Morphological adaptations - adaptations of animals to environmental factors. Behavioral adaptations of organisms to the action of environmental factors. Examples of Types of Behavioral Adaptation

Behavioral adaptations - these are behaviors developed in the process of evolution of individuals that allow them to adapt and survive in specific environmental conditions.

Typical example - a bear's winter sleep.

Examples can also be 1) creation of shelters, 2) movement in order to select optimal temperature conditions, especially in extreme temperatures. 3) the process of tracking and pursuing prey in predators, and in victims - in operational responses (for example, hiding).

Common for animals way of adapting to unfavorable periods- migration (saiga antelopes annually go for the winter to the southern semi-deserts with little snow, where winter grasses are more nutritious and accessible due to the dry climate. However, in the summer, semi-desert grass stands quickly burn out, so for the breeding season saigas move to the wetter northern steppes).

Examples: 4) behavior when searching for food and a sexual partner, 5) mating, 6) feeding offspring, 7) avoiding danger and protecting life in the event of a threat, 8) aggression and threatening postures, 9) caring for offspring, which increases the likelihood of survival of the cubs, 10) uniting in packs, 11) imitation of injury or death in the event of a threat of attack.

21.Life forms as a result of the adaptation of organisms to the action of a complex of environmental factors. Classification of life forms of plants according to K. Raunkier, I.G. Serebryakov, animals according to D.N. Kashkarov.

The term “life form” was introduced in the 80s by E. Warming. He understood life form as “the form in which the vegetative body of a plant (individual) is in harmony with the external environment throughout its entire life, from cradle to grave, from seed to death.” This is a very deep definition.

Life forms as types of adaptive structures demonstrate 1) a variety of ways of adaptation of different plant species even to the same conditions,

2) the possibility of similarity of these pathways in completely unrelated plants belonging to different species, genera, and families.

->The classification of life forms is based on the structure of vegetative organs and reflects the convergent paths of ecological evolution.

According to Raunkier: applied his system to elucidate the relationship between plant life forms and climate.

He identified an important feature that characterizes the adaptation of plants to endure unfavorable seasons - cold or dry.

This sign is the position of renewal buds on the plant in relation to the level of the substrate and snow cover. Raunkier linked this to protecting the kidneys during unfavorable times of the year.

1)phanerophytes- the buds overwinter or endure the dry period “openly”, high above the ground (trees, shrubs, woody vines, epiphytes).

-> they are usually protected by special bud scales, which have a number of devices for preserving the growth cone and young leaf primordia enclosed in them from loss of moisture.

2)chamephytes- buds are located almost at the soil level or no higher than 20-30 cm above it (shrubs, subshrubs, creeping plants). In cold and cold climates, these buds very often receive additional protection in winter, in addition to their own bud scales: they overwinter under the snow.

3)cryptophytes- 1) geophytes - buds are located in the ground at a certain depth (they are divided into rhizomatous, tuberous, bulbous),

2) hydrophytes - buds overwinter under water.

4)hemicryptophytes- usually herbaceous plants; their renewal buds are at the soil level or are buried very shallowly, in the litter formed by leaf litter - another additional “cover” for the buds. Among the hemicryptophytes, Raunkier distinguishes “ irotogeiicryptophytes» with elongated shoots that die annually to the base, where renewal buds are located, and rosette hemicryptophytes, in which shortened shoots can overwinter entirely at the soil level.

5)therophytes- special group; these are annuals in which all vegetative parts die off by the end of the season and there are no overwintering buds left - these plants are renewed the next year from seeds that overwinter or survive a dry period on or in the soil.

According to Serebryakov:

Having used and generalized the classifications proposed at different times, he proposed calling a unique habitus a life form - (characteristic form, appearance org-ma) specific groups of plants that arise as a result of growth and development in specific conditions - as an expression of adaptability to these conditions.

The basis of its classification is a sign of the life span of the entire plant and its skeletal axes.

A. Woody plants

1.Trees

2.Shrubs

3. Shrubs

B. Semi-woody plants

1.Subshrubs

2.Subshrubs

B. Terrestrial herbs

1.Polycarpic herbs (perennial herbs, bloom many times)

2.Monocarpic herbs (live for several years, bloom once and die)

G. Aquatic herbs

1.Amphibian grasses

2.Floating and underwater grasses

The life form of a tree turns out to be an adaptation to conditions most favorable for growth.

IN forests of the humid tropics- most tree species (up to 88% in the Amazon region of Brazil), and in the tundra and highlands there are no real trees. In area taiga forests trees are represented by only a few species. No more than 10–12% of total number species are trees and in the flora of the temperate forest zone of Europe.

According to Kashkarov:

I. Floating forms.

1. Purely aquatic: a) nekton; b) plankton; c) benthos.

2. Semi-aquatic:

a) diving; b) not diving; c) only those that extract food from water.

II. Burrowing forms.

1. Absolute diggers (spending their entire lives underground).

2.Relative excavators (coming to the surface).

III. Ground forms.

1. Those who do not make holes: a) running; b) jumping; c) crawling.

2. Making holes: a) running; b) jumping; c) crawling.

3. Animals of the rocks.

IV. Woody climbing forms.

1. Not coming down from trees.

2.Only those who climb trees.

V. Air forms.

1. Foraging for food in the air.

2.Looking for food from the air.

In appearance In birds, their association with specific types of habitats and the nature of their movement when obtaining food are manifested.

1) woody vegetation;

2) open spaces of land;

3) swamps and shallows;

4) water spaces.

In each of these groups, specific forms are distinguished:

a) obtain food by climbing (pigeons, parrots, woodpeckers, passerines)

b) foraging for food in flight (long-winged birds, in forests - owls, nightjars, over water - tubenoses);

c) feeding while moving on the ground (on open spaces- cranes, ostriches; forest - most chicken; in swamps and shallows - some passerines, flamingos);

d) obtaining food by swimming and diving (loons, copepods, geese, penguins).

22. The main environments of life and their characteristics: ground-air and water.

Ground-air- most animals and plants live there.
It is characterized by 7 main abiotic factors:

1.Low air density makes it difficult to maintain the shape of the body and provokes an image of the support system.

EXAMPLE: 1. Aquatic plants do not have mechanical tissues: they appear only in terrestrial forms. 2.Animals necessarily have a skeleton: a hydroskeleton (in roundworms), or the exoskeleton (in insects), or the internal skeleton (in mammals).

The low density of the environment facilitates the movement of animals. Many terrestrial species are capable of flight.(birds and insects, but there are also mammals, amphibians and reptiles). Flight is associated with searching for prey or settling. Land dwellers live only on the Earth, which serves as their support and attachment point. Due to active flight in such organisms modified forelimbs And pectoral muscles are developed.

2) Mobility of air masses

*provides the essence of aeroplankton. It includes pollen, seeds and fruits of plants, small insects and arachnids, spores of fungi, bacteria and lower plants.

This ecological group of organisms adapted due to a large variety of wings, outgrowths, webs, or due to its very small size.

* way of pollinating plants by wind - anemophily- har-n for birch, spruce, pine, nettle, cereals and sedges.

*dispersal by wind: poplar, birch, ash, linden, dandelion, etc. The seeds of these plants have parachutes (dandelions) or wings (maple).

