At first glance, it might seem that bacteria in hot springs do not live. However, nature convincingly proves that this is not so.
Everyone knows that water boils at 100 degrees Celsius. Until quite recently, people believed that absolutely nothing survives at this temperature. Scientists thought so until the bottom Pacific Ocean, in hot springs, did not find bacteria unknown to science. They feel great at 250 degrees!
At great depths, water does not turn into steam, but remains just water, because there is great depth and great pressure. In water of this temperature there are many chemicals that feed on the bacteria mentioned above. It is not clear how living creatures have taken root at such a temperature, but they are used to living there in such a way that if they are brought to a temperature that is below 80 degrees Celsius, it will be cold for them.
As it turned out - not the limit for the life of bacteria - a temperature of 250 degrees. In the same Pacific Ocean they found very hot spring, the water in which reaches 400 degrees. Even in such conditions, not only many bacteria live, but also some worms, as well as several types of molluscs.
Everyone knows that when the Earth appeared (it was a lot of millions of years ago), it was an ordinary hot ball. For centuries, people believed that life appeared on our planet when the Earth cooled. And it was also believed that life could not exist on other planets with high temperatures. Probably, scientists will now have to reconsider their views in relation to this fact.
For those who are not interested in animals, but are looking for where to buy a cheap gift for the New Year, the Groupon promo code will definitely come in handy.Some organisms, when compared with others, have a number of undeniable advantages, for example, the ability to withstand extremely high or low temperatures. There are a lot of such hardy living creatures in the world. In the article below you will get acquainted with the most amazing of them. Without exaggeration, they are able to survive even in extreme conditions.
1. Himalayan jumping spiders
mountain geese are known to be among the highest flying birds in the world. They are able to fly at an altitude of more than 6 thousand meters above the ground.
Do you know where the highest locality on the ground? In Peru. This is the city of La Rinconada, located in the Andes near the border with Bolivia at an altitude of about 5100 meters above sea level.
Meanwhile, the record for the highest living creatures on planet Earth went to the Himalayan jumping spiders Euophrys omnisuperstes (Euophrys omnisuperstes - “standing above everything”), which live in secluded nooks and crevices on the slopes of Mount Everest. Climbers found them even at an altitude of 6700 meters. These tiny spiders feed on insects carried to the top of a mountain. strong wind. They are the only living creatures that permanently live at such a great height, apart from, of course, some species of birds. It is also known that Himalayan jumping spiders are able to survive even in conditions of lack of oxygen.
2. Giant kangaroo jumper
When we are asked to name an animal that can go without drinking water for long periods of time, the first thing that comes to mind is the camel. However, in the desert without water, it can last no more than 15 days. And no, camels do not store water in their humps, as many mistakenly believe. Meanwhile, on Earth there are still such animals that live in the desert and are able to live without a single drop of water throughout their lives!
Giant jumping kangaroos are related to beavers. Their life span is three to five years. Giant kangaroo jumpers get water with food, and they feed mainly on seeds.
Giant kangaroo jumpers, as scientists note, do not sweat at all, so they do not lose, but, on the contrary, accumulate water in the body. You can find them in Death Valley (California). Giant jumping kangaroos are currently endangered.
3. Worms resistant to high temperatures
Since water conducts heat away from the human body about 25 times more efficiently than air, a temperature of 50 degrees Celsius in the depths of the sea will be much more dangerous than on land. That is why bacteria thrive under water, and not multicellular organisms that cannot withstand too high temperatures. But there are exceptions...
Marine deep-sea annelid worms Paralvinella sulfincola (Paralvinella sulfincola), which live near hydrothermal vents at the bottom of the Pacific Ocean, are perhaps the most heat-loving living creatures on the planet. The results of an experiment conducted by scientists with heating the aquarium showed that these worms prefer to settle where the temperature reaches 45-55 degrees Celsius.
4 Greenland Shark
Greenland sharks are one of the largest living creatures on planet Earth, but scientists know almost nothing about them. They swim very slowly, on par with the average amateur swimmer. However, it is almost impossible to see the Greenland sharks in the ocean waters, since they usually live at a depth of 1200 meters.
Greenland sharks are also considered the most cold-loving creatures in the world. They prefer to live in places where the temperature reaches 1-12 degrees Celsius.
Greenland sharks live in cold waters, therefore, they have to conserve energy; this explains the fact that they swim very slowly - at a speed of no more than two kilometers per hour. Greenland sharks are also called "sleeping sharks". In food, they are not picky: they eat everything that they can catch.
According to some scientists, the life expectancy of the Greenland polar sharks can reach 200 years, but so far this has not been proven.
5. Devil Worms
For decades, scientists thought that only single-celled organisms could survive at very great depths. It was believed that multicellular life forms could not live there due to lack of oxygen, pressure and high temperatures. However, more recently, researchers have discovered microscopic worms at a depth of several thousand meters from the earth's surface.
The nematode Halicephalobus mephisto, named after a demon from German folklore, was discovered by Gaetan Borgoni and Tallis Onstott in 2011 in water samples taken at a depth of 3.5 kilometers in a cave in South Africa. Scientists have found that they show high resilience in various extreme conditions, like those roundworms that survived the Columbia shuttle disaster on February 1, 2003. The discovery of devil worms could expand the search for life on Mars and every other planet in our galaxy.
6. Frogs
Scientists have noticed that some types of frogs literally freeze with the onset of winter and, thawing in the spring, return to a full life. AT North America There are five species of such frogs, the most common of which is Rana sylvatica, or the Forest Frog.
