thermophilic organisms. Thermal water organisms Bacteria in hot springs
In boiling water, at a temperature of 100°C, all forms of living organisms die, including bacteria and microbes, which are known for their resistance and vitality - this is a widely known and generally recognized fact. But how wrong it turns out!
In the late 1970s, with the appearance of the first deep-sea submersibles, hydrothermal springs, from which streams of over hot highly mineralized water continuously beat. The temperature of such streams reaches incredible 200-400°C. At first, no one could have imagined that life could exist at a depth of several thousand meters from the surface, in eternal darkness, and even at such a temperature. But she was there. And not primitive unicellular life, but entire independent ecosystems, consisting of species previously unknown to science.
A hydrothermal spring found at the bottom of the Cayman Trench at a depth of about 5,000 meters. Such sources are called black smokers because of the eruption of black smoke-like water.
The basis of ecosystems living near hydro thermal springs chemosynthetic bacteria are microorganisms that obtain the necessary nutrients by oxidizing various chemical elements; in the specific case by the oxidation of carbon dioxide. All other representatives of thermal ecosystems, including filter-feeding crabs, shrimps, various mollusks and even huge sea worms, depend on these bacteria.
This black smoker is completely enveloped in white sea anemones. Conditions that mean death to other marine organisms are the norm for these creatures. White anemones get their food by absorbing chemosynthetic bacteria.
Organisms living in black smokers"are completely dependent on local conditions and are not able to survive in the habitat familiar to the vast majority marine life. For this reason, for a long time it was not possible to raise a single creature alive to the surface, they all died when the water temperature dropped.
Pompeii worm (lat. Alvinella pompejana) - this inhabitant of underwater hydrothermal ecosystems received a rather symbolic name.
An ISIS underwater unmanned vehicle managed by British oceanologists managed to raise the first living creature. Scientists have found that temperatures below 70°C are deadly for these amazing creatures. This is quite remarkable, as temperatures of 70°C are lethal to 99% of the organisms living on Earth.
The discovery of underwater thermal ecosystems was extremely important for science. First, the limits within which life can exist have been expanded. Secondly, the discovery led scientists to new version about the origin of life on Earth, according to which life originated in hydrothermal vents. And thirdly, this discovery once again made us realize that we know very little about the world around us.
.(Source: "Biological Encyclopedic Dictionary." Chief editor M. S. Gilyarov; Editorial staff: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected . - M .: Sov. Encyclopedia, 1986.)
See what "TERMOPHILE ORGANISMS" are in other dictionaries:
- (thermo ... gr. phileo love) thermophilic organisms (predominantly microscopic), able to live at relatively high temperatures (up to 70); their natural habitats are various hot springs and thermal waters cf. cryophilic ... ... Dictionary of foreign words of the Russian language
- (from thermo (See Thermo ...) ... and Greek philéo I love) thermophiles, organisms that live at temperatures exceeding 45 ° C (fatal for most living beings). These are some fish, representatives of various invertebrates (worms, ... ... Great Soviet Encyclopedia
- ... Wikipedia
Organisms Scientific classification Classification: Organisms of the Kingdom Nuclear Non-nuclear Organism (Late Latin organismus from Late Latin organizo ... Wikipedia
Lower organisms, like all living beings in general, can live only under precisely defined external conditions of their existence, i.e., the conditions of the environment in which they live, moreover, for each external factor, for temperature, pressure, humidity, etc ...
This is the name of bacteria that have the ability to develop at temperatures above 55 60 ° C. Miquel (Miquel) was the first to find and isolated from the Seine water an immobile bacillus that can live and multiply at a temperature of 70 ° C. Van Tieghem ... encyclopedic Dictionary F. Brockhaus and I.A. Efron
Organisms Scientific classification Classification: Organisms of the Kingdom Nuclear Non-nuclear Organism (Late Latin organismus from Late Latin organizo ... Wikipedia - See also: The largest organisms The smallest organisms are all representatives of bacteria, animals, plants and other organisms found on Earth, which have minimal values in their classes (detachments) according to parameters such as ... Wikipedia
Some organisms have a special advantage that allows them to withstand the most extreme conditions, where others simply cannot cope. Among these abilities, resistance to enormous pressure, extreme temperatures and others can be noted. These ten creatures from our list will give odds to anyone who dares to claim the title of the hardiest organism.
10 Himalayan Jumping Spider
The Asiatic wild goose is famous for flying over 6.5 kilometers, while the highest human settlement is at 5,100 meters in the Peruvian Andes. However, the high-altitude record does not belong to geese at all, but to the Himalayan jumping spider (Euophrys omnisuperstes). Living at an altitude of over 6700 meters, this spider feeds mainly on small insects brought there by gusts of wind. A key feature of this insect is the ability to survive in conditions of almost complete absence of oxygen.
9 Giant Kangaroo Jumper
Usually, when we think about the animals that can live the longest without water, the camel immediately comes to mind. But camels can survive without water in the desert for only 15 days. Meanwhile, you will be surprised when you find out that there is an animal in the world that can live its whole life without drinking a single drop of water. The giant kangaroo jumper is a close relative of the beaver. Their average life expectancy is usually 3 to 5 years. They usually get moisture from food by eating various seeds. In addition, these rodents do not sweat, thereby avoiding additional water loss. Usually these animals live in the Valley of Death, and are currently under threat of extinction.
Since heat in water is more efficiently transferred to organisms, a water temperature of 50 degrees Celsius will be much more dangerous than the same air temperature. For this reason, bacteria predominately thrive in hot underwater springs, which cannot be said about multicellular life forms. However, there is a special kind of worm called paralvinella sulfincola, which is happy to settle in places where the water reaches temperatures of 45-55 degrees. Scientists conducted an experiment where one of the walls of the aquarium was heated, as a result it turned out that the worms preferred to stay in this place, ignoring cooler places. It is believed that this feature has developed in worms so that they can feast on bacteria that are abundant in hot springs. Because they didn't have it before. natural enemies, bacteria were relatively easy prey.
