Many kinds of relationships exist between living beings on Earth, but not all of them are positive. Today we will learn about amensalism. How does this unique relationship type work? What are the most striking examples of amensalism?
Amensalism definition
There are different relationships that different species all over the world are in. In nature, no organism lives its life in complete isolation. It must somehow interact with other organisms and the environment. One type of relationship that has been classified by biologists and ecologists is amensalism. It is any relationship between organisms of different species in which one of them is inhibited or destroyed while the other remains intact.
Types of amensalism
There are basically two types of amensalism:
- Competition is a relationship in which a larger or stronger organism excludes another organism from its shelter (habitat) and takes away its food source.
- Antibiosis isa relationship in which one organism releases a chemical that kills the other, while the one that releases the harmful compound remains unharmed.
Examples of amensalism in nature
Almost everyone has experienced the appearance of mold on bakery products. This is a common example of amensalism. Many types of bacteria and fungi can appear under certain conditions, 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 amensalism illustrates how one form that can produce penicillin destroys other forms of bacteria that would also like to grow on this bread. It was these killer properties of penicillin that led to its use as an antibiotic drug. Penicillin kills other bacteria, and those, in turn, do no harm to him.
Another great example of amensalism is in the category of competition. Large, tall black walnut trees can be found in many parts of the United States. Interestingly, there are no other plants under them. This is due to the evolution that has led to the ability of this plant to secrete a certain chemical, juglone, which destroys many herbaceous plants in its root zone.
Amensalism - what is it?
This is an interaction between organisms,in which one of them harms the other and receives neither harm nor tangible benefits. A clear example of amensalism in animals is when sheep or any cattle trample grass. While the grass does not have a tangible negative effect on the hooves of the animal, it itself suffers from compression.
Negative biological interaction
In nature, no living creature lives in absolute isolation, and thus they all 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 amensalism 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 walnut tree mentioned above, there are several more examples of amensalism in plants. 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 grasses and other plants up to 1-2 meters from their secreting counterparts.
Amensalism is an ecological interaction in which one organism harms another without benefit. This type of relationship can be observed between people and wildlife. Due to the destructive human impact on the environment, many species of animals and plants are under threat of extinction.
In almost all such cases, other species of animals and plants are affected by human activities. For example, air pollution caused by cars, power plants, or iron and steel works often causes severe damage to lichens and plants in the affected area, while people do not directly benefit from these relationships.
The rarest kind of symbiosis
Amensalism is by far the rarest type of symbiotic relationship that involves negatively affecting one organism while the other is not affected at all. However, in nature there are examples of mutual negative action. For example, the relationship between sphagnum mosses and vascular plants on a sphagnum bog, pine and sedge, and others. In this case, there is a situation of harmonious mutual oppression - some prevent growth, the latter take away sunlight.
Relationships that are harmful to one partner and neutral to the other position themselves in natural communities as the ultimate in asymmetric competition. For example, the tacit struggle for resources and natural selection. The stronger suppresses the weak, which inevitably leads to a new evolutionary step. An example of amensalism can be observed between tall trees and young seedlings or ground cover grasses in a forest,who share sunlight, the soil resources they need to feed, and nitrogen.
Complicated relationships
The relationships of organisms are diverse and changeable. This can be influenced by the environment, when the confrontation in the struggle for limited resources escalates, as well as different stages of the life cycle. Here is an example of the relationship between salmon and a bivalve mollusc.
Being a larva, the pearl oyster gets into the gills of the salmon and plays the role of a parasite, however, the grown-up individuals become independent organisms that live at the bottom and filter the water, thereby improving the living space for the fish. Some relationships cannot be described only from one side. Young molluscs parasitize fish, whose offspring will later hide between clusters of shells from local predators.
What conclusions can be drawn
Interactions between organisms can be both positive and negative. The former are very important in the organization of 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, while the second will develop normally.
Recalling the example of amensalism with penicillin, it is worth mentioning that this substance inhibits the growth of other harmful or neutralbacteria, and those, in turn, cannot give a worthy rebuff to mold. However, clinical trials were conducted, and as a result, researchers found that the use of penicillin for medicinal purposes increases the number of diseases caused by the fungus. This is due to the fact that in natural conditions there is a certain inhibition of the development of fungi by a variety of bacteria.
