.[72] Feeding relations require extensive investigations, e.g. into the gut contents of organisms, which can be difficult to decipher, or stable isotopes can be used to trace the flow of nutrient diets and energy through a food web.[73] Despite these limitations, food webs remain a valuable tool in understanding community ecosystems.[74]

Food webs illustrate important principles of ecology: some species have many weak feeding links (e.g.,

primary predators). Such linkages explain how ecological communities remain stable over time[75][76] and eventually can illustrate a "complete" web of life.[71][77][78][79]

The disruption of food webs may have a dramatic impact on the ecology of individual species or whole ecosystems. For instance, the replacement of an ant species by another (invasive) ant species has been shown to affect how elephants reduce tree cover and thus the predation of lions on zebras.[80][81]

Trophic levels

Main article: Trophic level
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.[5]
: 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.[83] When the relative abundance or biomass of each species is sorted into its respective trophic level, they naturally sort into a 'pyramid of numbers'.[84]

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).[85] 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.[86]

Trophic levels are part of the

complex systems view of ecosystems.[87][88] Each trophic level contains unrelated species that are grouped together because they share common ecological functions, giving a macroscopic view of the system.[89] 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."[90]: 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."[91]
: 612 

Keystone species

Main article: 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.[92][93] 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.[94]

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.[95] Hunting of sea otters, for example, is thought to have led indirectly to the extinction of the Steller's sea cow (Hydrodamalis gigas).[96] While the keystone species concept has been used extensively as a conservation tool, it has been criticized for being poorly defined from an operational stance. It is difficult to experimentally determine what species may hold a keystone role in each ecosystem. Furthermore, food web theory suggests that keystone species may not be common, so it is unclear how generally the keystone species model can be applied.[95][97]

Complexity

Main article: Complexity
See also: Emergence

Complexity is understood as a large computational effort needed to piece together numerous interacting parts exceeding the iterative memory capacity of the human mind. 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. "What were wholes on one level become parts on a higher one."[98]: 209  Small scale patterns do not necessarily explain large scale phenomena, otherwise captured in the expression (coined by Aristotle) 'the sum is greater than the parts'.[99][100][E]

"Complexity in ecology is of at least six distinct types: spatial, temporal, structural, process, behavioral, and geometric."[101]: 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.[48][102] Ecological complexity relates to the dynamic resilience of ecosystems that transition to multiple shifting steady-states directed by random fluctuations of history.[9][103] Long-term ecological studies provide important track records to better understand the complexity and resilience of ecosystems over longer temporal and broader spatial scales. These studies are managed by the International Long Term Ecological Network (LTER).[104] The longest experiment in existence is the Park Grass Experiment, which was initiated in 1856.[105] Another example is the Hubbard Brook study, which has been in operation since 1960.[106]

Holism

Main article: Holism

Holism remains a critical part of the theoretical foundation in contemporary ecological studies. 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.[107] "New properties emerge because the components interact, not because the basic nature of the components is changed."[5]: 8 

Ecological studies are necessarily holistic as opposed to

biomolecular properties of the exterior shells.[109]

Relation to evolution

Main article: Evolutionary ecology

Ecology and evolutionary biology are considered sister disciplines of the life sciences.

Trends in Ecology and Evolution.[111] There is no sharp boundary separating ecology from evolution, and they differ more in their areas of applied focus. Both disciplines discover and explain emergent and unique properties and processes operating across different spatial or temporal scales of organization.[36][48] While the boundary between ecology and evolution is not always clear, ecologists study the abiotic and biotic factors that influence evolutionary processes,[112][113] and evolution can be rapid, occurring on ecological timescales as short as one generation.[114]

Behavioural ecology

Main article:
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.[115]

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

weevils, the mating dance of a salamander, or social gatherings of amoeba.[117][118][119][120][121]

Adaptation is the central unifying concept in behavioural ecology.[122] 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.[123][124]

Mutualism: Leafhoppers (Eurymela fenestrata) are protected by ants (Iridomyrmex purpureus) in a mutualistic relationship. The ants protect the leafhoppers from predators and stimulate feeding in the leafhoppers, and in return, the leafhoppers feeding on plants exude honeydew from their anus that provides energy and nutrients to tending ants.[125]

Predator-prey interactions are an introductory concept into food-web studies as well as behavioural ecology.

flight initiation distance occurs where expected postencounter fitness is maximized, which depends on the prey's initial fitness, benefits obtainable by not fleeing, energetic escape costs, and expected fitness loss due to predation risk."[129]

Elaborate sexual

suitors.[130]

Cognitive ecology

Cognitive ecology integrates theory and observations from

neurobiology, primarily cognitive science, in order to understand the effect that animal interaction with their habitat has on their cognitive systems and how those systems restrict behavior within an ecological and evolutionary framework.[131] "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."[132][133] As a study involving the 'coupling' or interactions between organism and environment, cognitive ecology is closely related to enactivism,[131] a field based upon the view that "...we must see the organism and environment as bound together in reciprocal specification and selection...".[134]

Social ecology

Main article: Social ecology (academic field)

Social-ecological behaviours are notable in the

eusocialism has evolved. Social behaviours include reciprocally beneficial behaviours among kin and nest mates[119][124][135] 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.[124] 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.[124][136]

Coevolution

Main article: 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.[140]

Indirect mutualisms occur where the organisms live apart. For example, trees living in the equatorial regions of the planet supply oxygen into the atmosphere that sustains species living in distant polar regions of the planet. This relationship is called

Red Queen Hypothesis, for example, posits that parasites track down and specialize on the locally common genetic defense systems of its host that drives the evolution of sexual reproduction to diversify the genetic constituency of populations responding to the antagonistic pressure.[144][145]

Biogeography

Main article: Biogeography

Biogeography (an amalgamation of biology and geography) is the comparative study of the geographic distribution of organisms and the corresponding evolution of their traits in space and time.

