Summary: Biotic environmental factors. Biotic environmental factors
Federal Agency for Education
Russian State University
Innovative Technologies and Entrepreneurship
Penza branch
Abstract on the discipline "Ecology"
On the topic: “Biotic factors of the environment”
Completed: student gr. 05U2
Morozov A.V.
Checked by: Kondrev S.V.
Penza 2008
Introduction
1. General pattern action of biotic factors
2. Biotic factors of the environment and ecosystems
Conclusion
List of used literature
Appendix
Introduction
The most important biotic factors include the availability of food, food competitors and predators.
1. General pattern of action of biotic factors
An important role in the life of each community is played by the conditions of the habitat of organisms. Any element of the environment that has a direct impact on a living organism is called an environmental factor (for example, climatic factors).
There are abiotic and biotic environmental factors. Abiotic factors include solar radiation, temperature, humidity, illumination, soil properties, and water composition.
Food is considered an important ecological factor for animal populations. The quantity and quality of food affect the fertility of organisms (their growth and development), life expectancy. It has been established that small organisms need more food per unit mass than large ones; warm-blooded - more than organisms with unstable body temperature. For example, a blue tit with a body weight of 11 g needs to consume annually food in the amount of 30% of its mass, a song thrush with a weight of 90 g - 10%, and a buzzard with a weight of 900 g - only 4.5%.
Biotic factors include various relationships between organisms in natural community. Distinguish relationships between individuals of the same species and individuals different types. Relationships between individuals of the same species great importance for his survival. Many species can only reproduce normally when they live in a fairly large group. Thus, a cormorant lives and reproduces normally if its colony has at least 10,000 individuals. Principle minimum size populations explains why rare species are difficult to save from extinction. For survival African elephants there must be at least 25 individuals in the herd, and reindeer- 300-400 heads. Living together facilitates the search for food and the fight against enemies. So, only a pack of wolves can catch large-sized prey, and a herd of horses and bison can successfully defend themselves from predators.
At the same time, an excessive increase in the number of individuals of one species leads to overpopulation of the community, intensification of competition for territory, food, and leadership in the group.
Population ecology is the study of the relationships between individuals of the same species in a community. the main task population ecology - the study of the number of populations, its dynamics, causes and consequences of changes in numbers.
Populations of different species long time living together in a certain territory, form communities, or biocenoses. Community different populations interacts with environmental environmental factors, together with which it forms a biogeocenosis.
The existence of individuals of the same and different species in the biogeocenosis is greatly influenced by the limiting, or limiting, environmental factor, that is, the lack of a particular resource. For individuals of all species, the limiting factor can be low or high temperature, for the inhabitants of aquatic biogeocenoses - water salinity, oxygen content. For example, the distribution of organisms in the desert is limited high temperature air. Applied ecology is the study of limiting factors.
For economic activity It is important for a person to know the limiting factors that lead to a decrease in the productivity of agricultural plants and animals, to the destruction of insect pests. So, scientists have found that the limiting factor for the larvae of the click beetle is very low or very high humidity soil. Therefore, to combat this pest of agricultural plants, drainage or strong soil moisture is carried out, which leads to the death of larvae.
Ecology studies the interaction of organisms, populations, communities with each other, the impact on them of environmental factors. Autecology studies the relationship of individuals with the environment, and synecology - the relationship of populations, communities and habitats. There are abiotic and biotic environmental factors. For the existence of individuals, populations importance have limiting factors. Population and applied ecology has received great development. Achievements in ecology are used to develop measures for the protection of species and communities, in agricultural practice.
Biotic factors are a set of influences of the vital activity of some organisms on the vital activity of others, as well as on inanimate nature. Classification of biotic interactions:
1. Neutralism - no population affects another.
2. Competition is the use of resources (food, water, light, space) by one organism, which thereby reduces the availability of this resource for another organism.
Competition is intraspecific and interspecific. If the population size is small, then intraspecific competition is weak and resources are abundant.
