Social Sciences

What is amensalism and give an example?

We explain what amensalism is and some examples of this biological relationship. Also, what is commensalism?

What is Amensalism?

Amensalism is a biological relationship that is established between two organisms in which one prevents the other from growing and developing (or even surviving).

In amensalism, the individual who is harmed is usually the smallest or the weakest, while the other organism does not even register its presence.

This relationship is the result of the survival instinct that many species have and that occurs at the moment when a certain organism is installed in a habitat . Once there, it strives so that other individuals or species fail to survive in the same space, which harms these other species.

In general, this survival instinct is produced from the generation of toxic substances that come from microorganisms and that prevent other species from developing in nearby areas.

The term “amensalism” is not synonymous with competition . Although both are biological relationships that are registered in nature , in competition two individuals face each other to make the same resource, which is indispensable for the subsistence of both. In this relationship, one of the individuals always benefits and the other is injured. On the other hand, in the amensalismo the organism that carries out the delimiting action does not acquire any type of benefit.

Examples of amensalism

The toxicity of pine leaves prevents the seeds in the area from germinating.
  • When the leaves of the pines fall to the ground, their toxicity prevents the seeds of the area from germinating.
  • The fungi feed from organic matter , that is, absorb nutrients from other populations they harm, weaken or neutralize.
  • An animal crushes with its paws the herbs that grow in its habitat and this prevents the rest of the species from using them to feed.
  • The overpopulation of algae results in an increase in its toxicity and this harms the fish or plants that grow or develop around it.
  • The substance produced by eucalyptus complicates and even prevents other vegetables from developing near it.
  • Like eucalyptus, black walnut generates a toxin known as juglone, which disables other plants to develop, which generates a very reduced competition in survival.
  • Sequoias prevent the passage of sunlight with its branches, which causes plants to grow near them.
  • Urine and fecal matter of elephants have substances that attract pathogens that pollute the soil and water , and hinder the survival of other species.

Commensalism and amensalism

Commensalism - amensalism
An example of commensalism is when bees build their honeycomb on a tree.

Commensalism and amensalism are two types of interactions that occur between different organisms in the environment .

The difference between commensalism and amensalism has to do with the fact that, in the first case, one of the individuals is benefited from the relationship while, in amensalism, none of the members of the relationship obtains any advantage from that link.

In commensalism, one of the individuals is benefited while the other is neither benefited nor harmed: the link is neutral.

Some examples of commensalism can be when bees build their honeycomb on a tree , when roars are mounted on sharks to transport them or when birds build their nests on any tree.

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