A detailed decision paragraph § 76 on biology for students of grade 10, authors Kamensky AA, Kriksunov EA, Pasechnik VV 2014
- Gdz Biology workbook for grade 10 can be found
1. What is a habitat?
Answer. Habitat (habitat) - a set of biotic, abiotic and anthropogenic (if any) environmental factors in any particular territory or water area, formed on the site of the primary complex of abiotic factors - ecotope. The habitat of a species or population is an important component of his / her ecological niche. In relation to terrestrial animals, the term is considered synonymous with the concepts of station (habitat of a species) and biotope (habitat of a community).
Habitats characterized by different severity of environmental factors, but having a similar vegetation cover, are called biologically equivalent. Their existence is possible due to partial compensation of factors by each other.
T. Southwood (1977) suggested classifying habitats by the nature of the change in factors over time, highlighting the following:
invariable - environmental conditions remain favorable indefinitely;
predictably seasonal - there is a regular change in favorable and unfavorable periods;
unpredictable - favorable and unfavorable periods have different durations;
ephemeral - with a short favorable period.
2. What is the food chain?
Answer. Food (trophic) chain - a series of species of plants, animals, fungi and microorganisms that are related to each other by relationships: food - the consumer (a sequence of organisms in which the phased transfer of matter and energy from source to consumer).
Organisms of the next link eat up the organisms of the previous link, and thus the chain transfer of energy and matter is carried out, which underlies the cycle of matter in nature. With each transfer from link to link, a large part (up to 80-90%) of potential energy is lost, dissipated in the form of heat. For this reason, the number of links (species) in the food chain is limited and usually does not exceed 4-5.
3. What is interspecific struggle?
Questions after § 76
1. What is the difference between the terms “habitat” and “ecological niche”?
Answer. The position of the species that it occupies in the biogeocenosis, the complex of its connections with other species and the requirements for abiotic environmental factors is called an ecological niche. The concept of "ecological niche" should be distinguished from the concept of "habitat". In the latter case, we are talking about the part of space where the species lives and where there are necessary abiotic conditions for its existence. The ecological niche of a species depends not only on abiotic conditions, it characterizes the whole lifestyle that a species can lead in a given community. In the figurative expression of ecologist Yu. Odum, the habitat is the address of the species, and the ecological niche is its “profession”. Distinguish between fundamental (or potential) and realized niches. A fundamental ecological niche is a set of optimal conditions under which a given species can exist and reproduce. Realized niche - conditions where the species actually occurs in a given ecosystem; it always makes up some part of the fundamental niche.
For the reproduction and long-term existence of many animal species, the differentiation of niches at different stages of ontogenesis is of great importance: caterpillars and adults of Lepidoptera, larvae and beetles of May chrysanthemum, tadpoles and adult frogs do not compete with each other, because they differ in habitat and enter different food chains.
Interspecific competition leads to a narrowing of the ecological niche and prevents its potentials from manifesting itself. Intraspecific competition, on the contrary, contributes to the expansion of the ecological niche. In connection with the increase in the number of species, the use of additional feed begins, the development of new habitats, the emergence of new biocenotic relationships.
2. Can different species occupy the same ecological niche?
Answer. No, they can’t. A large number of organisms of various species live in one habitat. For example, a mixed forest is a habitat for hundreds of species of plants and animals, but each of them has its own and only one “profession” - an ecological niche.
Elk and squirrel have a similar habitat in the forest, but their niches are completely different: the squirrel lives mainly in the crowns of trees, feeds on seeds and fruits, and reproduces in the same place. The entire life cycle of an elk is associated with a subsystem space: feeding on green plants or their parts, reproduction and shelter in thickets.
Elements of an ecological niche:
food (species);
time and ways of eating;
breeding place;
place of shelter.
Environmental niches exist according to certain rules:
the wider the requirements (tolerance limits) of the species for any or many environmental factors, the greater the space that it can occupy in nature, and therefore, the wider its distribution;
if the regime of any, at least one environmental factor in the habitat of individuals of one species has changed in such a way that its values \u200b\u200bextend beyond the limits of a niche, this means the destruction of a niche, i.e., the restriction or impossibility of maintaining the species in a given habitat. There are other important regularities associated with the concept of “ecological niche” - each species has its own ecological niche, which is unique to it, that is, how many species there are on the Earth, so many ecological niches (2.2 million species of living organisms, 1.7 of them million species of animals). Two different species (even very close ones) cannot occupy one ecological niche in space;
in each ecosystem there are species that claim the same niche or its elements (food, shelters). In this case, competition is inevitable, the struggle for the possession of a niche. Such relations are reflected in the Gause rule: if two species with similar environmental requirements (nutrition, behavior, breeding places) enter into a competitive relationship, then one of them must die or change its lifestyle and occupy a new ecological niche.
