Ecology（2）

Behavioral ecology

All organisms are motile to some extent. Even plants express complex behavior, including memory and communication. Behavioral ecology is the study of ethology and its ecological and evolutionary implications. Ethology is the study of observable movement or behavior in nature(Sony VGN-FZ11L battery). This could include investigations of motile sperm of plants, mobile phytoplankton, zooplankton swimming toward the female egg, the cultivation of fungi by weevils, the mating dance of a salamander, or social gatherings of amoeba.

Adaptation is the central unifying concept in behavioral ecology(Sony VGN-FZ15G battery)."International Society for Behavioral Ecology". Behaviors can be recorded as traits and inherited in much the same way that eye and hair color can. Behaviors evolve and become adapted to the ecosystem because they are subject to the forces of natural selection(Sony VGP-BPS9/B battery). Hence, behaviors can be adaptive, meaning that they evolve functional utilities that increases reproductive success for the individuals that inherit such traits.[121] This is also the technical definition for fitness in biology, which is a measure of reproductive success over successive generations(Sony VGN-FZ190 battery).

Predator-prey interactions are an introductory concept into food-web studies as well as behavioral ecology. Prey species can exhibit different kinds of behavioral adaptations to predators, such as avoid, flee or defend(Sony VGN-FZ190E battery). Many prey species are faced with multiple predators that differ in the degree of danger posed. To be adapted to their environment and face predatory threats, organisms must balance their energy budgets as they invest in different aspects of their life history, such as growth, feeding, mating, socializing, or modifying their habitat(Sony VGN-FZ18 battery). Hypotheses posited in behavioral ecology are generally based on adaptive principals of conservation, optimization or efficiency. For example,

"The threat-sensitive predator avoidance hypothesis predicts that prey should assess the degree of threat posed by different predators and match their behavior according to current levels of risk(Sony Vaio VGN-FZ21E battery )."

"The optimal 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(Sony Vaio VGN-FZ21S battery)."

Elaborate sexual displays and posturing are encountered in the behavioral ecology of animals. The birds of paradise, for example, display elaborate ornaments and song during courtship. These displays serve a dual purpose of signaling healthy or well-adapted individuals and desirable genes(Sony VGN-FZ230E battery). The elaborate displays are driven by sexual selection as an advertisement of quality of traits among male suitors.

Social ecology

Social ecological behaviors are notable in the social insects, slime moulds, social spiders, human society, and naked mole rats where eusocialismhas evolved. Social behaviors include reciprocally beneficial behaviors among kin and nest mates(Sony Vaio VGN-FZ210CE battery). Social behaviors evolve from kin and group selection. Kin selection explains altruism through genetic relationships, whereby an altruistic behavior leading to death is rewarded by the survival of genetic copies distributed among surviving relatives(Sony Vaio VGN-FZ18S battery). 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(Sony VGN-FW11 battery). 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 behaviors to one another. Groups that are predominantly altruists beat groups that are predominantly selfish(Sony VGN-FW11M battery).

Coevolution

Ecological interactions can be divided into host and associate relationships. A host is any entity that harbors another that is called the associate. Host and associate relationships among species that are mutually or reciprocally beneficial are called mutualisms(Sony VGN-FZ18L battery). If the host and associate are physically connected, the relationship is called symbiosis. Approximately 60% of all plants, for example, have a symbiotic relationship with arbuscular mycorrhizal fungi(Sony Vaio VGN-FZ31B battery). Symbiotic plants and fungi exchange carbohydrates for mineral nutrients. Symbiosis differs from indirect mutualisms where the organisms live apart. For example, tropical rainforests regulate the Earth's atmosphere(Sony VGN-FZ145E battery). 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 commensalism because many other host species receive the benefits of clean air at no cost or harm to the associate tree species supplying the oxygen(Sony Vaio VGN-FZ31J battery). The host and associate relationship is called parasitism if one species benefits while the other suffers. Competition among species or among members of the same species is defined as reciprocal antagonism, such as grasses competing for growth space.