Edward O. Wilson in 1967[148] is considered one of the fundamentals of ecological theory.[149]

Biogeography has a long history in the natural sciences concerning the spatial distribution of plants and animals. Ecology and evolution provide the explanatory context for biogeographical studies.

global warming.[151][152]

r/K selection theory

Main article: r/K selection theory

A population ecology concept is 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.[153]

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.[33] Different species evolve different life-history strategies spanning a continuum between these two selective forces. An r-selected species is one that has high birth rates, low levels of parental investment, and high rates of mortality before individuals reach maturity. Evolution favours high rates of fecundity in r-selected species. Many kinds of insects and invasive species exhibit r-selected characteristics. In contrast, a K-selected species has low rates of fecundity, high levels of parental investment in the young, and low rates of mortality as individuals mature. Humans and elephants are examples of species exhibiting K-selected characteristics, including longevity and efficiency in the conversion of more resources into fewer offspring.[148][154]

Molecular ecology

Main article: Molecular ecology

The important 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

monogamous.[157] In a biogeographical context, the marriage between genetics, ecology, and evolution resulted in a new sub-discipline called phylogeography.[158]

Human ecology

Main article: Human ecology

The history of life on Earth has been a history of interaction between living things and their surroundings. To a large extent, the physical form and the habits of the earth's vegetation and its animal life have been molded by the environment. Considering the whole span of earthly time, the opposite effect, in which life actually modifies its surroundings, has been relatively slight. 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"[159]

Ecology is as much a biological science as it is 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."[160]: 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.[160][161]

The ecological complexities human beings are facing through the technological transformation of the planetary biome has brought on the

ecosystem goods and services. Ecosystems produce, regulate, maintain, and supply services of critical necessity and beneficial to human health (cognitive and physiological), economies, and they even provide an information or reference function as a living library giving opportunities for science and cognitive development in children engaged in the complexity of the natural world. Ecosystems relate importantly to human ecology as they are the ultimate base foundation of global economics as every commodity, and the capacity for exchange ultimately stems from the ecosystems on Earth.[107][162][163][164]

Main article:
Restoration ecology
See also: Natural resource management

Ecosystem management is not just about science nor is it simply an extension of traditional resource management; it offers a fundamental reframing of how humans may work with nature.

Grumbine (1994)[165]: 27 

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".[166] Ecological science has boomed in the industrial investment of restoring ecosystems and their processes in abandoned sites after disturbance. Natural resource managers, in forestry, for example, employ ecologists to develop, adapt, and implement ecosystem based methods into the planning, operation, and restoration phases of land-use. Another example of conservation is seen on the east coast of the United States in Boston, MA. The city of Boston implemented the Wetland Ordinance,[167] improving the stability of their wetland environments by implementing soil amendments that will improve groundwater storage and flow, and trimming or removal of vegetation that could cause harm to water quality.[citation needed] Ecological science is used in the methods of sustainable harvesting, disease, and fire outbreak management, in fisheries stock management, for integrating land-use with protected areas and communities, and conservation in complex geo-political landscapes.[22][165][168][169]

Relation to the environment

Main article: Natural 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.[172]

The distinction between external and internal environments, however, is an abstraction parsing life and environment into units or facts that are inseparable in reality. There is an interpenetration of cause and effect between the environment and life. The laws of

dialectical approach to ecology. The dialectical approach examines the parts but integrates the organism and the environment into a dynamic whole (or umwelt). Change in one ecological or environmental factor can concurrently affect the dynamic state of an entire ecosystem.[36][173]

Disturbance and resilience

Main article:
Resilience (ecology)

Ecosystems are regularly confronted with natural environmental variations and disturbances over time and geographic space. A disturbance is any process that removes biomass from a community, such as a fire, flood, drought, or predation.[174] Disturbances occur over vastly different ranges in terms of magnitudes as well as distances and time periods,[175] and are both the cause and product of natural fluctuations in death rates, species assemblages, and biomass densities within an ecological community. These disturbances create places of renewal where new directions emerge from the patchwork of natural experimentation and opportunity.[174][176][177] Ecological resilience is a cornerstone theory in ecosystem management. Biodiversity fuels the resilience of ecosystems acting as a kind of regenerative insurance.[177]

Metabolism and the early atmosphere

Main article:
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.[178]: 991 

The Earth was formed approximately 4.5 billion years ago.[179] 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.[180]

The leaf is the primary site of photosynthesis in most 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 to 1 billion years prior.[181][182]

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

homeotherms regulate their internal body temperature by expending metabolic energy.[112][113][173]

There is a relationship between light, primary production, and ecological

autotrophs. Autotrophs—responsible for primary production—assimilate light energy which becomes metabolically stored as potential energy in the form of biochemical enthalpic bonds.[112][113][173]

