In the course "Ecology"
on the topic: “Environmental factors. Law of Optimum"

Odessa 2010

Environmental conditions and resources- interrelated concepts. They characterize the habitat of organisms. Environmental conditions are usually defined as environmental factors that influence (positively or negatively) the existence and geographical distribution of living things.
Environmental factors are very diverse both in nature and in their impact on living organisms. Conventionally, all environmental factors are divided into three main groups.

Resource classification

- by origin :

• Resources of natural components (mineral, climatic, water, plant, land, soil, animal world)
• Resources of natural-territorial complexes (mining, industrial, water, residential, forestry)

- by type of economic use

• Industrial Production Resources
• Energy resources (Combustible minerals, hydropower resources, biofuels, nuclear raw materials)
• Non-energy resources (mineral, water, land, forest, fish resources)
• Agricultural production resources (agroclimatic, land-soil, plant resources - food supply, irrigation water, watering and maintenance)

- by type of exhaustibility

• Exhaustible
• Non-renewable (mineral, land resources)
• Renewable (resources of flora and fauna)
• Incompletely renewable - the recovery rate is below the level of economic consumption (arable soils, mature forests, regional water resources)
• Inexhaustible resources (water, climate)

Biotic factors

Biotic environment- part of an ecosystem that consists of groups of organisms that differ from each other in the way they feed: producers, consumers, dedritivores and decomposers.
Producers (producentis - producing) Using photosynthesis 2 they create organic matter and release oxygen into the atmosphere. These include green plants (grass, trees), blue-green algae and photosynthetic bacteria.
Consumers (consumo - I consume) feed on producers or other consumers. These include animals, birds, fish and insects.
Detritivores (detritus - worn out, phagos - devourer) They feed on dead plant debris and carcasses of animal organisms. These include earthworms, crabs, ants, dung beetles, rats, jackals, vultures, crows, etc.
Decomposers (reducentis - returning)- destroyers (destructors) of organic matter. These include bacteria and fungi, which, unlike detritivores, break down dead organic matter into mineral compounds. These compounds return to the soil and are used again by plants for nutrition.
But the main biotic factors are not organisms, but the relationships between them.

Abiotic factors include space, planetary, climate and soil .

Solar radiation consists mainly of electromagnetic (light) and thermal radiation, thanks to which life on Earth arose and is developing.
The rotation of the Earth around the Sun and its axis ensures the change of seasons, day and night.
The tilt of the earth's axis and the shape of our planet affect the distribution of heat over the surface of the globe.
Cosmic planetary factors determined the formation of latitudinal geographic zones (equatorial, tropical, temperate and polar).

Climatic factors include: temperature, light, air humidity, atmospheric pressure, precipitation, wind.
Temperature. There are organisms with variable body temperature and organisms with constant body temperature. The body temperature of the former depends on the ambient temperature. Its increase causes them to intensify their life processes and accelerate (within certain limits) development. These are fish, amphibians and reptiles. Animals with a constant body temperature - birds and mammals - depend to a much lesser extent on environmental temperature conditions.
Light. Light in the form of solar radiation powers all life processes on Earth. Ultraviolet rays with a wavelength greater than 0.3 microns account for 10% of radiant energy reaching the earth's surface. In small doses they are necessary for animals and humans. Under their influence, vitamin D is formed in the body. The greatest influence on the body is exerted by visible light with a wavelength of 0.4-0.75 microns, whose energy makes up about 45% of the total amount of radiant energy falling on the Earth. Blue (0.4-0.5 µm) and red (0.6-0.7 µm) light is especially strongly absorbed by chlorophyll.
Infrared radiation makes up 45% of the total amount of radiant energy incident on the Earth. Infrared rays increase the temperature of plant and animal tissues and are well absorbed by inanimate objects, including water.
Humidity. In nature, as a rule, there are daily fluctuations in air humidity, which, along with light and temperature, regulate the activity of organisms. Humidity as an environmental factor is also important because it changes the body’s response to temperature fluctuations. Temperature has a greater effect on the body if the humidity is very high or low. Likewise, the role of humidity increases if temperatures are close to the species' tolerance limits.
Climate largely determines the formation of ecosystems within geographic zones (geographic zones).
Thus, in the temperate zone, zones of coniferous (taiga), mixed and broad-leaved forests, forest-steppe, steppe, semi-desert and desert are formed.
In mountain systems, from the foothills to the peaks, high-altitude geographic zones (altitudinal zonality or zonality) are distinguished, which are also formed as a result of climate change with the height of the relief.