3) Low pressure, norm=760 mm. Pressure differences, compared with aquatic habitats, are very small; Thus, at h=5800 m it is only half of its normal value.

=>almost all land inhabitants are sensitive to strong pressure changes, i.e. they are stenobionts in relation to this factor.

The upper limit of life for most vertebrates is 6000 m, because pressure decreases with altitude, which means the solubility of o in the blood decreases. To maintain a constant concentration of O 2 in the blood, the respiratory rate must increase. However, we exhale not only CO 2, but also water vapor, so frequent breathing should invariably lead to dehydration of the body. This simple dependence is not typical only for rare species organisms: birds and some invertebrates, mites, spiders and springtails.

4) Gas composition It is characterized by a high content of O 2: it is more than 20 times higher than in the aquatic environment. This allows animals to have a very high metabolic rate. Therefore, only on land could it arise homeothermicity- the ability to maintain a constant t of the body due to internal energy. Thanks to homeothermy, birds and mammals can maintain vital activity in the harshest conditions

5) Soil and terrain are very important, first of all, for plants. For animals, the structure of the soil is more important than its chemical composition.

*For ungulates that perform long migrations on dense ground, adaptation is a decrease in the number of fingers and a => decrease in the amount of support.

*Inhabitants of quicksand typically require an increase in the support surface (fan-toed gecko).

*Soil density is also important for burrowing animals: prairie dogs, marmots, gerbils and others; some of them develop digging limbs.

6) Significant water shortage on land provokes the development of various adaptations aimed to save water in the body:

Development of respiratory organs capable of absorbing O2 from the air of the integument (lungs, trachea, pulmonary sacs)

Development of waterproof covers

The change will highlight the system and metabolic products (urea and uric acid)

Internal fertilization.

In addition to providing water, precipitation also plays an ecological role.

*Snow reduces temperature fluctuations to a depth of 25 cm. Deep snow protects plant buds. For black grouse, hazel grouse and tundra partridges, snowdrifts are a place to spend the night, that is, at 20–30 o frost at a depth of 40 cm, it remains ~0 ° C.

7) Temperature more variable than aquatic. ->many land dwellers eurybiont to this factor, i.e. they are capable of beings in a wide range of temperatures and demonstrate very different methods of thermoregulation.

Many species of animals that live in areas with snowy winters molt in the fall, changing the color of their fur or feathers to white. Perhaps this seasonal molting of birds and animals is also an adaptation - camouflage coloring, which is typical for the snowshoe hare, weasel, arctic fox, tundra partridge and others. However, not all white animals change color seasonally, which reminds us of the indefinability and impossibility of considering all properties of the body as beneficial or harmful.

Water. Water covers 71% of the earth's S or 1370 m3. The main mass of water is in the seas and oceans - 94-98%, polar ice contains about 1.2% of water and a very small proportion - less than 0.5%, in fresh waters of rivers, lakes and swamps.

The aquatic environment is home to about 150,000 species of animals and 10,000 plants, which is only 7 and 8% of the total number of species on Earth. Thus, evolution on land was much more intense than in water.

In the seas and oceans, as in the mountains, it is expressed vertical zoning.

All inhabitants of the aquatic environment can be divided into three groups.

1) Plankton- countless accumulations of tiny organisms that cannot move on their own and are carried by currents in the upper layer of sea water.

It consists of plants and living organisms - copepods, eggs and larvae of fish and cephalopods, + unicellular algae.

2) Nekton- a large number of organizations floating freely in the depths of the world's oceans. The largest of them are blue whales and giant shark feeding on plankton. But among the inhabitants of the water column there are also dangerous predators.

3) Benthos- inhabitants of the bottom. Some deep-sea inhabitants lack vision, but most can see in dim light. Many inhabitants lead an attached lifestyle.

Adaptations of hydrobionts to high water density:

Water has high density (800 times the density of air) and viscosity.

1) Plants have very poorly developed or absent mechanical tissues“The water itself is their support. Most are characterized by buoyancy. Har-no active vegetative propagation, the development of hydrochory - the removal of flower stalks above the water and the distribution of pollen, seeds and spores by surface currents.

2) The body has a streamlined shape and is lubricated with mucus, which reduces friction when moving. Developed devices to increase buoyancy: accumulations of fat in tissues, swim bladders in fish.

Passively swimming animals have outgrowths, spines, appendages; the body is flattened, and skeletal organs are reduced.

Different ways movement: bending of the body, with the help of flagella, cilia, reactive mode of movement (cephalomolluscs).

In benthic animals, the skeleton disappears or is poorly developed, body size increases, vision reduction is common, and tactile organs develop.

Adaptations of hydrobionts to water mobility:

Mobility is determined by the ebb and flow of the tides, sea ​​currents, storms, different levels of elevations of river beds.

1) In flowing waters, plants and animals are firmly attached to stationary underwater objects. The bottom surface is primarily a substrate for them. These are green and diatom algae, water mosses. From animals - gastropods, barnacles + hide in crevices.

2) Different body shapes. Fish that live in flowing waters have a round body in diameter, while fish that live near the bottom have a flat body.

Adaptations of hydrobionts to water salinity:

Natural bodies of water have a certain chemical composition. (carbonates, sulfates, chlorides). In fresh water bodies, the salt concentration is not >0.5 g/, in the seas - from 12 to 35 g/l (ppm). With a salinity of more than 40 ppm, the reservoir is called g hyperhaline or oversalted.

1) *In fresh water (hypotonic environment), osmoregulation processes are well expressed. Hydrobionts are forced to constantly remove water that penetrates them, they homoiosmotic.

*In salt water (isotonic environment), the concentration of salts in the bodies and tissues of hydrobionts is the same as the concentration of salts dissolved in water - they poikiloosmotic. ->inhabitants of salt water bodies have not developed osmoregulatory functions, and they were unable to populate fresh water bodies.

2) Aquatic plants are able to absorb water and nutrients from water - “broth”, with their entire surface Therefore, their leaves are strongly dissected and their conducting tissues and roots are poorly developed. The roots serve to attach to the underwater substrate.

Typically maritime and typically freshwater species – stenohaline, cannot tolerate changes in water salinity. Euryhaline species A little. They are common in brackish waters (pike, bream, mullet, coastal salmon).

Adaptation of hydrobionts to the composition of gases in water:

In water, O2 is the most important environmental factor. Its source is the atmosphere and photosynthetic plants.

When stirring the water and decreasing t, the O2 content increases. *Some fish are very sensitive to O2 deficiency (trout, minnow, grayling) and therefore prefer cold mountain rivers and streams.

*Other fish (crucian carp, carp, roach) are unpretentious to O2 content and can live at the bottom of deep reservoirs.

*Many aquatic insects, mosquito larvae, and pulmonate mollusks are also tolerant of the O2 content in water, because from time to time they rise to the surface and swallow fresh air.

Carbon dioxide in water it is enough - almost 700 times more than in air. It is used in plant photosynthesis and goes into the formation of calcareous skeletal structures of animals (mollusk shells).

Identifying limiting factors is of great importance practical significance. Primarily for growing crops: applying the necessary fertilizers, liming soils, land reclamation, etc. allow you to increase productivity, increase soil fertility, and improve the existence of cultivated plants.

