Environmental factors. Environmental conditions have a certain impact (positive or negative) on the existence and geographical distribution of living beings. In this regard, environmental conditions are considered as environmental factors.

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 - abiotic, biotic and anthropogenic.

Abiotic factors- these are factors of inanimate nature, primarily climatic: sunlight, temperature, humidity and local: relief, soil properties, salinity, currents, wind, radiation, etc. (Fig. 14). These factors can influence organisms directly, that is, directly, like light or heat, or indirectly, such as relief, which determines the action of direct factors - illumination, moisture, wind and others.

Rice. 14. The influence of light on the development of dandelion:
1 - in bright light; 2 - in low light (in the shade)

These are all those forms of human activity that affect the natural environment, changing the living conditions of living organisms, or directly affect individual species of plants and animals (Fig. 15).

Rice. 15. Anthropogenic factors

In turn, organisms themselves can influence the conditions of their existence. For example, the presence of vegetation cover softens daily temperature fluctuations near the surface of the earth (under the canopy of a forest or grass) and affects the structure and chemical composition of soils.

All environmental factors have a certain impact on organisms and are necessary for their life. But especially sudden changes in the external appearance and internal structure of organisms are caused by such factors of inanimate nature as light, temperature, humidity.

New concepts

Environmental factors: abiotic, biotic, anthropogenic

Questions

1. What are environmental factors?
2. Which groups environmental factors do you know?

Think

What importance do green plants have for life on our planet?

Tasks

To better understand educational material, learn to work correctly with the textbook text.

How to work with textbook text

1. Read the title of the paragraph. It reflects its main content.
2. Read the questions before the text of the paragraph. Try to answer them. This will help you understand the text of the paragraph better.
3. Read the questions at the end of the paragraph. They will help highlight the most important material in the paragraph.
4. Read the text, mentally break it down into “meaningful units,” and make a plan.
5. Sort the text (learn new terms and definitions by heart, remember the main points, be able to prove them and confirm them with examples).
6. Briefly summarize the paragraph.

Biology is the science of life, of living organisms living on Earth.

Biology studies the structure and vital functions of living organisms, their diversity, and the laws of historical and individual development.

The area of ​​distribution of life makes up a special shell of the Earth - the biosphere.

The branch of biology about the relationships of organisms with each other and with their environment is called ecology.

Biology is closely related to many aspects of practical human activity - agriculture, medicine, various industries, in particular food and light, etc.

Living organisms on our planet are very diverse. Scientists distinguish four kingdoms of living beings: Bacteria, Fungi, Plants and Animals.

Every living organism is made up of cells (with the exception of viruses). Living organisms eat, breathe, excrete waste products, grow, develop, reproduce, perceive influences environment and react to them.

Each organism lives in a specific environment. Everything that surrounds a living being is called its habitat.

There are four main habitats on our planet, developed and inhabited by organisms. These are water, ground-air, soil and the environment inside living organisms.

Each environment has its own specific living conditions to which organisms adapt. This explains the great diversity of living organisms on our planet.

Environmental conditions have a certain impact (positive or negative) on the existence and geographical distribution of living beings. In this regard, environmental conditions are considered as environmental factors.

Conventionally, all environmental factors are divided into three main groups - abiotic, biotic and anthropogenic.

The influence of the environment on the body.

Any organism is open system, which means it receives matter, energy, information from the outside and, thus, is completely dependent on the environment. This is reflected in the law discovered by the Russian scientist K.F. Roulier: “the results of development (changes) of any object (organism) are determined by the ratio of its internal features and the characteristics of the environment in which he is located." This law is sometimes called the first environmental law because it is universal.

Organisms influence the environment by changing the gas composition of the atmosphere (H: as a result of photosynthesis), participate in the formation of soil, relief, climate, etc.

The limit of the influence of organisms on the habitat is described by another ecological law (Kurazhkovsky Yu.N.): each type of organism, consuming the substances it needs from the environment and releasing products of its vital activity into it, changes it in such a way that the habitat becomes unsuitable for its existence .

1.2.2. Ecological environmental factors and their classification.

The set of individual elements of the environment that influence organisms at at least one stage of individual development are called environmental factors.

According to the nature of origin, abiotic, biotic and anthropogenic factors are distinguished. (Slide 1)

Abiotic factors- these are the properties of inanimate nature (temperature, light, humidity, composition of air, water, soil, natural radiation background of the Earth, terrain), etc., which directly or indirectly affect living organisms.

Biotic factors- these are all forms of influence of living organisms on each other. The effect of biotic factors can be both direct and indirect, expressed in changes in environmental conditions, for example, changes in soil composition under the influence of bacteria or changes in the microclimate in the forest.

Mutual connections between individual species of organisms underlie the existence of populations, biocenoses and the biosphere as a whole.

Previously, human influence on living organisms was also classified as biotic factors, but now a special category of factors generated by humans is distinguished.

Anthropogenic factors- these are all forms of activity of human society that lead to changes in nature as a habitat and other species and directly affect their lives.

Human activity on the planet should be identified as a special force that has both direct and indirect effects on nature. Direct impacts include human consumption, reproduction and settlement of individual species of animals and plants, as well as the creation of entire biocenoses. Indirect impact is carried out by changing the habitat of organisms: climate, river regime, land conditions, etc. As the population grows and the technological level of mankind grows, the proportion of anthropogenic environmental factors is steadily increasing.

Environmental factors vary in time and space. Some environmental factors are considered to be relatively constant over long periods of time in the evolution of species. For example, gravity, solar radiation, salt composition of the ocean. Most environmental factors - air temperature, humidity, air speed - are very variable in space and time.

In accordance with this, depending on the regularity of exposure, environmental factors are divided into (Slide 2):

· regularly periodic , changing the strength of the impact due to the time of day, season of the year or the rhythm of the tides in the ocean. For example: a decrease in temperature in the temperate climate zone of northern latitude with the onset of winter, etc.

· irregularly periodic , catastrophic phenomena: storms, rainfalls, floods, etc.

· non-periodic, arising spontaneously, without a clear pattern, one-time. For example, the emergence of a new volcano, fires, human activity.

Thus, every living organism is influenced by inanimate nature, organisms of other species, including humans, and, in turn, affects each of these components.

In order of order, the factors are divided into primary And secondary .

Primary environmental factors have always existed on the planet, even before the appearance of living beings, and all living things have adapted to these factors (temperature, pressure, tides, seasonal and daily frequency).

Secondary environmental factors arise and change due to the variability of primary environmental factors (water turbidity, air humidity, etc.).

Based on their effect on the body, all factors are divided into factors direct action And indirect .

According to the degree of impact, they are divided into lethal (leading to death), extreme, limiting, disturbing, mutagenic, teratogenic, leading to deformities during individual development).

Each environmental factor is characterized by certain quantitative indicators: force, pressure, frequency, intensity, etc.

1.2.3. Patterns of the action of environmental factors on organisms. Limiting factor. Liebig's law of the minimum. Shelford's law of tolerance. The doctrine of ecological optimums of species. Interaction of environmental factors.

Despite the variety of environmental factors and the different nature of their origin, there are some general rules and patterns of their impact on living organisms. Any environmental factor can affect the body as follows (Slide):

· change the geographical distribution of species;

· change the fertility and mortality of species;

· cause migration;

· promote the emergence of adaptive qualities and adaptations in species.

The action of a factor is most effective at a certain value of the factor that is optimal for the body, and not at its critical values. Let us consider the patterns of the factor’s action on organisms. (Slide).

The dependence of the result of the action of an environmental factor on its intensity; the favorable range of action of the environmental factor is called optimum zone (normal life activities). The more significant the deviation of a factor’s action from the optimum, the more this factor inhibits the vital activity of the population. This range is called zone of oppression (pessimum) . The maximum and minimum transferable values ​​of a factor are critical points beyond which the existence of an organism or population is no longer possible. The range of action of a factor between critical points is called zone of tolerance (endurance) of the body in relation to this factor. The point on the x-axis, which corresponds to the best indicator of the body’s vital activity, means the optimal value of the factor and is called optimum point. Since it is difficult to determine the optimum point, they usually talk about optimum zone or comfort zone. Thus, the points of minimum, maximum and optimum are three cardinal points , which determine the body’s possible reactions to a given factor. Environmental conditions in which any factor (or set of factors) goes beyond the comfort zone and has a depressing effect are called in ecology extreme .

