Environmental factors
The interaction between man and his environment has been the object of study in medicine at all times. To assess the effects of various environmental conditions, the term “ecological factor” was proposed, which is widely used in environmental medicine.
A factor (from the Latin factor - doing, producing) is the cause, the driving force of any process, phenomenon, determining its character or certain features.
An environmental factor is any environmental impact that can have a direct or indirect effect on living organisms. An environmental factor is an environmental condition to which a living organism reacts with adaptive reactions.
Environmental factors determine the living conditions of organisms. The conditions of existence of organisms and populations can be considered as regulating environmental factors.
Not all environmental factors (for example, light, temperature, humidity, the presence of salts, the supply of nutrients, etc.) are equally important for the successful survival of the organism. The relationship of an organism with its environment is a complex process in which the weakest, “vulnerable” links can be identified. Those factors that are critical or limiting for the life of an organism are of greatest interest, primarily from a practical point of view.
The idea that the body's endurance is determined by its weakest link
all his needs, was first expressed by K. Liebig in 1840. He formulated a principle that is known as Liebig’s law of the minimum: “The substance found in the minimum controls the harvest and determines the size and stability of the latter over time.”
The modern formulation of J. Liebig’s law is as follows: “The vital capabilities of an ecosystem are limited by those environmental environmental factors, the quantity and quality of which are close to the minimum required by the ecosystem; their reduction leads to the death of the organism or the destruction of the ecosystem.”
The principle, originally formulated by K. Liebig, is currently extended to any environmental factors, but it is supplemented by two restrictions:
Applies only to systems in a stationary state;
Refers not only to one factor, but also to a complex of factors that are different in nature and interact in their influence on organisms and populations.
According to prevailing ideas, a limiting factor is considered to be one in which a minimum relative change in this factor is required to achieve a given (sufficiently small) relative change in the response.
Along with the influence of a deficiency, a “minimum” of environmental factors, the influence of an excess, that is, a maximum of factors such as heat, light, moisture, can also be negative. The idea of the limiting influence of the maximum, along with the minimum, was introduced by V. Shelford in 1913, who formulated this principle as the “law of tolerance”: The limiting factor in the prosperity of an organism (species) can be both the minimum and the maximum of environmental impact, the range between which determines the amount of endurance ( tolerance) of the body in relation to this factor.
The law of tolerance, formulated by V. Shelford, was supplemented by a number of provisions:
Organisms may have a wide range of tolerance for one factor and a narrow range for another;
Organisms with a large range of tolerance are the most widespread;
The range of tolerance for one environmental factor may depend on other environmental factors;
If conditions for one environmental factor are not optimal for a species, then this also affects the range of tolerance for other environmental factors;
The limits of tolerance depend significantly on the state of the body; Thus, the tolerance limits for organisms during the reproductive period or at an early stage of development are usually narrower than for adults;
The range between the minimum and maximum of environmental factors is usually called the limits or range of tolerance. To designate the limits of tolerance to environmental conditions, the terms “eurybiont” - an organism with a wide limit of tolerance - and “stenobiont” - with a narrow one - are used.
At the level of communities and even species, the phenomenon of factor compensation is known, which is understood as the ability to adapt (adapt) to environmental conditions in such a way as to weaken the limiting influence of temperature, light, water and other physical factors. Species with a wide geographic distribution almost always form populations adapted to local conditions - ecotypes. In relation to people, there is the term ecological portrait.
It is known that not all natural environmental factors are equally important for human life. Thus, the most significant are considered to be the intensity of solar radiation, air temperature and humidity, the concentration of oxygen and carbon dioxide in the ground layer of air, and the chemical composition of soil and water. The most important environmental factor is food. To maintain life, for growth and development, reproduction and preservation of the human population, energy is needed, which is obtained from the environment in the form of food.
There are several approaches to classifying environmental factors.
In relation to the body, environmental factors are divided into: external (exogenous) and internal (endogenous). It is believed that external factors, acting as an organism, they themselves are not subject or almost not subject to its influence. These include factors external environment.
External environmental factors in relation to the ecosystem and living organisms are impacts. The reaction of an ecosystem, biocenosis, populations and individual organisms to these impacts is called a response. The nature of the response to exposure determines the body’s ability to adapt to environmental conditions, adapt and acquire resistance to the influence of various environmental factors, including adverse effects.
There is also such a thing as a lethal factor (from Latin - letalis - deadly). This is an environmental factor, the action of which leads to the death of living organisms.
When certain concentrations are reached, many chemical and physical pollutants can be lethal.
Internal factors correlate with the properties of the organism itself and form it, i.e. are included in its composition. Internal factors are the number and biomass of populations, the number of different chemical substances, characteristics of water or soil mass, etc.
According to the criterion of “life,” environmental factors are divided into biotic and abiotic.
The latter include non-living components of the ecosystem and its external environment.
Abiotic environmental factors are components and phenomena of inanimate, inorganic nature that directly or indirectly affect living organisms: climatic, soil and hydrographic factors. The main abiotic environmental factors are temperature, light, water, salinity, oxygen, electromagnetic characteristics, soil.
Abiotic factors are divided into:
Physical
Chemical
Biotic factors (from the Greek biotikos - life) are factors of the living environment that affect the life of organisms.
Biotic factors are divided into:
Phytogenic;
Microbiogenic;
Zoogenic:
Anthropogenic (socio-cultural).
Action biotic factors is expressed in the form of mutual influence of some organisms on the life activity of other organisms and all together on the habitat. There are: direct and indirect relationships between organisms.
In recent decades, the term anthropogenic factors has been increasingly used, i.e. caused by man. Anthropogenic factors are contrasted with natural or natural factors.
An anthropogenic factor is a set of environmental factors and impacts caused by human activity in ecosystems and the biosphere as a whole. An anthropogenic factor is the direct impact of humans on organisms or the impact on organisms through human changes in their habitat.
Environmental factors are also divided into:
1. Physical
Natural
Anthropogenic
2. Chemical
Natural
Anthropogenic
3. Biological
Natural
Anthropogenic
4. Social (socio-psychological)
5. Informational.
Ecological factors are also divided into climatic-geographical, biogeographical, biological, as well as soil, water, atmospheric, etc.
Physical factors.
Physical natural factors include:
Climatic, including local microclimate;
Geomagnetic activity;
Natural background radiation;
Cosmic radiation;
Terrain;
Physical factors are divided into:
Mechanical;
Vibration;
Acoustic;
EM radiation.
Physical anthropogenic factors:
Microclimate settlements and premises;
Pollution of the environment by electromagnetic radiation (ionizing and non-ionizing);
Noise pollution;
Thermal pollution of the environment;
Deformation of the visible environment (changes in terrain and color range in populated areas).
Chemical factors.
Natural chemical factors include:
Chemical composition of the lithosphere:
Chemical composition of the hydrosphere;
Chemical composition of the atmosphere,
Chemical composition of food.
The chemical composition of the lithosphere, atmosphere and hydrosphere depends on the natural composition + release of chemicals as a result of geological processes (for example, hydrogen sulfide impurities as a result of a volcano eruption) and the vital activity of living organisms (for example, impurities in the air of phytoncides, terpenes).