1. What do the prefixes “evry” and “steno” mean in the name of the species? Give examples of eurybionts and stenobionts.

Wide range of species tolerance in relation to abiotic environmental factors, they are designated by adding the prefix to the name of the factor "every. The inability to tolerate significant fluctuations in factors or a low limit of endurance is characterized by the prefix "stheno", for example, stenothermic animals. Small changes in temperature have little effect on eurythermal organisms and can be disastrous for stenothermic organisms. A species adapted to low temperatures is cryophilic(from the Greek krios - cold), and to high temperatures - thermophilic. Similar patterns apply to other factors. Plants can be hydrophilic, i.e. demanding on water and xerophilic(dry-tolerant).

In relation to content salts in the habitat they distinguish eurygals and stenogals (from the Greek gals - salt), to illumination – euryphotes and stenophotes, in relation to to the acidity of the environment– euryionic and stenoionic species.

Since eurybiontism makes it possible to populate a variety of habitats, and stenobiontism sharply narrows the range of places suitable for the species, these 2 groups are often called eury – and stenobionts. Many terrestrial animals living in continental climates are able to withstand significant fluctuations in temperature, humidity, and solar radiation.

Stenobionts include- orchids, trout, Far Eastern hazel grouse, deep-sea fish).

Animals that are stenobiont in relation to several factors at the same time are called stenobionts in the broad sense of the word ( fish that live in mountain rivers and streams that cannot tolerate too high temperatures and low oxygen levels, inhabitants of the humid tropics, unadapted to low temperatures and low air humidity).

Eurybionts include Colorado potato beetle, mouse, rats, wolves, cockroaches, reeds, wheatgrass.

1. Adaptation of living organisms to environmental factors. Types of adaptation.

Adaptation ( from lat. adaptation - adaptation ) - this is an evolutionary adaptation of environmental organisms, expressed in changes in their external and internal characteristics.

Individuals that for some reason have lost the ability to adapt, in conditions of changes in the regimes of environmental factors, are doomed to elimination, i.e. to extinction.

Types of adaptation: morphological, physiological and behavioral adaptation.

Morphology is the study of the external forms of organisms and their parts.

1.Morphological adaptation- this is an adaptation manifested in adaptation to fast swimming in aquatic animals, to survival in conditions of high temperatures and lack of moisture - in cacti and other succulents.

2.Physiological adaptations lie in the peculiarities of the enzymatic set in the digestive tract of animals, determined by the composition of the food. For example, inhabitants of dry deserts are able to meet their moisture needs through the biochemical oxidation of fats.

3.Behavioral (ethological) adaptations manifest themselves in the most various forms. For example, there are forms of adaptive behavior of animals aimed at ensuring optimal heat exchange with the environment. Adaptive behavior can manifest itself in the creation of shelters, movements in the direction of more favorable, preferred temperature conditions, selection of places with optimal humidity or illumination. Many invertebrates are characterized by a selective attitude towards light, manifested in approaches or distances from the source (taxis). Daily and seasonal movements of mammals and birds are known, including migrations and flights, as well as intercontinental movements of fish.

Adaptive behavior can manifest itself in predators during the hunt (tracking and pursuing prey) and in their victims (hiding, confusing the trail). The behavior of animals during the mating season and during feeding of offspring is extremely specific.

There are two types of adaptation to external factors. Passive way of adaptation– this adaptation according to the type of tolerance (tolerance, endurance) consists in the emergence of a certain degree of resistance to a given factor, the ability to maintain functions when the strength of its influence changes.. This type of adaptation is formed as a characteristic species property and is realized at the cellular-tissue level. The second type of device is active. In this case, the body, with the help of specific adaptive mechanisms, compensates for changes caused by the influencing factor in such a way that the internal environment remains relatively constant. Active adaptations are adaptations of the resistant type (resistance) that maintain the homeostasis of the internal environment of the body. An example of a tolerant type of adaptation is poikilosmotic animals, an example of a resistant type is homoyosmotic animals. .

1. Define population. Name the main group characteristics of the population. Give examples of populations. Growing, stable and dying populations.

Population- a group of individuals of the same species interacting with each other and jointly inhabiting a common territory. The main characteristics of the population are as follows:

1. Number - total individuals in a certain area.

2. Population density - the average number of individuals per unit area or volume.

3. Fertility - the number of new individuals appearing per unit of time as a result of reproduction.

4. Mortality - the number of dead individuals in a population per unit of time.

5. Population growth is the difference between birth and death rates.

6. Growth rate - average increase per unit of time.

The population is characterized by a certain organization, the distribution of individuals over the territory, the ratio of groups by sex, age, and behavioral characteristics. It is formed, on the one hand, on the basis of general biological properties species, and on the other hand, under the influence of abiotic environmental factors and the population of other species.

The population structure is unstable. The growth and development of organisms, the birth of new ones, death from various causes, changes in environmental conditions, an increase or decrease in the number of enemies - all this leads to changes in various ratios within the population.

Increasing or growing population– this is a population in which young individuals predominate, such a population is growing in number or is being introduced into the ecosystem (for example, third world countries); More often, the birth rate exceeds the death rate and the population grows to the point where an outbreak may occur mass reproduction. This is especially true for small animals.

With a balanced intensity of fertility and mortality, a stable population. In such a population, mortality is compensated by growth and its number, as well as its range, are kept at the same level . Stable population – This is a population in which the number of individuals of different ages varies evenly and has the character of a normal distribution (as an example, we can cite the population of Western European countries).

Declining (dying) population is a population in which the mortality rate exceeds the birth rate . A declining or dying population is a population in which older individuals predominate. An example is Russia in the 90s of the 20th century.

However, it also cannot shrink indefinitely.. At a certain population level, the mortality rate begins to fall and fertility begins to increase . Ultimately, a declining population, having reached a certain minimum size, turns into its opposite - a growing population. The birth rate in such a population gradually increases and at a certain point equalizes the mortality rate, that is, the population becomes stable for a short period of time. In declining populations, old individuals predominate, no longer able to reproduce intensively. Such age structure indicates unfavorable conditions.

1. Ecological niche of an organism, concepts and definitions. Habitat. Mutual arrangement of ecological niches. Human ecological niche.

Any type of animal, plant, or microbe is capable of normally living, feeding, and reproducing only in the place where evolution has “prescribed” it for many millennia, starting with its ancestors. To designate this phenomenon, biologists borrowed term from architecture - the word “niche” and they began to say that each type of living organism occupies its own ecological niche in nature, unique to it.

Ecological niche of an organism- this is the totality of all its requirements for environmental conditions (the composition and regimes of environmental factors) and the place where these requirements are satisfied, or the entire set of biological characteristics And physical parameters environment that determines the conditions of existence of a particular species, its transformation of energy, the exchange of information with the environment and its own kind.

The concept of ecological niche is usually used when using the relationships of ecologically similar species belonging to the same trophic level. The term “ecological niche” was proposed by J. Grinnell in 1917 to characterize the spatial distribution of species, that is, the ecological niche was defined as a concept close to the habitat. C. Elton defined an ecological niche as the position of a species in a community, emphasizing the special importance of trophic relationships. A niche can be imagined as part of an imaginary multidimensional space (hypervolume), the individual dimensions of which correspond to the factors necessary for the species. The more the parameter varies, i.e. adaptability of a species to a particular environmental factor, the wider his niche. A niche can also increase in the case of weakened competition.