Physical environments

Water

Main article: Aquatic ecosystem

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)[183]: 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

facultative anaerobes and use oxygen during respiration when the soil becomes drier. The activity of soil microorganisms and the chemistry of the water reduces the oxidation-reduction potentials of the water. Carbon dioxide, for example, is reduced to methane (CH4) by methanogenic bacteria.[183] The physiology of fish is also specially 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.[184]

Gravity

The shape and energy of the land are significantly affected by gravitational forces. On a large scale, the distribution of gravitational forces on the earth is uneven and influences the shape and movement of

geomorphic processes such as orogeny and erosion. These forces govern many of the geophysical properties and distributions of ecological 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.[112] 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.[185] 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).[186]

Pressure

Climatic and

seals are specially adapted to deal with changes in sound due to water pressure differences.[192] Differences between hagfish species provide another example of adaptation to deep-sea pressure through specialized protein adaptations.[193]

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).[194][195]

Columbia Basin in western North America) to intermix with sister lineages that are segregated to the interior mountain systems.[199][200]

Fire

Main article: Fire ecology
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.[201] 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.[202] While the issue of fire in relation to ecology and plants has been recognized for a long time,[203] Charles Cooper brought attention to the issue of forest fires in relation to the ecology of forest fire suppression and management in the 1960s.[204][205]

resilience of ecosystems.[176]

Soils

Main article: Soil ecology

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

colonization of land in the Devonian period played a significant role in the early development of ecological trophism in soils.[212][215][216]

Biogeochemistry and climate

Main article: Biogeochemistry
See also: Nutrient cycle and Climate

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

recycled through the environment.[112][113][173] 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 upon billions of ecological processes amplify and ultimately regulate the biogeochemical cycles of the Earth. Understanding the relations and cycles mediated between these elements and their ecological pathways has significant bearing toward understanding global biogeochemistry.[217]

The ecology of global carbon budgets gives one example of the linkage between biodiversity and biogeochemistry. It is estimated that the Earth's oceans hold 40,000 gigatonnes (Gt) of carbon, that vegetation and soil hold 2070 Gt, and that fossil fuel emissions are 6.3 Gt carbon per year.

ppm.[219]

In the Oligocene, from twenty-five to thirty-two million years ago, there was another significant restructuring of the global carbon cycle as grasses evolved a new mechanism of photosynthesis, C4 photosynthesis, and expanded their ranges. This new pathway evolved in response to the drop in atmospheric CO2 concentrations below 550 ppm.[220] The relative abundance and distribution of biodiversity alters the dynamics between organisms and their environment such that ecosystems can be both cause and effect in relation to climate change. Human-driven modifications to the planet's ecosystems (e.g., disturbance, biodiversity loss, agriculture) contributes to rising atmospheric greenhouse gas levels. Transformation of the global carbon cycle in the next century is projected to raise planetary temperatures, lead to more extreme fluctuations in weather, alter species distributions, and increase extinction rates. The effect of global warming is already being registered in melting glaciers, melting mountain ice caps, and rising sea levels. Consequently, species distributions are changing along waterfronts and in continental areas where migration patterns and breeding grounds are tracking the prevailing shifts in climate. Large sections of permafrost are also melting to create a new mosaic of flooded areas having increased rates of soil decomposition activity that raises methane (CH4) emissions. There is concern over increases in atmospheric methane in the context of the global carbon cycle, because methane is a greenhouse gas that is 23 times more effective at absorbing long-wave radiation than CO2 on a 100-year time scale.[221] Hence, there is a relationship between global warming, decomposition and respiration in soils and wetlands producing significant climate feedbacks and globally altered biogeochemical cycles.[107][222][223][224][225][226]

History

Main article: History of ecology

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)[227]: 140  [B]

Ecology has a complex origin, due in large part to its interdisciplinary nature.[228] Ancient Greek philosophers such as Hippocrates and Aristotle were among the first to record observations on natural history. However, they viewed life in terms of essentialism, where species were conceptualized as static unchanging things while varieties were seen as aberrations of an idealized type. This contrasts against the modern understanding of ecological theory where varieties are viewed as the real phenomena of interest and having a role in the origins of adaptations by means of natural selection.[5][229][230] Early conceptions of ecology, such as a balance and regulation in nature can be traced to Herodotus (died c. 425 BC), who described one of the earliest accounts of mutualism in his observation of "natural dentistry". Basking Nile crocodiles, he noted, would open their mouths to give sandpipers safe access to pluck leeches out, giving nutrition to the sandpiper and oral hygiene for the crocodile.[228] Aristotle was an early influence on the philosophical development of ecology. He and his student Theophrastus made extensive observations on plant and animal migrations, biogeography, physiology, and their behavior, giving an early analogue to the modern concept of an ecological niche.[231][232]

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)[233]