Soil factors: thermal regime, humidity and fertility. Where the soil is more fertile, the vegetation is richer and, accordingly, the animal world is more diverse. The poorer the soil, the poorer the animal world.

Anthropogenic factors

Anthropogenic factors consist of direct and indirect human impact on nature: deforestation, plowing of fields, extermination or resettlement of animals and plants, pollution of water, soil and atmosphere. More about this in the section applied ecology .
The most significant impact is associated with the operation of industrial enterprises and the use of heavy equipment. In these cases, anthropogenic factors are called man-made .

Law of Optimum

Environmental factors are extremely diverse, and each species, experiencing their influence, responds to it differently. However, there are some general laws that govern the responses of organisms to any environmental factor.
The main one is law of optimum. It reflects how living organisms tolerate different strengths of environmental factors. The law of optimum indicates the extent of each factor for the viability of organisms. On a graph it is expressed by a symmetrical curve showing how the vital activity of the species changes with a gradual increase in the measure of the factor.

The results of the action of a variable factor depend primarily on the strength of its manifestation, or dosage. Factors have a positive effect on organisms only within certain limits. Their insufficient or excessive effect has a negative effect on organisms.

Optimum zone- this is the range of action of the factor that is most favorable for life. Deviations from the optimum define pessimum zones. In them, organisms experience oppression.

Minimum and maximum transferable factor values- these are critical points beyond which the body dies.

The law of optimum is universal. It determines the boundaries of the conditions in which the existence of species is possible, as well as the measure of variability of these conditions. Species are extremely diverse in their ability to tolerate changing factors. In nature, there are two extreme options - narrow specialization and broad endurance. In specialized species, the critical points of the factor values ​​are very close; such species can only live in relatively constant conditions. Thus, many deep-sea inhabitants - fish, echinoderms, crustaceans - cannot tolerate temperature fluctuations even within 2-3 °C. Plants in humid habitats (marsh marigold, impatiens, etc.) instantly wither if the air around them is not saturated with water vapor. Species with a narrow range of endurance are called stenobionts, and those with a wide range are called eurybionts. If it is necessary to emphasize the relationship to any factor, use the combinations “steno-” and “eury-” in relation to its name, for example, stenothermic species - cannot tolerate temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc.

It has certain limits of positive influence on living organisms.

The results of the action of a variable factor depend primarily on the strength of its manifestation, or dosage. Factors have a positive effect on organisms only within certain limits. Their insufficient or excessive effect has a negative effect on organisms.

Optimum zone- this is the range of action of the factor that is most favorable for life. Deviations from the optimum define pessimum zones. In them, organisms experience oppression.

Minimum and maximum transferable factor values- these are critical points beyond which the body dies. The beneficial force of influence is called zone of optimum environmental factor or simply optimum for an organism of a given species. The greater the deviation from the optimum, the more pronounced the inhibitory effect of this factor on organisms ( pessimum zone).

The law of optimum is universal. It determines the boundaries of the conditions in which the existence of species is possible, as well as the measure of variability of these conditions. Species are extremely diverse in their ability to tolerate changing factors. In nature, there are two extreme options - narrow specialization and broad endurance. In specialized species, the critical points of the factor values ​​are very close; such species can only live in relatively constant conditions. Thus, many deep-sea inhabitants - fish, echinoderms, crustaceans - cannot tolerate temperature fluctuations even within 2-3 °C. Plants in humid habitats (marsh marigold, impatiens, etc.) instantly wither if the air around them is not saturated with water vapor. Species with a narrow range of endurance are called stenobionts, and those with a wide range are called eurybionts. If it is necessary to emphasize the relationship to any factor, use the combinations “steno-” and “eury-” in relation to its name, for example, stenothermic species - cannot tolerate temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc.