Habitat of the species- this is the physical space occupied by a species, organism, community, it is determined by the totality of conditions of the abiotic and biotic environment that ensure the entire development cycle of individuals of the same species.

The habitat of the species can be designated as "spatial niche".

The functional position in the community, in the pathways of processing matter and energy during nutrition is called trophic niche.

Figuratively speaking, if a habitat is, as it were, the address of organisms of a given species, then a trophic niche is a profession, the role of an organism in its habitat.

The combination of these and other parameters is usually called an ecological niche.

Ecological niche(from the French niche - a recess in the wall) - this place occupied by a biological species in the biosphere includes not only its position in space, but also its place in trophic and other interactions in the community, as if the “profession” of the species.

Fundamental ecological niche(potential) is an ecological niche in which a species can exist in the absence of competition from other species.

Ecological niche realized (real) – ecological niche, part of the fundamental (potential) niche that a species can defend in competition with other species.

Based on the relative position, the niches of the two species are divided into three types: non-adjacent ecological niches; niches touching but not overlapping; touching and overlapping niches.

Man is one of the representatives of the animal kingdom, a biological species of the class of mammals. Despite the fact that it has many specific properties (intelligence, articulate speech, labor activity, biosociality, etc.), it has not lost its biological essence and all the laws of ecology are valid for it to the same extent as for other living organisms . The man has his own, inherent only to him, ecological niche. The space in which a person’s niche is localized is very limited. As a biological species, humans can only live within the landmass of the equatorial belt (tropics, subtropics), where the hominid family arose.

1. Formulate Gause's fundamental law. What is a "life form"? What ecological (or life) forms are distinguished among the inhabitants of the aquatic environment?

Both in the plant and animal worlds, interspecific and intraspecific competition is very widespread. There is a fundamental difference between them.

Gause's rule (or even law): two species cannot simultaneously occupy the same ecological niche and therefore necessarily displace each other.

In one of the experiments, Gause bred two types of ciliates - Paramecium caudatum and Paramecium aurelia. They regularly received as food a type of bacteria that does not reproduce in the presence of paramecium. If each type of ciliate was cultivated separately, then their populations grew according to a typical sigmoid curve (a). In this case, the number of paramecia was determined by the amount of food. But when they coexisted, paramecia began to compete and P. aurelia completely replaced its competitor (b).

Rice. Competition between two closely related species of ciliates occupying a common ecological niche. a – Paramecium caudatum; b – P. aurelia. 1. – in one culture; 2. – in a mixed culture

When ciliates were grown together, after some time only one species remained. At the same time, the ciliates did not attack individuals of another type and did not emit harmful substances. The explanation is that the species studied had different growth rates. The faster reproducing species won the competition for food.

When breeding P. caudatum and P. bursaria no such displacement occurred; both species were in equilibrium, with the latter concentrated on the bottom and walls of the vessel, and the former in free space, i.e., in a different ecological niche. Experiments with other types of ciliates have demonstrated the pattern of relationships between prey and predator.

Gauseux's principle is called the principle exception competitions. This principle leads either to the ecological separation of closely related species or to a decrease in their density where they are able to coexist. As a result of competition, one of the species is displaced. Gause's principle plays a huge role in the development of the niche concept, and also forces ecologists to seek answers to a number of questions: How do similar species coexist? How large must the differences between species be for them to coexist? How can competitive exclusion be avoided?

Life form of the species - this is a historically developed complex of its biological, physiological and morphological properties, which determines a certain response to environmental influences.

Among the inhabitants of the aquatic environment (hydrobionts), the classification distinguishes the following life forms.

1.Neuston(from Greek neuston - capable of swimming) – a collection of marine and freshwater organisms that live near the surface of the water , for example, mosquito larvae, many protozoa, water strider bugs, and among plants, the well-known duckweed.

2. Lives closer to the surface of the water plankton.

Plankton(from the Greek planktos - soaring) - floating organisms capable of making vertical and horizontal movements mainly in accordance with movement water masses. Highlight phytoplankton- photosynthetic free-floating algae and zooplankton- small crustaceans, mollusc and fish larvae, jellyfish, small fish.

3.Nekton(from the Greek nektos - floating) - free-floating organisms capable of independent vertical and horizontal movement. Nekton lives in the water column - these are fish, in the seas and oceans, amphibians, large aquatic insects, crustaceans, and also reptiles ( sea ​​snakes and turtles) and mammals: cetaceans (dolphins and whales) and pinnipeds (seals).

4. Periphyton(from the Greek peri - around, about, phyton - plant) - animals and plants attached to the stems of higher plants and rising above the bottom (molluscs, rotifers, bryozoans, hydra, etc.).

5. Benthos ( from Greek benthos - depth, bottom) - bottom organisms leading an attached or free lifestyle, including those living in the thickness of the bottom sediment. These are mainly mollusks, some lower plants, crawling insect larvae, worms. The bottom layer is inhabited by organisms that feed mainly on decaying debris.

1. What is biocenosis, biogeocenosis, agrocenosis? Structure of biogeocenosis. Who is the founder of the doctrine of biocenosis? Examples of biogeocenoses.

Biocenosis(from the Greek koinos - common bios - life) is a community of interacting living organisms, consisting of plants (phytocenosis), animals (zoocenosis), microorganisms (microbocenosis), adapted to living together in a given territory.

The concept of “biocenosis” – conditional, since organisms cannot live outside their environment, but it is convenient to use in the process of studying ecological connections between organisms. Depending on the area, the attitude towards human activity, the degree of saturation, usefulness, etc. distinguish biocenoses of land, water, natural and anthropogenic, saturated and unsaturated, complete and incomplete.

Biocenoses, like populations - this is a supraorganismal level of life organization, but of a higher rank.

The sizes of biocenotic groups are different- these are large communities of lichen cushions on tree trunks or a rotting stump, but they are also the population of steppes, forests, deserts, etc.

A community of organisms is called a biocenosis, and the science that studies the community of organisms - biocenology.

V.N. Sukachev the term was proposed (and generally accepted) to denote communities biogeocenosis(from Greek bios – life, geo – Earth, cenosis – community) - This is a collection of organisms and natural phenomena characteristic of a given geographical area.

The structure of biogeocenosis includes two components biotic – community of living plant and animal organisms (biocenosis) – and abiotic - a set of inanimate environmental factors (ecotope, or biotope).

Space with more or less homogeneous conditions, which occupies a biocenosis, is called a biotope (topis - place) or ecotope.

Ecotop includes two main components: climatetop- climate in all its diverse manifestations and edaphotope(from the Greek edaphos - soil) - soils, relief, water.

Biogeocenosis= biocenosis (phytocenosis+zoocenosis+microbocenosis)+biotope (climatope+edaphotope).

Biogeocenoses – these are natural formations (they contain the element “geo” - Earth ) .

Examples biogeocenoses there may be a pond, meadow, mixed or single-species forest. At the level of biogeocenosis, all processes of transformation of energy and matter occur in the biosphere.

Agrocenosis(from the Latin agraris and the Greek koikos - general) - a community of organisms created by man and artificially maintained by him with increased yield (productivity) of one or more selected species of plants or animals.

Agrocenosis differs from biogeocenosis main components. It cannot exist without human support, since it is an artificially created biotic community.