Popular ecological study systems for mutualism include(Sony VGN-FZ72B battery), fungus-growing ants employing agricultural symbiosis, bacteria living in the guts of insects and other organisms, the fig wasp and yucca moth pollination complex, lichens with fungi and photosynthetic algae, andcorals with photosynthetic algae(Sony VGN-FZ71B battery). Nevertheless, many organisms exploit host rewards without reciprocating and thus have been branded with a myriad of not-very-flattering names such as 'cheaters', 'exploiters', 'robbers', and 'thieves'. Although cheaters impose several host cots (Sony VGN-FZ70B battery) (e.g., via damage to their reproductive organs or propagules, denying the services of a beneficial partner), their net effect on host fitness is not necessarily negative and, thus, becomes difficult to forecast.

Biogeography

The word biogeography is an amalgamation of biology and geography(Sony VGN-FZ62B battery). Biogeography is the comparative study of the geographic distribution of organisms and the corresponding evolution of their traits in space and time. The Journal of Biogeography was established in 1974. Biogeography and ecology share many of their disciplinary roots(Sony VGN-FZ140E battery). For example, the theory of island biogeography, published by the mathematician Robert MacArthur and ecologist Edward O. Wilson in 1967 is considered one of the fundamentals of ecological theory.

Biogeography has a long history in the natural sciences where questions arise concerning the spatial distribution of plants and animals(Sony Vaio VGN-FZ21J battery). Ecology and evolution provide the explanatory context for biogeographical studies. Biogeographical patterns result from ecological processes that influence range distributions, such as migration and dispersal. and from historical processes that split populations or species into different areas(Sony VGN-FZ440N battery). The biogeographic processes that result in the natural splitting of species explains much of the modern distribution of the Earth's biota. The splitting of lineages in a species is called vicariance biogeography and it is a sub-discipline of biogeography(Sony VGN-FZ11E battery). There are also practical applications in the field of biogeography concerning ecological systems and processes. For example, the range and distribution of biodiversity and invasive species responding to climate change is a serious concern and active area of research in context of global warming(Sony VGP-BPS13B/B battery).

r/K-Selection theory

A population ecology concept (introduced in MacArthur and Wilson's (1967) book, The Theory of Island Biogeography) is r/K selection theory, one of the first predictive models in ecology used to explain life-history evolution(Sony VGP-BPS13A/B battery). The premise behind the r/K selection model is that natural selection pressures change according to population density. For example, when an island is first colonized, density of individuals is low(Sony VGP-BPS13/S battery). 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-independentforces of natural selection, which is called r-selection. As the population becomes more crowded(Sony VGP-BPS13/B battery), 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(Sony VGP-BPS13AS battery).

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. Different species evolve different life-history strategies spanning a continuum between these two selective forces(Sony VGP-BPS13S battery). 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 favors high rates of fecundity in r-selected species(Sony VGP-BPS13B/S battery). 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(Sony VGP-BPS13A/S battery). Humans and elephants are examples of species exhibiting K-selected characteristics, including longevity and efficiency in the conversion of more resources into fewer offspring.

Molecular ecology

The important relationship between ecology and genetic inheritance predates modern techniques for molecular analysis(Sony VGN-FW31J battery). Molecular ecological research became more feasible with the development of rapid and accessible genetic technologies, such as the polymerase chain reaction (PCR). The rise of molecular technologies and influx of research questions into this new ecological field resulted in the publication Molecular Ecology in 1992(Sony VGP-BPS21 battery). Molecular ecology uses various analytical techniques to study genes in an evolutionary and ecological context. In 1994, John Avisealso played a leading role in this area of science with the publication of his book, Molecular Markers, Natural History and Evolution(Sony VGP-BPS21B battery). Newer technologies opened a wave of genetic analysis into organisms once difficult to study from an ecological or evolutionary standpoint, such as bacteria, fungi and nematodes.

Molecular ecology engendered a new research paradigm to investigate ecological questions considered otherwise intractable(Sony VGP-BPS21/S battery). Molecular investigations revealed previously obscured details in the tiny intricacies of nature and improved resolution into probing questions about behavioral and biogeographical ecology. For example, molecular ecology revealed promiscuous sexual behavior and multiple male partners in tree swallows previously thought to be socially monogamous(Sony VGP-BPS21A/B battery). In a biogeographical context, the marriage between genetics, ecology and evolution resulted in a new sub-discipline called phylogeography.