The considered patterns are called "optimum rule" .

For organisms to live, a certain combination of conditions is necessary. If all environmental conditions are favorable, with the exception of one, then this condition becomes decisive for the life of the organism in question. It limits (limites) the development of the organism, therefore it is called limiting factor . That. limiting factor - an environmental factor whose significance goes beyond the limits of survival of the species.

For example, fish kills in water bodies in winter are caused by a lack of oxygen, carp do not live in the ocean (salt water), and the migration of soil worms is caused by excess moisture and lack of oxygen.

Initially, it was found that the development of living organisms is limited by the lack of any component, for example, mineral salts, moisture, light, etc. In the mid-19th century, the German organic chemist Eustace Liebig was the first to experimentally prove that plant growth depends on the nutrient element that is present in relatively minimal quantities. He called this phenomenon the law of the minimum; it is also called after the author Liebig's law . (Liebig barrel).

In modern formulation law of the minimum sounds like this: The endurance of an organism is determined by the weakest link in the chain of its environmental needs. However, as it turned out later, not only a deficiency, but also an excess of a factor can be limiting, for example, crop loss due to rain, oversaturation of the soil with fertilizers, etc. The concept that, along with a minimum, a maximum can also be a limiting factor was introduced 70 years after Liebig by the American zoologist W. Shelford, who formulated law of tolerance . According to According to the law of tolerance, the limiting factor in the prosperity of a population (organism) can be either a minimum or maximum environmental impact, and the range between them determines the amount of endurance (tolerance limit) or the ecological valency of the organism to this factor

The principle of limiting factors is valid for all types of living organisms - plants, animals, microorganisms and applies to both abiotic and biotic factors.

For example, competition from another species may become a limiting factor for the development of organisms of a given species. In agriculture, pests and weeds often become the limiting factor, and for some plants the limiting factor in development is the lack (or absence) of representatives of another species. For example, a new type of fig was brought to California from the Mediterranean, but it did not bear fruit until the only species of pollinating bees for it was brought from there.

In accordance with the law of tolerance, any excess of matter or energy turns out to be a pollutant.

Thus, excess water even in dry areas is harmful and water can be considered as a common pollutant, although in optimal quantities it is simply necessary. In particular, excess water prevents normal soil formation in the chernozem zone.

The broad ecological valency of a species in relation to abiotic environmental factors is indicated by adding the prefix “evry” and the narrow “steno” to the name of the factor. Species whose existence requires strictly defined environmental conditions are called stenobiont , and species adapting to an ecological situation with a wide range of changes in parameters - eurybiont .

For example, animals that can tolerate large temperature fluctuations are called eurythermic, a narrow temperature range is typical for stenothermic organisms. (Slide). Small changes in temperature have little effect on eurythermal organisms and can be disastrous for stenothermic organisms (Fig. 4). Euryhydroids And stenohydroid Organisms differ in their response to fluctuations in humidity. Euryhaline And stenohaline – have different reactions to the degree of salinity of the environment. Euryoic organisms are able to live in different places, and wall-mounted – exhibit strict requirements for the choice of habitat.

In relation to pressure, all organisms are divided into eurybates And stenobat or stopobats (deep sea fish).

In relation to oxygen they release euryoxybionts (crucian carp) and stenooxybiont s (grayling).

In relation to the territory (biotope) – eurytopic (great tit) and stenotopic (osprey).

In relation to food - euryphages (corvids) and stenophages , among which we can highlight ichthyophages (osprey), entomophagous (buzzard, swift, swallow), herpetophagous (The bird is the secretary).

The ecological valencies of a species in relation to different factors can be very diverse, which creates a variety of adaptations in nature. The totality of environmental valences in relation to various environmental factors is ecological spectrum of the species .

The body's tolerance limit changes during the transition from one stage of development to another. Often young organisms turn out to be more vulnerable and more demanding of environmental conditions than adult individuals.

The most critical period from the point of view of the influence of various factors is the breeding period: during this period, many factors become limiting. The ecological valency for reproducing individuals, seeds, embryos, larvae, eggs is usually narrower than for adult non-reproducing plants or animals of the same species.

For example, many marine animals can tolerate brackish or fresh water with high chloride content, so they often enter upstream rivers. But their larvae cannot live in such waters, so the species cannot reproduce in the river and does not establish a permanent habitat here. Many birds fly to raise their chicks in places with a warmer climate, etc.

Until now we have been talking about the limit of tolerance of a living organism in relation to one factor, but in nature all environmental factors act together.

The optimal zone and limits of the body's endurance in relation to any environmental factor can shift depending on the combination in which other factors act simultaneously. This pattern is called interactions of environmental factors (constellation ).

For example, it is known that heat is easier to bear in dry rather than humid air; the risk of freezing is significantly higher at low temperatures with strong wind than in calm weather. For plant growth, in particular, an element such as zinc is necessary; it is often the limiting factor. But for plants growing in the shade, the need for it is less than for those in the sun. The so-called compensation of factors occurs.

However, mutual compensation has certain limits and it is impossible to completely replace one of the factors with another. The complete absence of water or at least one of the necessary elements of mineral nutrition makes plant life impossible, despite the most favorable combinations of other conditions. It follows that all environmental conditions necessary to support life play an equal role and any factor can limit the possibilities of existence of organisms - this is the law of equivalence of all living conditions.

It is known that each factor has different effects on different body functions. Conditions that are optimal for some processes, for example, for the growth of an organism, may turn out to be a zone of oppression for others, for example, for reproduction, and go beyond the limits of tolerance, that is, lead to death, for others. Therefore, the life cycle, according to which the organism primarily performs certain functions during certain periods - nutrition, growth, reproduction, settlement - is always consistent with seasonal changes environmental factors, such as seasonality in the plant world due to the changing seasons.

Among the laws that determine the interaction of an individual or individual with his environment, we highlight rule of compliance of environmental conditions with the genetic predetermination of the organism . It claims that a species of organisms can exist until and to the extent that the natural environment surrounding it corresponds to the genetic capabilities of adapting this species to its fluctuations and changes. Each living species arose in a certain environment, adapted to it to one degree or another, and the further existence of the species is possible only in this or a similar environment. A sharp and rapid change in the living environment can lead to the fact that the genetic capabilities of a species will be insufficient to adapt to new conditions. This, in particular, is the basis for one of the hypotheses for the extinction of large reptiles with a sharp change in abiotic conditions on the planet: large organisms are less variable than small ones, so they need much more time to adapt. In this regard, radical transformations of nature are dangerous for today existing species, including for the person himself.

1.2.4. Adaptation of organisms to unfavorable environmental conditions

Environmental factors can act as:

· irritants and cause adaptive changes in physiological and biochemical functions;

· limiters , causing the impossibility of existence in these conditions;

· modifiers , causing anatomical and morphological changes in organisms;

· signals , indicating changes in other environmental factors.

In the process of adaptation to unfavorable environmental conditions, organisms were able to develop three main ways to avoid the latter.

Active path– helps to strengthen resistance, the development of regulatory processes that allow all vital functions of organisms to be carried out, despite unfavorable factors.

For example, warm-bloodedness in mammals and birds.

Passive way associated with the subordination of the vital functions of the body to changes in environmental factors. For example, the phenomenon hidden life , accompanied by suspension of vital activity when the reservoir dries up, cold weather, etc., up to the state imaginary death or suspended animation .

For example, dried plant seeds, their spores, as well as small animals (rotifers, nematodes) are able to withstand temperatures below 200 o C. Examples of anabiosis? Winter dormancy of plants, hibernation of vertebrates, preservation of seeds and spores in the soil.