Anthropogenic chemical factors:
Household waste,
Industrial waste,
Synthetic materials used in everyday life, agriculture and industrial production,
Pharmaceutical industry products,
Food additives.
The effect of chemical factors on the human body can be due to:
Excess or deficiency of natural chemical elements in
environment (natural microelementoses);
Excessive content of natural chemical elements in the environment
environment associated with human activities (anthropogenic pollution),
The presence in the environment of chemical elements unusual for it
(xenobiotics) due to anthropogenic pollution.
Biological factors
Biological, or biotic (from the Greek biotikos - life) environmental factors are factors of the living environment that affect the life activity of organisms. The action of biotic factors is expressed in the form of mutual influence of some organisms on the life activity of others, as well as their joint influence on the habitat.
Biological factors:
Bacteria;
Plants;
Protozoa;
Insects;
Invertebrates (including helminths);
Vertebrates.
Social environment
Human health is not determined entirely by biological and psychological properties. Man is a social being. He lives in a society governed by state laws, on the one hand, and on the other, by so-called generally accepted laws, moral guidelines, rules of behavior, including various restrictions etc.
Society becomes more and more complex every year and has an increasing impact on the health of the individual, population, and society. In order to enjoy the benefits of a civilized society, a person must live in strict dependence on the lifestyle accepted in society. For these benefits, often very dubious, the individual pays with part of his freedom, or completely with all his freedom. But a person who is not free and dependent cannot be completely healthy and happy. Some part of human freedom, given to a techno-critical society in exchange for the advantages of civilized life, constantly keeps him in a state of neuropsychic tension. Constant neuropsychic stress and overstrain leads to a decrease in mental stability due to a decrease in the reserve capabilities of the nervous system. In addition, there are many social factors, which can lead to disruption of a person’s adaptive capabilities and the development of various diseases. These include social disorder, uncertainty about the future, and moral oppression, which are regarded as leading risk factors.
Social factors
Social factors are divided into:
1. social system;
2. production sector (industry, agriculture);
3. household sphere;
4. education and culture;
5. population;
6. Zoo and medicine;
7. other spheres.
There is also the following grouping of social factors:
1. Social politics, forming the sociotype;
2. Social security, which has a direct impact on the formation of health;
3. Environmental policy that shapes the ecotype.
Sociotype is an indirect characteristic of the integral social load based on the totality of factors in the social environment.
Sociotype includes:
2. working, rest and living conditions.
Any environmental factor in relation to a person can be: a) favorable - contributing to his health, development and realization; b) unfavorable, leading to his illness and degradation, c) exerting influence of both kinds. It is also equally obvious that in reality most impacts belong to the latter type, having both positive and negative sides.
In ecology there is a law of optimum, according to which any environmental
the factor has certain limits of positive influence on living organisms. The optimal factor is the intensity of the environmental factor that is most favorable for the body.
Impacts may also vary in scale: some affect the entire population of the country as a whole, others - residents of a particular region, others - groups identified by demographic characteristics, and others - an individual citizen.
The interaction of factors is the simultaneous or sequential total impact on organisms of various natural and anthropogenic factors, leading to a weakening, strengthening or modification of the action of an individual factor.
Synergism is the combined effect of two or more factors, characterized by the fact that their combined biological effect significantly exceeds the effect of each component and their sum.
It should be understood and remembered that the main harm to health is caused not by individual environmental factors, but by the total integrated environmental load on the body. It consists of an environmental load and a social load.
Environmental load is a set of factors and conditions of the natural and man-made environment unfavorable to human health. Ecotype is an indirect characteristic of the integral environmental load based on a combination of natural and man-made environmental factors.
Ecotype assessments require hygienic data on:
Quality of housing,
Air,
Soil, food,
Medicines, etc.
Social burden is a set of factors and conditions of social life unfavorable to human health.
Environmental factors shaping public health
1. Climatic and geographical characteristics.
2. Socio-economic characteristics of the place of residence (city, village).
3. Sanitary and hygienic characteristics of the environment (air, water, soil).
4. Peculiarities of nutrition of the population.
5. Characteristics of work activity:
Profession,
Sanitary and hygienic working conditions,
The presence of occupational hazards,
Psychological microclimate at work,
6. Family and household factors:
Family composition,
The nature of the housing
Average income per family member,
Organization of family life.
Distribution of non-working time,
Psychological climate in family.
Indicators characterizing the attitude towards the state of health and determining the activity to maintain it:
1. Subjective assessment of one’s own health (healthy, sick).
2. Determining the place of personal health and the health of family members in the system of individual values (hierarchy of values).
3. Awareness of factors contributing to the preservation and strengthening of health.
4. The presence of bad habits and addictions.
The environment is a unique set of conditions surrounding a living organism, which affect it, perhaps a combination of phenomena, material bodies, energies. An environmental factor is an environmental factor to which organisms have to adapt. This could be a decrease or increase in temperature, humidity or drought, background radiation, human activity, competition among animals, etc. The term “habitat” inherently means the part of nature in which organisms live, among the influences on them direct or indirect influence. These are factors, because they influence the subject in one way or another. The environment is constantly changing, its components are diverse, so animals, plants and even people have to constantly adapt, adapt to new conditions in order to somehow survive and reproduce.
Classification of environmental factors
Living organisms can be affected by both natural and artificial influences. There are several types of classifications, but the most common types of environmental factors are abiotic, biotic and anthropogenic. All living organisms are influenced in one way or another by phenomena and components of inanimate nature. These are abiotic factors that influence the life activity of humans, plants, and animals. They, in turn, are divided into edaphic, climatic, chemical, hydrographic, pyrogenic, orographic.
Light mode, humidity, temperature, atmospheric pressure and precipitation, solar radiation, wind can be attributed to climatic factors. Edaphic influence living organisms through heat, air and its chemical composition and mechanical structure, groundwater level, acidity. Chemical factors are the salt composition of water and the gas composition of the atmosphere. Pyrogenic - the effect of fire on environment. Living organisms are forced to adapt to the terrain, elevation changes, as well as to the characteristics of the water and the content of organic and mineral substances in it.
A biotic environmental factor is the relationship of living organisms, as well as the impact of their relationships on the environment. The influence can be both direct and indirect. For example, some organisms are able to influence the microclimate, change, etc. Biotic factors are divided into four types: phytogenic (plants influence the environment and each other), zoogenic (animals influence the environment and each other), mycogenic ( fungi have an impact) and microbiogenic (microorganisms are at the center of events).
An anthropogenic environmental factor is a change in the living conditions of organisms due to human activity. Actions can be either conscious or unconscious. However, they lead to irreversible changes in nature. Man destroys the soil layer, pollutes the atmosphere and water harmful substances, disrupts natural landscapes. Anthropogenic factors can be divided into four main subgroups: biological, chemical, social and physical. All of them, to one degree or another, affect animals, plants, microorganisms, contribute to the emergence of new species and wipe out old ones from the face of the earth.