7. Greenlandic polar shark
The Greenland shark is one of the largest and least studied sharks on the planet. Despite the fact that they swim quite slowly (any amateur swimmer can overtake them), they are extremely rare. This is due to the fact that this species of sharks, as a rule, lives at a depth of 1200 meters. In addition, this shark is one of the most resistant to cold. Usually she prefers to stay in water, the temperature of which fluctuates between 1 and 12 degrees Celsius. Since these sharks live in cold waters, they have to move extremely slowly in order to minimize the use of their energy. In food they are illegible and eat everything that comes in their way. Rumor has it that their lifespan is about 200 years, but no one has yet been able to confirm or deny it.
6. Devil Worm
For decades, scientists believed that only single-celled organisms could survive at great depths. In their opinion, high pressure, lack of oxygen and extreme temperatures stood in the way of multicellular creatures. But then microscopic worms were discovered at a depth of several kilometers. Named halicephalobus mephisto, after a demon from German folklore, it was found in water samples 2.2 kilometers below the surface of the earth, lying in one of the caves in South Africa. They were able to survive extreme environmental conditions, suggesting that life is possible on Mars and other planets in our galaxy.
5. Frogs
Some types of frogs are widely known for their ability to literally freeze for the whole winter period and revive with the arrival of spring. IN North America five species of such frogs have been found, the most common of which is the common tree frog. Since tree frogs are not very strong at burrowing, they simply hide under fallen leaves. They have a substance like antifreeze in their veins, and although their hearts eventually stop, this is temporary. The basis of their survival technique is the huge concentration of glucose that enters the bloodstream from the frog's liver. What is even more surprising is the fact that frogs are able to demonstrate their ability to freeze not only in natural environment, but also in the laboratory, allowing scientists to discover their secrets.
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4 Deep Sea Microbes
We all know that the deepest point in the world is the Mariana Trench. Its depth reaches almost 11 kilometers, and the pressure there exceeds atmospheric pressure by 1100 times. A few years ago, scientists managed to find giant amoebae there, which they managed to capture with a high-resolution camera and protected by a glass sphere from the enormous pressure that reigns at the bottom. Moreover, a recent expedition sent by James Cameron himself showed that other forms of life may exist in the depths of the Mariana Trench. Samples of bottom sediments were obtained, which proved that the depression is literally teeming with microbes. This fact amazed scientists, because the extreme conditions prevailing there, as well as the huge pressure, are far from a paradise.
3. Bdelloidea
Rotifers of the species Bdelloidea are incredibly tiny female invertebrates, usually found in fresh water. Since their discovery, no males of this species have been found, and rotifers themselves reproduce asexually, which in turn destroys their own DNA. They restore their native DNA by eating other types of microorganisms. Thanks to this ability, rotifers can withstand extreme dehydration, moreover, they are able to withstand levels of radiation that would kill most living organisms on our planet. Scientists believe that their ability to repair their DNA came about as a result of the need to survive in an extremely arid environment.
2. Cockroach
There is a myth that cockroaches will be the only living organisms that will survive a nuclear war. In fact, these insects can live without water and food for several weeks, and what's more, they can live for weeks without a head. Cockroaches have been around for 300 million years, even outliving the dinosaurs. The Discovery Channel conducted a series of experiments that were supposed to show whether cockroaches would survive or not with a powerful nuclear radiation. As a result, it turned out that almost half of all insects were able to survive 1000 rad radiation (such radiation can kill an adult healthy person in just 10 minutes of exposure), moreover, 10% of cockroaches survived when exposed to 10,000 rad radiation, which is equal to radiation from a nuclear explosion in Hiroshima. Unfortunately, none of these small insects survived 100,000 rads of radiation.
1. Tardigrades
Tiny aquatic organisms called tardigrades have been found to be the most hardy organisms our planet. These, at first glance, cute animals are able to survive almost any extreme conditions, whether it be heat or cold, huge pressure or high radiation. They are able to survive for some time even in space. Under extreme conditions and in a state of extreme dehydration, these creatures are able to stay alive for several decades. They come to life, one has only to place them in a pond.
Temperature is the most important environmental factor. Temperature has a huge impact on many aspects of the life of organisms, their geography of distribution, reproduction and other biological properties of organisms that depend mainly on temperature. Range, i.e. the temperature limits at which life can exist range from about -200°C to +100°C, sometimes the existence of bacteria is found in hot springs at a temperature of 250°C. In fact, most organisms can survive within an even narrower range of temperatures.
Some types of microorganisms, mainly bacteria and algae, are able to live and multiply in hot springs at temperatures close to the boiling point. The upper temperature limit for hot spring bacteria lies around 90°C. Temperature variability is very important from an ecological point of view.
Any species is able to live only within a certain range of temperatures, the so-called maximum and minimum lethal temperatures. Beyond these critical extreme temperatures, cold or hot, death of the organism occurs. Somewhere in between is optimum temperature, in which the vital activity of all organisms, living matter as a whole, is active.
According to the tolerance of organisms to temperature regime they are divided into eurythermal and stenothermic, i.e. capable of withstanding wide or narrow temperature fluctuations. For example, lichens and many bacteria can live at different temperatures, or orchids and other heat-loving plants tropical belts- are stenothermal.
Some animals are able to maintain a constant body temperature, regardless of the ambient temperature. Such organisms are called homeothermic. In other animals, body temperature changes depending on the ambient temperature. They are called poikilotherms. Depending on the way organisms adapt to the temperature regime, they are divided into two types. environmental groups: cryophylls - organisms adapted to cold, to low temperatures; thermophiles - or heat-loving.
Allen's rule- an ecogeographic rule established by D. Allen in 1877. According to this rule, among related forms of homoiothermic (warm-blooded) animals leading a similar lifestyle, those that live in colder climates have relatively smaller protruding body parts: ears, legs, tails, etc.