The phenomenon in which there is temporary physiological rest in the individual development of some living organisms, caused by unfavorable environmental factors, is called diapause .

Avoidance of Adverse Effects– the development by the body of such life cycles in which the most vulnerable stages of its development are completed in the most favorable periods of the year in terms of temperature and other conditions.

The usual route for such adaptations is migration.

Evolutionary adaptations of organisms to environmental conditions, expressed in changes in their external and internal characteristics, are called adaptation . There are different types of adaptations.

Morphological adaptations. Organisms have such characteristics external structure, which contribute to the survival and successful functioning of organisms in their usual conditions.

For example, the streamlined body shape of aquatic animals, the structure of succulents, and the adaptations of halophytes.

The morphological type of adaptation of an animal or plant, in which they have an external form that reflects the way they interact with their environment, is called life form of the species . In the process of adaptation to the same environmental conditions, different species can have a similar life form.

For example, whale, dolphin, shark, penguin.

Physiological adaptations manifest themselves in the peculiarities of the enzymatic set in the digestive tract of animals, determined by the composition of the food.

For example, providing moisture through the oxidation of fat in camels.

Behavioral adaptations– manifest themselves in the creation of shelters, movement in order to choose the most favorable conditions, repelling predators, hiding, school behavior, etc.

The adaptations of each organism are determined by its genetic predisposition. The rule of compliance of environmental conditions with genetic predetermination states: as long as the environment surrounding a certain species of organisms corresponds to the genetic capabilities of adaptation of this species to its fluctuations and changes, this species can exist. A sharp and rapid change in environmental conditions can lead to the fact that the speed of adaptive reactions will lag behind the change in environmental conditions, which will lead to the elimination of the species. The above fully applies to humans.

1.2.5. Main abiotic factors.

Let us recall once again that abiotic factors are properties of inanimate nature that directly or indirectly affect living organisms. Slide 3 shows the classification of abiotic factors.

Temperature is the most important climatic factor. Depends on her metabolic rate organisms and their geographical distribution. Any organism is capable of living within a certain temperature range. And although for different types organisms ( eurythermic and stenothermic) these intervals are different, for most of them the zone optimal temperatures, in which vital functions are carried out most actively and efficiently, is relatively small. The range of temperatures in which life can exist is approximately 300 C: from -200 to +100 C. But most species and most of their activity are confined to an even narrower temperature range. Some organisms, especially those in the dormant stage, can survive for at least some time at very low temperatures. Certain types of microorganisms, mainly bacteria and algae, are able to live and reproduce at temperatures close to the boiling point. The upper limit for hot spring bacteria is 88 C, for blue-green algae - 80 C, and for the most resistant fish and insects - about 50 C. As a rule, the upper limit values ​​of the factor are more critical than the lower ones, although many organisms near the upper limits of the tolerance range function more effectively.

Aquatic animals tend to have a narrower range of temperature tolerance than terrestrial animals because the temperature range in water is smaller than on land.

From the point of view of the impact on living organisms, temperature variability is extremely important. Temperatures ranging from 10 to 20 C (average 15 C) do not necessarily affect the body in the same way as a constant temperature of 15 C. The vital activity of organisms that are usually exposed to variable temperatures in nature is suppressed completely or partially or slowed down by the influence constant temperature. Using variable temperature, it was possible to accelerate the development of grasshopper eggs by an average of 38.6% compared to their development at a constant temperature. It is not yet clear whether the accelerating effect is due to temperature fluctuations themselves or to enhanced growth caused by a short-term increase in temperature and not compensated by a slowdown in growth when it decreases.

Thus, temperature is an important and very often limiting factor. Temperature rhythms largely control the seasonal and daily activity of plants and animals. Temperature often creates zonation and stratification in aquatic and terrestrial habitats.

Water physiologically necessary for any protoplasm. From an ecological point of view, it serves as a limiting factor both in terrestrial habitats and in aquatic habitats, where its quantity is subject to strong fluctuations, or where high salinity contributes to the loss of water by the body through osmosis. All living organisms, depending on their need for water, and therefore on differences in habitat, are divided into a number of ecological groups: aquatic or hydrophilic- permanently living in water; hygrophilic- living in very wet habitats; mesophilic- characterized by a moderate need for water and xerophilic- living in dry habitats.

Precipitation and humidity are the main quantities measured when studying this factor. The amount of precipitation depends mainly on the paths and nature of large movements of air masses. For example, winds blowing from the ocean leave most of the moisture on the slopes facing the ocean, resulting in a “rain shadow” behind the mountains, which contributes to the formation of the desert. Moving inland, the air accumulates a certain amount of moisture, and the amount of precipitation increases again. Deserts tend to be located behind high mountain ranges or along coastlines where winds blow from vast inland dry areas rather than from the ocean, such as the Nami Desert in South West Africa. The distribution of precipitation over the seasons is an extremely important limiting factor for organisms. The conditions created by uniformly distributed rainfall are completely different from those created by rainfall during one season. In this case, animals and plants have to endure periods of prolonged drought. As a rule, an uneven distribution of precipitation over the seasons is found in the tropics and subtropics, where the wet and dry seasons are often well defined. In the tropical zone, the seasonal rhythm of humidity regulates the seasonal activity of organisms, similar to the seasonal rhythm of heat and light in the temperate zone. Dew can be a significant and, in places with little rainfall, a very important contribution to total precipitation.

Humidity- a parameter characterizing the content of water vapor in the air. Absolute humidity is the amount of water vapor per unit volume of air. Due to the dependence of the amount of vapor retained by air on temperature and pressure, the concept relative humidity is the ratio of the vapor contained in the air to the saturated vapor at a given temperature and pressure. Since in nature there is a daily rhythm of humidity - an increase at night and a decrease during the day, and its fluctuations vertically and horizontally, this factor, along with light and temperature, plays an important role in regulating the activity of organisms. Humidity modifies the effects of temperature altitude. For example, under humidity conditions close to critical, temperature has a more important limiting effect. Similarly, humidity plays a more critical role if the temperature is close to the extreme values. Large bodies of water significantly soften the climate of land, since water is characterized by a large latent heat of vaporization and melting. There are actually two main types of climate: continental with extremes of temperature and humidity and nautical, which is characterized by less sharp fluctuations, which is explained by the moderating influence of large bodies of water.

Reserve available to living organisms surface water depends on the amount of precipitation in the area, but these values ​​do not always coincide. Thus, using underground sources, where water comes from other areas, animals and plants can receive more water than from receiving it with precipitation. And vice versa, rainwater sometimes it immediately becomes inaccessible to organisms.

Radiation from the Sun represents electromagnetic waves various lengths. It is absolutely necessary for living nature, as it is the main external source of energy. The distribution spectrum of solar radiation energy outside the earth's atmosphere (Fig. 6) shows that about half of the solar energy is emitted in the infrared region, 40% in the visible and 10% in the ultraviolet and x-ray regions.

It must be borne in mind that the spectrum of electromagnetic radiation from the Sun is very wide (Fig. 7) and its frequency ranges affect living matter in different ways. The Earth's atmosphere, including the ozone layer, selectively, that is, selectively in frequency ranges, absorbs the energy of electromagnetic radiation from the Sun and mainly radiation with a wavelength of 0.3 to 3 microns reaches the Earth's surface. Longer and shorter wavelength radiation is absorbed by the atmosphere.

With increasing zenith distance of the Sun, the relative content of infrared radiation increases (from 50 to 72%).

Qualitative signs of light are important for living matter - wavelength, intensity and duration of exposure.

It is known that animals and plants respond to changes in the wavelength of light. Color vision is common in different groups animals are spotted: it is well developed in some species of arthropods, fish, birds and mammals, but in other species of the same groups it may be absent.

The rate of photosynthesis varies with changes in the wavelength of light. For example, when light passes through water, the red and blue parts of the spectrum are filtered out and the resulting greenish light is weakly absorbed by chlorophyll. However, red algae have additional pigments (phycoerythrins) that allow them to harness this energy and live at greater depths than green algae.