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

Ecological concepts such as food chains, population regulation, and productivity were first developed in the 1700s, through the published works of microscopist Antonie van Leeuwenhoek (1632–1723) and botanist Richard Bradley (1688?–1732).[5] Biogeographer Alexander von Humboldt (1769–1859) was an early pioneer in ecological thinking and was among the first to recognize ecological gradients, where species are replaced or altered in form along environmental gradients, such as a cline forming along a rise in elevation. Humboldt drew inspiration from Isaac Newton, as he developed a form of "terrestrial physics". In Newtonian fashion, he brought a scientific exactitude for measurement into natural history and even alluded to concepts that are the foundation of a modern ecological law on species-to-area relationships.[234][235][236] Natural historians, such as Humboldt, James Hutton, and Jean-Baptiste Lamarck (among others) laid the foundations of the modern ecological sciences.[237] The term "ecology" (German: Oekologie, Ökologie) was coined by Ernst Haeckel in his book Generelle Morphologie der Organismen (1866).[238] Haeckel was a zoologist, artist, writer, and later in life a professor of comparative anatomy.[227][239]

Opinions differ on who was the founder of modern ecological theory. Some mark Haeckel's definition as the beginning;

The Origin of Species.[227] Linnaeus was the first to frame the balance of nature as a testable hypothesis. Haeckel, who admired Darwin's work, defined ecology in reference to the economy of nature, which has led some to question whether ecology and the economy of nature are synonymous.[243]

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.[244][245]

From Aristotle until Darwin, the natural world was predominantly considered static and unchanging. Prior to The Origin of Species, there was little appreciation or understanding of the dynamic and reciprocal relations between organisms, their adaptations, and the environment.[229] An exception is the 1789 publication Natural History of Selborne by Gilbert White (1720–1793), considered by some to be one of the earliest texts on ecology.[246] While Charles Darwin is mainly noted for his treatise on evolution,[247] he was one of the founders of soil ecology,[248] and he made note of the first ecological experiment in The Origin of Species.[244] Evolutionary theory changed the way that researchers approached the ecological sciences.[249]

Since 1900

Modern ecology is a young science that first attracted substantial scientific attention toward the end of the 19th century (around the same time that evolutionary studies were gaining scientific interest). The scientist

oekology" (which eventually morphed into home economics) in the U.S. as early as 1892.[250]

In the early 20th century, ecology transitioned from a more

Henry Gleason,[253] who stated that ecological communities develop from the unique and coincidental association of individual organisms. This perceptual shift placed the focus back onto the life histories of individual organisms and how this relates to the development of community associations.[254]

The Clementsian superorganism theory was an overextended application of an idealistic form of holism.[36][109] The term "holism" was coined in 1926 by Jan Christiaan Smuts, a South African general and polarizing historical figure who was inspired by Clements' superorganism concept.[255][C] Around the same time, Charles Elton pioneered the concept of food chains in his classical book Animal Ecology.[84] Elton[84] defined ecological relations using concepts of food chains, food cycles, and food size, and described numerical relations among different functional groups and their relative abundance. Elton's 'food cycle' was replaced by 'food web' in a subsequent ecological text.[256] Alfred J. Lotka brought in many theoretical concepts applying thermodynamic principles to ecology.

In 1942,

Robert MacArthur advanced mathematical theory, predictions, and tests in ecology in the 1950s, which inspired a resurgent school of theoretical mathematical ecologists.[237][257][258] Ecology also has developed through contributions from other nations, including Russia's Vladimir Vernadsky and his founding of the biosphere concept in the 1920s[259] and Japan's Kinji Imanishi and his concepts of harmony in nature and habitat segregation in the 1950s.[260] Scientific recognition of contributions to ecology from non-English-speaking cultures is hampered by language and translation barriers.[259]

This whole chain of poisoning, then, seems to rest on a base of minute plants which must have been the original concentrators. But what of the opposite end of the food chain—the human being who, in probable ignorance of all this sequence of events, has rigged his fishing tackle, caught a string of fish from the waters of Clear Lake, and taken them home to fry for his supper?

Rachel Carson (1962)[261]: 48 

Ecology surged in popular and scientific interest during the 1960–1970s environmental movement. There are strong historical and scientific ties between ecology, environmental management, and protection.[237] The historical emphasis and poetic naturalistic writings advocating the protection of wild places by notable ecologists in the history of conservation biology, such as Aldo Leopold and Arthur Tansley, have been seen as far removed from urban centres where, it is claimed, the concentration of pollution and environmental degradation is located.[237][262] Palamar (2008)[262] notes an overshadowing by mainstream environmentalism of pioneering women in the early 1900s who fought for urban health ecology (then called euthenics)[250] and brought about changes in environmental legislation. Women such as Ellen Swallow Richards and Julia Lathrop, among others, were precursors to the more popularized environmental movements after the 1950s.

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, bioaccumulating in the environment. Carson used ecological science to link the release of environmental toxins to human and ecosystem health. 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.[22][237][262][263]