Relation to the environment

The environment is dynamically interlinked, imposed upon and constrains organisms at any time throughout their life cycle. Like the term ecology, environment has different conceptual meanings and to many these terms also overlap with the concept of nature(Sony VAIO PCG-5G2L battery). Environment "...includes the physical world, the social world of human relations and the built world of human creation." The environment in ecosystems includes both physical parameters and biotic attributes. The physical environment is external to the level of biological organization under investigation(Sony VAIO PCG-5G3L battery), including abiotic factors such as temperature, radiation, light, chemistry, climate and geology. The biotic environment includes genes, cells, organisms, members of the same species (conspecifics) and other species that share a habitat(Sony VAIO PCG-5J1L battery). The laws of thermodynamicsapplies to ecology by means of its physical state. Armed with an understanding of metabolic and thermodynamic principles a complete accounting of energy and material flow can be traced through an ecosystem(Sony VAIO PCG-5J2L battery).

Environmental and ecological relations are studied through reference to conceptually manageable and isolated parts. Once the effective environmental components are understood they conceptually link back together as a holocoenotic system(Sony VAIO PCG-5K2L battery). In other words, the organism and the environment form a dynamic whole (or umwelt). Change in one ecological or environmental factor can concurrently affect the dynamic state of an entire ecosystem.

Ecological studies are necessarily holistic as opposed to reductionistic. Holism has three scientific meanings or uses that identify with: 1) (Sony VAIO PCG-5L1L battery) the mechanistic complexity of ecosystems, 2) the practical description of patterns in quantitative reductionist terms where correlations may be identified but nothing is understood about the causal relations without reference to the whole system(Sony VAIO PCG-6S2L battery), which leads to 3) ametaphysicalhierarchy whereby the causal relations of larger systems are understood without reference to the smaller parts. An example of the metaphysical aspect to holism is the trend of increased exterior thickness in shells of different species(Sony VAIO PCG-6S3L battery). The reason for a thickness increase can be understood through reference to principals of natural selection via predation without any reference to the biomolecular properties of the exterior shells.

Metabolism and the early atmosphere

The Earth formed approximately 4.5 billion years ago and environmental conditions were too extreme for life to form for the first 500 million years(Sony VAIO PCG-6V1L battery). During this early Hadean period, the Earth started to cool, allowing a crust and oceans to form. Environmental conditions were unsuitable for the origins of life for the first billion years after the Earth formed(Sony VAIO PCG-6W1L battery). The Earth's atmosphere transformed from being dominated by hydrogen, to one composed mostly ofmethane and ammonia. Over the next billion years the metabolic activity of life transformed the atmosphere to higher concentrations of carbon dioxide,nitrogen, and water vapor(Sony VAIO PCG-7111L battery). 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 oxidizinggasses that set the stage for primitive ecosystems to evolve and, in turn, the atmosphere also evolved(Sony VAIO PCG-6W3L battery).

Throughout history, the Earth's atmosphere and biogeochemical cycles have been in a dynamic equilibrium with planetary ecosystems. The history is characterized by periods of significant transformation followed by millions of years of stability(Sony VAIO PCG-7113L battery). The evolution of the earliest organisms, likely anaerobic methanogen microbes, started the process by converting atmospheric hydrogen into methane (4H2 + CO2 → CH4 + 2H2O). Anoxygenic photosynthesis converting hydrogen sulfide into other sulfur compounds or water (2H2S + CO2 → hv → CH2O → H2O → + 2S or 2H2 + CO2 + hv → CH2O + H2O) (Sony VAIO PCG-7133L battery), as occurs in deep sea hydrothermal vents today, reduced hydrogen concentrations and increased atmospheric methane. Early forms of fermentation also increased levels of atmospheric methane(Sony VAIO PCG-7Z1L battery). The transition to an oxygen dominant atmosphere (the 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.

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(Sony VAIO PCG-7Z2L battery). Heat affects growth rates, activity, behavior andprimary production. Temperature is largely dependent on the incidence of solar radiation. The latitudinal and longitudinal spatial variation of temperature greatly affects climates and consequently the distribution of biodiversity and levels of primary production in different ecosystems or biomes across the planet(Sony VAIO PCG-8Y1L battery). Heat and temperature relate importantly to metabolic activity. Poikilotherms, for example, have a body temperature that is largely regulated and dependent on the temperature of the external environment. In contrast, homeothermsregulate their internal body temperature by expending metabolic energy(Sony VAIO PCG-8Y2L battery).