Both ground and aquatic plants photosynthesis is related to light intensity by a linear relationship up to optimal level light saturation, which in many cases is followed by a decrease in the rate of photosynthesis at high intensities of direct sunlight. In some plants, such as eucalyptus, photosynthesis is not inhibited by direct sunlight. In this case, compensation of factors takes place, as individual plants and entire communities adapt to different light intensities, becoming adapted to shade (diatoms, phytoplankton) or to direct sunlight.

The length of daylight, or photoperiod, is a "time switch" or trigger mechanism that turns on the sequence physiological processes, leading to growth, flowering of many plants, molting and accumulation of fat, migration and reproduction in birds and mammals and to the onset of diapause in insects. Some higher plants flower as the day length increases (long-day plants), others flower as the day shortens (short-day plants). In many photoperiod-sensitive organisms, the biological clock setting can be altered by experimentally altering the photoperiod.

Ionizing radiation knocks electrons out of atoms and attaches them to other atoms to form pairs of positive and negative ions. Its source is radioactive substances contained in rocks, in addition, it comes from space.

Different types of living organisms differ greatly in their ability to withstand large doses of radiation exposure. For example, a dose of 2 Sv (siver) causes the death of the embryos of some insects at the crushing stage, a dose of 5 Sv leads to sterility of some types of insects, a dose of 10 Sv is absolutely lethal for mammals. Most studies show that rapidly dividing cells are most sensitive to radiation.

The effects of low doses of radiation are more difficult to assess because they can cause long-term genetic and somatic effects. For example, irradiation of a pine tree with a dose of 0.01 Sv per day for 10 years caused a slowdown in growth rate similar to a single dose of 0.6 Sv. An increase in the level of radiation in the environment above the background level leads to an increase in the frequency of harmful mutations.

U higher plants sensitivity to ionizing radiation is directly proportional to size cell nucleus, or rather the volume of chromosomes or DNA content.

In higher animals no such simple relationship has been found between sensitivity and cell structure; For them, the sensitivity of individual organ systems is more important. Thus, mammals are very sensitive even to low doses of radiation due to the fact that the rapidly dividing hematopoietic tissue of the bone marrow is easily damaged by irradiation. Even very low levels of chronically acting ionizing radiation can cause the growth of tumor cells in bones and other sensitive tissues, which may not appear until many years after irradiation.

Gas composition atmosphere is also an important climatic factor (Fig. 8). Approximately 3-3.5 billion years ago, the atmosphere contained nitrogen, ammonia, hydrogen, methane and water vapor, and there was no free oxygen in it. The composition of the atmosphere was largely determined by volcanic gases. Due to the lack of oxygen, there was no ozone screen to block ultraviolet radiation from the Sun. Over time, due to abiotic processes, oxygen began to accumulate in the planet’s atmosphere, and the formation of the ozone layer began. Around the middle of the Paleozoic, oxygen consumption equaled its production; during this period, the O2 content in the atmosphere was close to modern levels - about 20%. Further, from the middle of the Devonian, fluctuations in oxygen content are observed. At the end of the Paleozoic, there was a noticeable decrease in oxygen content and an increase in carbon dioxide content, down to about 5% of modern levels, which led to climate change and, apparently, gave rise to abundant “autotrophic” blooms that created reserves of fossil hydrocarbon fuels. This was followed by a gradual return to an atmosphere low in carbon dioxide and high in oxygen, after which the O2/CO2 ratio remained in a state of so-called oscillatory steady-state equilibrium.

Currently, the Earth's atmosphere has the following composition: oxygen ~21%, nitrogen ~78%, carbon dioxide ~0.03%, inert gases and impurities ~0.97%. Interestingly, the concentrations of oxygen and carbon dioxide are limiting for many higher plants. In many plants, it is possible to increase the efficiency of photosynthesis by increasing the concentration of carbon dioxide, but it is little known that decreasing the concentration of oxygen can also lead to an increase in photosynthesis. In experiments on legumes and many other plants, it was shown that reducing the oxygen content in the air to 5% increases the intensity of photosynthesis by 50%. Nitrogen also plays an extremely important role. This is the most important biogenic element involved in the formation of protein structures of organisms. Wind has a limiting effect on the activity and distribution of organisms.

Wind It can even change the appearance of plants, especially in those habitats, for example in alpine zones, where other factors have a limiting effect. It has been experimentally shown that in open mountain habitats the wind limits plant growth: when a wall was built to protect the plants from the wind, the height of the plants increased. Storms are of great importance, although their effect is purely local. Hurricanes and ordinary winds can transport animals and plants over long distances and thereby change the composition of communities.

Atmosphere pressure, apparently, is not a direct limiting factor, but it is directly related to weather and climate, which have a direct limiting effect.

Water conditions create a unique habitat for organisms, differing from the ground environment primarily in density and viscosity. Density water approximately 800 times, and viscosity approximately 55 times higher than air. Together with density And viscosity the most important physical and chemical properties aquatic environment are: temperature stratification, that is, temperature changes along the depth of a water body and periodic temperature changes over time, and transparency water, which determines the light regime under its surface: photosynthesis of green and purple algae, phytoplankton, and higher plants depends on transparency.

As in the atmosphere, an important role is played gas composition aquatic environment. In aquatic habitats, the amount of oxygen, carbon dioxide and other gases dissolved in water and therefore available to organisms varies greatly over time. In reservoirs with a high content of organic matter, oxygen is a limiting factor of paramount importance. Despite the better solubility of oxygen in water compared to nitrogen, even in the most favorable case, water contains less oxygen than air, approximately 1% by volume. Solubility is affected by water temperature and the amount of dissolved salts: as the temperature decreases, the solubility of oxygen increases, and as the salinity increases, it decreases. The supply of oxygen in water is replenished due to diffusion from the air and photosynthesis of aquatic plants. Oxygen diffuses into water very slowly, diffusion is facilitated by wind and water movement. As already mentioned, the most important factor ensuring the photosynthetic production of oxygen is light penetrating the water column. Thus, the oxygen content of water varies depending on the time of day, season and location.

The carbon dioxide content of water can also vary greatly, but carbon dioxide behaves differently from oxygen, and its ecological role is poorly understood. Carbon dioxide is highly soluble in water; in addition, CO2, formed during respiration and decomposition, as well as from soil or underground sources, enters water. Unlike oxygen, carbon dioxide reacts with water:

to form carbonic acid, which reacts with lime to form carbonates CO22- and bicarbonates HCO3-. These compounds maintain the concentration of hydrogen ions at a level close to neutral value. A small amount of carbon dioxide in water increases the intensity of photosynthesis and stimulates the development processes of many organisms. A high concentration of carbon dioxide is a limiting factor for animals, since it is accompanied by a low oxygen content. For example, if the content of free carbon dioxide in the water is too high, many fish die.

Acidity- the concentration of hydrogen ions (pH) is closely related to the carbonate system. The pH value changes in the range 0? pH? 14: at pH=7 the medium is neutral, at pH<7 - кислая, при рН>7 - alkaline. If acidity does not approach extreme values, then communities are able to compensate for changes in this factor - the community's tolerance to the pH range is very significant. Acidity can serve as an indicator of the overall metabolic rate of a community. Waters with low pH contain few nutrients, so productivity is extremely low.

Salinity- content of carbonates, sulfates, chlorides, etc. - is another significant abiotic factor in water bodies. IN fresh waters There are few salts, of which about 80% are carbonates. The content of minerals in the world's oceans averages 35 g/l. Open ocean organisms are generally stenohaline, whereas coastal brackish water organisms are generally euryhaline. The concentration of salts in body fluids and tissues of most marine organisms is isotonic with the concentration of salts in sea ​​water, so there are no problems with osmoregulation here.

Flow not only greatly influences the concentration of gases and nutrients, but also directly acts as a limiting factor. Many river plants and animals are morphologically and physiologically specially adapted to maintaining their position in the flow: they have well-defined limits of tolerance to the flow factor.

