Many types of relationships exist between living things on Earth, but not all of them are positive. Today we learn about amensalism. How does this unique type of relationship work? What are the most striking examples of amenalism?
The definition of amenismism
There are various relationships in which various species are found throughout the world. In nature, no organism lives its life in complete isolation. It must somehow interact with other organisms and the environment. One of the types of relationships that have been classified by biologists and ecologists is amenalism. This is any connection between organisms of different species in which one of them is inhibited or destroyed, while the other remains intact.
Types of Amenismism
Basically, there are two types of amenalism:
- Competition - a relationship in which a larger or stronger organism excludes another organism from the shelter (habitat) and takes away its food source.
- Antibiosis is a relationship in which one organism releases a chemical that kills another, while one that releases a harmful compound remains unscathed.
Examples of amenalism in nature
Almost everyone has experienced mold on bakery products. This is a common example of amenalism. Under certain conditions, many types of bacteria and fungi can appear, for example, on bread. As a rule, this happens with the expiration of its expiration date. This is a classic manifestation of antibiosis.
This example of amenalism illustrates how one form capable of producing penicillin destroys other forms of bacteria that would also like to grow on this bread. It is these killer properties of penicillin that led to its use as an antibiotic drug. Penicillin kills other bacteria, and they, in turn, do no harm to it.
Another fine example of amenalism is in the category of competition. Large, tall black walnut trees can be found in many areas of the United States. Interestingly, there are no other plants under them. This is due to evolution, which has led to the ability of this plant to secrete a specific chemical substance - juglone, which destroys many herbaceous plants in its root zone.
What is arsenalism?
This is an interaction between organisms in which one of them harms the other and at the same time does not receive any harm or tangible benefits. A clear example of animal amenalism is when sheep or any cattle trample on grass. While the grass does not have a noticeable negative effect on the animal's hooves, it itself suffers from compression.
Negative biological interaction
In nature, no living creature lives in absolute isolation, and, therefore, all of them must interact with the environment and other organisms. The survival of species and the functioning of the ecosystem as a whole largely depend on this.
One of the mechanisms of amenalism is allelopathy, which occurs in plants. It involves the production and release of chemicals that inhibit the growth and development of others. Allelopathic substances range from acids to simple organic compounds.
In addition to the above walnut tree, there are several more examples of plant amenalism. Shrubs such as Salvia leucophylla (mint) and Artemisia californica (wormwood) are known to produce allelopathic substances. Often, these chemicals accumulate in the soil during the dry season, reducing the germination and development of herbs and other plants in an area of up to 1-2 meters from secreting counterparts.
Amensalism is an environmental interaction in which one organism harms another without profit. This type of relationship can be observed between people and wildlife. Due to the destructive impact of humans on the environment, many species of animals and plants are in danger of extinction.
In almost all such cases, other species of animals and plants suffer from human activities. For example, air pollution caused by automobiles, power plants or metallurgical plants often causes serious damage to lichens and plants in the affected area, while people do not directly benefit from this relationship.
The rarest kind of symbiosis
Amensalism is by far the rarest kind of symbiotic relationship that has a negative effect on one organism, while the other is not exposed at all. However, in nature there are examples of mutual negative effects. For example, the relationship between sphagnum mosses and vascular plants in the sphagnum swamp, pine and sedge, and others. In this case, a situation of harmonious mutual oppression is observed - some interfere with growth, the second take sunlight.
Relations that are harmful to one partner and neutral to another position themselves in natural communities as the ultimate variant of asymmetric competition. For example, the unspoken struggle for resources and natural selection. The stronger suppresses the weak, which inevitably leads to a new evolutionary step. An example of amenalism can be observed between tall trees and young seedlings or ground cover grasses in a forest that share sunlight, soil resources that they need for food, and nitrogen.
Difficult relationship
The relationships of organisms are varied and changeable. This can be influenced by the environment, when the confrontation in the struggle for limited resources, as well as different stages of the life cycle, escalates. Here is an example of the relationship between salmon and bivalve pearl mussel.
Being a larva, the pearl mussel enters the gills of salmon and acts as a parasite, however, the grown individuals become independent organisms that live at the bottom and are engaged in filtering water, thereby improving the living space for fish. Some relationships cannot be described on one side only. Young mollusks parasitize on fish, whose offspring will later hide between clusters of shells from local predators.
What conclusions can be drawn
Interactions between organisms are both positive and negative. The former are very important in organizing ecosystems, they are responsible for the natural balance and act as a counterweight to competition - both interspecific and intraspecific, as well as such negative manifestations of cooperation as predation and parasitism. Amensalism is not considered a harmonious type of relationship, since one type will necessarily be oppressed, and the second will develop normally.
Recalling the example of amenalism with penicillin, it is worth mentioning that this substance inhibits the growth of other harmful or neutral bacteria, and they, in turn, can not give a decent rebuff to mold. However, clinical trials were conducted, and as a result, the researchers found that when using penicillin for medicinal purposes, the number of diseases caused by the fungus increases. This is due to the fact that in natural conditions there is a certain inhibition of the development of fungi by various bacteria.