There is a relationship between light, primary production, and ecological energy budgets. Sunlight is the primary input of energy into the planet's ecosystems. Light is composed of electromagnetic energy of different wavelengths. Radiant energy from the sun generates heat(Sony VAIO PCG-8Z2L battery), provides photons of light measured as active energy in the chemical reactions of life, and also acts as a catalyst for genetic mutation. Plants, algae, and some bacteria absorb light and assimilate the energy through photosynthesis. Organisms capable of assimilating energy by photosynthesis or through inorganic fixation of H2S are autotrophs(Sony VAIO PCG-8Z1L battery). Autotrophs—responsible for primary production—assimilate light energy that becomes metabolically stored as potential energy in the form of biochemical enthalpic bonds.

Physical environments

Water

The rate of diffusion of carbon dioxide and oxygen is approximately 10,000 times slower in water than it is in air(Sony VAIO PCG-7112L battery). When soils become flooded, they quickly lose oxygen and transform into a low-concentration (hypoxic -with less than 2 mg O2l−1) environment and eventually become completely (anoxic) environment where anaerobic bacteria thrive among the roots(Sony VAIO PCG-6W2L battery). Water also influences the spectral composition and amount of light as it reflects off the water surface and submerged particles. Aquatic plants exhibit a wide variety of morphological and physiological adaptations that allow them to survive(Sony VAIO PCG-5K1L battery), compete and diversify these environments. For example, the roots and stems develop large air spaces (Aerenchyma) that regulate the efficient transportation gases (for example, CO2 and O2) used in respiration and photosynthesis. In drained soil, microorganisms use oxygen during respiration(SONY VGP-BPS21A/B Battery). In aquatic environments, anaerobic soil microorganisms use nitrate, manganese ions, ferric ions, sulfate, carbon dioxide and some organic compounds. The activity of soil microorganisms and the chemistry of the water reduces the oxidation-reduction potentials of the water(SONY VGP-BPS21B Battery). Carbon dioxide, for example, is reduced to methane (CH4) by methanogenic bacteria. Salt water plants (or halophytes) have specialized physiological adaptations, such as the development of special organs for shedding salt and osmo-regulate their internal salt (NaCl) concentrations(SONY VGP-BPS21 Battery), to live in estuarine,brackish, or oceanic environments. The physiology of fish is also specially adapted to deal with high levels of salt through osmoregulation. Their gills form electrochemical gradients that mediate salt excresion in saline environments and uptake in fresh water(SONY VGP-BPS21/S Battery).

Gravity

The shape and energy of the land is affected to a large degree by gravitational forces. On a larger scale, the distribution of gravitational forces on the earth are uneven and influence the shape and movement oftectonic plates as well as having an influence on geomorphic processes such as orogeny and erosion(SONY VGP-BPS13A/Q Battery). These forces govern many of the geophysical properties and distributions of ecological biomes across the Earth. On a organism scale, gravitational forces provide directional cues for plant and fungal growth (gravitropism) (SONY VGN NR11Z/T battery), orientation cues for animal migrations, and influence the biomechanics and size of animals. 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(SONY VGN NR11Z/S battery). The cardiovascular systems of all animals are functionally adapted to overcome pressure and gravitational forces that change according to the features of organisms (e.g., height, size, shape), their behavior (e.g., diving, running, flying), and the habitat occupied (e.g., water, hot deserts, cold tundra) (SONY VGN NR11M/S battery).

Pressure

Climatic and osmotic pressure places physiological constraints on organisms, such as flight and respiration at high altitudes, or diving to deep ocean depths. These constraints influence vertical limits of ecosystems in the biosphere as organisms are physiologically sensitive and adapted to atmospheric and osmotic water pressure differences(SONY VGN NR11S/S battery). Oxygen levels, for example, decrease with increasing pressure and are a limiting factor for life at higher altitudes.[171] Water transportation through trees is another important ecophysiological parameter where osmotic pressure gradients factor in. Water pressure in the depths of oceans requires that organisms adapt to these conditions(SONY VGP-BPS13B/Q Battery). For example, mammals, such as whales, dolphins and seals are specially adapted to deal with changes in sound due to water pressure differences. Different species of hagfish provide another example of adaptation to deep-sea pressure through specialized protein adaptations(SONY VGP-BPS13Q Battery).