1. The concept of "ecosystem". Three principles of ecosystem functioning.

Ecological system- one of the most important concepts of ecology, abbreviated as ecosystem.

Ecosystem(from the Greek oikos - dwelling and system) is any community of living beings along with their habitat, connected inside complex system relationships.

Ecosystem - These are supraorganismal associations, including organisms and the inanimate (inert) environment that interact, without which it is impossible to maintain life on our planet. This is a community of plant and animal organisms and inorganic environment.

Based on the interaction of living organisms that form an ecosystem with each other and their habitat, interdependent aggregates are distinguished in any ecosystem biotic(living organisms) and abiotic(inert or non-living nature) components, as well as environmental factors (such as solar radiation, humidity and temperature, atmospheric pressure), anthropogenic factors and others.

To the abiotic components of ecosystems These include inorganic substances - carbon, nitrogen, water, atmospheric carbon dioxide, minerals, organic substances found mainly in the soil: proteins, carbohydrates, fats, humic substances, etc., which enter the soil after the death of organisms.

To the biotic components of the ecosystem include producers, autotrophs (plants, chemosynthetics), consumers (animals) and detritivores, decomposers (animals, bacteria, fungi).

Kazan physiological school. F.V. Ovsyannikov, N.O. Kovalevsky, N.A. Mislavsky, A.V. Kibyakov

The textbook complies with the Federal State educational standard secondary (complete) general education, recommended by the Ministry of Education and Science of the Russian Federation and included in the Federal List of Textbooks.

The textbook is addressed to 11th grade students and is designed to teach the subject 1 or 2 hours a week.

Modern design, multi-level questions and assignments, additional information and the ability to work in parallel with an electronic application contribute to the effective assimilation of educational material.

Rice. 33. Winter coloring of a hare

So, as a result of the action driving forces evolution, organisms develop and improve adaptations to environmental conditions. The consolidation of various adaptations in isolated populations can ultimately lead to the formation of new species.

Review questions and assignments

1. Give examples of the adaptation of organisms to living conditions.

2. Why do some animals have bright, unmasking colors, while others, on the contrary, have protective colors?

3. What is the essence of mimicry?

4. Does natural selection apply to animal behavior? Give examples.

5. What are the biological mechanisms for the emergence of adaptive (hiding and warning) coloration in animals?

6. Are physiological adaptations factors that determine the level of fitness of the organism as a whole?

7. What is the essence of the relativity of any adaptation to living conditions? Give examples.

Think! Do it!

1. Why is there no absolute adaptation to living conditions? Give examples that prove the relative nature of any device.

2. Boar cubs have a characteristic striped coloring, which disappears with age. Give similar examples of color changes in adults compared to offspring. Can this pattern be considered common to the entire animal world? If not, then for which animals and why is it characteristic?

3. Gather information about animals with warning colors that live in your area. Explain why knowledge of this material is important for everyone. Make an information stand about these animals. Give a presentation on this topic to primary school students.

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Talk to electronic application. Study the material and complete the assignments.

Repeat and remember!

Human

Behavioral adaptations are innate, unconditional reflex behavior. Innate abilities exist in all animals, including humans. A newborn baby can suck, swallow and digest food, blink and sneeze, react to light, sound and pain. These are examples unconditioned reflexes. Such forms of behavior arose in the process of evolution as a result of adaptation to certain, relatively constant environmental conditions. Unconditioned reflexes are inherited, so all animals are born with a ready-made complex of such reflexes.

Each unconditioned reflex occurs in response to a strictly defined stimulus (reinforcement): some - for food, others - for pain, others - for the appearance of new information, etc. The reflex arcs of unconditioned reflexes are constant and pass through the spinal cord or brain stem.

One of the most complete classifications of unconditioned reflexes is the classification proposed by Academician P. V. Simonov. The scientist proposed dividing all unconditioned reflexes into three groups, differing in the characteristics of the interaction of individuals with each other and with the environment. Vital reflexes(from Latin vita - life) are aimed at preserving the life of the individual. Failure to comply with them leads to the death of the individual, and implementation does not require the participation of another individual of the same species. This group includes food and drinking reflexes, homeostatic reflexes (maintaining a constant body temperature, optimal breathing rate, heart rate, etc.), defensive ones, which, in turn, are divided into passive-defensive (running away, hiding) and active ones. defensive (attack on a threatening object) and some others.

TO zoosocial, or role-playing reflexes include those options innate behavior, which arise when interacting with other individuals of their species. These are sexual, child-parent, territorial, hierarchical reflexes.

The third group is self-development reflexes. They are not related to adaptation to specific situation, but as if facing the future. These include exploratory, imitative and playful behavior.

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In the process of evolution, as a result of natural selection and the struggle for existence, adaptations of organisms to certain living conditions arise. Evolution itself is essentially a continuous process of formation of adaptations, occurring according to the following scheme: intensity of reproduction -> struggle for existence -> selective death -> natural selection -> fitness.

Adaptations affect different aspects of the life processes of organisms and therefore can be of several types.

Morphological adaptations

They are associated with changes in body structure. For example, the appearance of membranes between the toes in waterfowl (amphibians, birds, etc.), thick fur in northern mammals, long legs and a long neck in wading birds, a flexible body in burrowing predators (for example, weasels), etc. In warm-blooded animals, when moving north, an increase in average body size is observed (Bergmann's rule), which reduces the relative surface area and heat transfer. Benthic fish develop a flat body (rays, flounder, etc.). In plants in northern latitudes and in high mountain areas, creeping and cushion-shaped forms are common, less damaged by strong winds and better warmed by the sun in the soil layer.

Protective coloration

Protective coloration is very important for animal species that do not have effective means of protection against predators. Thanks to it, animals become less noticeable in the area. For example, female birds hatching eggs are almost indistinguishable from the background of the area. Bird eggs are also colored to match the color of the area. Patronizing coloring have bottom-dwelling fish, most insects and many other animal species. In the north, white or light colors are more common, helping to camouflage in the snow (polar bears, polar owls, arctic foxes, baby pinnipeds - squirrels, etc.). A number of animals developed a coloration formed by alternating light and dark stripes or spots, making them less noticeable in bushes and dense thickets (tigers, young wild boars, zebras, sika deer, etc.). Some animals are capable of changing color very quickly depending on conditions (chameleons, octopuses, flounder, etc.).

Disguise

The essence of camouflage is that the shape of the body and its color make animals look like leaves, twigs, branches, bark or thorns of plants. Often found in insects that live on plants.

Warning or threatening coloring

Some types of insects that have poisonous or odorous glands have bright warning colors. Therefore, predators that once encounter them remember this coloring for a long time and no longer attack such insects (for example, wasps, bumblebees, ladybugs, Colorado potato beetles and a number of others).

Mimicry

Mimicry is the coloring and body shape of harmless animals that imitate their poisonous counterparts. For example, some non-venomous snakes resemble venomous ones. Cicadas and crickets resemble large ants. Some butterflies have large spots on their wings that resemble the eyes of predators.

Physiological adaptations

This type of adaptation is associated with a restructuring of metabolism in organisms. For example, the emergence of warm-bloodedness and thermoregulation in birds and mammals. In more simple cases- this is an adaptation to certain forms of food, the salt composition of the environment, high or low temperatures, humidity or dryness of soil and air, etc.