An ecological niche is a combination of all the requirements of a species (population) for environmental conditions (composition and regime of environmental factors) and the place where these requirements are met.
Ecological niches of living species together may partially overlap, but never completely coincide, because in this case, the law of competitive exclusion comes into force.
3. Can one species occupy different ecological niches? What does it depend on?
4. What is the role of ecological niches in community life?
Answer. The concept of ecological niche is very useful for understanding the laws of coexistence of species. For example, any green plant, taking one or another part in the formation of biogeocenosis, ensures the existence of a number of ecological niches. Among them there may be niches, including organisms that feed on root tissues (root beetles) or leaf tissues (leaf beetles and suckers), flowers (flowering beetles), fruits (fruit-eaters), root secretions (ekcisotrophs), etc. All together they form an integral system of diverse use plant mass of the body. Moreover, all heterotrophs eating plant biomass almost do not compete with each other.
Each of these niches includes groups of organisms that are heterogeneous in species composition. For example, the ecological group of root-eaters includes both nematodes and the larvae of some beetles (May beetle, nutcracker), and bugs, aphids are in the niche of sucking plant juices.
Ecological niches of animals feeding on plant biomass
Groups of species in a community that have similar functions and niches of the same property are called guilds by some authors (guild of root eaters, guild of nocturnal predators, guild of scavengers, etc.).
Consider Figure 122. Are herbivores in the African savannah occupying one or different niches? Justify your answer. Consider Figure 123. Do dragonflies and their larva occupy one or different niches? Justify the answer.
Answer. In the savannah, animals occupy different ecological niches. An ecological niche is a place occupied by a species in a biocenosis, including a complex of its biocenotic connections and requirements for environmental factors. The term was introduced in 1914 by J. Grinnell and in 1927 by Charles Elton.
An ecological niche is the sum of the factors of the existence of this species, the main of which is its place in the food chain.
The ecological niche may be:
fundamental - determined by a combination of conditions and resources, allowing the species to maintain a viable population;
implemented - the properties of which are due to competing species.
This distinction emphasizes that interspecific competition leads to a decrease in fertility and viability, and that there may be such a part in the fundamental ecological niche that the species occupying as a result of interspecific competition are no longer able to live and successfully reproduce.
The ecological niche cannot be empty. If a niche becomes empty as a result of the extinction of a species, then it is immediately filled with another species.
The habitat usually consists of separate areas ("spots") with favorable and unfavorable conditions; these spots are often only available temporarily, and they arise unpredictably both in time and in space.
Free sites or “gaps” in habitats occur unpredictably in many biotopes. Fires or landslides can lead to wasteland formation in forests; a storm can expose an open stretch of the seashore, and gluttonous predators can exterminate potential victims anywhere. These vacant sites are invariably populated again. However, the very first settlers will not necessarily be those species that for a long time are able to successfully compete with other species and displace them. Therefore, the coexistence of transient and competitive species is possible for as long as unpopulated areas appear with a suitable frequency. The transient species is usually the first to populate a free site, master it and multiply. A more competitive species populates these areas slowly, but if the settlement has begun, then over time it wins the transient species and multiplies.
The doctrine of environmental niches is of great practical importance. When introducing foreign species into the local flora and fauna, it is necessary to find out what ecological niche they occupy at home, whether they will have competitors in the places of introduction. The wide distribution of muskrat in Europe and Asia is explained precisely by the absence in these regions of rodents with a similar lifestyle.
In related species living together, there is a very subtle distinction between ecological niches. For example, ungulates grazing in the African savannah use pasture food in different ways: zebras mostly pick grass tops, wildebeests feed on zebras, gazelles pluck the lowest grasses, and swamp antelopes are content with dry stalks left after other herbivores. Due to the separation of niches, the total bio-productivity of such a herd with a complex species composition is growing. The peasant herd, consisting of cows, sheep, goats, is much more efficient, from an environmental point of view, uses meadows and pastures than a single-herd, monoculture is the least effective way of farming.
If we compare the adult insect and dragonfly larvae, we can conclude:
1) Larvae usually serve as a stage intended for resettlement and ensuring the distribution of the species.