Wind and turbulence

Turbulent forces in air and water have significant effects on the environment and ecosystem distribution, form and dynamics. On a planetary scale, ecosystems are affected by circulation patterns in the global trade winds(SONY Vaio VGN-FW21M Battery). Wind power and the turbulent forces it creates can influence heat, nutrient, and biochemical profiles of ecosystems. For example, wind running over the surface of a lake creates turbulence(SONY Vaio VGN-FW21L Battery), mixing the water column and influencing the environmental profile to createthermally layered zones, partially governing how fish, algae, and other parts of the aquatic ecology are structured. Wind speed and turbulence also exert influence on rates of evapotranspiration rates and energy budgets in plants and animals(SONY Vaio VGN-FW21J Battery). Wind speed, temperature and moisture content can vary as winds travel across different landfeatures and elevations. The westerlies, for example, come into contact with the coastal and interior mountains of western North America to produce a rain shadow on the leeward side of the mountain(SONY Vaio VGN-FW21E Battery). The air expands and moisture condenses as the winds move up in elevation which can cause precipitation; this is calledorographic lift. This environmental process produces spatial divisions in biodiversity(SONY Vaio VGN-FW11S Battery), as species adapted to wetter conditions are range-restricted to the coastal mountain valleys and unable to migrate across the xeric ecosystems of the Columbia Basinto intermix with sister lineages that are segregated to the interior mountain systems(SONY Vaio VGN-FW11M Battery).

Fire

Plants convert carbon dioxide into biomass and emit oxygen into the atmosphere. Approximately 350 million years ago (near the Devonian period) the photosynthetic process brought the concentration of atmospheric oxygen above 17%, which allowed combustion to occur(SONY Vaio VGN-FW11 Battery). 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 in management. While the issue of fire in relation to ecology and plants has been recognized for a long time(SONY VAIO VGN-FZ21J Battery), Charles Cooper brought attention to the issue of forest fires in relation to the ecology of forest fire suppression and management in the 1960s.

Fire creates environmental mosaics and a patchiness to ecosystem age and canopy structure(SONY VAIO VGN-FZ21Z Battery). Native North Americans were among the first to influence fire regimes by controlling their spread near their homes or by lighting fires to stimulate the production of herbaceous foods and basketry materials. The altered state of soil nutrient supply and cleared canopy structure also opens new ecological niches for seedling establishment(SONY VAIO VGN-FZ21E Battery). Most ecosystem are adapted to natural fire cycles. Plants, for example, are equipped with a variety of adaptations to deal with forest fires. Some species (e.g., Pinus halepensis) cannot germinate until after their seeds have lived through a fire(SONY Vaio VGN-FW31M Battery). This environmental trigger for seedlings is called serotiny. Some compounds from smoke also promote seed germination. Fire plays a major role in the persistence and resilience of ecosystems.

Biogeochemistry

Ecologists study and measure nutrient budgets to understand how these materials are regulated and flow through the environment(SONY Vaio VGN-FW465J Battery). This research has led to an understanding that there is a global feedback between ecosystems and the physical parameters of this planet including minerals, soil, pH, ions, water and atmospheric gases. There are six major elements, including H (hydrogen) (SONY Vaio VGN-FW139E/H Battery), C (carbon), N (nitrogen), O (oxygen), S (sulfur), and P (phosphorus) that 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(SONY Vaio VGN-FW139E Battery). Understanding the relations and cycles mediated between these elements and their ecological pathways has significant bearing toward understanding global biogeochemistry.