Biochemical adaptations

Behavioral adaptations

This type of adaptation is associated with changes in behavior in certain conditions. For example, caring for offspring leads to better survival of young animals and increases the stability of their populations. IN mating seasons many animals form separate families, and in winter they unite in flocks, which makes it easier for them to feed or protect (wolves, many species of birds).

Adaptations to periodic environmental factors

These are adaptations to environmental factors that have a certain periodicity in their manifestation. This type includes daily alternations of periods of activity and rest, states of partial or complete anabiosis (shedding of leaves, winter or summer diapauses of animals, etc.), migrations of animals caused by seasonal changes and so on.

Adaptations to extreme living conditions

Plants and animals living in deserts and polar regions also acquire a number of specific adaptations. In cacti, the leaves have been transformed into spines (reducing evaporation and protecting them from being eaten by animals), and the stem has turned into a photosynthetic organ and reservoir. Desert plants have long root systems that allow them to obtain water from great depths. Desert lizards can survive without water by eating insects and obtaining water by hydrolyzing their fats. In addition to thick fur, northern animals also have a large supply of subcutaneous fat, which reduces body cooling.

Relative nature of adaptations

All devices are appropriate only for certain conditions in which they were developed. If these conditions change, adaptations may lose their value or even cause harm to the organisms that have them. The white coloration of hares, which protects them well in the snow, becomes dangerous during winters with little snow or severe thaws.

The relative nature of adaptations is well proven by paleontological data, which indicates the extinction of large groups of animals and plants that did not survive the change in living conditions.

Reactions to unfavorable environmental factors are detrimental to living organisms only under certain conditions, but in most cases they have adaptive significance. Therefore, these responses were called “general adaptation syndrome” by Selye. In later works, he used the terms “stress” and “general adaptation syndrome” as synonyms.

Adaptation is a genetically determined process of the formation of protective systems that ensure increased stability and the course of ontogenesis in unfavorable conditions for it.

Adaptation is one of the most important mechanisms that increases the stability of a biological system, including a plant organism, in changed conditions of existence. The better an organism is adapted to a certain factor, the more resistant it is to its fluctuations.

The genotypically determined ability of an organism to change metabolism within certain limits depending on the action of the external environment is called reaction norm. It is controlled by the genotype and is characteristic of all living organisms. Most modifications that occur within the normal range of reaction have adaptive significance. They correspond to changes in the environment and ensure better plant survival under fluctuating environmental conditions. In this regard, such modifications have evolutionary significance. The term “reaction norm” was introduced by V.L. Johannsen (1909).

The greater the ability of a species or variety to be modified in accordance with the environment, the wider its reaction rate and the higher its ability to adapt. This property distinguishes resistant varieties of crops. As a rule, slight and short-term changes in environmental factors do not lead to significant violations physiological functions plants. This is due to their ability to maintain relative dynamic balance of the internal environment and the stability of basic physiological functions in a changing external environment. At the same time, sudden and prolonged impacts lead to disruption of many functions of the plant, and often to its death.

Adaptation includes all processes and adaptations (anatomical, morphological, physiological, behavioral, etc.) that contribute to increased stability and contribute to the survival of the species.

1.Anatomical and morphological devices. In some representatives of xerophytes, the length of the root system reaches several tens of meters, which allows the plant to use groundwater and not experience a lack of moisture in conditions of soil and atmospheric drought. In other xerophytes, the presence of a thick cuticle, pubescent leaves, and the transformation of leaves into spines reduce water loss, which is very important in conditions of lack of moisture.

Stinging hairs and spines protect plants from being eaten by animals.

Trees in the tundra or at high mountain altitudes look like squat creeping shrubs; in winter they are covered with snow, which protects them from severe frosts.

In mountainous regions with large daily temperature fluctuations, plants often have the form of spread out pillows with numerous stems densely spaced. This allows you to maintain moisture inside the pillows and a relatively uniform temperature throughout the day.

In the swamp and aquatic plants a special air-bearing parenchyma (aerenchyma) is formed, which is an air reservoir and facilitates the breathing of plant parts immersed in water.

2. Physiological-biochemical adaptations. In succulents, an adaptation for growing in desert and semi-desert conditions is the assimilation of CO 2 during photosynthesis via the CAM pathway. These plants have stomata that are closed during the day. Thus, the plant retains internal reserves water from evaporation. In deserts, water is the main factor limiting plant growth. The stomata open at night, and at this time CO 2 enters the photosynthetic tissues. The subsequent involvement of CO 2 in the photosynthetic cycle occurs during the day when the stomata are closed.

Physiological and biochemical adaptations include the ability of stomata to open and close, depending on external conditions. The synthesis in cells of abscisic acid, proline, protective proteins, phytoalexins, phytoncides, increased activity of enzymes that counteract the oxidative breakdown of organic substances, accumulation of sugars in cells and a number of other changes in metabolism help to increase plant resistance to unfavorable environmental conditions.

The same biochemical reaction can be carried out by several molecular forms of the same enzyme (isoenzymes), with each isoform exhibiting catalytic activity in a relatively narrow range of some environmental parameter, such as temperature. The presence of a number of isoenzymes allows the plant to carry out reactions in a much wider temperature range compared to each individual isoenzyme. This allows the plant to successfully perform vital functions in changing temperature conditions.

3. Behavioral adaptations, or avoidance of an unfavorable factor. An example is ephemera and ephemeroids (poppy, chickweed, crocuses, tulips, snowdrops). They go through their entire development cycle in the spring in 1.5-2 months, even before the onset of heat and drought. Thus, they seem to leave, or avoid falling under the influence of the stressor. Similarly, early ripening varieties of agricultural crops form a harvest before the onset of unfavorable weather conditions. seasonal phenomena: August fogs, rains, frosts. Therefore, the selection of many agricultural crops is aimed at creating early ripening varieties. Perennial plants overwinter in the form of rhizomes and bulbs in the soil under snow, which protects them from freezing.

Adaptation of plants to unfavorable factors is carried out simultaneously at many levels of regulation - from an individual cell to a phytocenosis. The higher the level of organization (cell, organism, population), the greater the number of mechanisms simultaneously involved in plant adaptation to stress.

Regulation of metabolic and adaptation processes inside the cell is carried out using systems: metabolic (enzymatic); genetic; membrane These systems are closely interconnected. Thus, the properties of membranes depend on gene activity, and the differential activity of the genes themselves is under the control of membranes. The synthesis of enzymes and their activity are controlled at the genetic level, while at the same time enzymes regulate nucleic acid metabolism in the cell.

On organismal level new ones are added to the cellular mechanisms of adaptation, reflecting the interaction of organs. In unfavorable conditions, plants create and retain such an amount of fruit elements that are sufficiently provided with the necessary substances to form full-fledged seeds. For example, in the inflorescences of cultivated cereals and in the crowns fruit trees in unfavorable conditions, more than half of the established ovaries may fall off. Such changes are based on competitive relationships between organs for physiologically active substances and nutrients.

Under stress conditions, the processes of aging and falling of the lower leaves sharply accelerate. At the same time, substances needed by plants move from them to young organs, responding to the organism’s survival strategy. Thanks to the recycling of nutrients from the lower leaves, the younger ones, the upper leaves, remain viable.