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See what the “Law of Optimum” is in other dictionaries:

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Shelford's Law of Tolerance- Shelford's maxim law is a law according to which the existence of a species is determined by limiting factors that are not only at a minimum, but also at a maximum. The law of tolerance extends Liebig's law of the minimum. The wording “Limiting... ... Wikipedia

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LAW OF LIMITING FACTORS- the law of limiting factors, a law that is an extension of Shelford’s Law of Tolerance, according to which environmental factors that have a pessimal value in specific conditions, i.e., those that are furthest from the optimum, make it especially difficult... ... Ecological dictionary

LAW OF TOLERANCE- (W. SHELFORD’S LAW OF ECOLOGICAL OPTIMUM) the limiting factor of an organism’s prosperity can be either a minimum or a maximum of an environmental factor, the range between which determines the limits of the organism’s tolerance to this factor.… … Ecological dictionary

W. SHELFORD'S LAW OF ECOLOGICAL OPTIMUM- (LAW OF TOLERANCE) the limiting factor of an organism’s prosperity can be either a minimum or a maximum of an environmental factor, the range between which determines the limits of the organism’s tolerance to a given factor. The body may have... Ecological dictionary

LAW OF CRITICAL FACTOR VALUE- the law according to which if at least one of the environmental factors approaches or goes beyond critical (threshold or extreme) values, then, despite the optimal combination of other values, individuals are threatened with death. Such… … Ecological dictionary

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Law of Optimum (in ecology) - any environmental factor has certain limits of positive influence on living organisms.

The results of the action of a variable factor depend primarily on the strength of its manifestation, or dosage. Factors have a positive effect on organisms only within certain limits. Their insufficient or excessive effect has a negative effect on organisms.

Optimum zone- this is the range of action of the factor that is most favorable for life. Deviations from the optimum define pessimum zones. In them, organisms experience oppression.

Minimum and maximum transferable factor values- these are critical points beyond which the body dies. The beneficial force of influence is called zone of optimum environmental factor or simply optimum for an organism of a given species. The greater the deviation from the optimum, the more pronounced the inhibitory effect of this factor on organisms ( pessimum zone).

The law of optimum is universal. It determines the boundaries of the conditions in which the existence of species is possible, as well as the measure of variability of these conditions. Species are extremely diverse in their ability to tolerate changing factors. In nature, there are two extreme options - narrow specialization and broad endurance. In specialized species, the critical points of the factor values ​​are very close; such species can only live in relatively constant conditions. Thus, many deep-sea inhabitants - fish, echinoderms, crustaceans - cannot tolerate temperature fluctuations even within 2-3 °C. Plants in humid habitats (marsh marigold, impatiens, etc.) instantly wither if the air around them is not saturated with water vapor. Species with a narrow range of endurance are called stenobionts, and those with a wide range are called eurybionts. If it is necessary to emphasize the relationship to any factor, use the combinations “steno-” and “eury-” in relation to its name, for example, stenothermic species - cannot tolerate temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc.

Law of Energy Maximization(formulated by G and Yu Odum and supplemented by M Reimers): in competition with other systems, the one that contributes more to the flow of energy and information and uses the maximum amount of them effectively is preserved.

The system forms reservoirs of high-quality energy, part of which is spent on ensuring the supply of new energy, ensures the normal circulation of substances and creates mechanisms for regulation, support, stability of the system, its ability to adapt to changes, establishes exchange with other systems. Maximization ensures an increase in the chances of survival.

Law of maximum biogenic energy(Vernadsky-Bauer law): any biological and biological system that is in a state of stable disequilibrium (dynamically unstable equilibrium with the environment) increases, as it develops, its influence on the environment.

In the process of evolution of species, those that increase biogenic geochemical energy survive. Living systems are never in a state of equilibrium and, at the expense of their free energy, perform useful work on the balance required by the laws of physics and chemistry under existing external conditions. This law, along with others, is the basis development of environmental management strategy.

Basic laws (4 rules of factorial ecology)

Law of Optimum

Environmental factors are extremely diverse, and each species, experiencing their influence, responds to it differently. However, there are some general laws that govern the responses of organisms to any environmental factor.

The main one is the law of optimum. It reflects how living organisms tolerate different strengths of environmental factors. The law of optimum indicates the extent of each factor for the viability of organisms. On the graph it is expressed by a symmetrical curve showing how the vital activity of a species changes with a gradual increase in the measure of the factor. The results of the action of a variable factor depend primarily on the strength of its manifestation, or dosage. Factors have a positive effect on organisms only within certain limits. Their insufficient or excessive effect has a negative effect on organisms.

The optimum zone is the range of action of the factor that is most favorable for life. Deviations from the optimum define pessimum zones. In them, organisms experience oppression.

The minimum and maximum tolerable values ​​of a factor are critical points beyond which the organism dies.