The ecology of global carbon budgets gives one example of the linkage between biodiversity and biogeochemistry(SONY Vaio VGN-FW31E Battery). For starters, the Earth's oceans are estimated to hold 40,000 gigatonnes (Gt) carbon, vegetation and soil is estimated to hold 2070 Gt carbon, and fossil fuel emissions are estimated to emit an annual flux of 6.3 Gt carbon(SONY Vaio VGN-FW17W Battery). At different times in the Earth's history there has been major restructuring in these global carbon budgets that was regulated to a large extent by the ecology of the land. For example, through the early-mid Eocene volcanic outgassing(SONY Vaio VGN-FW32J Battery), the oxidation of methane stored in wetlands, and seafloor gases increased atmospheric CO2 concentrations to levels as high as 3500 ppm. In the Oligocene, from 25 to 32 million years ago(SONY Vaio VGN-FW31J Battery), there was another significant restructuring in the global carbon cycle as grasses evolved a special type of C4 photosynthesis and expanded their ranges. This new photosynthetic pathway evolved in response to the drop in atmospheric CO2concentrations below 550 ppm(SONY VGN-CR42E battery). These kinds of ecosystem functions feed back significantly into global atmospheric models for carbon cycling. Loss in the abundance and distribution of biodiversity causes global carbon cycle feedbacks that are expected to increase rates of global warming in the next century(SONY VGN-CR42S battery). The effect of global warming melting large sections of permafrost creates a new mosaic of flooded areas where decomposition results in the emission of methane (CH4). Hence, there is a relationship between global warming, decomposition and respiration in soils and wetlands producing significant climate feedbacks and altered global biogeochemical cycles(SONY VGN-CR42Z battery). There is concern over increases in atmospheric methane in the context of the global carbon cycle, because methane is also a greenhouse gas that is 23 times more effective at absorbing long-wave radiation than CO2 on a 100 year time scale(SONY VGN-CR42ZR battery).

History

Early beginnings

Ecology has a complex origin due in large part to its interdisciplinary nature. Ancient philosophers of Greece, including Hippocratesand Aristotle were among the first to record their observations on natural history(SONY VGN-CR41SR battery). However, philosophers in ancient Greece viewed life as a static element that did not require an understanding of adaptation, a modern cornerstone of ecological theory. Topics more familiar in the modern context, including food chains, population regulation, and productivity(SONY VAIO PCG-5K1L battery), did not develop until the 1700s through the published works of microscopist Antoni van Leeuwenhoek (1632–1723) and botanist Richard Bradley(1688?-1732). Biogeographer Alexander von Humbolt(1769–1859) was another early pioneer in ecological thinking and was among the first to recognize ecological gradients(SONY VAIO PCG-6W2L battery). Humbolt alluded to the modern ecological law of species to area relationships.

In the early 20th century, ecology was an analytical form of natural history. Following in the traditions of Aristotle, the descriptive nature of natural history examined the interaction of organisms with both their environment and their community(SONY VAIO PCG-7112L battery). Natural historians, including James Hutton and Jean-Baptiste Lamarck, contributed significant works that laid the foundations of the modern ecological sciences. The term "ecology" (German: Oekologie) is of a more recent origin and was first coined by the German biologist Ernst Haeckel in his book Generelle Morphologie der Organismen (1866) (SONY VAIO PCG-8Z1L battery).

Opinions differ on who was the founder of modern ecological theory. Some mark Haeckel's definition as the beginning, others say it was Eugenius Warming with the writing of Oecology of Plants: An Introduction to the Study of Plant Communities (1895) (SONY VAIO PCG-8Z2L battery). Ecology may also be thought to have begun with Carl Linnaeus' research principals on the economy of nature that matured in the early 18th century. He founded an early branch of ecological study he called the economy of nature. The works of Linnaeus influenced Darwin in The Origin of Species where he adopted the usage of Linnaeus' phrase on the economy or polity of nature(SONY VAIO PCG-8Y2L battery). 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 if ecology is synonymous with Linnaeus' concepts for the economy of nature(SONY VAIO PCG-8Y1L battery).

The modern synthesis of ecology is a young science, which first attracted substantial formal attention at the end of the 19th century (around the same time as evolutionary studies) and become even more popular during the 1960s environmental movement, though many observations(SONY VAIO PCG-7Z2L battery), interpretations and discoveries relating to ecology extend back to much earlier studies in natural history. For example, the concept on the balance or regulation of nature can be traced back to Herodotos (died c. 425 BC) who described an early account of mutualismalong the Nile river where crocodiles open their mouths to beneficially allow sandpipers safe access to remove leeches(SONY VAIO PCG-7Z1L battery). In the broader contributions to the historical development of the ecological sciences, Aristotle is considered one of the earliest naturalists who had an influential role in the philosophical development of ecological sciences(SONY VAIO PCG-7133L battery). One of Aristotle's students, Theophrastus, made astute ecological observations about plants and posited a philosophical stance about the autonomous relations between plants and their environment that is more in line with modern ecological thought(SONY VAIO PCG-7113L battery). Both Aristotle and Theophrastus made extensive observations on plant and animal migrations, biogeography, physiology, and their habits in what might be considered an analog of the modern ecological niche. Hippocrates, another Greek philosopher, is also credited with reference to ecological topics in its earliest developments(SONY VAIO PCG-6W3L battery).