2) Larvae differ from adults in nutritional biology, in their habitat, and in their mode of movement (flying dragonfly and its floating larva), and their behavior. Thanks to this, one species can take advantage of the opportunities provided by two ecological niches throughout its entire life cycle. This increases the chances of the species surviving.
3) they can adapt to various conditions that await them in their second life, they have physiological stamina.
Each organism during its existence lends itself to the influence of various environmental conditions. These may be factors of animate or inanimate nature. Under their influence, through adaptation, each species takes its place - its ecological niche.
general characteristics
The general characteristic of a cell occupied by an animal or plant consists of a definition and description of its model.
An ecological niche is a place that a species or an individual organism occupies in a biocenosis. It is determined taking into account a complex of biocenotic connections, abiotic and biotic environmental factors. There are many interpretations of this term. According to the definitions of various scientists, the ecological niche is also called spatial or trophic. This is because, settling in his cell, the individual occupies the territory he needs and creates his own food chain.
The hypervolume model created by J.E. Hudcens dominates at present. It is a cube, on its axes are environmental factors that have their own range (valency). The scientist divided the niches into 2 groups:
- Fundamental are those that create optimal conditions and are equipped with the necessary resources to support the life of the population.
- Realized. They have a number of properties that are due to competing species.
Characteristics of ecological niches
The characteristic of ecological niches includes three main components:
- A behavioral characteristic is a way of reacting this or that kind to stimuli. As well as how he obtains food, the features of his shelter from enemies, his adaptability to abiotic factors (for example, the ability to resist cold or heat).
- Spatial characteristic. These are the coordinates of the location of the population. For example, penguins live in Antarctica, New Zealand, South America.
- Temporary. It describes the activity of species in a certain period of time: day, year, season.
Principle of competitive exclusion
The principle of competitive exclusion states that there are as many ecological niches as there are species of various organisms. Its author is the famous scientist Gause. He discovered patterns while working with ciliates of various types. The scientist first grew organisms in a monoculture, examining their density and diet, and later combined the species for breeding in one tank. It was noted that each species significantly reduced its number, and as a result of the struggle for food, each organism occupied its own ecological niche.
It cannot be that two different species occupy the same cell in a biocenosis. To become a winner in this competition, one of the species must have some advantage over the other, be more adapted to environmental factors, since even very similar species always have some differences.
Law of constancy
The law of constancy is based on the theory that the biomass of all organisms on the planet should remain unchanged. This statement was confirmed by V.I. Vernadsky. He - the founder of the doctrine of the biosphere and noosphere - was able to prove that with an increase or decrease, the number of organisms in one niche is necessarily compensated in another.
This means that the extinct species is replaced by any other that can easily and quickly adapt to environmental conditions and increase its numbers. Or, conversely, with a significant increase in the number of some organisms, the number of others decreases.
Mandatory Rule
The rule of compulsory filling states that the ecological niche never remains empty. When a species dies out for any reason, its place is immediately occupied by another. The organism that occupies the cell enters the competition. If it turns out to be weaker, it is forced out of the territory and forced to look for another place for settlement.
Methods of coexistence of organisms
The methods of coexistence of organisms can be conditionally divided into positive ones - those that benefit all organisms, and negative ones that are beneficial only to one species. The former received the name "symbiosis", the latter - "mutualism".
Commensalism is a relationship in which organisms do not harm each other, but also do not help. It can be intraspecific and interspecific.
Amensalism is an interspecific mode of coexistence in which one species is oppressed by another. At the same time, one of them does not receive nutrients in the required amount, which is why its growth and development are slowed down.
Predation - predator species with this method of coexistence feed on the body of the victims.
Competition can be within the same species or between different. It appears under the condition when the organisms need the same food or territory with optimal climatic conditions for them.
The evolution of human ecological niches
The evolution of human ecological niches began with the existence of archanthropes. They led a collective way of life, used only those abundances of nature that were as accessible to them as possible. The use of animal food in this segment of existence was minimized. To search for food, archanthropes had to develop a large amount of fodder territory.
After man the tool was mastered, people began to hunt, thereby exerting a considerable impact on the environment. As soon as a man made fire, he made the transition to the next stage of development. After an increase in the population, agriculture emerged as one of the ways to adapt to food shortages in those places where intensive hunting and gathering of natural resources were almost depleted. In the same period, cattle breeding occurs. This led to a settled way of life.
Then came the nomadic cattle breeding. As a result of the nomadic activity of man, a huge number of pastures is depleted, this forces the nomads to move and master more and more new lands.