The law of optimum is universal. It determines the boundaries of the conditions in which the existence of species is possible, as well as the measure of variability of these conditions. Species are extremely diverse in their ability to tolerate changing factors. In nature, there are two extreme options - narrow specialization and broad endurance. In specialized species, the critical points of the factor values ​​are very close; such species can only live in relatively constant conditions. Thus, many deep-sea inhabitants - fish, echinoderms, crustaceans - cannot tolerate temperature fluctuations even within 2-3 °C. Plants in humid habitats (marsh marigold, impatiens, etc.) instantly wither if the air around them is not saturated with water vapor. Species with a narrow range of endurance are called stenobionts, and those with a wide range are called eurybionts. If it is necessary to emphasize the relationship to any factor, use the combinations “steno-” and “eury-” in relation to its name, for example, stenothermic species - intolerant of temperature fluctuations, euryhaline - capable of living with wide fluctuations in water salinity, etc. P.

The law of tolerance, one of the fundamental principles of ecology, according to which the presence or prosperity of a population of k.-l. organisms in a given habitat depends on the complex of ecology. factors, to each of which the body has a definition. range of tolerance (endurance). The range of tolerance for each factor is limited by its minimum. and max, values ​​within which only an organism can exist. The degree of well-being of a population (or species), depending on the intensity of the factor affecting it, is presented in the form of the so-called. tolerance curve, which usually has a bell-shaped shape with a maximum corresponding to the optimal value of a given factor. Sh. p. was put forward in 1913 by W. Shelford on the basis of experiments. Together with Liebig's law, it is combined into the principle of limiting factors. Any ecology can be limiting. factor (for example, the number of places suitable for making a nest), but the most important ones are often temperature, water, food (for plants - the presence of nutrients in the soil). A number of provisions have been proposed to supplement the law: ranges of tolerance to dep. factors and their combinations are different; organisms with wide ranges of tolerance (eurybionts) are widespread; if the level of one factor goes beyond the limits of tolerance, the range of endurance to other factors narrows, etc.

The law of the limiting factor or Liebig's law of minimum is one of the fundamental laws in ecology, which states that the most significant factor for an organism is the one that deviates most from its optimal value. Therefore, when predicting environmental conditions or performing examinations, it is very important to determine the weak link in the life of organisms.

It is on this minimally (or maximally) represented environmental factor at a given moment that the survival of the organism depends. At other times, other factors may be limiting. During their lives, individuals of species encounter a variety of limitations to their life activities. Thus, the factor limiting the spread of deer is the depth of the snow cover; moths of the winter cutworm (pest of vegetables and grain crops) - winter temperature, etc.

This law is taken into account in agricultural practice. The German chemist Justus Liebig found that the productivity of cultivated plants primarily depends on the nutrient (mineral element) that is most poorly represented in the soil. For example, if phosphorus in the soil is only 20% of the required norm, and calcium is 50% of the norm, then the limiting factor will be a lack of phosphorus; It is necessary first of all to add phosphorus-containing fertilizers to the soil. The figurative representation of this law is named after the scientist - the so-called “Liebig barrel”. The essence of the model is that when the barrel is filled, water begins to flow over the smallest board in the barrel and the length of the remaining boards no longer matters.

is expressed in the fact that any environmental factor has limits of positive influence on living organisms.

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Rice. . Scheme of the action of environmental factors on living organisms.

Consider the effect of the law of optimum on a specific example: animals and plants do not tolerate both extreme heat and severe frosts; average temperatures are optimal for them - the so-called optimum zone. The greater the deviation from the optimum, the more this environmental factor inhibits the vital activity of the organism. This zone is called pessimum zones. There are critical points in it - " maximum factor value" And " minimum factor value"; beyond their limits, the death of organisms occurs. The distance between the minimum and maximum values ​​of the factor is called ecological valence (plasticity) or tolerance body (Fig. 3).

The property of organisms to adapt to existence in a particular range of environmental factors is called ecological plasticity.

The wider the range of environmental factors within which a given organism can live, the greater its ecological plasticity. According to the degree of plasticity, two types of organisms are distinguished: stenobiont(stenoeki) and eurybiont(euryeks).

Stenobiont and eurybiont organisms differ in the range of environmental factors in which they can live.

Stenobionts(gr. stenos - narrow, cramped), or narrowly adapted species are able to exist only with small deviations of the factor from the optimal value.