From Aristotle to Darwin the natural world was predominantly considered static and unchanged since its original creation. Prior to The Origin of Species there was little appreciation or understanding of the dynamic and reciprocal relations between organisms(SONY VAIO PCG-7111L battery), their adaptations and their modifications to the environment. WhileCharles Darwin is most notable for his treatise on evolution, he is also one of the founders of soil ecology. In The Origin of Species Darwin also made note of the first ecological experiment that was published in 1816(SONY VAIO PCG-6W1L battery). In the science leading up to Darwin the notion of evolving species was gaining popular support. This scientific paradigm changed the way that researchers approached the ecological sciences(SONY VAIO PCG-6V1L battery).

After the turn of 20th century

Some suggest that the first ecological text (Natural History of Selborne) was published in 1789, byGilbert White (1720–1793). The first American ecology book was published in 1905 by Frederic Clements(SONY VAIO PCG-6S3L battery). In his book, Clements forwarded the idea of plant communities as a superorganism. This publication launched a debate between ecological holism and individualism that lasted until the 1970s. The Clements superorganism concept proposed that ecosystems progress through regular and determined stages of seral development that are analogous to developmental stages of an organism whose parts function to maintain the integrity of the whole(SONY VAIO PCG-6S2L battery). The Clementsian paradigm was challenged by Henry Gleason. According to Gleason, 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(SONY VAIO PCG-5J2L battery).

The Clementsian superorganism theory has not been completely rejected, but some suggest it was an overextended application of holism. Holism remains a critical part of the theoretical foundation in contemporary ecological studies(SONY VAIO PCG-5L1L battery). Holism was first introduced in 1926 by a polarizing historical figure, a South African General named Jan Christian Smuts. Smuts was inspired by Clement's superorganism theory as he developed and published on the concept of holism, which contrasts starkly against his racial political views as the father of apartheid(SONY VAIO PCG-5K2L battery). Around the same time, Charles Elton pioneered the concept of food chains in his classical book "Animal Ecology".Elton defined ecological relations using concepts of food chains, food cycles, food size(SONY VAIO PCG-5J1L battery), 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.

Ecology has developers in many nations(SONY VAIO PCG-5G3L battery), including Russia's Vladimir Vernadsky and his founding of the biosphere concept in the 1920s or Japan's Kinji Imanishi and his concepts of harmony in nature and habitat segregation in the 1950s. The scientific recognition or importance of contributions to ecology from other cultures is hampered by language and translation barriers(SONY VAIO PCG-5G2L battery).

Human ecology

Ecosystem services

The ecosystems of planet Earth are coupled to human environments. Ecosystems regulate the global geophysical cycles of energy, climate, soil nutrients, and water that in turn support and grow natural capital (including the environmental, physiological, cognitive, cultural, and spiritual dimensions of life) (SONY VGP-BPS13B/S Battery). Ultimately, every manufactured product in human environments comes from natural systems. Ecosystems are considered common-pool resources because ecosystems do not exclude beneficiaries and they can be depleted or degraded(SONY VGP-BPS13S Battery). For example, green space within communities provides sustainable health services that reduces mortality and regulates the spread of vector borne disease. Research shows that people who are more engaged with regular access to natural areas have lower rates of diabetes(SONY VGP-BPS13AS Battery), heart disease and psychological disorders. These ecological health services are regularly depleted through urban development projects that do not factor in the common-pool value of ecosystems(SONY VGP-BPS13A/S Battery).

The ecological commons delivers a diverse supply of community services that sustains the well-being of human society. The Millennium Ecosystem Assessment, an international UN initiative involving more than 1,360 experts worldwide(Sony VAIO VGN-FZ15G Battery), identifies four main ecosystem service types having 30 sub-categories stemming from natural capital. The ecological commons includes provisioning (e.g., food, raw materials, medicine, water supplies), regulating (e.g., climate, water, soil retention, flood retention) (Sony VAIO VGN-FZ15T Battery), cultural (e.g., science and education, artistic, spiritual), and supporting (e.g., soil formation, nutrient cycling, water cycling) services.