The ecological niche of man
The ecological niche of a person changes along with changes in the way people live. From other living organisms, Homo sapiens is distinguished by its ability to articulate speech, abstract thinking, and a high level of development of material and non-material culture.
Man as a biological species was common in the tropics and subtropics, in places where the altitude was up to 3–3.5 km. Due to certain characteristics that a person is endowed with, his habitat has greatly increased in size. But as for the fundamental ecological niche, it has remained virtually unchanged. The existence of a person is complicated beyond the original space, he has to confront various adverse factors. This is possible not only through the adaptation process, but also through the invention of various protective mechanisms and devices. For example, a person invented different types of heating systems to deal with such an abiotic factor as cold.
Thus, we can conclude that the ecological niche is occupied by each organism after competition and adheres to certain rules. It should have an optimal area, suitable climatic conditions and be provided with living organisms that are part of the food chain of the dominant species. All living things that are within a niche necessarily interact.
Ecological niche - the place of the species in the biogeocenosis, determined by its biotic potential and the totality of environmental factors to which it is adapted. This is not only the physical space occupied by the body, but also its functional role in the community (position in the food chain), and its place relative to external factors.
3 components are distinguished in the structure of the ecological niche:
- Spatial niche (habitat) - the "address" of the organism;
- Trophic niche - characteristic features of nutrition and the role of the species in the community - "profession";
- A multidimensional (hyperspace) ecological niche is the range of all conditions under which an individual or population lives and reproduces itself.
Distinguish fundamental (potential) niche, which the organism or species could occupy in the absence of competition, predators, in which the abiotic conditions are optimal; and niche realized - the actual range of conditions for the existence of an organism that is less than or equal to a fundamental niche.
The rule of obligation to fill an ecological niche.
An empty ecological niche is always and always naturally filled. In saturated biogeocenoses, vital resources are used to the fullest - all ecological niches are occupied in them. In unsaturated biogeocenoses, vital resources are partially utilized; they are characterized by the presence of free ecological niches.
Environmental duplication - occupation of the vacated ecological niche with another species, capable of performing the same functions in the community as the extinct species. It follows that, knowing the distribution of species by ecological niche in the community and the parameters of each ecological niche, it is possible to describe in advance a species that can occupy a particular niche if it is released.
Environmental diversification - The phenomenon of separation of the ecological niche as a result of interspecific competition. It is carried out in three parameters:
- by spatial location
- according to diet
- by the distribution of activity over time.
Due to diversification, there is a shift of characters - individuals of two closely related species are more similar to each other in those parts of their habitats where they are found separately than in areas of cohabitation.
Characteristics of the ecological niche:
1. Width
2. Overlapping this niche with neighboring
The width of the ecological niche - a relative parameter, which is estimated by comparing with the width of the ecological niche of other species. Eurybionts usually have wider ecological niches than stenobionts. However, the same ecological niche can have different widths in different directions: for example, in spatial distribution, food relations, etc.
Overlapping ecological niche arises if different species use the same resources for cohabitation. Overlapping can be full or partial, according to one or several parameters of the ecological niche.
If the ecological niches of the organisms of the two species are very different from each other, then these species having the same habitat do not compete with each other (Fig. 3).
If ecological niches partially overlap (Fig. 2), then their joint coexistence will be possible due to the presence of specific devices in each type.
If the ecological niche of one species includes the ecological niche of another (Fig. 1), then intense competition occurs, the dominant competitor will displace its rival to the periphery of the fitness zone.
Competition leads to important environmental consequences. In nature, individuals of each species are simultaneously subjected to interspecific and intraspecific competition. Interspecific in its consequences is opposite to intraspecific, since it narrows the area of \u200b\u200bhabitats and the quantity and quality of the necessary environmental resources.
Intraspecific competition promotes the territorial distribution of species, that is, the expansion of the spatial ecological niche. The end result is the ratio of interspecific and intraspecific competition. If interspecific competition is greater, the range of a given species decreases to a territory with optimal conditions and at the same time, specialization of the species increases.
Any living organism is adapted (adapted) to certain environmental conditions. Changing its parameters, their going beyond certain boundaries suppresses the vital activity of organisms and can cause their death. The requirements of an organism for environmental environmental factors determine the area (distribution boundaries) of the species to which the organism belongs, and within the area of \u200b\u200bdistribution - specific habitats.
Habitat - spatially limited set of environmental conditions (abiotic and biotic), providing the entire cycle of development and reproduction of individuals (or groups of individuals) of the same species. This, for example, hedge, pond, grove, rocky shore, etc. In this case, places with special conditions (for example, under the bark of a rotting tree trunk in a grove) can be allocated within the habitat, in some cases it is called micro habitats.