Eurybiont(gr. eurys - wide) are widely adapted organisms that can withstand large amplitudes of environmental factor fluctuations.

Thus, stenobionts are ecologically nonplastic, i.e. are not hardy, but eurybionts are ecologically plastic, that is, they are more hardy. The first include, for example, typical inhabitants of the seas that live in conditions of high salinity (flounder), and typical inhabitants of fresh waters (crucian carp). They have low environmental plasticity. But the three-spined stickleback can live in both fresh and salt waters, i.e. characterized by high plasticity

Organisms that live for a long time in relatively stable conditions lose their ecological plasticity, while those that were subject to significant fluctuations in the factor become more tolerant to it, and their ecological plasticity increases.

To indicate the relationship of organisms to a specific factor, the words steno- or eury- are added to its name. Thus, in relation to temperature, there are stenothermic (dwarf birch, banana tree) and eurythermic (temperate zone plants) species; in relation to salinity - stenohaline (crucian carp, flounder) and euryhaline (stickleback); in relation to light - stenophotic (spruce) and euryphotic (rose hips), etc.

Steno- or eurybiontism manifests itself in relation to one or a few factors. Thus, a eurythermal plant can be stenohygrobiont (intolerant to fluctuations in humidity), and stenohaline fish turns out to be eurythermic, etc.

Eurybionts are usually widespread. Stenobionts have a limited distribution area.

Historically, adapting to environmental factors, animals, plants, and microorganisms are distributed across various environments, forming the entire diversity of ecosystems that form the Earth's biosphere.

The laws of J. Liebig and W. Shelford helped to understand many phenomena and the distribution of organisms in nature. Organisms cannot be distributed everywhere because populations have a certain tolerance limit in relation to fluctuations in environmental environmental factors.

The following was found:

The actual limits of tolerance observed in nature are less than the potential capabilities of the body to adapt to this factor. This is explained by the fact that in nature the limits of tolerance in relation to the physical conditions of the environment can be narrowed by biotic relationships: competition, lack of pollinators, predators, etc. The potential ecological plasticity of an organism, determined in laboratory conditions, is greater than the realized possibilities in natural conditions. Accordingly, potential and realized ecological niches are distinguished;

The limits of tolerance in breeding individuals and offspring are less than in adult individuals, i.e. females during the breeding season and their offspring are less hardy than adult organisms. Thus, the geographic distribution of game birds is more often determined by the influence of climate on eggs and chicks, rather than on adult birds. Caring for offspring and careful attitude towards motherhood are dictated by the laws of nature. Unfortunately, sometimes social “achievements” contradict these laws;

Extreme (stressful) values ​​of one of the factors lead to a decrease in the tolerance limit for other factors. If heated water is released into a river, fish and other organisms spend almost all their energy coping with stress. They lack energy to obtain food, protect themselves from predators, and reproduce, which leads to gradual extinction. Psychological stress can also cause many somatic (gr. soma - body) diseases not only in humans, but also in some animals (for example, dogs). With stressful values ​​of the factor, adaptation to it becomes more and more “expensive”.

Many organisms are capable of changing tolerance to individual factors if conditions change gradually. You can, for example, get used to the high temperature of the water in the bath if you get into warm water and then gradually add hot water. This adaptation to a slow change in factor is a useful protective property. But it can also be dangerous. Unexpectedly, without warning signs, even a small change can be critical. A threshold effect occurs: the “last straw” may be fatal. For example, a thin twig can cause a camel's already overloaded back to break. If the value of at least one of the environmental factors approaches a minimum or maximum, the existence and prosperity of an organism, population or community becomes dependent on this factor, which limits the life activity.

Limiting factor any environmental factor that approaches or exceeds the extreme values ​​of tolerance limits is called. Such factors that strongly deviate from the optimum become of paramount importance in the life of organisms and biological systems. They are the ones who control the conditions of existence.

The value of the concept of limiting factors is that it allows us to understand the complex relationships in ecosystems.

Examples: For example, oxygen content in terrestrial habitats is high, and it is so available that it almost never serves as a limiting factor (except at high altitudes and anthropogenic systems). Oxygen is of little interest to ecologists interested in terrestrial ecosystems. And in water it is often a factor limiting the development of living organisms (“killing” of fish, for example). Therefore, a hydrobiologist always measures the oxygen content in water, unlike a veterinarian or ornithologist, although oxygen is no less important for terrestrial organisms than for aquatic ones.