Reducing the protruding parts of the body leads to a decrease in the relative surface of the body and helps to save heat.
An example of this rule are representatives of the Canine family from various regions. The smallest (relative to body length) ears and a less elongated muzzle in this family are in the arctic fox (range - Arctic), and the largest ears and narrow, elongated muzzle - in the fennec fox (range - Sahara).
This rule is also carried out in relation to human populations: the shortest (relative to body size) nose, arms and legs are characteristic of the Eskimo-Aleut peoples (Eskimos, Inuit), and long arms and legs for furs and Tutsis.
Bergman's rule is an ecogeographical rule formulated in 1847 by the German biologist Carl Bergman. The rule says that among similar forms of homoiothermic (warm-blooded) animals, the largest are those that live in colder climates - in high latitudes or in the mountains. If there are closely related species (for example, species of the same genus) that do not differ significantly in their diet and lifestyle, then larger species also occur in more severe (cold) climates.
The rule is based on the assumption that the total heat production in endothermic species depends on the volume of the body, and the rate of heat transfer depends on its surface area. With an increase in the size of organisms, the volume of the body grows faster than its surface. Experimentally, this rule was first tested on dogs of different sizes. It turned out that heat production in small dogs is higher per unit mass, but regardless of size, it remains almost constant per unit surface area.
Bergman's rule is indeed often fulfilled both within the same species and among closely related species. For example, the Amur form of the tiger with Far East larger than the Sumatran from Indonesia. The northern subspecies of the wolf are on average larger than the southern ones. Among related species of the genus bear, the largest live in northern latitudes ( polar bear, brown bears with about. Kodiak), and most small species(for example, a spectacled bear) - in areas with a warm climate.
At the same time, this rule was often criticized; it was noted that it cannot be of a general nature, since the size of mammals and birds is influenced by many other factors besides temperature. In addition, adaptations to a harsh climate at the population and species level often occur not due to changes in body size, but due to changes in body size. internal organs(an increase in the size of the heart and lungs) or through biochemical adaptations. In view of this criticism, it must be emphasized that Bergman's rule is statistical in nature and manifests its effect clearly, other things being equal.
Indeed, there are many exceptions to this rule. Thus, the smallest race of the woolly mammoth is known from the polar Wrangel Island; many forest subspecies of the wolf are larger than the tundra ones (for example, the extinct subspecies from the Kenai Peninsula; it is assumed that large sizes could give these wolves an advantage when hunting large elks inhabiting the peninsula). The Far Eastern subspecies of the leopard living on the Amur is significantly smaller than the African one. In the examples given, the compared forms differ in their way of life (island and continental populations; the tundra subspecies, feeding on smaller prey, and the forest subspecies, feeding on larger prey).
In relation to man, the rule is applicable to a certain extent (for example, the tribes of pygmies, apparently, repeatedly and independently appeared in different areas with a tropical climate); however, due to differences in local diets and customs, migration and genetic drift between populations, restrictions are placed on the applicability of this rule.
Gloger's rule consists in the fact that among related forms (different races or subspecies of the same species, related species) of homoiothermic (warm-blooded) animals, those that live in warm and humid climates are brighter than those that live in cold and dry climate. Established in 1833 by Konstantin Gloger (Gloger C. W. L.; 1803-1863), Polish and German ornithologist.
For example, most desert bird species are dimmer than their relatives from subtropical and rainforest. Gloger's rule can be explained both by masking considerations and by the influence of climatic conditions on the synthesis of pigments. To a certain extent, Gloger's rule also applies to drunken-kilothermic (cold-blooded) animals, in particular insects.
Humidity as an environmental factor
Initially, all organisms were aquatic. Having conquered land, they did not lose their dependence on water. Water is an integral part of all living organisms. Humidity is the amount of water vapor in the air. Without humidity or water, there is no life.
Humidity is a parameter that characterizes the content of water vapor in the air. Absolute humidity is the amount of water vapor in the air and depends on temperature and pressure. This amount is called relative humidity (i.e. the ratio of the amount of water vapor in the air to the saturated amount of vapor under certain conditions of temperature and pressure.)
In nature, there is a daily rhythm of humidity. Humidity fluctuates both vertically and horizontally. This factor, along with light and temperature, plays an important role in regulating the activity of organisms and their distribution. Humidity also changes the effect of temperature.
Air drying is an important environmental factor. Especially for terrestrial organisms, the drying effect of air is of great importance. Animals adapt by moving to protected areas and are active at night.
Plants absorb water from the soil and almost completely (97-99%) evaporate through the leaves. This process is called transpiration. Evaporation cools the leaves. Thanks to evaporation, ions are transported through the soil to the roots, transport of ions between cells, etc.
A certain amount of moisture is essential for terrestrial organisms. Many of them need a relative humidity of 100% for normal life, and vice versa, an organism in a normal state cannot live for a long time in absolutely dry air, because it constantly loses water. Water is an essential part of living matter. Therefore, the loss of water in a certain amount leads to death.
Plants of a dry climate adapt to morphological changes, reduction of vegetative organs, especially leaves.
Land animals also adapt. Many of them drink water, others suck it up through the integument of the body in a liquid or vapor state. For example, most amphibians, some insects and mites. Most of the desert animals never drink; they satisfy their needs at the expense of water supplied with food. Other animals receive water in the process of fat oxidation.
Water is essential for living organisms. Therefore, organisms spread throughout the habitat depending on their needs: aquatic organisms live in water constantly; hydrophytes can only live in very humid environments.
From the point of view of ecological valence, hydrophytes and hygrophytes belong to the group of stenogigers. Humidity greatly affects the vital functions of organisms, for example, 70% relative humidity was very favorable for field maturation and fertility of migratory locust females. With favorable reproduction, they cause enormous economic damage to the crops of many countries.