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

    1. ^ S. E. Kingsland, "Foundational Papers: Defining Ecology as a Science", in L. A. Real and J. H. Brown, eds., Foundations of Ecology: Classic Papers with Commentaries. Chicago: U of Chicago Press, 1991. pp. 1–2.
    2. ISSN 0012-9658
      .
    3. PMID 16535678
      .
    4. PMID 23029061
      .
    5. ^
      ISBN 978-0-534-42066-6. Archived
      from the original on 28 July 2020. Retrieved 6 January 2020.
    6. ISBN 978-0-12-554720-8
      .
    7. ^
      ISBN 0-691-08436-X
      .
    8. S2CID 23760946
      .
    9. ^
      S2CID 7432683
      .
    10. ISBN 978-0-7382-0319-5. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    11. ISBN 978-1-55963-248-5. Archived
      from the original on 1 August 2020. Retrieved 27 June 2015.
    12. JSTOR 2385928
      .
    13. ^
      S2CID 206514712. Archived from the original
      (PDF) on 10 July 2011.
    14. ^
      S2CID 4333166. Archived
      (PDF) from the original on 21 September 2017. Retrieved 10 August 2019.
    15. PMID 11041790
      .
    16. S2CID 4333920. Archived from the original
      (PDF) on 28 April 2014.
    17. PMID 19220353
      .
    18. doi:10.1890/070176. Archived from the original
      (PDF) on 29 December 2010. Retrieved 1 February 2010.
    19. S2CID 32115412. Archived from the original
      (PDF) on 20 July 2011. Retrieved 16 March 2010.
    20. hdl:1808/13308. Archived from the original
      (PDF) on 11 June 2010.
    21. PMID 18666834
      .
    22. ^
      ISBN 978-0-9734779-0-0. Archived from the original
      on 5 December 2009. Retrieved 31 January 2010.
    23. S2CID 206523585. Archived
      (PDF) from the original on 12 January 2011. Retrieved 12 April 2020.
    24. ^
      S2CID 84504783. Archived from the original
      (PDF) on 5 September 2012.
    25. PMID 20566501
      .
    26. JSTOR 1942423
      .
    27. PMID 9108063
      .
    28. ^
      PMID 10468593
      .
    29. ^
      PMID 18951653. Archived from the original
      (PDF) on 6 June 2011. Retrieved 28 January 2010.
    30. ^
      doi:10.1146/annurev.ecolsys.36.102803.095431. Archived from the original
      (PDF) on 24 October 2012.
    31. ISBN 0-471-42572-9
      .
    32. ^
      doi:10.1101/SQB.1957.022.01.039
      .
    33. ^
      ISBN 1-4051-1117-8. Archived from the original
      on 30 October 2013. Retrieved 14 December 2010.
    34. S2CID 84328940
      .
    35. PMID 18289716
      .
    36. ^
      S2CID 46984334. Archived from the original
      (PDF) on 10 May 2013.
    37. S2CID 18542809
      .
    38. PMID 16585519
      .
    39. S2CID 44870405
      .
    40. JSTOR 3545850
      .
    41. ISSN 0006-3568
      .
    42. JSTOR 3236162. Archived from the original
      (PDF) on 5 September 2012.
    43. JSTOR 2845499. Archived
      (PDF) from the original on 20 December 2022. Retrieved 11 December 2022.
    44. PMID 17943116
      .
    45. S2CID 205216984. Archived from the original
      (PDF) on 18 July 2011. Retrieved 14 January 2010.
    46. S2CID 10709679. Archived from the original
      (PDF) on 3 March 2016.
    47. S2CID 129803613
      .
    48. ^
      S2CID 30308855
      .
    49. S2CID 9715923. Archived
      from the original on 25 October 2019. Retrieved 10 August 2019.
    50. ^
      S2CID 27090414
      .
    51. ^
      ISBN 0-691-11440-4
      .
    52. S2CID 84321947
      .
    53. JSTOR 3803199. Archived from the original
      (PDF) on 2 June 2013. Retrieved 4 August 2012.
    54. PMID 16701236. Archived
      (PDF) from the original on 14 October 2012.
    55. doi:10.1093/besa/15.3.237. Archived
      from the original on 8 April 2022. Retrieved 19 November 2020.
    56. ISBN 978-0-8218-1152-8. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    57. doi:10.1111/j.0906-7590.2005.04042.x
      .
    58. S2CID 4405264. Archived from the original
      (PDF) on 31 December 2010.
    59. ^ Nebel, S. (2010). "Animal migration". Nature Education Knowledge. 10 (1): 29. Archived from the original on 16 July 2011.
    60. JSTOR 1313224. Archived
      (PDF) from the original on 6 July 2011.
    61. ISBN 0-19-509723-8. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    62. ISBN 0-12-323448-4. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    63. ISBN 978-0-12-088766-8. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    64. PMID 17296244
      .
    65. ^
      JSTOR 1930070. Archived from the original
      (PDF) on 26 July 2011.
    66. doi:10.1146/annurev.es.12.110181.001011
      .
    67. ^ Marsh, G. P. (1864). Man and Nature: Physical Geography as Modified by Human Action. Cambridge, MA: Belknap Press. p. 560.
    68. ISSN 0012-9658. Archived from the original
      (PDF) on 19 May 2011. Retrieved 20 June 2011.
    69. S2CID 29793247
      .
    70. ISBN 978-0-226-66832-1. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    71. ^