For a comprehensive description of the physical space occupied by the species' organisms, their functional role in the biotic environment, including the way of feeding (trophic status), lifestyle and relationships with other species, the American scientist J. Grinnell in 1928. introduced the term "ecological niche". Its modern definition is as follows.
An ecological niche is a combination
· All requirements of the body to the environment (composition and regimes of environmental factors) and the place where these requirements are met;
· A whole set of biological characteristics and physical parameters of the environment that determine the conditions for the existence of one kind or another, its conversion of energy, the exchange of information with the environment and their own kind.
Thus, the ecological niche characterizes the degree of biological specialization of the species. It can be argued that the habitat of the organism is its “address”, while the ecological niche is its “occupation” or “lifestyle” or “profession”. For example, the thrush habitat includes forests, parks, meadows, gardens, vegetable gardens and yards. Its ecological niche includes factors such as nesting and hatching of chicks on trees, feeding on insects, earthworms and fruits, transfer of fruit and berry seeds with their excrement.
Ecological specificity of species is emphasized axiom of environmental adaptation: each species is adapted to a strictly defined set of conditions of existence specific to it — an ecological niche.
Since species of organisms are ecologically individual, they also have specific ecological niches.
Thus, how many species of living organisms on Earth - the same number of ecological niches.
Organisms leading a similar lifestyle, as a rule, do not live in the same places due to interspecific competition. According to the established in 1934. Soviet biologist G.F. Gauze (1910-1986) competitive exclusion principle: two species do not occupy the same ecological niche.
It also acts in nature rule of mandatory filling of ecological niches: an empty ecological niche will always and certainly be filled.
Popular wisdom formulated these two postulates as follows: “Two bears cannot get on in one den” and “Nature does not tolerate emptiness”.
These systemic observations are implemented in the formation of biotic communities and biocenoses. Ecological niches are always filled, although this sometimes takes considerable time. The occurrence of the expression “free ecological niche” means that in a certain place there is little competition for any type of feed and there is an underutilized sum of other conditions for a species that is part of similar natural systems but is absent in the considered one.
It is especially important to take into account natural patterns when trying to intervene in an existing (or prevailing in a certain place) situation in order to create more favorable conditions for a person. So, biologists have proved the following: in cities with an increase in contamination of the territory with food waste, the number of ravens increases. When trying to improve the situation, for example, by physically destroying them, the population may encounter the fact that the ecological niche in the urban environment, freed by crows, will quickly be occupied by a species having a close ecological niche, namely, rats. Such a result can hardly be considered a victory.
Each biological species plays a role in its ecosystem. Environmentalists have proven that some species called key species, dramatically affect many other organisms in the ecosystem. The disappearance of a key species from the ecosystem can trigger a cascade of sharp drops in the population size and even the extinction of those species that depended on it in one form or another.
An example of a key species is an earthen tortoise. An earthen tortoise lives on sandy hills in Florida and other southern parts of the United States. This is a slow, the size of a dinner plate, the animal pulls out a hole up to 9 meters deep. In the hot, inhospitable ecosystems of the southern United States, such burrows become shelters from heat for almost 40 other animal species, such as gray fox, possum, indigo snake and many insects. In those places where the earthen tortoise was exterminated or brought to the brink of extinction by numerous hunters for its exquisite meat, many species dependent on the tortoise ceased to exist.
The ecological niches of all living organisms are divided into specialized and general. This division depends on the main food sources of the corresponding species, habitat sizes, sensitivity to abiotic environmental factors.
Specialized niches. Most species of plants and animals are adapted to exist only in a narrow range of climatic conditions and other environmental characteristics; they feed on a limited set of plants or animals. Such species have a specialized niche that determines their habitat in the natural environment.
So, the giant panda has a narrowly specialized niche, because it feeds 99% on bamboo leaves and shoots. The mass destruction of some species of bamboo in areas of China where the panda lived, led this animal to extinction.
The diversity of species and forms of flora and fauna that exists in tropical rainforests is associated with the presence of a number of specialized ecological niches in each of the clearly defined tiers of forest vegetation. Therefore, the intensive deforestation of these forests has caused the extinction of millions of specialized species of plants and animals.
Common niches. Species with common niches are characterized by easy adaptability to changes in environmental environmental factors. They can successfully exist in various places, eat various foods and withstand sharp fluctuations in natural conditions. Common ecological niches are found in flies, cockroaches, mice, rats, humans, etc.