The chemical influence of environmental factors on organisms mainly has a negative impact on the environment. To achieve good harvests, people use mineral fertilizers and kill pests with poisons, thereby polluting the soil and water. Transport and industrial waste should also be added here. Physical factors include travel on planes, trains, cars, the use of nuclear energy, and the effect of vibration and noise on organisms. We should also not forget about the relationships between people and life in society. Biological factors include organisms for which humans are a source of food or habitat, and food products should also be included here.
Environmental conditions
Depending on their characteristics and strengths, different organisms react differently to abiotic factors. Environmental conditions change over time and, of course, change the rules of survival, development and reproduction of microbes, animals, and fungi. For example, the life of green plants at the bottom of a reservoir is limited by the amount of light that can penetrate the water column. The number of animals is limited by the abundance of oxygen. Temperature has a huge impact on living organisms, because its decrease or increase affects development and reproduction. During the Ice Age, not only mammoths and dinosaurs became extinct, but also many other animals, birds and plants, thereby changing the environment. Humidity, temperature and light are the main factors that determine the living conditions of organisms.
Light
The sun gives life to many plants; it is not as important for animals as it is for representatives of the flora, but still they cannot do without it. Natural light is a natural source of energy. Many plants are divided into light-loving and shade-tolerant. Different types animals show a negative or positive reaction to light. But the sun has the most important influence on the cycle of day and night, because different representatives of the fauna lead an exclusively nocturnal or diurnal lifestyle. The effect of environmental factors on organisms is difficult to overestimate, but if we talk about animals, then lighting does not affect them directly, it only signals the need to rearrange the processes occurring in the body, due to which living beings respond to changing external conditions.
Humidity
All living beings depend on water very much, because it is necessary for their normal functioning. Most organisms are unable to live in dry air; sooner or later they die. The amount of precipitation falling during a specific period characterizes the humidity of the area. Lichens catch water vapor from the air, plants feed using roots, animals drink water, insects and amphibians are able to absorb it through the integument of the body. There are creatures that obtain liquid through food or through the oxidation of fats. Both plants and animals have many adaptations that allow them to waste water more slowly and save it.
Temperature
Each organism has its own temperature range. If it goes beyond the limits, rising or falling, then he can simply die. The influence of environmental factors on plants, animals and humans can be both positive and negative. Within the temperature range, the organism develops normally, but as soon as the temperature approaches the lower or upper limits, life processes slow down and then stop altogether, which leads to the death of the creature. Some people need cold, some need warmth, and some can live with different conditions environment. For example, bacteria and lichens can withstand a wide range of temperatures; tigers thrive in the tropics and Siberia. But most organisms survive only within narrow temperature limits. For example, corals grow in water at 21°C. Low temperatures or overheating are deadly for them.
In tropical areas, weather fluctuations are almost imperceptible, which cannot be said about the temperate zone. Organisms are forced to adapt to the changing seasons; many make long migrations with the onset of winter, and plants die off altogether. Under unfavorable temperature conditions, some creatures hibernate in order to wait out the period that is unsuitable for them. These are just the main environmental factors; organisms are also affected by atmospheric pressure, wind, and altitude.
The impact of environmental factors on a living organism
The development and reproduction of living beings is significantly influenced by their environment. All groups of environmental factors usually act in a complex manner, and not one at a time. The strength of influence of one depends on the others. For example, lighting cannot be replaced by carbon dioxide, but by changing the temperature, it is quite possible to stop the photosynthesis of plants. All factors influence organisms to one degree or another differently. The leading role may vary depending on the time of year. For example, in the spring, temperature is important for many plants, during the flowering period - soil moisture, and during ripening - air humidity and nutrients. There is also an excess or deficiency of which is close to the limits of the body’s endurance. Their effect manifests itself even when living beings are in a favorable environment.
The influence of environmental factors on plants
For each representative of the flora, the surrounding nature is considered its habitat. It creates all the necessary environmental factors. The habitat provides the plant with the necessary soil and air moisture, lighting, temperature, wind, and the optimal amount of nutrients in the soil. Normal levels of environmental factors allow organisms to grow, develop and reproduce normally. Some conditions can negatively affect plants. For example, if you plant a crop in a depleted field whose soil does not have enough nutrients, it will grow very weak or not grow at all. This factor can be called limiting. But still, most plants adapt to living conditions.
Representatives of the flora growing in the desert adapt to the conditions with the help of a special form. They usually have very long and powerful roots that can go 30 m deep into the ground. A superficial root system is also possible, allowing them to collect moisture during short rains. Trees and bushes store water in trunks (often deformed), leaves, and branches. Some desert inhabitants are able to wait for several months for life-giving moisture, but others are pleasing to the eye for only a few days. For example, ephemerals scatter seeds that germinate only after rain, then the desert blooms early in the morning, and at noon the flowers fade.
The influence of environmental factors on plants also affects them in cold conditions. In the tundras it is very harsh climate, summer is short, you can’t call it warm, but frosts last from 8 to 10 months. The snow cover is insignificant, and the wind completely exposes the plants. Representatives of the flora usually have a superficial root system, thick leaf skin with a waxy coating. Plants accumulate the necessary supply of nutrients during the period when Tundra trees produce seeds that germinate only once every 100 years during the period of the most favorable conditions. But lichens and mosses have adapted to reproduce vegetatively.
Plants allow them to develop in the most different conditions. Representatives of the flora are dependent on humidity and temperature, but most of all they need sunlight. It changes their internal structure and appearance. For example, a sufficient amount of light allows trees to grow a luxurious crown, but bushes and flowers grown in the shade seem depressed and weak.
Ecology and people very often take different paths. Human activities have a detrimental effect on the environment. Job industrial enterprises, forest fires, transport, air pollution from emissions from power plants, factories, water and soil with residues of petroleum products - all this negatively affects the growth, development and reproduction of plants. In recent years, many species of flora have been included in the Red Book, many have become extinct.
The influence of environmental factors on humans
Just two centuries ago, people were much healthier and physically stronger than they are today. Labor activity constantly complicates the relationship between man and nature, but up to a certain point they managed to get along. This was achieved due to the synchronicity of people’s way of life with natural regimes. Each season had its own work spirit. For example, in the spring, peasants plowed the land, sowed cereals and other crops. In the summer they tended crops, grazed livestock, in the fall they harvested crops, in the winter they did household chores and rested. The culture of health was an important element of the general culture of man; the consciousness of the individual changed under the influence of natural conditions.
Everything changed dramatically in the twentieth century, during a period of huge leaps in the development of technology and science. Of course, even before this, human activity significantly harmed the environment, but here all records of negative impact on the environment were broken. The classification of environmental factors allows us to determine what people influence to a greater extent and what to a lesser extent. Humanity lives in a production cycle mode, and this cannot but affect its health. There is no periodicity, people do the same work throughout the year, have little rest, and are constantly in a hurry to get somewhere. Of course, working and living conditions have changed in better side, but the consequences of such comfort are very unfavorable.
Today, water, soil, air are polluted, fallout destroys plants and animals, and damages structures and structures. The thinning of the ozone layer also has frightening consequences. All this leads to genetic changes, mutations, people’s health worsens every year, the number of patients incurable diseases growing inexorably. Humans are greatly influenced by environmental factors; biology studies this impact. Previously, people could die from cold, heat, hunger, thirst, but in our time humanity is “digging its own grave.” Earthquakes, tsunamis, floods, fires - all these natural phenomena take the lives of people, but even more the person harms himself. Our planet is like a ship that is heading towards the rocks at high speed. We need to stop before it’s too late, correct the situation, try to pollute the atmosphere less, and become closer to nature.