      S2CID 4267587. Archived from the original
      (PDF) on 10 June 2010.
    72. doi:10.1016/j.tree.2003.09.003
      .
    73. S2CID 4428058
      .
    74. ISSN 0012-9658. Archived from the original
      (PDF) on 19 May 2011. Retrieved 27 November 2010.
    75. PMID 15101699. Archived
      (PDF) from the original on 6 June 2011.
    76. S2CID 1752696. Archived from the original
      (PDF) on 13 August 2011. Retrieved 4 June 2011.
    77. ISSN 0012-9623
      .
    78. PMID 16519227
      .
    79. S2CID 144922522
      .
    80. ISSN 0036-8075
      .
    81. ISSN 0036-8075
      .
    82. S2CID 55279332. Archived from the original
      (PDF) on 20 July 2011.
    83. PMID 17498151. Archived
      from the original on 5 March 2020. Retrieved 7 December 2019.
    84. ^
      ISBN 0-226-20639-4
      .
    85. hdl:10535/2966. Archived
      (PDF) from the original on 30 July 2020. Retrieved 24 September 2019.
    86. PMID 21232425
      .
    87. S2CID 85120393
      .
    88. S2CID 85371147. Archived
      (PDF) from the original on 1 November 2018. Retrieved 10 August 2019.
    89. doi:10.1016/S0169-2046(00)00078-5
      .
    90. S2CID 85155900. Archived from the original
      (PDF) on 20 July 2011.
    91. PMID 17503589. Archived from the original
      (PDF) on 15 August 2011.
    92. ISSN 1540-9295. Archived from the original
      (PDF) on 6 July 2011. Retrieved 2 February 2010.
    93. doi:10.1016/j.ecolmodel.2005.11.029. Archived from the original
      (PDF) on 19 May 2012.
    94. S2CID 83780992
      .
    95. ^
      S2CID 85204808
      .
    96. doi:10.1111/j.1748-7692.1995.tb00294.x
      .
    97. PMID 11050351. Archived from the original
      (PDF) on 7 December 2010. Retrieved 28 September 2009.
    98. PMID 17814095. Archived from the original
      (PDF) on 15 May 2011.
    99. ISSN 0006-3568. Archived
      (PDF) from the original on 3 March 2016.
    100. S2CID 40349801
      .
    101. doi:10.1016/j.ecocom.2003.09.001
      .
    102. ^
      S2CID 36862823
      .
    103. S2CID 8001853. Archived from the original
      (PDF) on 20 July 2011. Retrieved 4 June 2011.
    104. ^ "Welcome to ILTER". International Long Term Ecological Research. Archived from the original on 5 March 2010. Retrieved 16 March 2010.
    105. doi:10.1111/j.1365-2745.2006.01145.x
      .
    106. ^ "Hubbard Brook Ecosystem Study Front Page". Archived from the original on 24 March 2010. Retrieved 16 March 2010.
    107. ^
      S2CID 18167083. Archived from the original
      (PDF) on 9 August 2011.
    108. ^ Mikkelson, G. M. (2010). "Part-whole relationships and the unity of ecology" (PDF). In Skipper, R. A.; Allen, C.; Ankeny, R.; Craver, C. F.; Darden, L.; Richardson, R.C. (eds.). Philosophy Across the Life Sciences. Cambridge, MA: MIT Press. Archived (PDF) from the original on 11 September 2010.
    109. ^
      JSTOR 3566073
      .
    110. doi:10.1146/annurev.es.24.110193.003103
      .
    111. ^ Craze, P., ed. (2 August 2012). "Trends in Ecology and Evolution". Cell Press, Elsevier, Inc. Archived from the original on 24 July 2009. Retrieved 9 December 2009.
    112. ^
      ISBN 0-7216-1120-6
      .
    113. ^
      ISBN 0-7167-3847-3
      .
    114. S2CID 4425455
      .
    115. PMID 18232740
      .
    116. PMID 18400016
      .
    117. doi:10.1111/j.1439-0310.1963.tb01161.x. Archived
      (PDF) from the original on 9 June 2011.
    118. ^ Hamner, W. M. (1985). "The importance of ethology for investigations of marine zooplankton". Bulletin of Marine Science. 37 (2): 414–424. Archived from the original on 7 June 2011.
    119. ^
      S2CID 4307980
      .
    120. S2CID 30261494
      .
    121. JSTOR 1439987
      .
    122. ^ "Behavioral Ecology". International Society for Behavioral Ecology. Archived from the original on 10 April 2011. Retrieved 15 April 2011.
    123. S2CID 86436132
      .
    124. ^
      ISBN 978-0-674-00089-6. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    125. doi:10.1111/j.1440-6055.2003.00371.x. Archived from the original
      (PDF) on 17 September 2011.
    126. doi:10.1111/j.1461-0248.2004.00698.x
      .
    127. ISBN 978-0-632-03546-5. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    128. S2CID 52043639
      .
    129. doi:10.1093/beheco/arp151
      .
    130. S2CID 28245687. Archived from the original
      (PDF) on 29 June 2011.
    131. ^
      PMID 12795209
      .
    132. ISBN 978-0-226-16932-3. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    133. ISBN 978-0-226-16937-8. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015. Cognitive ecology focuses on the ecology and evolution of "cognition" defined as the neuronal processes concerned with the acquisition, retention, and use of information....we ought to rely on ecological and evolutionary knowledge for studying cognition.
    134. ISBN 978-0-262-26123-4. Archived