Mechanisms for regeneration of lost organs operate. For example, the surface of a wound is covered with secondary integumentary tissue (wound periderm), a wound on a trunk or branch is healed with nodules (calluses). When the apical shoot is lost, dormant buds awaken in plants and side shoots intensively develop. The regeneration of leaves in the spring instead of those that fell in the fall is also an example of natural organ regeneration. Regeneration as a biological device that provides vegetative propagation of plants by segments of roots, rhizomes, thallus, stem and leaf cuttings, isolated cells, individual protoplasts, is of great practical importance for plant growing, fruit growing, forestry, ornamental horticulture, etc.

The hormonal system also participates in the processes of protection and adaptation at the plant level. For example, under the influence of unfavorable conditions in a plant, the content of growth inhibitors sharply increases: ethylene and abscisic acid. They reduce metabolism, inhibit growth processes, accelerate aging, organ loss, and the plant’s transition to a dormant state. Inhibition of functional activity under stress conditions under the influence of growth inhibitors is a characteristic reaction for plants. At the same time, the content of growth stimulants in tissues decreases: cytokinin, auxin and gibberellins.

On population level selection is added, which leads to the emergence of more adapted organisms. The possibility of selection is determined by the existence of intrapopulation variability in plant resistance to various environmental factors. An example of intrapopulation variability in resistance can be the uneven emergence of seedlings on saline soil and the increase in variation in germination timing with increasing stressors.

View in modern concept consists of a large number of biotypes - smaller ecological units that are genetically identical, but exhibit different resistance to environmental factors. IN different conditions not all biotypes are equally vital, and as a result of competition, only those that best meet the given conditions remain. That is, the resistance of a population (variety) to one or another factor is determined by the resistance of the organisms that make up the population. Resistant varieties include a set of biotypes that provide good productivity even in unfavorable conditions.

At the same time, during long-term cultivation of varieties, the composition and ratio of biotypes in the population changes, which affects the productivity and quality of the variety, often not for the better.

So, adaptation includes all processes and adaptations that increase the resistance of plants to unfavorable environmental conditions (anatomical, morphological, physiological, biochemical, behavioral, population, etc.)

But to choose the most effective way adaptation is the main thing is the time during which the body must adapt to new conditions.

In the event of a sudden action of an extreme factor, the response cannot be delayed; it must follow immediately to avoid irreversible damage to the plant. With prolonged exposure to a small force, adaptive changes occur gradually, and the choice of possible strategies increases.

In this regard, there are three main adaptation strategies: evolutionary, ontogenetic And urgent. The goal of the strategy is the effective use of available resources to achieve the main goal - the survival of the body under stress. The adaptation strategy is aimed at maintaining the structural integrity of vital macromolecules and the functional activity of cellular structures, preserving life regulation systems, and providing plants with energy.

Evolutionary or phylogenetic adaptations(phylogeny - the development of a biological species over time) are adaptations that arise during the evolutionary process on the basis of genetic mutations, selection and are inherited. They are the most reliable for plant survival.

In the process of evolution, each plant species has developed certain needs for living conditions and adaptability to the ecological niche it occupies, a stable adaptation of the organism to its habitat. Moisture and shade tolerance, heat resistance, cold resistance and others environmental features specific plant species were formed as a result of prolonged action of appropriate conditions. Thus, heat-loving and short-day plants are characteristic of southern latitudes, while less demanding heat-loving and long-day plants are characteristic of northern latitudes. Numerous evolutionary adaptations of xerophyte plants to drought are well known: economical use of water, deep-lying root system, shedding leaves and transition to a dormant state, and other adaptations.

In this regard, varieties of agricultural plants exhibit resistance precisely to those environmental factors against the background of which breeding and selection of productive forms is carried out. If selection takes place in a number of successive generations against the background of the constant influence of some unfavorable factor, then the resistance of the variety to it can be significantly increased. It is natural that the varieties bred at the Research Institute of Agriculture of the South-East (Saratov) are more resistant to drought than the varieties created in the breeding centers of the Moscow region. In the same way in ecological zones With unfavorable soil-climatic conditions, resistant local plant varieties have formed, and endemic plant species are resistant precisely to the stressor that is expressed in their habitat.

Characteristics of resistance of spring wheat varieties from the collection of the All-Russian Institute of Plant Growing (Semyonov et al., 2005)

Variety	Origin	Sustainability
Enita	Moscow region	Moderately drought resistant
Saratovskaya 29	Saratov region	Drought resistant
Comet	Sverdlovsk region.	Drought resistant
Karasino	Brazil	Acid resistant
Prelude	Brazil	Acid resistant
Colonias	Brazil	Acid resistant
Trintani	Brazil	Acid resistant
PPG-56	Kazakhstan	Salt resistant
Osh	Kyrgyzstan	Salt resistant
Surkhak 5688	Tajikistan	Salt resistant
Messel	Norway	Salt tolerant

In a natural setting, environmental conditions usually change very quickly, and the time during which the stress factor reaches a damaging level is not enough for the formation of evolutionary adaptations. In these cases, plants use not permanent, but stressor-induced defense mechanisms, the formation of which is genetically predetermined (determined).

Ontogenetic (phenotypic) adaptations are not associated with genetic mutations and are not inherited. The formation of this kind of adaptation takes a relatively long time, which is why they are called long-term adaptations. One of these mechanisms is the ability of a number of plants to form a water-saving CAM-type photosynthetic pathway under conditions of water deficiency caused by drought, salinity, low temperatures and other stressors.

This adaptation is associated with the induction of the expression of “inactive” in normal conditions the phosphoenolpyruvate carboxylase gene and the genes of other enzymes of the CAM pathway of CO 2 assimilation, with the biosynthesis of osmolytes (proline), with the activation of antioxidant systems and changes in the daily rhythms of stomatal movements. All this leads to very economical use of water.

In field crops, for example, corn, aerenchyma is absent under normal growing conditions. But under conditions of flooding and a lack of oxygen in the tissues of the roots, some of the cells of the primary cortex of the root and stem die (apoptosis, or programmed cell death). In their place, cavities are formed through which oxygen is transported from the aboveground part of the plant to the root system. The signal for cell death is ethylene synthesis.

Urgent adaptation occurs with rapid and intense changes in living conditions. It is based on the formation and functioning of shock defense systems. Shock defense systems include, for example, the heat shock protein system, which is formed in response to rapid rise temperature. These mechanisms provide short-term conditions for survival under the influence of a damaging factor and thereby create the prerequisites for the formation of more reliable long-term specialized adaptation mechanisms. An example of specialized adaptation mechanisms is the new formation of antifreeze proteins at low temperatures or the synthesis of sugars during the overwintering of winter crops. At the same time, if the damaging effect of a factor exceeds the protective and reparation capabilities of the body, then death inevitably occurs. In this case, the organism dies at the stage of urgent or at the stage of specialized adaptation, depending on the intensity and duration of the extreme factor.

Distinguish specific And nonspecific (general) plant responses to stressors.

Nonspecific reactions do not depend on the nature of the acting factor. They are the same under the influence of high and low temperatures, lack or excess of moisture, high concentration of salts in the soil or harmful gases in the air. In all cases, the permeability of membranes in plant cells increases, respiration is impaired, the hydrolytic breakdown of substances increases, the synthesis of ethylene and abscisic acid increases, and cell division and elongation are inhibited.