For an ecological assessment of the distribution of organisms, an indicator of the dryness of the climate is used. Dryness serves as a selective factor for the ecological classification of organisms.
Thus, depending on the characteristics of the humidity of the local climate, the species of organisms are distributed into ecological groups:
1. Hydatophytes are aquatic plants.
2. Hydrophytes are terrestrial-aquatic plants.
3. Hygrophytes - terrestrial plants living in conditions of high humidity.
4. Mesophytes are plants that grow in medium moisture.
5. Xerophytes are plants growing with insufficient moisture. They, in turn, are divided into: succulents - succulent plants(cacti); sclerophytes are plants with narrow and small leaves, and folded into tubules. They are also divided into euxerophytes and stipaxerophytes. Euxerophytes are steppe plants. Stipaxerophytes are a group of narrow-leaved turf grasses (feather grass, fescue, thin-legged, etc.). In turn, mesophytes are also divided into mesohygrophytes, mesoxerophytes, etc.
Yielding in its value to temperature, humidity is nevertheless one of the main environmental factors. Throughout much of the history of wildlife organic world was represented exclusively by water norms of organisms. An integral part of the vast majority of living beings is water, and for the reproduction or fusion of gametes, almost all of them need an aquatic environment. Land animals are forced to create in their body an artificial aquatic environment for fertilization, and this leads to the fact that the latter becomes internal.
Humidity is the amount of water vapor in the air. It can be expressed in grams per cubic meter.
Light as an environmental factor. The role of light in the life of organisms
Light is one form of energy. According to the first law of thermodynamics, or the law of conservation of energy, energy can change from one form to another. According to this law, organisms are a thermodynamic system constantly exchanging energy and matter with the environment. Organisms on the surface of the Earth are exposed to the flow of energy, mainly solar energy, as well as long-wave thermal radiation from cosmic bodies.
Both of these factors determine climatic conditions environment (temperature, water evaporation rate, air and water movement). Sunlight with an energy of 2 cal falls on the biosphere from space. per 1 cm 2 in 1 min. This so-called solar constant. This light, passing through the atmosphere, is attenuated and no more than 67% of its energy can reach the Earth's surface on a clear noon, i.e. 1.34 cal. per cm 2 in 1 min. Passing through cloud cover, water and vegetation, sunlight is further weakened, and the distribution of energy in it in different parts of the spectrum changes significantly.
The degree of attenuation of sunlight and cosmic radiation depends on the wavelength (frequency) of the light. Ultraviolet radiation with a wavelength of less than 0.3 microns almost does not pass through the ozone layer (at an altitude of about 25 km). Such radiation is dangerous for a living organism, in particular for protoplasm.
In living nature, light is the only source of energy; all plants, except bacteria, photosynthesize, i.e. synthesize organic matter from inorganic substances(i.e. from water, mineral salts and CO- In wildlife, light is the only source of energy, all plants, except bacteria 2 - with the help of radiant energy in the process of assimilation). All organisms depend for food on terrestrial photosynthesizers i.e. chlorophyll-bearing plants.
Light as an environmental factor is divided into ultraviolet with a wavelength of 0.40 - 0.75 microns and infrared with a wavelength greater than these greatness.
The effect of these factors depends on the properties of organisms. Each type of organism is adapted to one or another spectrum of wavelengths of light. Some species of organisms have adapted to ultraviolet, while others to infrared.
Some organisms are able to distinguish the wavelength. They have special light-perceiving systems and have color vision, which are of great importance in their life. Many insects are sensitive to shortwave radiation, which humans do not perceive. Night butterflies perceive ultraviolet rays well. Bees and birds accurately determine their location and navigate the terrain even at night.
Organisms also react strongly to light intensity. According to these characteristics, plants are divided into three ecological groups:
1. Light-loving, sun-loving or heliophytes - which are able to develop normally only under the sun's rays.
2. Shade-loving, or sciophytes, are plants of the lower tiers of forests and deep-sea plants, for example, lilies of the valley and others.
As light intensity decreases, photosynthesis also slows down. All living organisms have threshold sensitivity to light intensity, as well as to other environmental factors. Different organisms have different threshold sensitivity to environmental factors. For example, intense light inhibits the development of Drosophyll flies, even causing their death. They do not like light and cockroaches and other insects. In most photosynthetic plants, at low light intensity, protein synthesis is inhibited, while in animals, biosynthesis processes are inhibited.
3. Shade-tolerant or facultative heliophytes. Plants that grow well in both shade and light. In animals, these properties of organisms are called light-loving (photophiles), shade-loving (photophobes), euryphobic - stenophobic.
Ecological valency
the degree of adaptability of a living organism to changes in environmental conditions. E. v. is a view property. Quantitatively, it is expressed by the range of environmental changes within which a given species retains normal vital activity. E. v. can be considered both in relation to the response of a species to individual environmental factors, and in relation to a complex of factors.
In the first case, species that tolerate wide changes in the strength of the influencing factor are designated by a term consisting of the name of this factor with the prefix "evry" (eurythermal - in relation to the influence of temperature, euryhaline - to salinity, eurybatic - to depth, etc.); species adapted only to small changes in this factor are designated by a similar term with the prefix "steno" (stenothermic, stenohaline, etc.). The types possessing wide E. in. in relation to a complex of factors, they are called eurybionts (See. Eurybionts) as opposed to stenobionts (See. Stenobionts), which have little adaptability. Since eurybiontism makes it possible to populate a variety of habitats, and stenobiontism sharply narrows the range of habitats suitable for the species, these two groups are often called eury- or stenotopic, respectively.
eurybionts, animal and plant organisms that can exist with significant changes in environmental conditions. So, for example, the inhabitants of the sea littoral endure regular drying during low tide, in summer - strong warming, and in winter - cooling, and sometimes freezing (eurythermal animals); the inhabitants of the estuaries of the rivers withstand means. fluctuations in water salinity (euryhaline animals); a number of animals exist in a wide range of hydrostatic pressure (eurybats). Many terrestrial inhabitants of temperate latitudes are able to withstand large seasonal temperature fluctuations.