Hydrostatic pressure in the ocean is of great importance. With immersion in water of 10 m, the pressure increases by 1 atm (105 Pa). In the deepest part of the ocean the pressure reaches 1000 atm (108 Pa). Many animals are able to tolerate sudden fluctuations in pressure, especially if they do not have free air in their bodies. Otherwise, gas embolism may develop. High pressures, characteristic of great depths, as a rule, inhibit vital processes.

Soil is the layer of substance lying on top of the rocks of the earth's crust. The Russian scientist and naturalist Vasily Vasilyevich Dokuchaev in 1870 was the first to consider soil as a dynamic, rather than inert, medium. He proved that the soil is constantly changing and developing, and chemical, physical and biological processes take place in its active zone. Soil is formed through a complex interaction of climate, plants, animals and microorganisms. Soviet academician soil scientist Vasily Robertovich Williams gave another definition of soil - it is a loose surface horizon of land capable of producing plant crops. Plant growth depends on the content of essential nutrients in the soil and its structure.

Soil consists of four main structural components: mineral base(usually 50-60% general composition soil), organic matter(up to 10%), air (15-25%) and water (25-30%).

Soil mineral skeleton- This is an inorganic component that was formed from the parent rock as a result of its weathering.

Over 50% of the mineral composition of the soil is occupied by silica SiO2, from 1 to 25% by alumina Al2O3, from 1 to 10% by iron oxides Fe2O3, from 0.1 to 5% by oxides of magnesium, potassium, phosphorus, and calcium. The mineral elements that form the substance of the soil skeleton vary in size: from boulders and stones to sand grains - particles with a diameter of 0.02-2 mm, silt - particles with a diameter of 0.002-0.02 mm and the smallest particles of clay less than 0.002 mm in diameter. Their ratio determines mechanical structure of the soil . It is of great importance for agriculture. Clays and loams, containing approximately equal amounts of clay and sand, are usually suitable for plant growth, as they contain sufficient nutrients and are able to retain moisture. Sandy soils drain faster and lose nutrients due to leaching, but they are more profitable to use for early harvests, since their surface dries out faster in the spring than clay soils, which leads to better warming. As soil becomes more rocky, its ability to hold water decreases.

organic matter soil is formed by the decomposition of dead organisms, their parts and excrement. Organic residues that have not completely decomposed are called litter, and the final product of decomposition - an amorphous substance in which it is no longer possible to recognize the original material - is called humus. Thanks to its physical and chemical properties, humus improves soil structure and aeration, and increases the ability to retain water and nutrients.

Simultaneously with the process of humification, vital elements are transferred from organic compounds to inorganic ones, for example: nitrogen - into ammonium ions NH4+, phosphorus - into orthophosphathions H2PO4-, sulfur - into sulfathions SO42-. This process is called mineralization.

Soil air, like soil water, is located in the pores between soil particles. Porosity increases from clays to loams and sands. Free gas exchange occurs between the soil and the atmosphere, as a result of which the gas composition of both environments is similar. Usually, due to the respiration of the organisms inhabiting it, the soil air contains slightly less oxygen and more carbon dioxide than the atmospheric air. Oxygen is necessary for plant roots, soil animals and decomposer organisms that decompose organic matter into inorganic components. If the process of waterlogging occurs, then soil air is replaced by water and conditions become anaerobic. The soil gradually becomes acidic as anaerobic organisms continue to produce carbon dioxide. The soil, if it is not rich in bases, can become extremely acidic, and this, along with the depletion of oxygen reserves, has an adverse effect on soil microorganisms. Prolonged anaerobic conditions lead to plant death.

Soil particles hold a certain amount of water around them, which determines soil moisture. Part of it, called gravitational water, can freely seep deep into the soil. This leads to the leaching of various minerals from the soil, including nitrogen. Water may also be retained around individual colloidal particles in the form of a thin, strong, cohesive film. This water is called hygroscopic. It is adsorbed on the surface of particles due to hydrogen bonds. This water is the least accessible to plant roots and is the last to be retained in very dry soils. The amount of hygroscopic water depends on the content of colloidal particles in the soil, therefore clay soils there is much more of it - approximately 15% of the soil mass than in sandy soils - approximately 0.5%. As layers of water accumulate around soil particles, it begins to fill first the narrow pores between these particles, and then spreads into increasingly wider pores. Hygroscopic water gradually turns into capillary water, which is held around soil particles by surface tension forces. Capillary water can rise through narrow pores and channels from the level groundwater. Plants easily absorb capillary water, which plays the greatest role in their regular supply of water. Unlike hygroscopic moisture, this water evaporates easily. Fine-textured soils, such as clays, hold more capillary water than coarse-textured soils, such as sands.

Water is necessary for all soil organisms. It enters living cells by osmosis.

Water is also important as a solvent for nutrients and gases absorbed from the aqueous solution by plant roots. It takes part in the destruction of the parent rock underlying the soil and in the process of soil formation.

The chemical properties of the soil depend on the content of minerals that are present in it in the form of dissolved ions. Some ions are poisonous for plants, others are vital. The concentration of hydrogen ions in the soil (acidity) pH>7, that is, on average close to a neutral value. The flora of such soils is especially rich in species. Calcareous and saline soils have pH = 8...9, and peat soils - up to 4. Specific vegetation develops on these soils.

The soil is home to many species of plant and animal organisms that influence its physicochemical characteristics: bacteria, algae, fungi or protozoa, worms and arthropods. Their biomass in various soils equal (kg/ha): bacteria 1000-7000, microscopic fungi - 100-1000, algae 100-300, arthropods - 1000, worms 350-1000.

Synthesis and biosynthesis processes take place in the soil; various chemical reactions transformations of substances associated with the life of bacteria. In the absence of specialized groups of bacteria in the soil, their role is played by soil animals, which convert large plant residues into microscopic particles and thus make organic substances available to microorganisms.

Organic substances are produced by plants using mineral salts, solar energy and water. Thus, the soil loses the minerals that plants took from it. In forests, some nutrients return to the soil through leaf fall. Over a period of time, cultivated plants remove significantly more nutrients from the soil than they return to it. Typically, nutrient losses are replenished by applying mineral fertilizers, which generally cannot be directly used by plants and must be transformed by microorganisms into a biologically accessible form. In the absence of such microorganisms, the soil loses fertility.

The main biochemical processes take place in top layer soil up to 40 cm thick, as it is inhabited by greatest number microorganisms. Some bacteria participate in the transformation cycle of only one element, while others participate in the transformation cycles of many elements. If bacteria mineralize organic matter - decompose organic matter into inorganic compounds, then protozoa destroy excess bacteria. Earthworms, beetle larvae, and mites loosen the soil and thereby contribute to its aeration. In addition, they process organic substances that are difficult to break down.

Abiotic factors in the habitat of living organisms also include relief factors (topography) . The influence of topography is closely related to other abiotic factors, as it can strongly influence local climate and soil development.

The main topographic factor is altitude above sea level. With altitude, average temperatures decrease, daily temperature differences increase, precipitation, wind speed and radiation intensity increase, and decrease Atmosphere pressure and gas concentrations. All these factors influence plants and animals, causing vertical zonation.

Mountain ranges may serve as climate barriers. Mountains also serve as barriers to the spread and migration of organisms and can play the role of a limiting factor in the processes of speciation.

Another topographic factor is slope exposure . In the northern hemisphere, south-facing slopes receive more sunlight, so the light intensity and temperature here are higher than on valley floors and northern-facing slopes. In the southern hemisphere the opposite situation occurs.

An important relief factor is also slope steepness . Steep slopes are characterized by rapid drainage and soil washing away, so the soils here are thin and drier. If the slope exceeds 35b, soil and vegetation usually do not form, but a scree of loose material is created.

Among abiotic factors, special attention deserves fire or fire . Currently, ecologists have come to the unequivocal conclusion that fire should be considered as one of the natural abiotic factors along with climatic, edaphic and other factors.