At a high population density, intense intraspecific competition reduces the availability of resources to a level that hinders further growth, thereby regulating the population size. Interspecific competition is the interaction between populations that adversely affects their growth and survival. When imported to the UK from North America carolinian squirrel population decreased common squirrel, because the Carolina squirrel was found to be more competitive. Competition is direct and indirect. Direct - this is intraspecific competition associated with the struggle for habitat, in particular the protection of individual sites in birds or animals, expressed in direct collisions.
With a lack of resources, it is possible to eat animals of their own species (wolves, lynxes, predatory bugs, spiders, rats, pike, perch, etc.) Indirect - between shrubs and herbaceous plants in California. The species that settled first excludes the other type. Fast-growing, deep-rooted grasses reduced soil moisture to levels unsuitable for shrubs.
A tall shrub shaded the grass, preventing them from growing due to lack of light.
Aphids, powdery mildew - plants.
High fertility.
They do not lead to the death of the host, but they inhibit the vital processes. Predation is the consumption of one organism (prey) by another organism (predator). Predators can eat herbivores, and also weak predators. Predators have a wide range of food, easily switch from one prey to another more accessible one. Predators often attack weak prey.
Mink destroys sick and old muskrats, but does not attack adults. An ecological balance is maintained between prey-predator populations.
Symbiosis is the cohabitation of two organisms of different species in which the organisms benefit each other.
According to the degree of partnership, symbiosis happens: Commensalism - one organism feeds at the expense of another, without harming it.
Cancer - actinia.
The sea anemone attaches itself to the shell, protecting it from enemies, and feeds on the remnants of food. Mutualism - both organisms benefit, while they cannot exist without each other.
Lichen - mushroom + algae.
The fungus protects the algae and the algae feeds it. Under natural conditions, one species will not lead to the destruction of another species. Ecosystem. An ecosystem is a collection of different types of organisms living together and the conditions for their existence, which are in a regular relationship with each other. The term was proposed in 1935 by the English ecologist Texley.
The largest ecosystem is the biosphere of the Earth, further in decreasing order: land, ocean, tundra, taiga, forest, lake, tree stump, flower pot. Ocean ecosystem. One of the largest ecosystems (94% of the hydrosphere). The living environment of the ocean is continuous, there are no boundaries in it that prevent the settlement of living organisms (on land, the boundary is the ocean between the continents, on the mainland - rivers, mountains, etc.).
10. Biotic factors, their classification
Biotic factors- is a set of influences of vital activity of some organisms on others.
The whole variety of relationships between organisms can be divided into two main types: antagonistic (gr. antagonism - wrestling) and non-antagonistic.
Non-antagonistic relationships can theoretically be expressed in many combinations: neutral, mutually beneficial, unilateral, etc.
Biotic factors are abiotic environmental conditions not altered by organisms (humidity, temperature, etc.) and not organisms themselves, but relationships between organisms, direct effects of some of them on others, i.e., the nature of biotic factors is determined by the form of relationships and relationships of living organisms.
When classifying biotic factors, they distinguish:
- zoogenic(animal exposure),
- phytogenic(plant effects) and
- microgenic(influence of microorganisms).
highlighted factors, depending on the number and density of organisms. Also, factors can subdivide:
- for regulatory (management) and
- adjustable (managed).
Biotic factors can be conditionally divided into the following groups:
1. Topical relationships organisms on the basis of their coexistence: oppression or suppression by one species of organisms of the development of other species; the release of volatile substances by plants - phytoncides with antibacterial properties, etc.
2. Trophic absorption. According to the method of nutrition, all organisms on the planet are divided into two groups: autotrophic and heterotrophic. Autotrophic organisms have the ability to create organic matter from inorganic, which are then used by heterotrophic organisms. The use of organic substances as food in heterotrophic organisms is different: some use living plants or their fruits as food, others use the dead remains of animals, etc.
3. Generative relations. They develop on the basis of reproduction. The formation of organic matter in biogeocenoses is carried out along food chains.
Biotic components are made up of three functional groups of organisms:
producers, consumers, decomposers.