Forest frogs do not know how to burrow into the ground, so with the onset of cold weather, they simply hide under fallen leaves and freeze, like everything around. Inside the body, they have a natural “antifreeze” protective mechanism, and they, like a computer, go into “sleep mode”. To survive the winter they are largely allowed by the reserves of glucose in the liver. But the most amazing thing is that Wood Frogs show their amazing ability both in wild nature as well as in laboratory conditions.
7 Deep Sea Bacteria
We all know that the deepest point of the World Ocean is the Mariana Trench, which is located at a depth of more than 11 thousand meters. At its bottom, the water pressure reaches 108.6 MPa, which is about 1072 times higher than normal. atmospheric pressure at the level of the oceans. A few years ago, scientists using high-resolution cameras placed in glass spheres discovered giant amoebas in the Mariana Trench. According to James Cameron, who led the expedition, other forms of life also thrive in it.
After studying water samples from the bottom of the Mariana Trench, scientists found a huge amount of bacteria in it, which, surprisingly, actively multiplied, despite the great depth and extreme pressure.
8. Bdelloidea
Bdelloidea rotifers are small invertebrates commonly found in fresh water.
Representatives of the Bdelloidea rotifers lack males, and the populations are represented only by parthenogenetic females. Bdelloidea reproduce asexually, which, according to scientists, negatively affects their DNA. And what is the most The best way overcome these harmful effects? Answer: eat the DNA of other life forms. Through this approach, Bdelloidea has developed an amazing ability to withstand extreme dehydration. Moreover, they can survive even after receiving a lethal dose of radiation for most living organisms.
Scientists believe that the ability of Bdelloidea to repair DNA was originally given to them to survive in conditions of high temperatures.
9. Cockroaches
There is a popular myth that after a nuclear war, only cockroaches will survive on Earth. These insects are able to go weeks without food and water, but what is even more amazing is the fact that they can live many days after they lose their heads. Cockroaches appeared on Earth 300 million years ago, even earlier than dinosaurs.
The hosts of the MythBusters in one of the programs decided to test the survivability of cockroaches in the course of several experiments. First, they exposed a number of insects to 1,000 rads of radiation, a dose capable of killing a healthy human in minutes. Almost half of them managed to survive. After the MythBusters increased the radiation power to 10 thousand rad (as in the atomic bombing of Hiroshima). This time, only 10 percent of the cockroaches survived. When the radiation power reached 100 thousand rads, not a single cockroach, unfortunately, managed to stay alive.
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. Average duration their life span 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. Since they had no natural enemies before, the bacteria were relatively easy prey.
7 Greenland 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 ground in a cave in South Africa. They managed to survive extreme conditions environment, which made it possible to assume that life is possible on Mars and on other planets in our galaxy.
5. Frogs
Some species of frogs are widely known for their ability to literally freeze for the entire winter period and come to life with the advent of spring. Five species of these frogs have been found in North America, the most common of which is the common tree frog. Insofar as tree frogs are not very strong in digging, then they simply hide under the 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 the natural environment, but also in the laboratory, allowing scientists to reveal their secrets.
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4 Deep Sea Microbes
We all know that the most deep 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 enormous pressure, are far from a paradise.
3. Bdelloidea
Bdelloidea rotifers 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 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 powerful nuclear radiation. As a result, it turned out that almost half of all insects were able to survive radiation of 1000 rad (such radiation can kill an adult healthy person in just 10 minutes of exposure), moreover, 10% of cockroaches survived when exposed to radiation of 10,000 rad, 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 proven to be our planet's hardiest organisms. 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.
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 in other places similar observations were nevertheless made. 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 create a rather 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 more low temperature, cocci and spirochaete-like bacteria were found (works by Rodina, Kantakouzena). However, here, too, spore-bearing rods are the predominant form.
Recently, the effect of temperature on species composition The bacterial population of the term was very colorfully shown in the work of Rodina (1945), who studied the hot springs of Khodji-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 the water with the highest temperature has 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 sparse micropopulation, while those containing dark-colored organic matter were rich in 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 thermophilic bacteria that decompose cellulose were not found either in the water or in the silts of Rodina. 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 sulfur sources in Pyatigorsk, contains a lot of elemental sulfur and basically has a mycelium 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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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 in hot springs at a temperature of 250°C is found. 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- ecogeographical 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 the smallest species (for example, the 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 wolf subspecies are larger than 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 climates. 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. Integral part of all living organisms is water. 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 fecundity 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 with average 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 the climatic conditions of the 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 substances from inorganic substances (i.e. from water, mineral salts and CO2). In living nature, light is the only source of energy, all plants, except bacteria 2, use 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. At various organisms threshold sensitivity to environmental factors is not the same. 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 valence
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 eurybionticity makes it possible to populate a variety of habitats, and stenobionticity 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 at 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 suspended animation (many bacteria, spores and seeds of many plants, adult perennials 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 represented not 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 of organization: population 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 the 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 the 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 the structural unit of a species.
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 areas of the range that are homogeneous in terms of living conditions is 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 totality of geographic populations with stable signs, the ability to interbreed and produce fertile offspring is called a subspecies. Darwin said that the formation of new species is coming 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 of various species, 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. For understanding the mechanisms of functioning and solving the problems of using populations, information about their structure is of great importance. 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 region of younger ages. Individuals that have survived the "critical" age demonstrate low mortality and live to big 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 that can change 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 group adaptation of a population as a supra-individual system are formed in certain territories, which indicates that the adaptive features of a population are much higher than those of its constituent individuals.
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 seen as 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.