The table presents a complex of nonspecific changes that occur in plants under the influence of various environmental factors.

Change physiological parameters in plants under stress conditions (according to G.V. Udovenko, 1995)

Options	The nature of changes in parameters under conditions
	drought	salinity	high temperature	low temperature
Ion concentration in tissues	Growing	Growing	Growing	Growing
Water activity in the cell	Falls	Falls	Falls	Falls
Osmotic potential of the cell	Growing	Growing	Growing	Growing
Water holding capacity	Growing	Growing	Growing	—
Water shortage	Growing	Growing	Growing	—
Permeability of protoplasm	Growing	Growing	Growing	—
Transpiration rate	Falls	Falls	Growing	Falls
Transpiration efficiency	Falls	Falls	Falls	Falls
Energy efficiency of breathing	Falls	Falls	Falls	—
Breathing intensity	Growing	Growing	Growing	—
Photophosphorylation	Decreasing	Decreasing	—	Decreasing
Stabilization of nuclear DNA	Growing	Growing	Growing	Growing
Functional activity of DNA	Decreasing	Decreasing	Decreasing	Decreasing
Proline concentration	Growing	Growing	Growing	—
Content of water-soluble proteins	Growing	Growing	Growing	Growing
Synthetic reactions	Depressed	Depressed	Depressed	Depressed
Absorption of ions by roots	Suppressed	Suppressed	Suppressed	Suppressed
Transport of substances	Depressed	Depressed	Depressed	Depressed
Pigment concentration	Falls	Falls	Falls	Falls
Cell division	Braking	Braking	—	—
Cell stretching	Suppressed	Suppressed	—	—
Number of fruit elements	Reduced	Reduced	Reduced	Reduced
Aging of organs	Accelerated	Accelerated	Accelerated	—
Biological harvest	Demoted	Demoted	Demoted	Demoted

Based on the data in the table, it can be seen that plant resistance to several factors is accompanied by unidirectional physiological changes. This gives reason to believe that an increase in plant resistance to one factor may be accompanied by an increase in resistance to another. This has been confirmed by experiments.

Experiments at the Institute of Plant Physiology of the Russian Academy of Sciences (Vl. V. Kuznetsov and others) have shown that short-term heat treatment of cotton plants is accompanied by an increase in their resistance to subsequent salinity. And the adaptation of plants to salinity leads to an increase in their resistance to high temperatures. Heat shock increases the ability of plants to adapt to subsequent drought and, conversely, during drought the body's resistance to high temperatures increases. Short-term exposure to high temperatures increases resistance to heavy metals and UV-B irradiation. Previous drought promotes plant survival in salinity or cold conditions.

The process of increasing the body's resistance to a given environmental factor as a result of adaptation to a factor of a different nature is called cross adaptation.

To study general (nonspecific) mechanisms of resistance, the response of plants to factors that cause water deficiency in plants: salinity, drought, low and high temperatures, and some others is of great interest. At the level of the whole organism, all plants respond to water deficiency in the same way. Characterized by inhibition of shoot growth, increased growth of the root system, abscisic acid synthesis, and decreased stomatal conductance. After some time, the lower leaves age rapidly and their death is observed. All these reactions are aimed at reducing water consumption by reducing the evaporating surface, as well as by increasing the absorption activity of the root.

Specific reactions- These are reactions to the action of any one stress factor. Thus, phytoalexins (substances with antibiotic properties) are synthesized in plants in response to contact with pathogens.

The specificity or non-specificity of response reactions implies, on the one hand, the attitude of the plant to various stressors and, on the other hand, the specificity of the reactions of plants of different species and varieties to the same stressor.

The manifestation of specific and nonspecific plant responses depends on the strength of stress and the speed of its development. Specific responses occur more often if stress develops slowly, and the body has time to rebuild and adapt to it. Nonspecific reactions usually occur with a shorter and stronger stressor. The functioning of nonspecific (general) resistance mechanisms allows the plant to avoid large energy expenditures for the formation of specialized (specific) adaptation mechanisms in response to any deviation from the norm in their living conditions.

Plant resistance to stress depends on the phase of ontogenesis. The most stable plants and plant organs are in a dormant state: in the form of seeds, bulbs; woody perennials - in a state of deep dormancy after leaf fall. Plants are most sensitive at a young age, since under stress conditions growth processes are damaged first. The second critical period is the period of gamete formation and fertilization. Stress during this period leads to a decrease in the reproductive function of plants and a decrease in yield.

If stressful conditions are repeated and have low intensity, then they contribute to plant hardening. This is the basis for methods of increasing resistance to low temperatures, heat, salinity, and increased levels of harmful gases in the air.

Reliability a plant organism is determined by its ability to prevent or eliminate failures at different levels biological organization: molecular, subcellular, cellular, tissue, organ, organismal and population.

To prevent disruptions in plant life under the influence unfavorable factors principles are used redundancy, heterogeneity of functionally equivalent components, systems for repairing lost structures.

Redundancy of structures and functionality is one of the main ways to ensure system reliability. Redundancy and redundancy have diverse manifestations. At the subcellular level, the redundancy and duplication of genetic material contribute to increasing the reliability of the plant organism. This is ensured, for example, by the double helix of DNA and an increase in ploidy. The reliability of the functioning of a plant organism under changing conditions is also supported by the presence of various messenger RNA molecules and the formation of heterogeneous polypeptides. These include isoenzymes that catalyze the same reaction, but differ in their physical and chemical properties and the stability of the structure of molecules in changing environmental conditions.

At the cellular level, an example of redundancy is an excess of cellular organelles. Thus, it has been established that a portion of the available chloroplasts is sufficient to provide the plant with photosynthetic products. The remaining chloroplasts seem to remain in reserve. The same applies to general content chlorophyll. Redundancy is also manifested in the large accumulation of precursors for the biosynthesis of many compounds.

At the organismal level, the principle of redundancy is expressed in the formation and in the laying down at different times of more than is required for the change of generations, the number of shoots, flowers, spikelets, in a huge amount of pollen, ovules, and seeds.

At the population level, the principle of redundancy is manifested in a large number of individuals that differ in resistance to a particular stress factor.

Reparation systems also operate at different levels - molecular, cellular, organismal, population and biocenotic. Reparative processes occur with the expenditure of energy and plastic substances, therefore, repair is possible only if sufficient metabolic rate is maintained. If metabolism stops, repair also stops. In extreme environmental conditions, maintaining respiration is especially important, since it is respiration that provides energy for repair processes.

The restorative ability of cells of adapted organisms is determined by the resistance of their proteins to denaturation, namely the stability of the bonds that determine the secondary, tertiary and quaternary structure of the protein. For example, the resistance of mature seeds to high temperatures is usually due to the fact that, after dehydration, their proteins become resistant to denaturation.

The main source of energy material as a substrate for respiration is photosynthesis, therefore, the energy supply of the cell and the associated repair processes depend on the stability and ability of the photosynthetic apparatus to recover after damage. To maintain photosynthesis under extreme conditions in plants, the synthesis of thylakoid membrane components is activated, lipid oxidation is inhibited, and the ultrastructure of plastids is restored.

At the organismal level, an example of regeneration can be the development of replacement shoots, the awakening of dormant buds when growth points are damaged.

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