Which organism has the maximum population

Environmental factors and ecological potency

In this article, we'll explain what environmental factors exist and how they affect their environment.

Start by watching this introductory video on ecology!

What is ecology ?! & Basic Principle of Ecology | ecology


A distinction is made between environmental factors

  • the Abiotic and
  • the biotic environment.

An organism that is in a particular location can only survive there if it can cope with both types of environmental factors.

Abiotic factors include things like light or temperature conditions, the climate in general, available water, minerals in the soil, pH value of the soil or water and many other factors that can be recorded by chemical or physical measurement methods.

Biotic factors include all social structures, such as competitors, predators, reproductive partners or parasites. It is very difficult to record all factors at one location, which is why predictions about the development or the influences of various factors in such an area are almost impossible. Often the exact relationships or effects of the factors on one another cannot be quantified in their entirety.

An important term in ecology is the ecological niche. This is understood to mean the totality of all interrelationships between a species and the biotic and abiotic environmental factors. The habitat, on the other hand, only describes the actual habitat of this species.

Another distinction is that between the fundamental niche and the real niche. The fundamental niche is about including only abiotic environmental factors in an investigation. The real niche, on the other hand, considers both biotic and abiotic factors and is therefore in most cases much smaller than the fundamental niche, as aspects such as competition and resources or predators can greatly limit the real niche.

In this learning video, the biotic and abiotic environmental factors are explained to you again!


Tolerance range of organisms towards environmental factors

With the help of the vitality of an organism with a variable environmental factor, a tolerance curve can be drawn up in relation to this factor. A tolerance curve always describes only one environmental factor.

Areas of the tolerance curve:
  • The tolerance range describes the entire range in which an organism can exist. It thus includes all manifestations of the environmental factor from the minimum to the maximum.
  • The point of the minimum or maximum describes the minimum or maximum expression that this environmental factor may have so that the organism can exist. If the minimum is not reached or the maximum is exceeded, the organism dies.
  • The edge areas shortly before the minimum and the maximum are called pessimum (plural: pessima). Here the organism can still survive, but no longer reproduces.
  • The preference describes the organism's range of preferences. This means the preferred area which the organism would most likely choose if the expression of the environmental factor was freely chosen.
  • The optimum denotes the optimum expression of the environmental factor in which an organism with the best possible vitality would exist and reproduce.

Tolerance curves are different for each species and each environmental factor. A distinction is made between two different types of potency:

The physiological potency of an organism in relation to an environmental factor describes the range of reactions without the natural competitive conditions that normally prevail at a location, which enables a species to flourish in the long term (i.e. from the middle to the respective pessimum, since there is no longer any reproduction here is possible).

The ecological potency, on the other hand, describes the range of reactions under natural competitive conditions in which this species can thrive in the long term. If a species is particularly competitive, i.e. it asserts itself well against other species, its ecological potency will probably be relatively similar to the physiological potency. If a species is rather weakly competitive, it is pushed to the edge of its own reaction range by more competitive species. Physiological and ecological potency can then differ very greatly.

If a species can only thrive under very specific environmental conditions, i.e. if it has a narrow tolerance range to many environmental conditions, it is referred to as stenök. However, if a species is relatively variable in terms of many environmental factors, it is referred to as euryök. Stenöke species are very sensitive to changes in environmental factors and are often adapted to very special habitats. With their occurrence at a certain location, one can therefore infer the existing environmental conditions there. Such types are also known as bioindicators or pointer types. Plant organisms are better suited to making statements about the prevailing environmental factors than animal organisms, since the latter are not tied to a specific location and can change their habitat.


Influencing factor: light

Plants in particular, which are sedentary for life and cannot vary their own location, have to adapt to the environmental factor light. Many plants, especially in warmer areas, are faced with a water-light dilemma: Plants need sunlight to generate their own energy, which plants do through photosynthesis. At the same time, however, they also need water to enable the chemical reactions.

If a plant is now in a location that receives a lot of sun, the plant will also transpire a lot and lose fluid as a result. However, it cannot close the stomata through which a plant transpires, as it has to absorb CO2 for photosynthesis, which also happens through its stomata. Therefore, some plants have developed morphological adaptations to specific locations. On the one hand, a distinction is made between the xerophythes (left in the picture) with special adaptations for dry and warm locations and the hygrophytes (right in the picture) with special adaptations for damp, but more shady locations.

Xerophytes have a particularly thick cuticle, which, as a layer of wax, ensures that not so much moisture escapes from the leaf and that the leaf does not dry out as quickly. This is followed by a multi-layered epidermis without chloroplasts and underneath the multi-layered palisade and sponge tissue, in which many chloroplasts enable a high rate of photosynthesis. Many smaller stomata and small intercellular spaces also reduce perspiration.

Hygrophytes, on the other hand, have only a thin cuticle and a single layer of epidermis. This is followed by a palisade fabric with many chloroplasts, which use the available sunlight for photosynthesis. Many raised, large stomata and large intercellular spaces also promote perspiration so that excess moisture can be released.

Another method that plants have developed in order to have the best possible rate of photosynthesis despite unfavorable climatic conditions is the temporal separation of the various steps for which the components sunlight and CO2 are needed. Sunlight is usually absorbed during the day and stored in the plant in an intermediate form, so that the next steps of photosynthesis take place at night when the stomata can be opened easily and CO2 can be absorbed.

Influencing factor: temperature

The ambient temperature not only changes with the course of the day and year, but also depends on the climatic zone in which one is located. For animals this means that they must have adapted to their habitat through morphological characteristics or they have to behave accordingly to the circumstances.

Mammals or birds are called homoiothermic animals. This means that you can keep your body temperature at a constant level even in cold or hot regions by regulating it. This ensures that physiological processes can run at a constant speed at all times. Regarding the regulatory mechanisms, a distinction is made between morphological adaptations (e.g. due to Winterfell) and behavioral adaptations (e.g. panting, sweating or trembling).

Insects and reptiles, on the other hand, are cold-blooded (poikilothermal). You do not have a constant body temperature and cannot regulate it independently.
Instead, they increase their temperature by looking for spots in the sun or in the shade. Your body temperature always adapts to the ambient temperature.

In the figure above, you can clearly see that the preference for animals of the same temperature is much broader than that of cold-blooded animals. However, the animals also have to do 5 to 10 times more for this extended range of reactions Consume food energy as cold blooded animals with the same body mass. A large part of the laboriously collected or captured food is only used to regulate body temperature.

In winter, regulating the body temperature is particularly difficult for animals of the same temperature and the solar energy is no longer sufficient to keep animals with cold blood temperatures at a sufficient temperature. Therefore, different species of animals have developed different concepts to survive the cold seasons:

Further adaptations are described by the so-called animal geographic rules or climate rules. They are about the general shape of the animals' bodies. The basis of this is that the heat given off by a body is proportional to the surface area and the heat generation in the body depends on the volume of the body. A body with a large volume-to-surface ratio has a higher heat storage capacity than a body with a low volume-to-surface ratio. The best way to produce as much heat as possible and at the same time give off as little of it as possible would be a circle.

The first climate rule, Bergmann’s rule, states that in the case of closely related, homoiothermal species, the representatives in colder regions are more voluminous and larger than those of the species in warmer climatic regions.

Allen's rule states that body appendages such as ears or extremities of closely related homoiothermal species in colder regions are usually smaller and stockier than those of representatives of the species in warmer climatic regions.

If the extreme temperature conditions at a location are only temporary, such as during the seasons, some species can also show an evasive reaction (avoidance) (e.g. bird migration to the south).