Human impact on the environment
People complain about sudden changes in the environment, deterioration in health and general well-being, but they rarely realize that they themselves are to blame for this. Various types of environmental factors have changed over the centuries, there have been periods of warming and cooling, seas have dried up, islands have gone under water. Of course, nature forced people to adapt to conditions, but it did not set strict limits for people and did not act spontaneously and quickly. With the development of technology and science, everything has changed significantly. In one century, humanity has polluted the planet so much that scientists are clutching their heads, not knowing how to change the situation.
We still remember the mammoths and dinosaurs that became extinct during the Ice Age due to a sharp cold snap, and how many species of animals and plants have been wiped off the face of the earth over the past 100 years, how many more are on the verge of extinction? Big cities they are crammed with plants and factories, villages actively use pesticides that pollute the soil and water, and everywhere there is a saturation of transport. There are practically no places left on the planet that can boast of clean air, unpolluted land and water. Deforestation, endless fires, which can be caused not only by abnormal heat, but also by human activity, pollution of water bodies with oil products, harmful exhaust gases in the atmosphere - all this negatively affects the development and reproduction of living organisms and does not improve human health in any way.
“Either a person will reduce the amount of smoke in the air, or smoke will reduce the number of people on Earth,” these are the words of L. Baton. Indeed, the picture of the future looks depressing. The best minds of humanity are struggling with how to reduce the scale of pollution, programs are being created, various cleaning filters are being invented, and alternatives are being sought for those objects that pollute the environment the most today.
Ways to solve environmental problems
Ecology and people today cannot reach a consensus. Everyone in government must work together to solve existing problems. Everything must be done to transfer production to waste-free, closed cycles; on the way to this, energy- and material-saving technologies can be used. Nature management must be rational and take into account the characteristics of the regions. The increase in species of creatures on the verge of extinction requires the immediate expansion of protected areas. Well, and most importantly, the population should be educated, in addition to general environmental education.
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ENVIRONMENTAL FACTORS
Environmental factors - these are certain conditions and elements of the environment that have a specific effect on a living organism. The body reacts to environmental factors with adaptive reactions. Environmental factors determine the living conditions of organisms.
Classification of environmental factors (by origin)
1. Abiotic factors is a set of factors of inanimate nature that influence the life and distribution of living organisms. Among them are:
1.1. Physical factors- such factors, the source of which is a physical condition or phenomenon (for example, temperature, pressure, humidity, air movement, etc.).
1.2. Chemical factors- factors that are determined by the chemical composition of the environment (salinity of water, oxygen content in the air, etc.).
1.3. Edaphic factors(soil) - a set of chemical, physical, mechanical properties of soils and rocks that affect both the organisms for which they are a habitat and the root system of plants (humidity, soil structure, content of nutrients, etc.).
2. Biotic factors - the totality of influences of the life activity of some organisms on the life activity of others, as well as on the inanimate component of the environment.
2.1. Intraspecific interactions characterize the relationships between organisms at the population level. They are based on intraspecific competition.
2.2. Interspecies interactions characterize the relationships between different species, which can be favorable, unfavorable and neutral. Accordingly, we denote the nature of the impact +, - or 0. Then the following types of combinations of interspecies relationships are possible:
00 neutralism- both types are independent and have no effect on each other; Rarely found in nature (squirrel and elk, butterfly and mosquito);
+0 commensalism- one species benefits, while the other has no benefit, no harm either; (large mammals (dogs, deer) serve as carriers of fruits and seeds of plants (burdock), receiving neither harm nor benefit);
-0 amensalism- one species experiences inhibition of growth and reproduction from another; (light-loving herbs growing under the spruce suffer from shading, but the tree itself does not care about this);
++ symbiosis- mutually beneficial relationships:
? mutualism- species cannot exist without each other; figs and the bees that pollinate them; lichen;
? protocooperation- coexistence is beneficial to both species, but is not a prerequisite for survival; pollination of various meadow plants by bees;
- - competition- each type has an effect on the other adverse effect; (plants compete with each other for light and moisture, i.e. when they use the same resources, especially if they are insufficient);
Predation - a predatory species feeds on its prey;
2 .3. Impact on inanimate nature(microclimate). For example, in a forest, under the influence of vegetation cover, a special microclimate or microenvironment is created, where, in comparison with an open habitat, its own temperature and humidity regime is created: in winter it is several degrees warmer, in summer it is cooler and more humid. A special microenvironment is also created in the crown of trees, in burrows, in caves, etc.
3. Anthropogenic factors - factors generated by human activity and affecting the natural environment: direct human impact on organisms or impact on organisms through human changes in their habitat (environmental pollution, soil erosion, forest destruction, desertification, reduction of biological diversity, climate change, etc. ). The following groups of anthropogenic factors are distinguished:
1. change in the structure of the earth's surface;
2. changes in the composition of the biosphere, the cycle and balance of the substances included in it;
3. changes in the energy and heat balance of individual areas and regions;
4. changes made to the biota.
There is another classification of environmental factors. Most factors change qualitatively and quantitatively over time. For example, climatic factors (temperature, illumination, etc.) change throughout the day, season, and year. Factors whose changes are repeated regularly over time are called periodic . These include not only climatic, but also some hydrographic ones - ebbs and flows, some ocean currents. Factors that arise unexpectedly (volcanic eruption, predator attack, etc.) are called non-periodic .
Patterns of action of environmental factors
The influence of environmental factors on living organisms is characterized by certain quantitative and qualitative patterns.
The German agrochemist J. Liebig, observing the effect of chemical fertilizers on plants, discovered that limiting the dose of any of them leads to a slowdown in growth. These observations allowed the scientist to formulate a rule called the law of the minimum (1840).
Law of the minimum : the vital capabilities of an organism (harvest, production) depend on a factor, the quantity and quality of which is close to the minimum required by the organism or ecosystem (despite the fact that other factors may be present in excess and not fully used). ecological adaptation abiotic soil
The same substances, when in excess, also reduce yield. Continuing his research, in 1913 the American biologist V. Shelford formulated the law of tolerance.
Law of tolerance: The vital capabilities of an organism are determined by environmental factors, which are not only at a minimum, but also at a maximum, that is, both a deficiency and an excess of an environmental factor can determine the viability of an organism. For example, a lack of water makes it difficult for the plant to assimilate minerals, and an excess causes rotting and acidification of the soil.
Factors that hinder the development of the body due to their deficiency or excess compared to the need (optimal content) are called limiting .
In the nature of the impact of environmental factors on the body and in the responses, a number of general patterns, which fit into a certain general scheme of the action of an environmental factor on the vital activity of an organism (Fig. 3).
In Fig. 3, the abscissa axis shows the intensity of the factor (for example, temperature, illumination, etc.), and the ordinate axis shows the body’s response to the influence of an environmental factor (for example, growth rate, productivity, etc.).