Fires as an environmental factor are various types and leave behind various consequences. Crown or wild fires, that is, very intense and uncontrollable, destroy all vegetation and all soil organic matter, while the consequences of ground fires are completely different. Crown fires have a limiting effect on most organisms - the biotic community has to start all over again with what little is left, and many years must pass before the site becomes productive again. Ground fires, on the contrary, have a selective effect: for some organisms they are a more limiting factor, for others - a less limiting factor and thus contribute to the development of organisms with high tolerance to fires. In addition, small ground fires complement the action of bacteria, decomposing dead plants and accelerating the conversion of mineral nutrients into a form suitable for use by new generations of plants.

If ground fires occur regularly every few years, little dead wood remains on the ground, which reduces the likelihood of crown fires. In forests that have not burned for more than 60 years, so much combustible litter and dead wood accumulates that when it ignites, a crown fire is almost inevitable.

Plants have developed specialized adaptations to fire, just as they have done to other abiotic factors. In particular, the buds of cereals and pines are hidden from fire in the depths of tufts of leaves or needles. In periodically burned habitats, these plant species benefit because fire promotes their preservation by selectively promoting their flourishing. Broad-leaved species are deprived protective devices from fire, it is destructive for them.

Thus, fires maintain the stability of only some ecosystems. For deciduous and humid tropical forests, the balance of which was formed without the influence of fire, even a ground fire can cause great damage, destroying the humus-rich upper soil horizon, leading to erosion and leaching of nutrients from it.

The question “to burn or not to burn” is unusual for us. The effects of burning can be very different depending on the time and intensity. Through his carelessness, people often cause an increase in the frequency of wild fires, so it is necessary to actively fight for fire safety in forests and recreation areas. In no case does a private person have the right to intentionally or accidentally cause a fire in nature. However, it is necessary to know that the use of fire by specially trained people is part of proper land management.

For abiotic conditions, all the considered laws of the influence of environmental factors on living organisms are valid. Knowledge of these laws allows us to answer the question: why did different ecosystems form in different regions of the planet? The main reason is the unique abiotic conditions of each region.

Populations are concentrated in a certain area and cannot be distributed everywhere with the same density because they have a limited range of tolerance to environmental factors. Consequently, each combination of abiotic factors is characterized by its own types of living organisms. Many variants of combinations of abiotic factors and species of living organisms adapted to them determine the diversity of ecosystems on the planet.

1.2.6. Main biotic factors.

The distribution areas and numbers of organisms of each species are limited not only by the conditions of the external inanimate environment, but also by their relationships with organisms of other species. The immediate living environment of an organism constitutes its biotic environment , and the factors of this environment are called biotic . Representatives of each species are able to exist in an environment where connections with other organisms provide them with normal living conditions.

The following forms of biotic relationships are distinguished. If we designate positive results relationships for an organism with a “+” sign, negative results with a “-” sign, and the absence of results with a “0” sign, then the types of relationships found in nature between living organisms can be presented in the form of a table. 1.

This schematic classification gives general idea about the diversity of biotic relationships. Let's consider characteristics relationships of various types.

Competition is the most comprehensive type of relationship in nature, in which two populations or two individuals influence each other in the struggle for the conditions necessary for life negative .

Competition may be intraspecific And interspecific . Intraspecific competition occurs between individuals of the same species, interspecific competition occurs between individuals of different species. Competitive interaction may concern:

· living space,

· food or nutrients,

· places of shelter and many other vital factors.

Competitive advantages are achieved by species in a variety of ways. Given equal access to a common resource, one type may have an advantage over another due to:

more intensive reproduction

consuming more food or solar energy,

· ability to better protect oneself,

· adapt to more wide range temperatures, light levels or concentrations of certain harmful substances.

Interspecific competition, regardless of what underlies it, can lead either to the establishment of equilibrium between two species, or to the replacement of the population of one species by the population of another, or to the fact that one species will displace another to another place or force it to move to another place. use of other resources. Determined that two species identical in ecological terms and needs cannot coexist in one place and sooner or later one competitor displaces the other. This is the so-called exclusion principle or Gause principle.

Populations of some species of living organisms avoid or reduce competition by moving to another region with acceptable conditions, or by switching to more inaccessible or difficult-to-digest food, or by changing the time or place of food production. For example, hawks feed during the day, owls at night; lions hunt larger animals, and leopards hunt smaller ones; Tropical forests are characterized by the established stratification of animals and birds into tiers.

From Gause's principle it follows that each species in nature occupies a certain unique place. It is determined by the position of the species in space, the functions it performs in the community and its relationship to the abiotic conditions of existence. The place occupied by a species or organism in an ecosystem is called an ecological niche. Figuratively speaking, if a habitat is like the address of organisms of a given species, then an ecological niche is a profession, the role of an organism in its habitat.

A species occupies its ecological niche in order to perform the function it has conquered from other species in its own unique way, thus mastering its habitat and at the same time shaping it. Nature is very economical: even two species occupying the same ecological niche cannot exist sustainably. In competition, one species will displace another.

Ecological niche as functional place a species in a life system cannot remain empty for a long time - this is evidenced by the rule of mandatory filling of ecological niches: an empty ecological niche is always naturally filled. An ecological niche as a functional place of a species in an ecosystem allows a form capable of developing new adaptations to fill this niche, but sometimes this requires considerable time. Often, empty ecological niches that seem empty to a specialist are just a deception. Therefore, a person should be extremely careful with conclusions about the possibility of filling these niches through acclimatization (introduction). Acclimatization is a set of measures to introduce a species into new habitats, carried out in order to enrich natural or artificial communities with organisms useful to humans.

The heyday of acclimatization occurred in the twenties and forties of the twentieth century. However, as time passed, it became obvious that either the experiments of acclimatization of species were unsuccessful, or, worse, brought very negative results - the species became pests or spread dangerous diseases. For example, with the Far Eastern bee acclimatized in the European part, mites were introduced, which were the causative agents of the disease varroatosis, which killed a large number of bee colonies. It could not have been otherwise: new species placed in a foreign ecosystem with an actually occupied ecological niche displaced those who were already doing similar work. New species did not meet the needs of the ecosystem, sometimes had no enemies and therefore could reproduce rapidly.

Classic example This is the introduction of rabbits to Australia. In 1859, rabbits were brought to Australia from England for sport hunting. Natural conditions turned out to be favorable for them, and local predators - dingoes - were not dangerous, since they did not run fast enough. As a result, the rabbits multiplied so much that they destroyed the vegetation of pastures in vast areas. In some cases, the introduction of a natural enemy of an alien pest into the ecosystem brought success in the fight against the latter, but not everything is as simple as it seems at first glance. An introduced enemy will not necessarily focus on exterminating its usual prey. For example, foxes, introduced to Australia to kill rabbits, found easier prey - local marsupials - in abundance, without causing much trouble to the intended victim.

Competitive relations are clearly observed not only at the interspecific, but also at the intraspecific (population) level. As the population grows, when the number of its individuals approaches saturation, internal physiological mechanisms regulation: mortality increases, fertility decreases, stressful situations, fights. Population ecology studies these issues.

Competitive relations are one of the most important mechanisms for the formation of the species composition of communities, the spatial distribution of population species and the regulation of their numbers.

Since the structure of the ecosystem is dominated by food interactions, the most characteristic form of interaction between species in trophic chains is predation , in which an individual of one species, called the predator, feeds on organisms (or parts of organisms) of another species, called the prey, and the predator lives separately from the prey. In such cases, the two species are said to be involved in a predator-prey relationship.

Prey species have evolved whole line defense mechanisms so as not to become easy prey for a predator: the ability to run or fly quickly, the release of chemicals with an odor that repels or even poisons the predator, the possession of thick skin or shell, protective coloration or the ability to change color.

Predators also have several ways of preying on prey. Carnivores, unlike herbivores, are usually forced to pursue and overtake their prey (compare, for example, herbivorous elephants, hippos, cows with carnivorous cheetahs, panthers, etc.). Some predators are forced to run quickly, others achieve their goal by hunting in packs, while others catch mainly sick, wounded and inferior individuals. Another way to provide oneself with animal food is the path that man took - the invention of fishing gear and the domestication of animals.