For species with common ecological niches, there is a significantly lower risk of extinction than for species with specialized niches.
As long as the ecosystem has enough public resources, different species consume them together. However, if two or more species in the same ecosystem begin to consume the same scarce resource, they will be in a relationship interspecific competition.
A species gains an advantage in interspecific competition, if it is characteristic
More intensive reproduction;
Adaptation to a wider range of temperature, light, salinity or
concentrations of certain harmful substances;
Deprivation of a competitor access to the resource.
Ways to reduce interspecific competition:
Relocation to another area;
Switching to more inaccessible or difficult to digest food;
Change of time and place of feed production.
The most characteristic form of interaction between species in food chains and nets is predation, in which a single individual of one species (predator) feeds on organisms (or parts of organisms) of another species (prey), and the predator lives separately from the prey. These two types of organisms are involved in predator-prey relationships.
Viper species use a range of defense mechanisms to avoid becoming easy prey for predators:
Ability to run or fly fast;
Possession of thick skin or shell;
Possessing protective coloring or a way to change color;
The ability to release chemicals with a smell or taste that scares off a predator or even poisons it.
Predators also have several ways to prey:
Ability to run fast (for example, cheetah);
Hunting in packs (for example, spotted hyenas, lions, wolves);
Trapping as victims of mainly sick, wounded and other inferior individuals;
The fourth way to provide yourself with animal food is the path that a reasonable person has taken, the path of inventing hunting tools and traps, as well as domesticating animals.
It often happens that two different kinds of organisms interact directly in such a way that they bring each other mutual benefit. Such mutually beneficial interspecies interactions are called mutualism. For example, flowers and pollinating insects.
Commensalism is characterized by the fact that one of the two types benefits from interspecific interaction, while the other practically does not affect it (either positively or negatively). For example, crustaceans in the jaws of a whale.
The concept of the so-called saturated and unsaturated biocenoses is closely connected with the concept of an ecological niche. The former are ecosystems in which the vital resources at each stage of biomass and energy conversion are used to the fullest. When vital resources are partially utilized, biocenoses can be called unsaturated. They are characterized by the presence of free ecological niches. However, this is highly arbitrary, since ecological niches cannot exist on their own, regardless of the species that occupy them.
Unused reserves, unrealized opportunities for intensifying the flow of substances and energy exist in almost any biogeocenosis (otherwise their constant development in time and space could not have been realized!), All biocenoses can conditionally be considered unsaturated. The lower the saturation of the biocenosis, the easier it is to enter into its composition and more successfully new species are acclimatized.
A very important property of biogeocenoses as biological systems is their self-regulation - the ability to withstand high loads of adverse external influences, the ability to return to the conditionally initial state after significant violations of their structure (Le Chatelier principle). But above a certain threshold of exposure, self-healing mechanisms do not work, and biogeocenosis is irreversibly destroyed.
During the evolutionary process, the global ecological niche of the biosphere expanded. When a species exhausted the genetically determined potential for developing an ecological niche where it was born, it either crowded out other species, conquering their ecological niches, or assimilated a previously lifeless niche, reconstructing it genetically, possibly creating a new kind of organisms.
At some stage in the development of the biosphere, the species Intelligent Man appeared, representatives of which are all of humanity, despite the diversity of races, peoples, nationalities, and tribes.
The potential for the development of adult individuals of each biological species is genetically determined for all qualities of an individual, although it may not be revealed, it may not be filled with real content if the environmental conditions do not have this. In relation to the population, genetic conditionality and the potential for its development are subordinated to probabilistic predetermination, reflected in the statistical laws of the fait accompli. This fully applies to humans - a biological species that carries the largest absolute and relative volume (compared with other types of living organisms of the Earth’s biosphere) of non-genetically determined behavioral information that provides the greatest flexibility in behavior in a rapidly changing environment.
1. General Provisions. Living creatures - both plants and animals - are numerous and diverse. There is no doubt that this diversity and abundance of organisms is determined by environmental factors. Thus, each species occupies a strictly assigned place in the geographical space with a specific set of physical and chemical parameters. However, the position of the species depends not only on abiotic environmental factors, but also on the relationships of this organism with other organisms both within its species and with representatives of other species. The wolf will not dwell on those geographical spaces, even if the set of abiotic factors is quite acceptable for him, if there is no food resource for him. Consequently, the place occupied by the species in a particular habitat should be determined not only by the territory, but also be related to the need for food and the function of reproduction. Each of the species, as well as a specific organism, in the community (biocenosis) has its own residence time and its own place, which distinguish it from other species.