The range of action of the environmental factor is limited by threshold values (points A and D), at which the existence of the organism is still possible. These are the lower (A) and upper (D) boundaries of life. Points B and C correspond to the boundaries of normal life.
The action of the environmental factor is characterized by the presence of three zones formed by characteristic threshold points:
1 - optimum zone - zone of normal life activity,
2 - stress zones (minimum zone and maximum zone) - zones of dysfunction due to a lack or excess of a factor,
3 - death zone.
Rice. 3. Scheme of the action of an environmental factor on living organisms:
1 - optimum, zone of normal life activity, 2 - zone of reduced vital activity (depression), 3 - zone of death
With a minimum and maximum factor, the body can live, but does not reach its peak (stress zones). The range between the minimum and maximum of a factor determines the amount of tolerance (stability) to a given factor ( tolerance - the body’s ability to tolerate deviations in the values of environmental factors from optimal values for it).
Adaptation of living organisms to environmental factors
Adaptation - This is the process of adaptation of the body to certain environmental conditions. Individuals that are not adapted to given or changing conditions die out.
Main types of adaptation:
Behavioral adaptation (hiding in victims, tracking prey in predators);
Physiological adaptation (wintering - hibernation, bird migration);
Morphological adaptation (changes in the life forms of plants and animals - plants in the desert do not have leaves, aquatic organisms have a body structure adapted for swimming).
Ecological niche
Ecological niche - this is the totality of all factors and environmental conditions within which a species can exist in nature.
Fundamental ecological niche determined by the physiological characteristics of organisms.
Implemented niche represents the conditions under which a species actually occurs in nature; it is part of a fundamental niche.
Abiotic factors of the terrestrial environment (climatic)
Temperature - the most important limiting factor. Any organism can live only within a certain temperature range. Temperature endurance limits vary.
Hot springs of Kamchatka, t > 80°C - insects, mollusks.
Antarctica, t up to -70°C - algae, lichens, penguins.
Light is the primary source of energy, without which life on Earth is impossible. Light is involved in the process of photosynthesis, ensuring that vegetation creates organic compounds from inorganic ones. This is its most important ecological function.
The region of physiologically active radiation is l = 380-760 nm (visible part of the spectrum).
Infrared region of the spectrum l > 760 nm (source of thermal energy).
Ultraviolet region of the spectrum l< 380 нм.
The lighting intensity is important for living organisms, especially plants. Thus, in relation to illumination, plants are divided into light-loving (cannot tolerate shadows), shade-loving (cannot tolerate bright sunlight), shade-tolerant (have a wide range of tolerance). The intensity of light is affected by the latitude of the area, time of day and year, as well as the inclination of the surface relative to the horizontal.
Organisms are physiologically adapted to the cycle of day and night. Almost all living organisms have daily rhythms of activity associated with the change of day and night.
Organisms are adapted to seasonal changes in day length (beginning of flowering, ripening).
Amount of precipitation. For living organisms, the most important limiting factor is the distribution of precipitation by season. This factor determines the division of ecosystems into forest, steppe and desert. So, if the amount of precipitation is > 750 mm/year - forests are formed, 250-750 mm/year - steppes (cereals),< 250 мм/год - пустыни (кактусы 50-100 мм/год). Maximum amount precipitation is typical for tropical rainforests 2500 mm/year, minimal amount recorded in the Sahara Desert - 0.18 mm/year.
Precipitation is one of the links in the water cycle on Earth. Precipitation patterns determine the migration of pollutants in the atmosphere.
Other climatic factors that have a significant impact on living organisms include humidity air environment, movement of air masses (wind), atmospheric pressure, altitude above sea level, terrain.
Abiotic factors of soil cover
Abiotic factors of soil cover are called edaphic (from the Greek. edaphos- the soil).
The soil - this is a special natural formation that arose as a result of changes in the surface layer of the lithosphere by the combined influence of water, air and living organisms. Soil is a link between biotic and abiotic factors of biogeocenosis.
The most important property of soil is fertility, that is, its ability to satisfy the needs of plants for nutrients, air and other factors, and on this basis to ensure the yield of agricultural crops, as well as the productivity of wild forms of vegetation.
Soil properties
? physical characteristics : structure, porosity, temperature, heat capacity, humidity.
Typically, the particles that make up the soil are divided into clay (smaller than 0.002 mm in diameter), silt (0.002-0.02 mm), sand (0.02-2.0 mm) and gravel (greater than 2 mm). The mechanical structure of the soil is very important for agriculture, determining the effort required to cultivate the soil, the required amount of watering, etc. Good soils contain approximately equal amounts of sand and clay; they are called loams. The predominance of sand makes the soil more crumbly and easier to work; on the other hand, it retains water and nutrients less well. Clay soils drain poorly, are soggy and sticky, but contain many nutrients and do not leach. Soil rockiness (presence of large particles) affects the wear of agricultural implements.
? Chemical characteristics : environmental reaction, degree of salinity, chemical composition.
pH = -logH, pH = 7 - neutral environment, pH< 7 - кислая, рН >7 - alkaline.
According to the chemical composition of the mineral component, the soil consists of sand and silt (a form of quartz (silica)SiO2 with additions of silicates (Al4(SiO4)3, Fe4(SiO4)3, Fe2SiO4) and clay minerals (crystalline compounds of silicates and aluminum hydroxide)).
? Biological characteristics : living organisms (worms) that inhabit the soil (fungi, bacteria, algae).
Soil profile
Soil formation occurs from top to bottom, this is reflected in the soil profile. As a result of the movement and transformation of substances, the soil is divided into separate layers or horizons, the combination of which makes up the soil profile. Three horizons are distinguished in the soil profile (Fig. 4).
1. A- humus-accumulative horizon (up to several tens of cm), which is divided into three subhorizons:
A0 - litter (turf): freshly fallen leaves and decomposing plant and animal remains;
A1 - humus horizon: a mixture of partially decomposed organic matter, living organisms and inorganic substances;
A2 - eluvial horizon (leaching): salts and organic substances are leached, washed out and washed into the B horizon.
2. IN- illuvial horizon (washing out): here organic substances are processed by decomposers into mineral form, accumulation of mineral substances (carbonates, gypsum, clay minerals) occurs.
3. WITH- parent rock (mountain).
Abiotic factors of the aquatic environment
Water occupies the predominant part of the earth's surface - 71%.
Density. The aquatic environment is very unique, for example, the density of water is 800 times greater than the density of air, and its viscosity is 55 times. This affects the lifestyle and life forms of its inhabitants.
Heat capacity. Possessing high heat capacity, water is the main receiver and accumulator of solar energy.
Mobility helps maintain relative homogeneity of physical and chemical properties.
Temperature. Temperature stratification (temperature changes with depth) affects the placement of living organisms in water and the transfer and dispersion of impurities. There are periodic changes in water temperature (annual, daily, seasonal).
Transparency water is determined by the light regime above the water surface and depends on the content of suspended substances. Plant photosynthesis depends on transparency.
Salinity. The content of carbonates, sulfates, and chlorides in water is of great importance for living organisms. IN fresh water ah, there are few salts, mostly carbonates. Sulfates and chlorides predominate in sea waters. The salt content in the waters of the World Ocean is 35 g/l, in the Black Sea - 19, in the Caspian Sea - 14, in the Dead Sea - 240 g/l.