1. Producers (producens- creating, producing) or autotrophic organisms (trophy- food) - creators of primary biological products, organisms that synthesize organic substances from inorganic compounds (carbon dioxide CO 2 and water). the main role in the synthesis of organic substances belongs to green plant organisms - photoautotrophs, which are used as a source of energy sunlight, and as a nutrient - inorganic substances, mainly carbon dioxide and water. Photosynthesis - Light energy absorbed by the green pigment (chlorophyll) of plants supports the process of their carbon nutrition.
2. Consumers (consume- consume), or heterotrophic organisms (heteros- another, trophy- food), carry out the process of decomposition of organic substances. These organisms use organic matter as food and energy sources. Heterotrophic organisms are divided into phagotrophs (phagos- devouring) and saprotrophs (sapros- rotten). Animals belong to phagotrophs; to saprotrophs - bacteria.
3. Bioreducers (reducers or destructors)- organisms that decompose organic matter, mainly microorganisms (bacteria, yeast, saprophytic fungi), which settle in corpses, excrement, on dying plants and destroy them. In other words, these are organisms that convert organic residues into inorganic substances. Decomposers: bacteria, fungi - participate in the last stage of decomposition - the mineralization of organic substances to inorganic compounds
The most common type of heterotypic relationships between animals - predation, i.e. direct pursuit and eating of some species by others.
Predation- a form of relationship between organisms of different trophic levels - a predator lives off the prey, eating it. This is the most common form of interaction between organisms in food chains. Predators can specialize in one species (lynx - hare) or be polyphagous (wolf).
Main forms of interaction the following: symbiosis, mutualism and commensalism.
Symbiosis(gr. symbiosis- Cohabitation is a mutually beneficial, but not mandatory, relationship between different types of organisms. An example of symbiosis is the cohabitation of a hermit crab and sea anemone: the sea anemone moves by attaching itself to the back of the cancer, and with the help of the sea anemone, it receives richer food and protection. A similar relationship can be observed between trees and certain types of fungi that grow on their roots: fungi get dissolved nutrients from the roots and themselves help the tree to extract water and minerals from the soil. Sometimes the term "symbiosis" is used in a broader sense - "to live together."
Mutualism(lat. mutuus- mutual) - mutually beneficial and mandatory for the growth and survival of the relationship of organisms of different species. Lichens are a good example of a positive relationship between algae and fungi that cannot exist separately. When insects spread plant pollen, both species develop specific adaptations: color and smell - in plants, proboscis - in insects, etc. They also cannot exist one without the other.
Commensalism(lat. sommepsalis - companion) - a relationship in which one of the partners benefits, while the other is indifferent. Commensalism is often observed at sea: in almost every shell of a mollusk, in the body of a sponge, there are "intruders" who use them as shelters. In the ocean, some species of crustaceans settle on the jaws of whales. The crustaceans acquire shelter and a stable source of food. For a whale, such a neighborhood does neither good nor harm. Sticking fish, following the sharks, pick up the remnants of their food. Birds and animals that feed on the remains of food from predators are examples of commensals.
Experience the cumulative effect of various conditions. Abiotic factors, biotic factors and anthropogenic affect the features of their life and adaptation.
What are environmental factors?
All conditions inanimate nature called abiotic factors. This is, for example, the amount of solar radiation or moisture. Biotic factors include all types of interaction between living organisms. AT recent times human activity has an increasing influence on living organisms. This factor is anthropogenic.
Abiotic environmental factors
The action of inanimate factors depends on climatic conditions habitat. One of them is sunlight. The intensity of photosynthesis, and hence the saturation of air with oxygen, depends on its quantity. It is this substance that living organisms need for respiration.
Abiotic factors also include temperature regime and air humidity. Depends on them species diversity and growing season of plants, features life cycle animals. Living organisms adapt to these factors in different ways. For example, most angiosperms shed their leaves for the winter to avoid excessive moisture loss. Desert plants have which reaches considerable depths. This provides them with the necessary amount of moisture. Primroses have time to grow and bloom in a few spring weeks. And the period of dry summer and cold winter with little snow they experience underground in the form of an onion. This underground modification of the shoot accumulates a sufficient amount of water and nutrients.