      from the original on 1 August 2020. Retrieved 27 June 2015.
    135. PMID 21237927. Archived from the original
      (PDF) on 19 July 2011.
    136. S2CID 37774648
      .
    137. JSTOR 2992256
      .
    138. PMID 10234251. Archived from the original
      (PDF) on 20 September 2009.
    139. ISBN 0-387-19550-5. Archived
      from the original on 1 August 2020. Retrieved 6 January 2020.
    140. PMID 16922314. Archived from the original
      (PDF) on 16 October 2009. Retrieved 31 December 2009.
    141. S2CID 98479424
      .
    142. doi:10.1046/j.1461-0248.2001.00218.x
      .
    143. doi:10.1146/annurev.ecolsys.110308.120330
      .
    144. S2CID 33027458
      .
    145. S2CID 12027050
      .
    146. ^
      ISBN 978-0-520-25945-4. Archived
      from the original on 11 September 2015. Retrieved 27 June 2015.
    147. doi:10.1111/(ISSN)1365-2699. Archived
      from the original on 9 February 2013. Retrieved 16 March 2018.
    148. ^ a b MacArthur, R.; Wilson, E. O. (1967). The Theory of Island Biogeography. Princeton, NJ: Princeton University Press.
    149. ^
      PMID 16701326. Archived
      (PDF) from the original on 1 June 2010.
    150. S2CID 55258511
      .
    151. S2CID 27131917
      .
    152. S2CID 82859453
      .
    153. ISSN 0012-9658. Archived from the original
      (PDF) on 30 December 2010. Retrieved 27 January 2010.
    154. S2CID 83947445
      .
    155. doi:10.1111/(ISSN)1365-294X
      .
    156. ^
      ISBN 0-412-03771-8. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    157. S2CID 2040456. Archived
      (PDF) from the original on 18 July 2011.
    158. ISBN 0-674-66638-0. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    159. ^ Rachel Carson (1962). ""Silent Spring" (excerpt)". Houghton Miffin. Archived from the original on 14 October 2012. Retrieved 4 October 2012.
    160. ^
      ISBN 978-0-12-013908-8
      .
    161. S2CID 233365777
      .
    162. ^ "Millennium Ecosystem Assessment – Synthesis Report". United Nations. 2005. Archived from the original on 4 February 2010. Retrieved 4 February 2010.
    163. doi:10.1016/S0921-8009(02)00089-7. Archived
      (PDF) from the original on 9 June 2011.
    164. S2CID 27553272
      .
    165. ^
      doi:10.1046/j.1523-1739.1994.08010027.x. Archived from the original
      (PDF) on 2 May 2013.
    166. ISBN 978-0-674-05817-0
      .
    167. ^ "Boston Wetlands Ordinance". City of Boston. 17 July 2016. Archived from the original on 5 December 2022. Retrieved 5 December 2022.
    168. JSTOR 1312148
      .
    169. S2CID 908668. Archived
      (PDF) from the original on 12 May 2013.
    170. JSTOR 1931693
      .
    171. doi:10.1037/h0091199
      .
    172. ISBN 0-13-250882-6. Archived
      from the original on 2 November 2014.
    173. ^
      ISBN 0-13-478116-3
      .
    174. ^ a b Hughes, A. R. "Disturbance and diversity: an ecological chicken and egg problem". Nature Education Knowledge. 1 (8): 26. Archived from the original on 5 December 2010.
    175. JSTOR 1941447
      .
    176. ^
      S2CID 53309505. Archived
      (PDF) from the original on 17 March 2020. Retrieved 10 August 2019.
    177. ^
      JSTOR 2096802. Archived from the original
      (PDF) on 18 October 2012.
    178. doi:10.1046/j.1461-0248.2003.00526.x. Archived from the original
      (PDF) on 8 June 2011. Retrieved 6 September 2009.
    179. doi:10.1016/0016-7037(95)00054-4
      .
    180. ISBN 978-0-7382-0493-2
      .
    181. ^
      S2CID 4425486. Archived from the original
      (PDF) on 20 August 2011.
    182. doi:10.1016/j.epsl.2005.06.013. Archived from the original
      (PDF) on 10 October 2008. Retrieved 6 September 2009.
    183. ^
      ISBN 1-56670-372-7. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    184. doi:10.1002/(SICI)1097-010X(19990601)283:7<641::AID-JEZ3>3.0.CO;2-W. Archived from the original
      (PDF) on 26 June 2010. Retrieved 9 December 2009.
    185. S2CID 429191
      .
    186. S2CID 16332609. Archived from the original
      (PDF) on 16 July 2011.
    187. ^ Neri Salvadori; Pasquale Commendatore; Massimo Tamberi (14 May 2014). Geography, structural Change and Economic Development: Theory and Empirics. Edward Elgar Publishing.
    188. S2CID 484645
      .
    189. S2CID 4404849
      .
    190. S2CID 31357329
      .
    191. PMID 12060254
      .
    192. S2CID 19008897
      .
    193. PMID 20411117
      .
    194. S2CID 20160390. Archived from the original
      (PDF) on 6 July 2011.
    195. PMID 19552694
      .
    196. doi:10.4319/lo.1995.40.5.0845
      .
    197. doi:10.4319/lo.2001.46.5.1158
      .
    198. JSTOR 2265716
      .
    199. JSTOR 3038197
      .
    200. PMID 15904859. Archived from the original
      (PDF) on 14 August 2010.
    201. doi:10.1029/1999GB900076
      .
    202. ISBN 978-0-471-93604-6. Archived from the original
      (PDF) on 6 January 2009. Retrieved 11 December 2009.