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Any properties or components of the external environment that influence organisms are called environmental factors. Light, heat, salt concentration in water or soil, wind, hail, enemies and pathogens - all these are environmental factors, the list of which can be very large.
Among them there are abiotic related to inanimate nature, and biotic related to the influence of organisms on each other.
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 strength of each of them is constantly changing. We live in a world with variable conditions, and only in certain places planets, the values of some factors are more or less constant (in the depths of caves, at the bottom of the oceans).
The law of optimum is expressed in the fact that any environmental factor has certain limits of positive influence on living organisms.
When deviating from these limits, the sign of the effect changes to the opposite. For example, animals and plants do not tolerate extreme heat and severe frost; Medium temperatures are optimal. Likewise, drought and constant heavy rains equally unfavorable for the crop. 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 the species changes with a gradual increase in the influence of the factor (Fig. 13).
Figure 13. Scheme of the action of environmental factors on living organisms. 1,2 - critical points
(to enlarge the image, click on the picture)
In the center under the curve - optimum zone. At optimal values factor, organisms actively grow, feed, and reproduce. The more the factor value deviates to the right or left, i.e. towards decreasing or increasing the force of action, the less favorable it is for organisms. The curve reflecting vital activity descends sharply on either side of the optimum. There are two pessimum zones. When the curve intersects the horizontal axis, there are two critical points. These are the values of the factor that organisms can no longer withstand, beyond which death occurs. The distance between critical points shows the degree of tolerance of organisms to changes in the factor. Conditions close to critical points are especially difficult for survival. Such conditions are called extreme.
If you draw optimum curves for a factor, such as temperature, for different species, they will not coincide. Often what is optimal for one species is pessimistic for another or even lies outside the critical points. Camels and jerboas could not live in the tundra, and reindeer and lemmings could not live in the hot southern deserts.
The ecological diversity of species is also manifested in the position of critical points: for some they are close together, for others they are widely spaced. This means that a number of species can live only in very stable conditions, with minor changes in environmental factors, while others can withstand wide fluctuations. For example, the impatiens plant withers if the air is not saturated with water vapor, and feather grass tolerates changes in humidity well and does not die even in drought.
Thus, the law of optimum shows us that for each type there is its own measure of the influence of each factor. Both a decrease and an increase in exposure beyond this measure leads to the death of organisms.
For understanding the relationship of species with the environment, it is no less important limiting factor law.
In nature, organisms are simultaneously influenced by a whole complex of environmental factors in different combinations and with different strengths. It is not easy to isolate the role of each of them. Which one means more than the others? What we know about the law of optimum allows us to understand that there are no entirely positive or negative, important or secondary factors, but everything depends on the strength of each influence.
The law of the limiting factor states that the most significant factor is the one that deviates the most from the optimal values for the body.
The survival of individuals in this particular period depends on it. At other periods of time, other factors may become limiting, and throughout life, organisms encounter a variety of restrictions on their life activity.
Agricultural practice constantly faces the laws of optimum and limiting factors. For example, the growth and development of wheat, and consequently the yield, are constantly limited either by critical temperatures, or by a lack or excess of moisture, or by a lack of mineral fertilizers, and sometimes such catastrophic impacts as hail and storms. It takes a lot of effort and money to maintain optimal conditions for crops, and at the same time, first of all, compensate or mitigate the effect of limiting factors.
The habitats of different species are surprisingly varied. Some of them, for example, some small mites or insects, spend their entire lives inside the leaf of a plant, which is the whole world for them, others master vast and varied spaces, such as reindeer, whales in the ocean, migratory birds.
Depending on where representatives of different species live, they are affected by different sets of environmental factors. On our planet there are several basic living environments, very different in terms of living conditions: water, ground-air, soil. Habitats are also the organisms themselves in which others live.
Aquatic living environment. All aquatic inhabitants, despite differences in lifestyle, must be adapted to the main features of their environment. These features are determined, first of all, by the physical properties of water: its density, thermal conductivity, and ability to dissolve salts and gases.
Density water determines its significant buoyant force. This means that the weight of organisms in water is lightened and it becomes possible to lead a permanent life in the water column without sinking to the bottom. Many species, mostly small, incapable of fast active swimming, seem to float in the water, being suspended in it. The collection of such small aquatic inhabitants is called plankton. Plankton includes microscopic algae, small crustaceans, fish eggs and larvae, jellyfish and many other species. Planktonic organisms are carried by currents and are unable to resist them. The presence of plankton in water makes possible the filtration type of nutrition, i.e., straining, using various devices, small organisms and food particles suspended in water. It is developed in both swimming and sessile bottom animals, such as crinoids, mussels, oysters and others. A sedentary lifestyle would be impossible for aquatic inhabitants if there were no plankton, and this, in turn, is possible only in an environment with sufficient density.
The density of water makes active movement in it difficult, so fast-swimming animals, such as fish, dolphins, squids, must have strong muscles and a streamlined body shape. Due to the high density of water, pressure increases greatly with depth. Deep-sea inhabitants are able to withstand pressure that is thousands of times higher than on the land surface.
Light penetrates water only to a shallow depth, so plant organisms can only exist in the upper horizons of the water column. Even in the cleanest seas, photosynthesis is possible only to depths of 100-200 m. At greater depths there are no plants, and deep-sea animals live in complete darkness.
Temperature in water bodies it is softer than on land. Due to the high heat capacity of water, temperature fluctuations in it are smoothed out, and aquatic inhabitants do not face the need to adapt to severe frosts or forty-degree heat. Only in hot springs can the water temperature approach the boiling point.
One of the difficulties in the life of aquatic inhabitants is limited amount of oxygen. Its solubility is not very high and, moreover, decreases greatly when the water is contaminated or heated. Therefore, in reservoirs there are sometimes freezes - mass death inhabitants due to a lack of oxygen, which occurs for various reasons.
Salt composition The environment is also very important for aquatic organisms. Marine species cannot live in fresh waters, and freshwater animals cannot live in the seas due to disruption of cell function.
Ground-air environment of life. This environment has a different set of features. It is generally more complex and varied than aquatic. It has a lot of oxygen, a lot of light, sharper temperature changes in time and space, significantly weaker pressure drops and moisture deficiency often occurs. Although many species can fly, and small insects, spiders, microorganisms, seeds and plant spores are carried by air currents, feeding and reproduction of organisms occurs on the surface of the ground or plants. In such a low-density environment as air, organisms need support. Therefore, terrestrial plants have developed mechanical tissues, and terrestrial animals have a more pronounced internal or external skeleton than aquatic animals. The low density of air makes it easier to move around in it.
M. S. Gilyarov (1912-1985), a prominent zoologist, ecologist, academician, founder of extensive research into the world of soil animals, passive flight was mastered by about two-thirds of land inhabitants. Most of them are insects and birds.
Air is a poor conductor of heat. This makes it easier to conserve heat generated inside organisms and maintain constant temperature in warm-blooded animals. The very development of warm-bloodedness became possible in a terrestrial environment. The ancestors of modern aquatic mammals - whales, dolphins, walruses, seals - once lived on land.