Abiotic environmental factors also involve the influence of local factors on living organisms. These include the nature of the relief, chemical composition and humus saturation of soils, water salinity, character ocean currents, wind direction and speed, directivity radiation. Their influence manifests itself both directly and indirectly. Thus, the nature of the relief determines the effect of winds, moisture and illumination.
Influence of abiotic factors
Factors of inanimate nature have a different nature of the impact on living organisms. Monodominant is the impact of one predominant influence with a slight manifestation of the rest. For example, if there is not enough nitrogen in the soil, root system develops on insufficient level and other elements cannot influence its development.
Strengthening the action of several factors at the same time is a manifestation of synergy. So, if there is enough moisture in the soil, plants begin to absorb both nitrogen and solar radiation. Abiotic factors, biotic factors and anthropogenic factors can be provocative. With an early onset of the thaw, the plants will most likely suffer from frost.
Features of the action of biotic factors
The biotic factors are various forms influence of living organisms on each other. They can also be direct and indirect and appear quite polar. In certain cases organisms have no effect. This is a typical manifestation of neutralism. This is a rare thing considered only if total absence direct interaction between organisms. Living in a common biogeocenosis, squirrels and moose do not interact in any way. However, they are affected by the general quantitative ratio in the biological system.
Examples of biotic factors
Commensalism is also a biotic factor. For example, when deer carry burdock fruits, they do not receive any benefit or harm from this. At the same time, they bring significant benefits, settling many types of plants.
Between organisms often arise and Their examples are mutualism and symbiosis. In the first case, there is a mutually beneficial cohabitation of organisms of different species. A typical example of mutualism is the hermit crab and anemone. Its predatory flower is a reliable defense of the arthropod. And the sea anemone shell is used as a dwelling.
Closer mutually beneficial cohabitation is a symbiosis. Its classic example is lichens. This group of organisms is a collection of filaments of fungi and cells of blue-green algae.
Biotic factors, examples of which we have considered, can be supplemented with predation. In this type of interaction, organisms of one species are food for others. In one case, predators attack, kill and eat their prey. In another, they are engaged in the search for organisms of certain species.
Action of anthropogenic factors
Abiotic factors, biotic factors long time were the only ones that affect living organisms. However, with the development of human society, its influence on nature increased more and more. The famous scientist V. I. Vernadsky even singled out a separate shell created by human activity, which he called the Noosphere. Deforestation, unlimited plowing of land, the extermination of many species of plants and animals, unreasonable nature management are the main factors that change the environment.
Habitat and its factors
The biotic factors, examples of which have been given, along with other groups and forms of influences, have their own significance in different habitats. Ground-air vital activity of organisms largely depends on fluctuations in air temperature. And in water, the same indicator is not so important. Action anthropogenic factor in this moment acquires special meaning in all habitats of other living organisms.
and adaptation of organisms
A separate group can be identified factors that limit the vital activity of organisms. They are called limiting or limiting. For deciduous plants, abiotic factors include the amount of solar radiation and moisture. They are limiting. AT aquatic environment limiting are its salinity level and chemical composition. So global warming leads to the melting of glaciers. In turn, this leads to an increase in the content fresh water and a decrease in its salinity. As a result, plant and animal organisms that cannot adapt to changes in this factor and adapt inevitably die. At the moment it is global environmental problem humanity.
So, abiotic factors, biotic and anthropogenic factors together act on different groups living organisms in their habitats, regulating their numbers and life processes, changing the species richness of the planet.
Commensalism is Cohabitation different organisms when one organism, settling inside the body of another and eating at its expense, does not harm the carrier (bacteria in the human intestine). In amensalism, one of the coexisting organisms suffers damage, while the other is indifferent to the effect of the first (penicillium kills bacteria that cannot affect it).
Symbiosis is all forms of cohabitation of organisms of different species. And the mutually beneficial coexistence of organisms belonging to different species is called mutualism. An example is the fact of the relationship between leguminous plants and nitrogen-fixing nodule bacteria that live on their root system. The roots of higher plants interact similarly with the mycelium of cap mushrooms. Both those and other organisms receive from each other the substances necessary for life.