    203. S2CID 31619796
      .
    204. JSTOR 1948549
      .
    205. doi:10.1038/scientificamerican0461-150
      .
    206. S2CID 85841606
      .
    207. JSTOR 1308941
      .
    208. S2CID 32500454
      .
    209. S2CID 24962708
      .
    210. S2CID 42979006
      .
    211. ISBN 0-12-179726-0. Archived
      from the original on 18 March 2015. Retrieved 27 June 2015.
    212. ^
      doi:10.1016/j.earscirev.2009.09.005. Archived
      from the original on 13 April 2020. Retrieved 3 August 2012.
    213. doi:10.1016/j.geoderma.2008.11.028
      .
    214. S2CID 14924423. Archived from the original
      (PDF) on 17 March 2015. Retrieved 2 January 2015.
    215. doi:10.1146/annurev.ecolsys.35.112202.130116. Archived
      (PDF) from the original on 24 August 2009.
    216. doi:10.1016/S0031-0182(02)00689-2
      .
    217. S2CID 2844984. Archived from the original
      (PDF) on 13 April 2020. Retrieved 24 October 2017.
    218. doi:10.1111/j.0022-0477.2004.00874.x
      .
    219. S2CID 205008176. Archived from the original
      (PDF) on 21 August 2011.
    220. S2CID 20277445
      .
    221. PMID 17479846. Archived from the original
      (PDF) on 30 June 2007.
    222. S2CID 2689847. Archived from the original
      (PDF) on 17 September 2012.
    223. S2CID 6913670
      .
    224. S2CID 7311971
      . Retrieved 12 June 2017.
    225. S2CID 243073. Archived
      (PDF) from the original on 8 June 2011.
    226. PMID 16525463
      .
    227. ^
      S2CID 84079279
      .
    228. ^ a b Egerton, F. N. (2001). "A history of the ecological sciences: early Greek origins" (PDF). Bulletin of the Ecological Society of America. 82 (1): 93–97. Archived from the original (PDF) on 17 August 2012. Retrieved 29 September 2010.
    229. ^
      PMID 10969480
      .
    230. S2CID 170129617
      .
    231. S2CID 155638387
      .
    232. doi:10.1080/00201747508601756
      .
    233. ^ Forbes, S. (1887). "The lake as a microcosm" (PDF). Bulletin of the Scientific Association. Peoria, IL: 77–87. Archived from the original (PDF) on 27 September 2011. Retrieved 22 December 2009.
    234. ^
      ISSN 1540-9295. Archived from the original
      (PDF) on 10 August 2011.
    235. S2CID 37891678
      .
    236. PMID 11725309
      .
    237. ^
      ISBN 0-521-27087-1
      .
    238. ^ Haeckel, Ernst (1866). Generelle Morphologie der Organismen [The General Morphology of Organisms] (in German). Vol. 2. Berlin, (Germany): Georg Reimer. p. 286. Archived from the original on 18 June 2019. Retrieved 27 February 2019. From p. 286: "Unter Oecologie verstehen wir die gesammte Wissenschaft von den Beziehungen des Organismus zur umgebenden Aussenwelt, wohin wir im weiteren Sinne alle "Existenz-Bedingungen" rechnen können." (By "ecology" we understand the comprehensive science of the relationships of the organism to its surrounding environment, where we can include, in the broader sense, all "conditions of existence".)
    239. JSTOR 1929981
      .
    240. S2CID 143709995
      .
    241. JSTOR 3543715
      .
    242. ^
      ISSN 0012-9623
      .
    243. ^
      JSTOR 1938247
      .
    244. ^
      S2CID 82975886
      .
    245. ^ Sinclair, G. (1826). "On cultivating a collection of grasses in pleasure-grounds or flower-gardens, and on the utility of studying the Gramineae". London Gardener's Magazine. Vol. 1. New-Street-Square: A. & R. Spottiswoode. p. 115. Archived from the original on 7 April 2022. Retrieved 19 November 2020.
    246. PMID 10670015
      .
    247. ISBN 0-8014-1319-2. Archived
      from the original on 13 July 2007.
    248. PMID 16901581
      .
    249. S2CID 83288244
      .
    250. ^ a b Hunt, Caroline Louisa (1912). The life of Ellen H. Richards. Boston: Whitcomb & Barrows.
    251. S2CID 238358762
      .
    252. ISBN 0-405-10381-6. Archived
      from the original on 1 August 2020. Retrieved 6 January 2020.
    253. S2CID 46962930
      .
    254. JSTOR 2479933. Archived from the original
      (PDF) on 22 July 2011.
    255. S2CID 145482219. Archived from the original
      (PDF) on 9 May 2013.
    256. ^ Allee, W. C. (1932). Animal Life and Social Growth. Baltimore: The Williams & Wilkins Company and Associates.
    257. S2CID 30340899. Archived
      (PDF) from the original on 5 October 2012.
    258. JSTOR 3881528
      .
    259. ^
      S2CID 85258634
      .
    260. S2CID 45293729
      .
    261. ISBN 0-618-24906-0
      .
    262. ^ a b c Palamar, C. R. (2008). "The justice of ecological restoration: Environmental history, health, ecology, and justice in the United States" (PDF). Human Ecology Review. 15 (1): 82–94. Archived from the original (PDF) on 26 July 2011. Retrieved 8 August 2012.
    263. S2CID 9929695. Archived from the original
      (PDF) on 31 March 2013.

    External links
    Retrieved from "https://en.wikipedia.org/w/index.php?title=Ecology&oldid=1219142532"