Land dwellers have a wide variety of adaptations related to providing themselves with water, especially in dry conditions. In plants, this is a powerful root system, a waterproof layer on the surface of leaves and stems, and the ability to regulate water evaporation through stomata. In animals, these are also different structural features of the body and integument, but, in addition, appropriate behavior also contributes to maintaining water balance. They may, for example, migrate to watering holes or actively avoid particularly dry conditions. Some animals can live their entire lives on dry food, such as jerboas or the well-known clothes moth. In this case, the water needed by the body arises due to the oxidation of food components.
In life terrestrial organisms big role Many other environmental factors also play a role, such as air composition, winds, and the topography of the earth’s surface. Weather and climate are especially important. The inhabitants of the land-air environment must be adapted to the climate of the part of the Earth where they live and tolerate variability in weather conditions.
Soil as a living environment. Soil is a thin layer of land surface, processed by the activity of living beings. Solid particles are permeated in the soil with pores and cavities, filled partly with water and partly with air, so small aquatic organisms can also inhabit the soil. The volume of small cavities in the soil is a very important characteristic of it. In loose soils it can be up to 70%, and in dense soils it can be about 20%. In these pores and cavities or on the surface of solid particles live a huge variety of microscopic creatures: bacteria, fungi, protozoa, roundworms, arthropods. Larger animals make passages in the soil themselves. The entire soil is penetrated by plant roots. Soil depth is determined by the depth of root penetration and the activity of burrowing animals. It is no more than 1.5-2 m.
The air in soil cavities is always saturated with water vapor, and its composition is enriched in carbon dioxide and depleted in oxygen. In this way, the living conditions in the soil resemble the aquatic environment. On the other hand, the ratio of water and air in soils is constantly changing depending on weather conditions. Temperature fluctuations are very sharp at the surface, but quickly smooth out with depth.
The main feature of the soil environment is the constant supply of organic matter, mainly due to dying plant roots and falling leaves. It is a valuable source of energy for bacteria, fungi and many animals, so soil is the most vibrant environment. Her hidden world is very rich and diverse.
By the appearance of different species of animals and plants, one can understand not only what environment they live in, but also what kind of life they lead in it.
If we have in front of us a four-legged animal with highly developed muscles of the thighs on the hind legs and much weaker muscles on the front legs, which are also shortened, with a relatively short neck and a long tail, then we can confidently say that this is a ground jumper, capable for fast and maneuverable movements, inhabitant of open spaces. The famous Australian kangaroos, desert Asian jerboas, African jumpers, and many other jumping mammals - representatives of various orders living on different continents - look like this. They live in steppes, prairies, and savannas - where fast movement on the ground is the main means of escape from predators. The long tail serves as a balancer during fast turns, otherwise the animals would lose their balance.
The hips are strongly developed on the hind limbs and in jumping insects - locusts, grasshoppers, fleas, psyllid beetles.
Compact body with short tail and short limbs, of which the front ones are very powerful and look like a shovel or rake, blind eyes, a short neck and short, as if trimmed, fur tell us that this is an underground animal that digs holes and galleries. This could be a forest mole, a steppe mole rat, an Australian marsupial mole, and many other mammals leading a similar lifestyle.
Burrowing insects - mole crickets are also distinguished by their compact, stocky body and powerful forelimbs, similar to a reduced bulldozer bucket. In appearance they resemble a small mole.
All flying species have developed wide planes - the wings of birds, bats, insects or spreading folds of skin on the sides of the body, like in gliding flying squirrels or lizards.
Organisms that disperse through passive flight, with air currents, are characterized by small sizes and very diverse shapes. However, everyone has one common feature- strong surface development compared to body weight. This is achieved in different ways: due to long hairs, bristles, various outgrowths of the body, its lengthening or flattening, lightening specific gravity. This is what small insects and flying fruits of plants look like.
External similarity that arises among representatives of different unrelated groups and species as a result of a similar lifestyle is called convergence.
It affects mainly those organs that directly interact with the external environment, and is much less pronounced in the structure internal systems- digestive, excretory, nervous.
The shape of a plant determines the characteristics of its relationship with the external environment, for example, the way it tolerates the cold season. Trees and tall shrubs have the highest branches.
The form of a vine - with a weak trunk entwining other plants, can be found in both woody and herbaceous species. These include grapes, hops, meadow dodder, and tropical vines. Wrapping around the trunks and stems of upright species, liana-like plants bring their leaves and flowers to the light.
In similar climatic conditions on different continents, similar appearance vegetation, which consists of different, often completely unrelated species.
The external form, reflecting the way it interacts with the environment, is called the life form of the species. Different species may have similar life forms, if they lead close image life.
The life form is developed during the centuries-long evolution of species. Those species that develop with metamorphosis naturally change their life form during the life cycle. Compare, for example, a caterpillar and an adult butterfly or a frog and its tadpole. Some plants can take on different life forms depending on their growing conditions. For example, linden or bird cherry can be both an upright tree and a bush.
Communities of plants and animals are more stable and more complete if they include representatives of different life forms. This means that such a community makes fuller use of environmental resources and has more diverse internal connections.
The composition of life forms of organisms in communities serves as an indicator of the characteristics of their environment and the changes occurring in it.
Engineers who design aircraft carefully study the different life forms of flying insects. Models of machines with flapping flight have been created, based on the principle of movement in the air of Diptera and Hymenoptera. Modern technology has constructed walking machines, as well as robots with lever and hydraulic methods of movement, like animals of different life forms. Such vehicles are capable of moving on steep slopes and off-road.
Life on Earth developed under conditions of a regular cycle of day and night and alternation of seasons due to the rotation of the planet around its axis and around the Sun. The rhythm of the external environment creates periodicity, i.e., repeatability of conditions in the life of most species. Both critical periods, difficult for survival, and favorable ones are repeated regularly.
Adaptation to periodic changes in the external environment is expressed in living beings not only by a direct reaction to changing factors, but also in hereditarily fixed internal rhythms.
Circadian rhythms. Circadian rhythms adapt organisms to the cycle of day and night. In plants intensive growth, the blooming of flowers is timed to a certain time of day. Animals change their activity greatly throughout the day. Based on this feature, diurnal and nocturnal species are distinguished.
The daily rhythm of organisms is not only a reflection of changing external conditions. If you place a person, or animals, or plants in a constant, stable environment without a change of day and night, then the rhythm of life processes is maintained, close to the daily rhythm. The body seems to live according to its internal clock, counting down time.
The circadian rhythm can affect many processes in the body. In humans, about 100 physiological characteristics are subject to the daily cycle: heart rate, breathing rhythm, secretion of hormones, secretions of the digestive glands, blood pressure, body temperature and many others. Therefore, when a person is awake instead of sleeping, the body is still tuned to the night state and sleepless nights have a bad effect on health.
However, circadian rhythms do not appear in all species, but only in those in whose lives the change of day and night plays an important ecological role. The inhabitants of caves or deep waters, where there is no such change, live according to different rhythms. And even among land dwellers, not everyone exhibits daily periodicity.