Competition is a type of interaction in which plants of the same or different species can compete with each other for the resources of the surrounding space - water, lighting, nutrients, location, etc. In this case, the consumption of certain resources by some organisms reduces their availability to others.
An example of intraspecific competition is an artificial pine forest, where trees of the same age compete for light. Those trees that do not keep up with growing faster grow much worse in the shade, and many of them die. Interspecific competition can be traced among plant species and genera close in needs, which are part of the same group, for example, in mixed forests between hornbeam and oak.
Many plant-eating animals are herbivores, and their association with plants is eating. So, in pastures, animals eat only certain types of plants, without touching others that are poisonous or have an unpleasant taste. Over time, this leads to fundamental changes. species composition vegetation in this area. Some plants have protective adaptations against being eaten by animals, for example, the release of toxic substances, modified leaves-thorns, thorns on the stems. Rare species carnivorous plants, such as sundew, nepenthes, can feed on animals (insects).
It should also be noted that indirect relationships between organisms are no less important than direct relationships for the life and survival of plants of different species. So, insects and some small birds pollinate flowering plants. And reproduction by seeds of many species of angiosperms without the participation of animals would be impossible.
Biotic factors
What are called biotic factors?
Give a description of intraspecific factors (homotypic reactions).
Describe interspecies factors (heterotypic reactions).
Under biotic factors understand the forms of interaction between individuals and populations. Biotic factors are divided into two groups: intraspecific (homotypic from Greek. homoios- the same) and interspecific (heterotypical from Greek. heteros- different) interactions.
homotypic reactions.
Homotypic reactions are interactions between individuals of the same species. Ecological significance have phenomena associated with group and mass effects, as well as with intraspecific competition.
group effect- this is the influence of the group as such and the number of individuals in the group on the behavior, physiology, development and reproduction of individuals, caused by the perception of the presence of individuals of their own species through the senses.
Wildebeest at the river crossing
Many insects (crickets, cockroaches, locusts, etc.) in a group have a more intense metabolism than when living alone, grow and mature faster.
Many species of animals develop normally only when they unite in a fairly large groups. For example, cormorants can exist in a colony that has at least 10,000 individuals, where there are at least 3 nests per 1 m2. It is known that for the survival of African elephants in the herd there must be at least 25 individuals, and the most productive herds of reindeer include 300-400 individuals. The life of animals in groups makes it easier for them to search for and obtain food, protection from enemies. Wolves united in a pack attack large animals, while single individuals are not able to do this. It is easier for flocks of pelicans to catch fish by driving it into shallow water.
Optimization of physiological processes, leading to an increase in viability in coexistence, is called "group effect". It manifests itself as a psychophysiological reaction of an individual to the presence of other individuals of its species. Outside the herd, the pulse and breathing become more frequent, and at the sight of the approaching herd, these processes normalize. Solitarily wintering the bats differ more high level metabolism than in the colony. This leads to increased energy expenditure, exhaustion and often ends in their death.
The effect of the group is manifested in the acceleration of the growth rate of animals, increased fertility, faster formation conditioned reflexes, increasing the average life span of an individual, etc. In a group, animals are often able to maintain optimum temperature(when crowded, in nests, in hives). Many animals outside the group do not realize fertility. Pigeons of some breeds do not lay eggs if they do not see other birds, but it is enough to put a mirror in front of the female for her to start laying.
The group effect does not appear in solitary species. If such animals are forced to artificially live together, their irritability increases, collisions become more frequent, and many physiological indicators strongly deviate from the norm. So, eared hedgehogs in a group, oxygen consumption is increased up to 134% compared to those contained alone.
mass effect caused by changes in habitat that occur when there is an excessive increase in the number of individuals and population density. As a rule, the mass effect negatively affects the fertility, growth rate, and life span of animals. For example, with the development of the flour beetle population, excrement and molting skins constantly accumulate in the flour, which leads to the deterioration of the flour as a habitat. This causes a drop in fertility and an increase in mortality in the beetle population. In overpopulated groups of house mice, fertility decreases, and sometimes reproduction stops altogether.