The eurybiontness of the species is increased by the ability to tolerate unfavourable conditions in a state of anabiosis (many bacteria, spores and seeds of many plants, adult perennial plants of cold and temperate latitudes, wintering buds of freshwater sponges and bryozoans, eggs of branchiopods, adult tardigrades and some rotifers, etc.) or hibernation (some mammals).
CHETVERIKOV'S RULE, as a rule, according to Krom in nature, all types of living organisms are not represented by separate isolated individuals, but in the form of aggregates of a number (sometimes very large) of individuals-populations. Bred by S. S. Chetverikov (1903).
View- this is a historically established set of populations of individuals that are similar in morphological and physiological properties, capable of freely interbreeding and producing fertile offspring, occupying a certain area. Each type of living organisms can be described by a set of characteristic features, properties, which are called features of the view. The characteristics of a species, by means of which one species can be distinguished from another, are called species criteria.
The most commonly used seven general view criteria are:
1. specific type organizations: aggregate characteristic features to distinguish individuals of a given species from individuals of another.
2. Geographical certainty: the existence of individuals of a species in a particular place on the globe; range - the area where individuals of a given species live.
3. Ecological certainty: individuals of a species live in a specific range of values of physical environmental factors, such as temperature, humidity, pressure, etc.
4. Differentiation: the species consists of smaller groups of individuals.
5. Discreteness: individuals of this species are separated from individuals of another by a gap - hiatus. Hiatus is determined by the action of isolating mechanisms, such as a mismatch in breeding periods, the use of specific behavioral reactions, the sterility of hybrids, etc.
6. Reproducibility: reproduction of individuals can be carried out asexually (the degree of variability is low) and sexually (the degree of variability is high, since each organism combines the characteristics of a father and mother).
7. A certain level of abundance: the population undergoes periodic (waves of life) and non-periodic changes.
Individuals of any species are distributed in space extremely unevenly. For example, stinging nettle within its range is found only in moist shady places with fertile soil, forming thickets in floodplains of rivers, streams, around lakes, along the outskirts of swamps, in mixed forests and thickets of shrubs. Colonies of the European mole, clearly visible on the mounds of the earth, are found on forest edges, meadows and fields. Suitable for life
although habitats are often found within the range, they do not cover the entire range, and therefore individuals of this species are not found in other parts of it. It makes no sense to look for nettles in a pine forest or a mole in a swamp.
Thus, the uneven distribution of the species in space is expressed in the form of "density islands", "clumps". Areas with a relatively high distribution of this species alternate with areas of low abundance. Such "centers of density" of the population of each species are called populations. A population is a collection of individuals of a given species, for a long time (a large number of generations) inhabiting a certain space (part of the range), and isolated from other similar populations.
Within the population, free crossing (panmixia) is practically carried out. In other words, a population is a group of individuals freely bonding among themselves, living for a long time in a certain territory, and relatively isolated from other similar groups. A species is thus a collection of populations, and a population is structural unit kind.
The difference between a population and a species:
1) individuals of different populations freely interbreed with each other,
2) individuals of different populations differ little from each other,
3) there is no gap between two neighboring populations, that is, there is a gradual transition between them.
Speciation process. Let us assume that a given species occupies a certain area, determined by the nature of its diet. As a result of divergence between individuals, the range increases. The new area will contain areas with various forage plants, physical and chemical properties etc. Individuals that find themselves in different parts of the range form populations. In the future, as a result of ever-increasing differences between the individuals of populations, it will become more and more clear that the individuals of one population differ in some way from the individuals of another population. There is a process of divergence of populations. Mutations accumulate in each of them.
Representatives of any species in the local part of the range form a local population. The totality of local populations associated with parts of the range that are homogeneous in terms of living conditions constitutes an ecological population. So, if a species lives in a meadow and in a forest, then they talk about its gum and meadow populations. Populations within the range of a species associated with certain geographic boundaries are called geographic populations.
The size and boundaries of populations can change dramatically. During outbreaks of mass reproduction, the species spreads very widely and gigantic populations arise.
The set of geographical populations with stable traits, the ability to interbreed and produce fertile offspring is called a subspecies. Darwin said that the formation of new species goes through varieties (subspecies).
However, it should be remembered that some element is often absent in nature.
Mutations that occur in individuals of each subspecies cannot by themselves lead to the formation of new species. The reason lies in the fact that this mutation will wander through the population, since individuals of subspecies, as we know, are not reproductively isolated. If the mutation is beneficial, it increases the heterozygosity of the population; if it is harmful, it will simply be rejected by selection.
As a result of the constantly ongoing mutation process and free crossing, mutations accumulate in populations. According to the theory of I. I. Schmalhausen, a reserve of hereditary variability is created, i.e., the vast majority of emerging mutations are recessive and do not appear phenotypically. Upon reaching a high concentration of mutations in the heterozygous state, the crossing of individuals carrying recessive genes becomes probable. In this case, homozygous individuals appear, in which mutations are already manifested phenotypically. In these cases, mutations are already under the control of natural selection.
But this is not yet of decisive importance for the process of speciation, because natural populations are open and alien genes from neighboring populations are constantly introduced into them.
There is sufficient gene flow to maintain the large similarity of the gene pools (the totality of all genotypes) of all local populations. It is estimated that the replenishment of the gene pool due to foreign genes in a population of 200 individuals, each of which has 100,000 loci, is 100 times more than - due to mutations. As a consequence, no population can change dramatically as long as it is subject to the normalizing influence of gene flow. The resistance of a population to changes in its genetic composition under the influence of selection is called genetic homeostasis.