Thus, we come across various concepts. The first is rangespecies - the distribution of the species in geographic space (the geographical aspect of the species), and secondly, species habitat(habitat or biotope) Is a type of geographical space according to a set of physical and chemical parameters and (or) biotic characteristics, where the species lives and, thirdly, ecological niche, implying something more than just the place where this species lives. Species in different parts of the range can occupy a number of different habitats.
The best and accurate comparative definition of ecological niche and environment was given by French ecologists R. Wiebert and K. Lagler: wednesdayIs the address at which the given organism lives, whereas niche additionally indicates the nature of his occupation in this place, his profession.
Some ecologists are more willing to use the term “habitat”, which is almost synonymous with “habitat”, and both concepts often overlap, but we will remember that “habitat” means only the space where the species is common. In this understanding, this term is very close to the concept of the species range.
2. Habitat. This is a land or water body area occupied by a population of one species or part of it and possessing all the necessary conditions for its existence (climate, topography, soil, nutrients). The habitat of a species is the totality of the plots within its species range that meet its environmental requirements. Thus, the habitat is nothing but a component of an ecological niche. The breadth of habitat use distinguishes stenotopic and eurytopic organisms i.e. organisms occupying specific spaces with a specific set of environmental factors, and organisms that exist in a wide range of environmental factors (cosmopolitans). If we are talking about the habitat of a community of organisms or the place of a biocenosis, the term “biotope” is more often used. Habitat has another synonym ecotope - geographical space, characterized by a specific set of environmental parameters. In this case, a population of any species living in this space is called ecotype.
The term “habitat” can be applied both to specific organisms and to communities in general. We can indicate the meadow as a single habitat for various grasses and animals, although grasses and animals occupy different ecological niches. But never should this term replace the concept of “ecological niche”.
A habitat can denote a complex of interconnected some living and non-living characteristics of geographical space. For example, the habitat of aquatic insects of the bedrock-bug and meltbug is shallow-water areas of lakes covered with vegetation. These insects occupy the same habitat, but have different trophic chains (the smoothfin is an active predator, and the platte feeds on decaying vegetation), which distinguishes the ecological niches of these two species.
Habitat can designate only biotic environment. So bacilli and bacteria live inside other organisms. Lice live in the host's hairline. Some mushrooms are associated with a specific type of forest (birch bark). But the habitat can also be represented by a purely physical-geographical environment. You can specify the tidal coast of the sea, where so diverse organisms live. This may be a desert, and a separate mountain, dunes, stream and river, lake, etc.
3. Ecological niche - concept, according to Yu. Odumamore capacious. An ecological niche, as the English scientist showed C. Elton (1927), includes not only the physical space occupied by the body, but also the functional role of the body in the community. Elton distinguished niches as a position of a species depending on other species in the community. C. Elton's idea that a niche is not a synonym for habitat has been widely recognized and disseminated. The body is very important for its trophic position, lifestyle, communication with other organisms, etc. and its position relative to the gradients of external factors as conditions of existence (temperature, humidity, pH, soil composition and type, etc.).
These three aspects of the ecological niche (space, the functional role of the organism, external factors) are conveniently designated as spatial niche (niche places) trophic niche (functional niche), in the understanding of C. Elton, and multidimensional niche (takes into account the entire volume and set of biotic and abiotic characteristics, hypervolume) The ecological niche of an organism depends not only on where it lives, but also includes the total amount of its environmental requirements. The body not only experiences the effects of environmental factors, but also makes its own demands on them.
4. Modern ecological niche concept formed on the basis of the model proposed J. Hutchinson (1957). According to this model, an ecological niche is a part of an imaginary multidimensional space (hypervolume), the individual dimensions of which correspond to factors necessary for the normal existence and reproduction of the body. The niche Hutchinson, which we will call multidimensional (hyperspace), can be described using quantitative characteristics and operated on with the help of mathematical calculations and models. R. Whittaker (1980) defines an ecological niche as the position of a species in a community, implying that the community is already connected by a specific biotope, i.e. with a specific set of physical and chemical parameters. Therefore, an ecological niche is a term used to denote the specialization of a population of a species within a community. Groups of species in a biocenosis that have similar functions and niches of the same size are called guilds. Species occupying the same niches in different geographical areas are called environmental equivalents.