In nature, group and mass effects most often appear simultaneously. Exclusively important role group and mass effects play in the dynamics of population size, appearing in a number of density-dependent environmental factors that regulate population size according to the principle feedback. This pattern is formulated as follows:
For each animal species, there is an optimal group size and an optimal population density (Alli's principle).
Homotypic reactions, in addition to the effect of group and mass, include another form of interaction between individuals
one kind - intraspecific competition. With regard to all types of competition, the rule is true: the more the needs of competitors coincide, the sharper the competition.
heterotypic reactions.
Heterotypic reactions are interactions between individuals belonging to different species. Different kinds interactions of similar populations (for example, A and B) are presented in Table 1.
Table 1.
Types of heterotypic reactions
|
Heterotypic reactions |
View A |
View B Legend:
Competition. Interspecies relationships in which populations in the struggle for food, habitat and other conditions necessary for life affect each other negatively. Intensified competition often explains the incompatibility of broad-toed and narrow-toed crayfish in one reservoir. Usually the narrow-clawed crayfish is the winner as the most prolific and adapted to changing environmental conditions. An example of plant competition is the relationship between meadow foxtail and fescue. Experiments have shown that fescue can grow in moist soil, but does not grow in the meadow foxtail community. Here he is suppressed by the shadow
Interspecific competition between lynx and wolverine There are two forms of competition: Straight- is carried out by direct influence of individuals on each other, for example, during aggressive clashes between animals or the release of toxins from plants and microorganisms. Indirect- does not imply direct interaction between individuals. It occurs indirectly - through the consumption of the same resource by different animals, which is a limiting (limiting) factor. Therefore, indirect competition is also called operational. It was found that in the process of life, some plants secrete into external environment various substances ( phytoncides - Phytoncides (from Greek phyton - plant and lat. caedo - kill) - biologically active substances secreted by plants and killing or inhibiting the growth and development of other organisms) , which, having a certain biological activity, affect other organisms. This phenomenon has been known since ancient times, but only in 1937 did the German botanist H. Molisch give it the name allelopathy (from Greek. allelon- mutual pathos- suffering, impact) - the interaction of organisms through specifically acting chemical products of metabolism. Most often, allelopathy manifests itself in the suppression of one species by another, for example, wheatgrass and weeds crowd out cultivated Symbiosis. Mutually beneficial cohabitation of individuals of different species. A classic example of symbiosis in animals is the cohabitation of a hermit crab and sea anemone, which attaches to the shell of a mollusk, masking and protecting it (coelenterates have stinging cells). In turn, the sea anemone feeds on bits of food left over from the crayfish meal and uses it as a means of transportation. The relationship of many ants and aphids takes on a form of symbiosis: the ants protect the aphids from enemies, while they themselves feed on their sugary secretions. Symbiosis is observed in termites, whose digestive tract serves as a haven for flagella. Termites are known for their ability to feed on wood, despite their lack of enzymes that hydrolyze cellulose. This is done for them by flagellates. The resulting sugar is used by termites. Termites cannot exist without this intestinal fauna. Symbiosis is represented in widespread lichens - a symbiosis of algae and fungi. 
An example of commensalism is big fish and fish stuck Amensalism (from lat. mensa table, meal). Relationships in which negative conditions arise for one Predation. Interaction between populations, in which one of them, adversely affecting the other, benefits from this. Usually the prey is killed by the predator and eaten in whole or in part. At the heart of the relationship "predator - prey" are food ties. Until recently, it was widely believed that all predators are harmful animals and should be destroyed. This is an erroneous idea, since the destruction of predators often leads to undesirable consequences and causes great damage to both nature and human economic activity. After all, the victims of predators are usually sick and weakened individuals, the destruction of which restrains the spread of diseases, one or another population heals. Today there is no doubt that wolves, for example, help to increase the viability of the reindeer population in the forest-tundra and tundra; pikes in pond farms, if they do not exceed a certain quantitative limit, stimulate the productivity of carps, etc.
An example of predation
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