As a result of genetic homeostasis in a population, the formation of a new species is very difficult. One more condition must be fulfilled! Namely, it is necessary to isolate the gene pool of the daughter population from the maternal gene pool. Isolation can be in two forms: spatial and temporal. Spatial isolation occurs due to various geographical barriers such as deserts, forests, rivers, dunes, floodplains. Most often, spatial isolation occurs due to a sharp reduction in the continuous range and its breakup into separate pockets or niches.
Often a population becomes isolated as a result of migration. In this case, an isolate population arises. However, since the number of individuals in an isolate population is usually small, there is a danger of inbreeding - degeneration associated with inbreeding. Speciation based on spatial isolation is called geographic.
The temporary form of isolation includes a change in the timing of reproduction and shifts in the entire life cycle. Speciation based on temporary isolation is called ecological.
The decisive thing in both cases is the creation of a new, incompatible with the old, genetic system. Through speciation, evolution is realized, which is why they say that a species is an elementary evolutionary system. A population is an elementary evolutionary unit!
Statistical and dynamic characteristics of populations.
Species of organisms are included in the biocenosis not as separate individuals, but as populations or their parts. A population is a part of a species (consists of individuals of the same species), occupying a relatively homogeneous space and capable of self-regulation and maintenance of a certain number. Each species within the occupied territory is divided into populations. If we consider the impact of environmental factors on a single organism, then at a certain level of the factor (for example, temperature), the individual under study will either survive or die. The picture changes when studying the impact of the same factor on a group of organisms of the same species.
Some individuals will die or reduce their vital activity at one specific temperature, others at a lower temperature, and still others at a higher one. Therefore, one more definition of a population can be given: in order to survive and give offspring, all living organisms must, under the conditions of dynamic environmental regimes, factors exist in the form of groupings, or populations, i.e. aggregates of individuals living together with similar heredity. The most important feature of a population is the total territory it occupies. But within a population there may be more or less isolated groupings for various reasons.
Therefore, it is difficult to give an exhaustive definition of the population due to the blurring of the boundaries between individual groups of individuals. Each species consists of one or more populations, and a population is thus the form of existence of a species, its smallest evolving unit. For populations various kinds there are acceptable limits for the decline in the number of individuals, beyond which the existence of a population becomes impossible. There are no exact data on the critical values of the population size in the literature. The given values are contradictory. However, the fact remains that the smaller the individuals, the higher the critical values of their numbers. For microorganisms, these are millions of individuals, for insects - tens and hundreds of thousands, and for large mammals - several tens.
The number should not decrease below the limits beyond which the probability of meeting sexual partners is sharply reduced. The critical number also depends on other factors. For example, for some organisms, a group lifestyle is specific (colonies, flocks, herds). Groups within a population are relatively isolated. There may be cases when the size of the population as a whole is still quite large, and the number of individual groups is reduced below critical limits.
For example, a colony (group) of the Peruvian cormorant must have a population of at least 10 thousand individuals, and a herd of reindeer - 300 - 400 heads. To understand the mechanisms of functioning and address issues of using populations great importance have information about their structure. There are gender, age, territorial and other types of structure. In theoretical and applied terms, the data on the age structure are most important - the ratio of individuals (often combined into groups) of different ages.
Animals are divided into the following age groups:
Juvenile group (children) senile group (senile, not involved in reproduction)
Adult group (individuals carrying out reproduction).
Usually, normal populations are characterized by the greatest viability, in which all ages are represented relatively evenly. In the regressive (endangered) population, senile individuals predominate, which indicates the presence of negative factors that disrupt reproductive functions. Urgent measures are required to identify and eliminate the causes of this condition. Invading (invasive) populations are represented mainly by young individuals. Their vitality usually does not cause concern, but outbreaks of excessively high numbers of individuals are likely, since trophic and other relationships have not formed in such populations.
It is especially dangerous if it is a population of species that were previously absent in the area. In this case, populations usually find and occupy a free ecological niche and realize their breeding potential, intensively increasing their numbers. If the population is in a normal or close to normal state, a person can remove from it the number of individuals (in animals) or biomass (in plants), which increases over the period of time between seizures. First of all, individuals of post-productive age (completed reproduction) should be withdrawn. If the goal is to obtain a certain product, then the age, sex and other characteristics of the populations are adjusted taking into account the task.
The exploitation of populations of plant communities (for example, to obtain timber) is usually timed to coincide with the period of age-related slowdown in growth (accumulation of production). This period usually coincides with the maximum accumulation of wood mass per unit area. The population is also characterized by a certain sex ratio, and the ratio of males and females is not equal to 1:1. There are known cases of a sharp predominance of one sex or another, alternation of generations with the absence of males. Each population can also have a complex spatial structure, (subdividing into more or less large hierarchical groups - from geographical to elementary (micropopulations).
So, if the mortality rate does not depend on the age of individuals, then the survival curve is a decreasing line (see figure, type I). That is, the death of individuals occurs evenly in this type, the mortality rate remains constant throughout life. Such a survival curve is characteristic of species whose development occurs without metamorphosis with sufficient stability of the born offspring. This type is usually called the type of hydra - it is characterized by a survival curve approaching a straight line. In species for which the role of external factors in mortality is small, the survival curve is characterized by a slight decrease until a certain age, after which there is a sharp drop due to natural (physiological) mortality.
Type II in the figure. A survival curve close to this type is characteristic of humans (although the human survival curve is somewhat flatter and thus somewhere between types I and II). This type is called the type of Drosophila: it is this type that Drosophila demonstrates in laboratory conditions (not eaten by predators). Many species are characterized by high mortality in the early stages of ontogeny. In such species, the survival curve is characterized by a sharp drop in the area younger ages. Individuals that have survived the "critical" age demonstrate low mortality and live to great ages. The type is called the type of oyster. Type III in the figure. The study of survival curves is of great interest to the ecologist. It allows you to judge at what age a particular species is most vulnerable. If the action of causes capable of changing the birth rate or mortality falls on the most vulnerable stage, then their influence on the subsequent development of the population will be the greatest. This pattern must be taken into account when organizing hunting or in pest control.