5. Individuality and originality of ecological niches. No matter how close the locality of the organisms to organisms (or species as a whole), no matter how close their functional characteristics are in biocenoses, they will never occupy the same ecological niche. Thus, the number of ecological niches on our planet is uncountable. Figuratively, one can imagine a human population, all individuals of which possess only their own unique niche. It is impossible to imagine two absolutely identical people with absolutely identical morphophysiological and functional characteristics, including those such as mental, attitude to oneself, the absolute need for the type and quality of food, sexual relations, norm of behavior, etc. But the individual niches of different people can overlap according to individual environmental parameters. For example, students can be connected among themselves by one university, specific teachers, and at the same time they can vary in behavior in society, in the choice of food, biological activity, etc.
6. Measuring Environmental Niches. Usually, two standard measurements are used to characterize a niche - niche widthand niche overlapping with neighboring niches.
The width of a niche is understood as the gradients or range of action of an environmental factor, but only within a given hyperspace. The width of the niche can be determined by the intensity of illumination, by the length of the trophic chain, by the intensity of the action of any abiotic factor. By overlapping ecological niches is meant both overlapping along the width of niches and overlapping hypervolumes.
7. Types of Environmental Niches. Two main types of ecological niches stand out. The first is fundamental (formal) niche is the largest “abstract populated hypervolume ”, where the action of environmental factors without the influence of competition ensures maximum abundance and functioning of the species. However, the species experiences constant changes in environmental factors within its range. In addition, as we already know, an increase in the action of one factor can change the relation of a species to another factor (a consequence of the Liebig law), and its range can change. The action of two factors at the same time can change the relationship of the species to each of them specifically. Biotic restrictions (predation, competition) always apply within ecological niches. All these actions lead to the fact that the view actually occupies an ecological space that is much smaller than the hyperspace of a fundamental niche. In this case we are talking about implemented niche i.e. real niche.
8 . Principle Vandermeera and Gause. J.H. Vandermeer (1972) significantly expanded the concept of Hutchinson's realized niche. He came to the conclusion that if N interacting species coexist in a given habitat, then they will occupy completely different realized ecological niches, the number of which will be equal to N. This observation is called vandermeer principle.
Competitive interaction can concern both space, nutrients, the use of light (trees in the forest), and the process of fighting for the female, for food, as well as dependence on the predator, susceptibility to diseases, etc. Usually, the most intense competition is observed at the interspecific level. It can lead to the replacement of a population of one species by a population of another species, but it can also lead to a balance between the two species (usually equilibrium by nature is established in the predator-prey system). Extreme cases are the displacement by one species of another beyond the boundaries of a given habitat. There are times when one species displaces the other in the trophic chain and forces it to switch to the use of other food. Observation of the behavior of closely related organisms with similar lifestyles and similar morphology shows that such organisms try to never live in the same place. This observation was made. Joseph Greenellin 1917-1928, who studied the life of mockingbirds in California. Greenell himself introduced the concept of "niche", but he did not distinguish between the niche and the habitat.
If closely related organisms live in the same place, then they will either use different food resources, or lead an active lifestyle at different times (night, day). This ecological division of closely related species is called competitive exclusion principle or gauze principle named after a Russian biologist who experimentally showed the effect of this principle in 1932. In his conclusions, Gauze used Elton's concept of the position of a species in a community depending on other species.
9. Niche space. Ecological niches of species are more than the relation of a species to any one environmental gradient. Many signs or axes of multidimensional space (hypervolume) are very difficult to measure or cannot be expressed by linear vectors (for example, behavior, addiction, etc.). Therefore, it is necessary, as rightly pointed out by R. Whittaker (1980), to switch from the concept of a niche axis (recall the width of a niche according to any one or several parameters) to the concept of its multidimensional determination, which will make it possible to identify the nature of species relations with their full range of adaptive relationships .
If a niche is a “place” or “position” of a species in a community according to Elton’s concept, then it has the right to give it some measurements. According to Hutchinson, a niche can be determined by a number of variable environmental conditions within the community to which species must be adapted. These variables include both biological indicators (e.g. food size) and non-biological (climatic, orographic, hydrographic, etc.). These variables can serve as axes along which the multidimensional space is called, which is called ecological spaceor niche space. Each of the species can adapt or be resistant to a certain range of values \u200b\u200bof each variable. The upper and lower limits of all these variables outline the ecological space that can occupy the view. This is a fundamental niche in the understanding of Hutchinson. In a simplified form, this can be imagined as an “n-sided box” with sides corresponding to the limits of stability of the view on the axes of the niche.
Using a multidimensional approach to the space of a community niche, we can find out the position of species in space, the nature of the reaction of a species to the impact of more than one variable, and the relative sizes of niches.