Biotic factors (factors of living nature) represent various forms of interactions between organisms of the same and different species.
Biological factors influencing the life activity of microorganisms are various relationships between living beings that arise in natural conditions and due to the presence of diverse species. Moreover, the nature of the interaction may be different depending on the characteristics of individual organisms in microbial communities.

Every living organism on Earth is influenced not only by factors of inanimate nature, but also by other living organisms (biotic factors). Animals and plants are not distributed chaotically, but necessarily form certain spatial groupings. The organisms included in them, of course, must have common or similar requirements for the given conditions of existence, on the basis of which corresponding dependencies and relationships are formed between them. This relationship arises primarily on the basis of nutritional needs (connections) and methods of obtaining energy necessary for life processes.

The group of biotic factors is divided into intraspecific and interspecific.

Intraspecific biotic factors
These include factors operating within a species, at the population level.
First of all, this is the population size and its density - the number of individuals of a species in a certain area or volume. Biotic factors of population rank also include the life expectancy of organisms, their fertility, sex ratio, etc., which to one degree or another influence and create the ecological situation both in the population and in the biocenosis. In addition, this group of factors includes behavioral features of many animals (ethological factors), primarily the concept of group effect, used to designate morphological behavioral changes observed in animals of the same species during group living.

Competition as a form of biotic communication between organisms is most clearly manifested at the population level. As the population grows, when its size approaches the saturating environment, internal physiological mechanisms for regulating the size of this population come into play: the mortality of individuals increases, fertility decreases, stressful situations arise, fights, etc. Space and food become the subject of competition.

Competition is a form of relationship between organisms that develops in the struggle for the same environmental conditions.

In addition to intraspecific competition, interspecific, direct and indirect competition are distinguished. The more similar the needs of competitors are, the more intense competition becomes. Plants compete for light and moisture; ungulates, rodents, locusts - for the same food sources (plants); birds of prey of the forest and foxes - for mouse-like rodents.

Interspecific biotic factors and interactions
The effect exerted by one species on another is usually carried out through direct contact between individuals, which is preceded or accompanied by changes in the environment caused by the vital activity of organisms (chemical and physical changes in the environment caused by plants, earthworms, unicellular organisms, fungi, etc.).
The interaction of populations of two or more species has various forms of manifestation, both on a positive and negative basis.

Negative interspecies interactions

Interspecific competition for space, food, light, shelter, etc., i.e., any interaction between two or more populations that is detrimental to their growth and survival. If two species come into competition for common conditions, one of them displaces the other. On the other hand, two species can exist if their ecological requirements are different.
With interspecific competition, representatives of two or more species actively search for the same food resources of the environment. (More broadly, it is any interaction between two or more populations that is detrimental to their growth and survival.)
Competitive relationships between organisms are observed when they share factors, the amount of which is minimal or insufficient for all consumers.

Predation is a form of interaction between organisms in which some prey, kill and eat others. Predators are insectivorous plants (sundews, Venus flytraps), as well as representatives of animals of all types. For example, in the phylum arthropods, predators are spiders, dragonflies, ladybugs; in the phylum chordates, predators are found in the classes of fish (sharks, pike, perches, ruffes), reptiles (crocodiles, snakes), birds (owls, eagles, hawks), and mammals (wolves, jackals, lions, tigers).

A type of predation is cannibalism, or intraspecific predation (eating by individuals of other individuals of their own species). For example, female karakurt spiders eat males after mating, Balkhash perch eats its young, etc. By eliminating the weakest and sickest animals from the population, predators help increase the viability of the species.

From an ecological point of view, such a relationship between two different species is favorable for one of them and unfavorable for the other. The destructive effect is much less if the population has developed together in an environment that is stable for a long period. Moreover, both species adopt such a way of life and such numerical ratios that, instead of the gradual disappearance of the prey or predator, ensure their existence, i.e., biological regulation of populations is carried out.

Antibiosis is a form of antagonistic relationship between organisms, when one of them inhibits the vital activity of others, most often by releasing special substances, so-called antibiotics and phytoncides. Antibiotics are released lower plants(mushrooms, lichens), phytoncides - higher. Thus, the penicillium fungus secretes the antibiotic penicillium, which suppresses the vital activity of many bacteria; lactic acid bacteria that live in the human intestine suppress putrefactive bacteria. Phytoncides that have a bactericidal effect are released by pine, cedar, onions, garlic and other plants. Phytoncides are used in folk medicine and medical practice.

There are different forms of antibiosis:

— Amensalism is a relationship in which one species creates negative conditions for another, but does not itself experience opposition. These are the relationships between molds that produce antibiotics and bacteria, whose vital activity is suppressed or significantly limited.

— Allelopathy is the interaction of plant organisms in phytocenoses — the chemical mutual influence of some plant species on others through specifically acting root secretions, metabolic products of the aerial parts (essential oils, glycosides, phytoncides, which are united under a single term — viburnum). Most often, allelopathy manifests itself in the displacement of one species by another. For example, wheatgrass or other weeds displace or oppress cultivated plants, walnut or oak suppress herbaceous vegetation under the crown with their secretions, etc.
Occasionally, mutual assistance or a beneficial effect from joint growth is observed (vegetable-oat mixture, corn and soybean crops, etc.).

Positive Interspecies Interactions

Symbiosis (mutualism) is a form of relationship between organisms of different systematic groups, in which coexistence is mutually beneficial for individuals of two or more species. Symbionts can be only plants, plants and animals, or only animals. Symbiosis is distinguished by the degree of connection of partners and by their food dependence on each other.

The symbiosis of nodule bacteria with legumes, mycorrhiza of some fungi with tree roots, lichens, termites and flagellated protozoa of their intestines, which destroy the cellulose of their plant foods, are examples of food-dependent symbionts.
Some coral polyps and freshwater sponges form communities with unicellular algae. Such a connection, not for the purpose of feeding one at the expense of the other, but only to obtain protection or mechanical support, is observed in climbing and climbing plants.

An interesting form of cooperation, reminiscent of symbiosis, is the relationship between hermit crabs and sea anemones (the sea anemone uses the crab for movement and at the same time serves as protection for it thanks to its stinging cells), often complicated by the presence of other animals (for example, polychaetnereids) feeding on the leftover food of the crayfish and sea anemone. Bird nests and rodent burrows are inhabited by permanent cohabitants who use the microclimate of the shelters and find food there.
A variety of epiphytic plants (algae, lichens) settle on the bark of tree trunks. This form of relationship between two species, when the activity of one of them provides food or shelter to the other, is called commensalism. This is the unilateral use of one species by another without causing harm to it.

Factors of inanimate nature (abiotic),

Why do you need to be familiar with sociology?

You can perversely represent graphical information through:

– moving the starting point of the line shown on the graph closer to the origin of the coordinate axis; slightly increasing the scale along the Y axis;

– absence of numerical divisions on the Y axis;

– increasing the scale of units along the Y axis and decreasing along the X axis

– biased selection of data

When submitting sociological information The number of respondents, who and where and when were interviewed must be indicated.

ETC. The newspaper “Novy Poglyad” published data from a sociological study on the right to abortion. Students aged 18-19 years took part in the survey. 24 people were interviewed. Percentages are given: 96% believe that freedom sexual relations should be limited if partners do not have contraceptive protection, 4% do not agree with this. But here 4% = 0.96 people. The conclusions: “modern youth have a negative attitude towards the phenomenon of abortion as such.” But are the “youth” and “students” who were surveyed identical?

Abiotic factors:

• climatic
• edaphogenic (soil) - physical and mechanical composition, moisture capacity, density, porosity, air permeability, etc.
• orographic - relief, height above sea level
• chemical - gas composition of air, salt composition of water, acidity, composition of soil solutions, type of ice cover, etc.

Biotic factors:

• phytogenic (plant organisms)
• zoogenic (animals)
• microbiogenic (viruses, bacteria, etc.)
• anthropogenic (human activity).

Classification of the nature of EF variability — primary periodic factors (related to astronomical processes, rotation of the earth, etc.); secondary periodic factors (humidity, temperature, etc.); non-periodic factors (often related to human activities).