Age and sex structure of populations.
Any population has a certain organization. The distribution of individuals over the territory, the ratio of groups of individuals by sex, age, morphological, physiological, behavioral and genetic characteristics reflect the corresponding population structure : spatial, gender, age, etc. The structure is formed, on the one hand, on the basis of the general biological properties of the species, and, on the other hand, under the influence of abiotic environmental factors and populations of other species.
The population structure thus has an adaptive character. Different populations of the same species have both similar features and distinctive features that characterize the specifics of environmental conditions in their habitats.
In general, in addition to the adaptive capabilities of individuals, adaptive features of the group adaptation of the population as a supra-individual system are formed in certain territories, which indicates that the adaptive features of the population are much higher than those of the individuals that make it up.
Age composition- is essential for the existence of the population. The average lifespan of organisms and the ratio of the number (or biomass) of individuals of different ages is characterized by the age structure of the population. The formation of the age structure occurs as a result of the combined action of the processes of reproduction and mortality.
In any population, 3 age ecological groups are conditionally distinguished:
Pre-reproductive;
reproductive;
Post-reproductive.
The pre-reproductive group includes individuals that are not yet capable of reproduction. Reproductive - individuals capable of reproduction. Post-reproductive - individuals who have lost the ability to reproduce. The duration of these periods varies greatly depending on the type of organisms.
Under favorable conditions, the population contains all age groups and maintains a more or less stable age composition. In rapidly growing populations, young individuals predominate, while in declining populations, old ones, no longer able to reproduce intensively, predominate. Such populations are unproductive and not stable enough.
There are views from simple age structure populations that consist of individuals of almost the same age.
For example, all annual plants of one population are in the seedling stage in spring, then bloom almost simultaneously, and produce seeds in autumn.
In species from complex age structure populations live simultaneously for several generations.
For example, in the experience of elephants there are young, mature and aging animals.
Populations that include many generations (of different age groups) are more stable, less susceptible to the influence of factors affecting reproduction or mortality in a particular year. Extreme conditions can lead to the death of the most vulnerable age groups, but the most resilient survive and produce new generations.
For example, a person is considered as a biological species with a complex age structure. The stability of the populations of the species manifested itself, for example, during the Second World War.
To study the age structures of populations, graphical techniques are used, for example, the age pyramids of a population, which are widely used in demographic studies (Fig. 3.9).
Fig.3.9. Age pyramids of the population.
A - mass reproduction, B - stable population, C - declining population
The stability of populations of a species largely depends on sexual structure , i.e. ratios of individuals of different sexes. Sex groups within populations are formed on the basis of differences in morphology (body shape and structure) and ecology of different sexes.
For example, in some insects, males have wings, but females do not, males of some mammals have horns, but they are absent in females, male birds have bright plumage, and females have camouflage.
Ecological differences are expressed in food preferences(females of many mosquitoes suck blood, while males feed on nectar).
The genetic mechanism provides an approximately equal ratio of individuals of both sexes at birth. However, the original ratio is soon broken as a result of physiological, behavioral and ecological differences between males and females, causing uneven mortality.
An analysis of the age and sex structure of populations makes it possible to predict its numbers for a number of next generations and years. This is important when assessing the possibilities of fishing, shooting animals, saving crops from locust invasions, and in other cases.
Hot springs, usually found in volcanic areas, have a fairly rich living population.
Long ago, when there was the most superficial idea about bacteria and other lower beings, the existence of a peculiar flora and fauna in the baths was established. Thus, for example, in 1774 Sonnerath reported the presence of fish in the hot springs of Iceland, which had a temperature of 69°. This conclusion was not later confirmed by other researchers in relation to the terms of Iceland, but similar observations were made in other places. On the island of Ischia, Ehrenberg (1858) noted the presence of fish in springs with temperatures above 55°. Hoppe-Seyler (1875) also saw fish in water with a temperature also of about 55°. Even if we assume that in all the cases noted the thermometering was inaccurate, it is still possible to draw a conclusion about the ability of some fish to live at a rather elevated temperature. Along with fish, the presence of frogs, worms and mollusks was sometimes noted in the baths. At a later time, protozoa were also discovered here.
In 1908, the work of Issel was published, which established in more detail the temperature limits for the animal world living in hot springs.
Along with the animal world, the presence of algae in the baths is extremely easy to establish, sometimes forming powerful fouling. According to Rodina (1945), the thickness of algae accumulated in hot springs often reaches several meters.
We have spoken enough about the associations of thermophilic algae and the factors that determine their composition in the section “Algae living at high temperatures”. Here we only recall that the most thermally stable of them are blue-green algae, which can develop up to a temperature of 80-85 °. Green algae tolerate temperatures slightly above 60°C, while diatoms stop developing at about 50°C.
As already noted, algae that develop in thermal baths play a significant role in the formation of various kinds of scales, which include mineral compounds.
Thermophilic algae have a great influence on the development of the bacterial population in the thermal baths. During their lifetime, by exosmosis, they release a certain amount of organic compounds into the water, and when they die, they even create a fairly favorable substrate for bacteria. It is not surprising, therefore, that the bacterial population of thermal waters is most richly represented in places where algae accumulate.
Turning to the thermophilic bacteria of hot springs, we must point out that in our country they have been studied by quite a few microbiologists. Here the names of Tsiklinskaya (1899), Gubin (1924-1929), Afanasyeva-Kester (1929), Egorova (1936-1940), Volkova (1939), Motherland (1945) and Isachenko (1948) should be noted.
Most of the researchers who dealt with hot springs limited themselves only to the fact of establishing a bacterial flora in them. Only a relatively few microbiologists have dwelled on the fundamental aspects of the life of bacteria in thermae.