Limiting factors determine and geographical range of the species. Thus, the movement of organisms to the north is limited, as a rule, by a lack of heat. Biotic factors also often limit the spread of certain organisms. For example, figs brought from the Mediterranean to California did not bear fruit there until they decided to bring there a certain type of wasp - the only pollinator of this plant.

Identification of limiting factors is very important for many activities, especially agriculture. 1. Thus, when growing wheat on acidic soils, no agronomic measures will be effective unless liming is used, which will reduce the limiting effect of acids. 2. Or, if you grow corn in soils with very low phosphorus content, then even with enough water, nitrogen, potassium and other nutrients, it stops growing. Phosphorus in this case is the limiting factor. And only phosphorus fertilizers can save the harvest. Plants can also die from too much water or excess fertilizer, which in this case are also limiting factors.

Ecological niche

An ecological niche is usually understood as the place of an organism in nature and the entire pattern of its life activity, or, as they say, life status, including relation to environmental factors, types of food, time and methods of feeding, breeding places, shelters, etc.

This concept is much broader and more meaningful than the concept of “habitat”. The American ecologist Odum figuratively called the habitat the “address” of an organism (species), and the ecological niche its “profession.” As a rule, a large number of organisms of different species live in one habitat. For example, a mixed forest is a habitat for hundreds of species of plants and animals, but each of them has its own and only one “profession” - an ecological niche. Thus, a similar habitat, as noted above, in the forest is occupied by elk and squirrel. But their niches are completely different: the squirrel lives mainly in the crowns of trees, feeds on seeds and fruits, reproduces there, etc. The entire life cycle of an elk is associated with the subcanopy space: feeding on green plants or their parts, reproduction and shelter in thickets, etc. . P.

If organisms occupy different ecological niches, they usually do not enter into competitive relationships; their spheres of activity and influence are separated. In this case, the relationship is considered neutral.

At the same time, in each ecosystem there are species that claim the same niche or its elements (food, shelter, etc.). In this case, competition is inevitable, the struggle to own a niche. Evolutionary relationships have developed in such a way that species with similar environmental requirements cannot exist together for a long time. This pattern is not without exceptions, but it is so objective that it is formulated in the form of a position called “ competitive exclusion rule" The author of this rule is ecologist G. F. Gause. It sounds like this: if two species with similar requirements for the environment (nutrition, behavior, breeding sites, etc.) enter into a competitive relationship, then one of them must die or change its lifestyle and occupy a new ecological niche. Sometimes, for example, in order to relieve acute competitive relations, it is enough for one organism (animal) to change the time of feeding without changing the type of food itself (if competition occurs at the bud of food relations), or to find a new habitat (if competition takes place on the basis of this factor) and etc.

Among other properties of ecological niches, we note that an organism (species) can change them throughout its life cycle. The most striking example in this regard is insects. Thus, the ecological niche of the cockchafer larvae is associated with the soil and feeding on the root systems of plants. At the same time, the ecological niche of beetles is associated with the terrestrial environment, feeding on green parts of plants.

Communities (biocenoses, ecosystems) are formed according to the principle of filling ecological niches. In a natural established community, usually all niches are occupied. It is in such communities, for example in long-standing (indigenous) forests, that the likelihood of introducing new species is very low. At the same time, it should be borne in mind that the occupation of ecological niches is to a certain extent a relative concept. All niches are usually occupied by those organisms that are characteristic of a given region. But if an organism comes from outside (for example, seeds or other germs are introduced) accidentally or intentionally, for example, as a result of the introduction of new species by humans (introduction, acclimatization), then it can find a free niche for itself due to the fact that there were no contenders for it from the set of existing species. For example, the breeding of rabbits introduced to Australia; movement of the muskrat from Asia to the European part; intensive promotion of the Colorado potato beetle to new areas.

Connections of organisms in ecosystems (for 36 hours of lectures)

Relationships between organisms. Relationships are usually classified according to the “interests” on which organisms base their relationships.

The most common type of connection is based on nutritional interests. Such connections are called food or trophic(Greek tropho - food). This type of connection includes the feeding of one organism by another or the products of its vital activity (for example, excrement), feeding with similar food (for example, dead organic matter). This type of connection unites plants and insects that pollinate their flowers. Food chains arise on the basis of trophic connections.