Sixth mass extinction

Global assessments of biodiversity indicate that the current epoch, the Holocene (or Anthropocene) is a sixth mass extinction(SONY VGP-BPS13/B Battery). Species loss is accelerating at 100–1000 times faster than average background rates in the fossil record. The field ofconservation biology involves ecologists that are researching, confronting, and searching for solutions to sustain the planet's ecosystems for future generations(Dell N3010 Battery).

Nature is a resilient system. Ecosystems regenerate, withstand, and are forever adapting to fluctuating environments. Ecological resilience is an important conceptual framework in conservation management and it is defined as the preservation of biological relations in ecosystems that persevere and regenerate in response to disturbance over time(Dell INSPIRON 1764 battery). Disturbances, such as fire, are both 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 out of the patchwork of natural experimentation and opportunity(Dell INSPIRON 1564 battery). However, persistent, systematic, large and nonrandom disturbance caused by the niche constructing behavior of human beings, habitat conversion and land development, has pushed many of the Earth's ecosystems to the extent of their resilient thresholds. Three planetary thresholds have already been crossed, including 1) biodiversity loss, 2) climate change, and 3) nitrogen cycles(Dell INSPIRON 1464 battery). These biophysical systems are ecologically interrelated and naturally resilient, but human civilization has transitioned the planet to the Anthropocene epoch, where the threshold for planetary scale resilience has been crossed and the ecological state of the Earth is deteriorating rapidly to the detriment of humanity(Dell INSPIRON 1520 battery). The world's fisheries and oceans, for example, are facing dire challenges as the threat of global collapse appears imminent, with serious ramifications for the well-being of humanity(Dell INSPIRON 1420 battery). The ecology of the planet is further threatened by global warming, but investments in nature conservation can provide a regulatory feedback to store and regulate carbon and other greenhouse gases(Dell INSPIRON E1505 battery).

Ecological footprint

In 1992, William Rees developed the ecological footprint concept. The ecological footprint and its close analog the water footprint has become a popular way of accounting for the level of impact that human society is imparting on the Earth's ecosystems(Dell INSPIRON 1525 battery). All indications are that the human enterprise is unsustainable as the footprint of society is placing too much stress on the ecology of the planet. The WWF 2008 living planet report and other researchers report that human civilization has exceeded the bio-regenerative capacity of the planet(ASUS EEE PC900 battery). This means that the footprint of human consumption is extracting more natural resources than can be replenished by ecosystems around the world.

Ecological economics

Ecological economics is an economic science that extends its methods of valuation onto nature in an effort to address the inequity between market growth and biodiversity loss(SONY VGP-BPS13B/B Battery). Natural capital is the stock of materials or information stored in biodiversity that generates services that can enhance the welfare of communities. Population losses are the more sensitive indicator of natural capital than are species extinction in the accounting of ecosystem services(SONY VGP-BPS13 Battery). The prospect for recovery in the economic crisis of nature is grim. Populations, such as local ponds and patches of forest are being cleared away and lost at rates that exceed species extinctions(HP PAVILION DV6000 battery). The mainstream growth-based economic system adopted by governments worldwide does not include a price or markets for natural capital. This type of economic system places further ecological debt onto future generations.

Human societies are increasingly being placed under stress as the ecological commons is diminished through an accounting system that has incorrectly assumed "(SONY VAIO VGN-FZ31B Battery)... that nature is a fixed, indestructible capital asset." The current wave of threats, including massive extinction rates and concurrent loss of natural capital to the detriment of human society, is happening rapidly(SONY VAIO VGN-FZ31M Battery). This is called a biodiversity crisis, because 50% of the worlds species are predicted to go extinct within the next 50 years. Conventional monetary analyses are unable to detect or deal with these sorts of ecological problems. Multiple global ecological economic initiatives are being promoted to solve this problem(SONY VAIO VGN-FZ31J Battery). For example, governments of the G8 met in 2007 and set forth The Economics of Ecosystems and Biodiversity (TEEB) initiative:

In a global study we will initiate the process of analyzing the global economic benefit of biological diversity, the costs of the loss of biodiversity and the failure to take protective measures versus the costs of effective conservation(SONY VAIO VGN-FZ31E Battery).