Typification of the most important astronomical and geophysical climatic factors:

• radiant energy of the Sun (48% comes in the visible part of the spectrum in the wavelength range 0.4-0.76 microns; 45% - at wavelengths 0.75 microns - 10-3 m; 7% - at L less than 0.4 µm, in the UV range). Amount of energy solar radiation, arriving at the Earth's surface - about 21.1023 kJ (0.14 J/cm2 per year)
• illumination of the earth's surface
• moisture and water content of the atmosphere, the difference between the maximum and absolute humidity of the air - humidity deficiency.

An important environmental parameter: the higher the moisture deficit, the drier and warmer the climate, which contributes to increased fruiting of plants at certain periods of time (growing season).

• precipitation, liquid and solid, is the most important factor determining, among other things, the transboundary transport of pollutants in the atmosphere
• gas composition of the atmosphere (the composition of the earth's atmosphere is relatively constant, it includes mainly nitrogen and oxygen with a small admixture of carbon dioxide and argon, as well as a number of other small gas components)
• earth surface temperature, seasonally frozen and permafrost soils (“permafrost”)
• movement of air masses, wind influence; wind is the most important factor in the transfer and distribution of impurities in the atmospheric air
• atmospheric pressure (normal 1 kPa - 750.1 mm Hg) - the distribution of pressure fields causes circulation processes in the atmosphere, the formation of cyclones and anticyclones
• abiotic factors of the state of the soil cover - soil fertility is determined by physical factors. and chem. soil properties
• abiotic factors of the aquatic environment (71% of the total area of ​​the earth's surface is occupied by the World Ocean) - salinity of water, content of oxygen and carbon dioxide in it.

Biotic factors are divided into direct and indirect . Any living organism is adapted to certain conditions of the OS. The complex of requirements of a particular living organism to the factors of the state of the environment (and the limits of their variability) determine boundaries of distribution (area) and place in the ecosystem. The set of many parameters of the OS state that determine the conditions of existence and the nature of the functional characteristics of the behavior of this organism (its transformation of solar energy, exchange of information with the environment and its own kind, etc.) is ecological niche of this type .

All living organisms exist only in the form populations. A population is a collection of individuals of the same species inhabiting a certain space, within which a certain degree of exchange of genetic information occurs. Each population has a certain structure - age, sexual, spatial. Man, influencing the animal and plant world, always affects populations, changing their parameters and structure, which can lead to degradation and death of populations.

The set of different types of organisms living together and the conditions of their existence, which are in a natural relationship with each other, is called an ecological system ( ecosystem ). To designate such communities, the term “biogeocenosis” is generally accepted (bio - life, geo - Earth, cenosis - community).

Ecosystem- a natural system in which living organisms and their habitat are united into a single functional whole through the metabolism and energy, close cause-and-effect relationship and dependence of its environmental components.

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Ideas about the origin and evolution of life

The idea of ​​the evolution of living nature

The idea of ​​the evolution of living nature arose in modern times as a contrast to creationism (from the Latin “Creation”) - the doctrine of the creation of the world by God from nothing and the immutability of the world created by the creator...

Organic Live nature in the concept of modern natural science

1. The main areas of the World are Space, Biota and Society. Specificity of living matter (Biota) and problems of studying living nature in natural science

living nature organism solar Cosmos (Greek kumpt - order) - in materialistic philosophy (starting from the Pythagorean school) - an ordered Universe (as opposed to chaos) ...

The difference between living and nonliving nature

Differences between living and inanimate nature

All systems of the inorganic world are subject to the principle of least action. In biological and flora This principle is not so widespread...

Field form of matter

8. The main conclusions of Vernadsky’s doctrine of the biosphere. Describe the concepts of “ecosystem”, “biogeocenosis”, “ecological niche”, “biocenosis”. How is their stability determined, what connections exist between organisms in an ecosystem, and how are they modeled?

IN AND. Vernadsky was the first to substantively analyze the foundations of the theory of the functioning of the biosphere, taking into account its systemic quality, the specifics of the organization, and the possibility of development in the “efficiency-optimum” mode. He saw…

The role of symmetry and asymmetry in scientific knowledge

8. Asymmetry as a dividing line between living and inanimate nature

Pasteur established that all amino acids and proteins that make up living organisms are “left-handed,” i.e., they differ in optical properties. He tried to explain the origin of the “leftism” of living nature with asymmetry...

Evolutionary teachings

4. Questions of the origin of the main kingdoms of living nature

The unit of classification for both plants and animals is species. One can, in the most general sense, define a species as a population of individuals possessing similar morphological and functional characters...

Biology
5th grade

§ 5. Environmental factors and their influence on living organisms

1. What does ecology study?
2. Give examples of the influence of environmental conditions on organisms.

Environmental factors. Environmental conditions have a certain impact (positive or negative) on the existence and geographical distribution of living beings. In this regard, environmental conditions are considered as environmental factors.

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 - abiotic, biotic and anthropogenic.

Abiotic factors- these are factors of inanimate nature, primarily climatic: sunlight, temperature, humidity and local: relief, soil properties, salinity, currents, wind, radiation, etc. (Fig. 14). These factors can influence organisms directly, that is, directly, like light or heat, or indirectly, such as relief, which determines the action of direct factors - illumination, moisture, wind and others.

Rice. 14. The influence of light on the development of dandelion:
1 - in bright light; 2 - in low light (in the shade)

Anthropogenic factors- these are all those forms of human activity that affect the natural environment, changing the living conditions of living organisms, or directly affect certain species of plants and animals (Fig. 15).

Rice. 15. Anthropogenic factors

In turn, organisms themselves can influence the conditions of their existence. For example, the presence of vegetation cover softens daily temperature fluctuations near the surface of the earth (under the canopy of a forest or grass) and affects the structure and chemical composition of soils.

All environmental factors have a certain impact on organisms and are necessary for their life.

But especially drastic changes in the external appearance and internal structure of organisms are caused by such factors of inanimate nature as light, temperature, and humidity.

New concepts

Environmental factors: abiotic, biotic, anthropogenic

Questions

1. What are environmental factors?
2. What groups of environmental factors do you know?

Think

What importance do green plants have for life on our planet?

Tasks

To better understand the educational material, learn to work correctly with the text of the textbook.

How to work with textbook text

1. Read the title of the paragraph. It reflects its main content.
2. Read the questions before the text of the paragraph. Try to answer them. This will help you understand the text of the paragraph better.
3. Read the questions at the end of the paragraph. They will help highlight the most important material in the paragraph.
4. Read the text, mentally break it down into “meaningful units,” and make a plan.
5. Sort the text (learn new terms and definitions by heart, remember the main points, be able to prove them and confirm them with examples).
6. Briefly summarize the paragraph.

Chapter summary

Biology is the science of life, of living organisms living on Earth.

Biology studies the structure and vital functions of living organisms, their diversity, and the laws of historical and individual development.

The area of ​​distribution of life makes up a special shell of the Earth - the biosphere.

The branch of biology about the relationships of organisms with each other and with their environment is called ecology.

Biology is closely related to many aspects of human practical activity - agriculture, medicine, various industries, in particular food and light industries, etc.

Living organisms on our planet are very diverse. Scientists distinguish four kingdoms of living beings: Bacteria, Fungi, Plants and Animals.

Every living organism is made up of cells (with the exception of viruses). Living organisms eat, breathe, excrete waste products, grow, develop, reproduce, perceive environmental influences and react to them.

Each organism lives in a specific environment. Everything that surrounds a living being is called its habitat.

There are four main habitats on our planet, developed and inhabited by organisms. These are water, ground-air, soil and the environment inside living organisms.

Each environment has its own specific living conditions to which organisms adapt. This explains the great diversity of living organisms on our planet.

Environmental conditions have a certain impact (positive or negative) on the existence and geographical distribution of living beings. In this regard, environmental conditions are considered as environmental factors.

Conventionally, all environmental factors are divided into three main groups - abiotic, biotic and anthropogenic.