In our review, we will linger only on the studies of the last group.
Thermophilic bacteria have been found in hot springs in a number of countries - Soviet Union, France, Italy, Germany, Slovakia, Japan, etc. Since the waters of hot springs are often poor in organic matter, it is not surprising that they sometimes contain a very small amount of saprophytic bacteria.
The reproduction of autotrophically feeding bacteria, among which iron and sulfur bacteria are quite widespread in the baths, is determined mainly by the chemical composition of the water, as well as its temperature.
Some thermophilic bacteria isolated from hot waters have been described as new species. These forms include: Bac. thermophilus filiformis. studied by Tsiklinskaya (1899), two spore-bearing rods - Bac. ludwigi and Bac. ilidzensis capsulatus isolated by Karlinsky (1895), Spirochaeta daxensis isolated by Kantakouzen (1910), and Thiospirillum pistiense isolated by Czurda (1935).
The water temperature of hot springs strongly affects the species composition of the bacterial population. In waters with a lower temperature, cocci and spirochaete-like bacteria have been found (works by Rodina and Kantakouzena). However, here, too, spore-bearing rods are the predominant form.
Recently, the influence of temperature on the species composition of the bacterial population of the term was very colorfully shown in the work of Rodina (1945), who studied the hot springs of Khoji-Obi-Garm in Tajikistan. The temperature of individual sources of this system ranges from 50-86°. Connecting, these terms give a stream, at the bottom of which, in places with a temperature not exceeding 68 °, a rapid growth of blue-green algae was observed. In places, algae formed thick layers of different colors. At the water's edge, on the side walls of the niches, there were deposits of sulfur.
In different sources, in the runoff, as well as in the thickness of blue-green algae, fouling glasses were placed for three days. In addition, the collected material was sown on nutrient media. It was found that water with the most high temperature contains predominantly rod-shaped bacteria. Wedge-shaped forms, in particular resembling Azotobacter, occur at temperatures not exceeding 60 °. Judging by all the data, it can be said that Azotobacter itself does not grow above 52°C, while the large round cells found in the fouling belong to other types of microbes.
The most heat-resistant are some forms of bacteria that develop on meat-peptone agar, thio-bacteria such as Tkiobacillus thioparus and desulphurizers. Incidentally, it is worth mentioning that Egorova and Sokolova (1940) found Microspira in water at a temperature of 50-60°.
In Rodina's work, nitrogen-fixing bacteria were not found in water at 50°C. However, when studying soils, anaerobic nitrogen fixers were found even at 77°C, and Azotobacter - at 52°C. This suggests that water is generally not a suitable substrate for nitrogen fixers.
The study of bacteria in the soils of hot springs revealed the same dependence of the group composition on temperature there as in water. However, the soil micropopulation was much richer numerically. Sandy soils poor in organic compounds had a rather poor micropopulation, while soils containing dark-colored organic matter were abundantly inhabited by bacteria. Thus, the relationship between the composition of the substrate and the nature of the microscopic creatures contained in it was revealed here very clearly.
It is noteworthy that neither in the water nor in the silts of the Motherland could not be found thermophilic bacteria that decompose fiber. This moment we are inclined to attribute it to methodological difficulties, since thermophilic cellulose-decomposing bacteria are quite demanding on nutrient media. As Imshenetsky showed, rather specific nutrient substrates are needed for their isolation.
In hot springs, in addition to saprophytes, there are autotrophs - sulfur and iron bacteria.
The oldest observations on the possibility of growth of sulfur bacteria in thermae were apparently made by Meyer and Ahrens, and also by Mioshi. Mioshi observed the development of filamentous sulfur bacteria in springs whose water temperature reached 70°C. Egorova (1936), who studied the Bragun sulfur springs, noted the presence of sulfur bacteria even at a water temperature of 80°C.
In the chapter " general characteristics Morphological and Physiological Features of Thermophilic Bacteria” we described in sufficient detail the properties of thermophilic iron and sulfur bacteria. It is not expedient to repeat this information, and we will confine ourselves here to a reminder that individual genera and even species of autotrophic bacteria terminate their development at different temperatures.
Thus, the maximum temperature for sulfur bacteria is about 80°C. For iron bacteria such as Streptothrix ochraceae and Spirillum ferrugineum, Mioshi set a maximum of 41-45°.
Dufrenois (Dufrencfy, 1921) found on sediments in hot waters with a temperature of 50-63° iron bacteria very similar to Siderocapsa. According to his observations, the growth of filamentous iron bacteria occurred only in cold waters.
Volkova (1945) observed the development of bacteria from the genus Gallionella in the mineral springs of the Pyatigorsk group when the water temperature did not exceed 27-32°. In the baths with a higher temperature, iron bacteria were completely absent.
Comparing the materials noted by us, we involuntarily have to conclude that in some cases it is not the temperature of the water, but its chemical composition determines the development of certain microorganisms.
Bacteria, along with algae, take an active part in the formation of some minerals, bioliths and caustobioliths. The role of bacteria in calcium precipitation has been studied in more detail. This issue is covered in detail in the section on physiological processes caused by thermophilic bacteria.
The conclusion made by Volkova deserves attention. She notes that the “barezina”, which is deposited in a thick cover in the streams of the sources of the sulfur sources of Pyatigorsk, contains a lot of elemental sulfur and basically has the mycelium of a mold fungus from the genus Penicillium. The mycelium makes up the stroma, which includes rod-shaped bacteria, apparently related to sulfur bacteria.
Brussoff believes that term bacteria also take part in the formation of silicic acid deposits.
Bacteria reducing sulfates were found in the baths. According to Afanasieva-Kester, they resemble Microspira aestuarii van Delden and Vibrio thermodesulfuricans Elion. Gubin (1924-1929) expressed a number of ideas about the possible role of these bacteria in the formation of hydrogen sulfide in the baths.
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