In experiments under strictly constant conditions, Drosophila fruit flies maintain a daily rhythm for tens of generations. This periodicity is inherited in them, as in many other species. So profound are the adaptive reactions associated with the daily cycle of the external environment.
Disturbances in the body's circadian rhythm during night work, space flights, scuba diving, etc. represent a serious medical problem.
Annual rhythms. Annual rhythms adapt organisms to seasonal changes in conditions. In the life of species, periods of growth, reproduction, molting, migration, and deep rest naturally alternate and repeat in such a way that critical time organisms are found in the most stable state. The most vulnerable process - reproduction and rearing of young animals - occurs during the most favorable season. This periodicity of changes in physiological state throughout the year is largely innate, that is, it manifests itself as an internal annual rhythm. If, for example, Australian ostriches or the wild dog dingo are placed in a zoo in the Northern Hemisphere, their breeding season will begin in the fall, when it is spring in Australia. The restructuring of internal annual rhythms occurs with great difficulty, over a number of generations.
Preparation for reproduction or overwintering is a long process that begins in organisms long before the onset of critical periods.
Sharp short-term changes in weather (summer frosts, winter thaws) usually do not disrupt the annual rhythms of plants and animals. The main environmental factor to which organisms respond in their annual cycles is not random changes in weather, but photoperiod- changes in the ratio of day and night.
The length of daylight hours naturally changes throughout the year, and it is these changes that serve as an accurate signal of the approach of spring, summer, autumn or winter.
The ability of organisms to respond to changes in day length is called photoperiodism.
If the day shortens, species begin to prepare for winter; if it lengthens, they begin to actively grow and reproduce. In this case, what is important for the life of organisms is not the change in the length of day and night itself, but its signal value, indicating impending profound changes in nature.
As you know, the length of the day greatly depends on geographic latitude. In the northern hemisphere, summer days are much shorter in the south than in the north. Therefore, southern and northern species react differently to the same amount of day change: southern species begin to reproduce when more short day than the northern ones.
ENVIRONMENTAL FACTORS
Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000
- Topic 18. "Habitat. Environmental factors." Chapter 1; pp. 10-58
- Topic 19. "Populations. Types of relationships between organisms." chapter 2 §8-14; pp. 60-99; Chapter 5 § 30-33
- Topic 20. "Ecosystems." chapter 2 §15-22; pp. 106-137
- Topic 21. "Biosphere. Cycles of matter." Chapter 6 §34-42; pp. 217-290
Remember:
What is meant by the natural and social nature of man?
Answer. Man, like all other living beings, is part of nature and a product of natural, biological evolution. Man, like animals, is characterized by instincts and vital needs. There are also biologically programmed patterns of human behavior as a specific biological species. Biological factors that determine existence and development are determined by the set of genes in humans, the balance of hormones produced, metabolism and other biological factors. All this characterizes a person as a biological being and determines his biological nature. But at the same time, it differs from any animal and, above all, in the following features:
Produces its own environment (housing, clothing, tools), but the animal does not produce, only uses what is available;
Changes the world not only according to the measure of its utilitarian needs, but also according to the laws of knowledge of this world, as well as according to the laws of morality and beauty, but an animal can change its world only according to the needs of its species;
It can act not only according to need, but also in accordance with the freedom of its will and imagination, while the action of an animal is oriented exclusively towards satisfying a physical need (hunger, procreation instinct, group, species instincts, etc.);
Capable of acting universally, an animal only in relation to specific circumstances;
He makes his life activity an object (he treats it meaningfully, purposefully changes it, plans it), but the animal is identical to his life activity and does not distinguish it from himself.
What factors are called biotic and abiotic?
Answer. Abiotic factors - conditions of the atmosphere, sea and fresh water, soil or bottom sediments) and physical or climatic (temperature, pressure, wind, currents, radiation regime, etc.). The structure of the surface (relief), geological and climatic differences of the earth's surface create a huge variety of abiotic factors that play a different role in the life of species of animals, plants and microorganisms that have adapted to them.
What is the diversity of anthropogenic factors?
Answer. Anthropogenic factors are very diverse. By nature, anthropogenic factors are divided into:
Mechanical - pressure from car wheels, deforestation, obstacles to the movement of organisms, and the like;
Physical - heat, light, electric field, color, changes in humidity, etc.;
Chemical - the action of various chemical elements and their compounds;
Biological - the influence of introduced organisms, breeding of plants and animals, forest planting and the like.
Landscape - artificial rivers and lakes, beaches, forests, meadows, etc.
Based on the time of origin and duration of action, anthropogenic factors are divided into the following groups:
Factors produced in the past: a) those that have ceased to act, but its consequences are still felt now (destruction of certain types of organisms, excessive grazing, etc.); b) those that continue to operate in our time (artificial relief, reservoirs, introduction, etc.);
Factors that are produced in our time: a) those that act only at the moment of production (radio waves, noise, light); b) those that operate for a certain time and after the end of production (persistent chemical pollution, cut down forest, etc.).
Questions after § 9
Describe the patterns of action of environmental factors on the body?
The ability of organisms to adapt to a certain range of variability in environmental factors is called ecological plasticity. This feature is one of the most important properties of all living things: by regulating their life activity in accordance with changes in environmental conditions, organisms acquire the ability to survive and leave offspring. There are upper and lower limits to endurance.
Environmental factors affect a living organism jointly and simultaneously. Moreover, the effect of one factor depends on the strength with which and in what combination other factors act simultaneously. This pattern is called the interaction of factors. For example, heat or frost is easier to bear in dry rather than humid air. The rate of water evaporation from plant leaves (transpiration) is much higher if the air temperature is high and the weather is windy.
In some cases, the deficiency of one factor is partially compensated by the strengthening of another. The phenomenon of partial interchangeability of the effects of environmental factors is called the compensation effect. For example, the wilting of plants can be stopped both by increasing the amount of moisture in the soil and by decreasing the air temperature, which reduces transpiration; in deserts, the lack of precipitation is to a certain extent compensated for by increased relative humidity at night; In the Arctic, long daylight hours in summer compensate for the lack of heat.
At the same time, none of the environmental factors necessary for the body can be completely replaced by another. The absence of light makes plant life impossible, despite the most favorable combinations of other conditions. Therefore, if the value of at least one of the vital environmental factors approaches a critical value or goes beyond its limits (below the minimum or above the maximum), then, despite the optimal combination of other conditions, the individuals are threatened with death. Such factors are called limiting factors.
What is the optimum, the limits of endurance?
Answer. Environmental factors have quantitative expression. In relation to each factor, one can distinguish an optimum zone (a zone of normal life activity), a zone of depression and the limits of the body’s endurance. Optimum is the amount of environmental factor at which the intensity of vital activity of organisms is maximum. In the zone of oppression, the vital activity of organisms is suppressed. Beyond the limits of endurance, the existence of an organism is impossible. There are lower and upper limits of endurance.
What factor is called the limiting factor?
Answer. An environmental factor, the quantitative value of which goes beyond the endurance of the species, is called a limiting factor. This factor will limit the spread of the species even if all other factors are favorable. Limiting factors determine the geographic range of a species. Human knowledge of the limiting factors for a particular type of organism allows, by changing environmental conditions, to either suppress or stimulate its development.
