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What is Amensalism? Definition, Types, Examples

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  • Last Updated : 16 Jun, 2022
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The natural habitat on earth is inhabited by various species. For any species, the minimum essential thing is another species on which it can feed. The plant synthesizes its food by photosynthesis, but even though it cannot survive alone because it needs microbes present in the soil to decompose the soil’s organic matter, converting it into the inorganic nutrients for absorption.

For pollination, plants are dependent on a pollinating animal agent. From this, it is clear that  in this nature plants, animals and microbes cannot live alone, but they interact and co-exist leading to the formation of  a biological community

The interaction of populations of two different species leads to interspecific interactions. These interspecific interactions could be either beneficial,  neutral, detrimental to one of the species, or both. A ‘+’ sign for beneficial interaction is represented by a + sign, neutral interaction is assigned as 0 and detrimental interaction is represented as minus (-).

Population Interactions

InteractionSpecies ASpecies B
Mutualism++
Competition
Predation+
Parasitism+
Commensalism0+
Amensalism0

In mutualism both species benefit from each other and in competition in their interactions both species will lose to each other. In predation and parasitism,  one species benefitted (predator and parasite, respectively), and the interaction is destructive to the other species that is host and prey. Commensalism is an interaction in which one species is benefitted and another is neither benefitted nor harmed, i.e. +/0 interaction. If one species is harmed and the other is neither harmed nor benefitted, the interaction is termed Amensalism.

Amensalism 

This single-sided interaction between species. Here there is a detrimental effect on one species but a neutral or null effect on another species.  Simply, amensalism is a form of single-sided competition.

Amensalism is of 2 types allelopathy and antibiosis:

Allelopathy 

There are some species of plants that make chemical substances that hinder the germination process and growth of other plants. This chemical phenomenon is termed allelopathy,

Examples: 

  • Adenostoma Fasciculatum– commonly called chamise produces a chemical that is water-soluble. This chemical gets aggregated over the surface of chamise leaves during dry periods. At the time of rainfall, this accumulated chemical substance gets washed off due to water solubility nature and spreads into the soil where it hinders the germination process and growth of many plants.
  • Juglans nigra commonly called black walnut tree secretes a chemical Juglone from its roots. This chemical kills the plants that are around the black walnut tree.
  • Another example of amensalism is small plants that grow under big trees. These big trees hinder the amount of available sunlight and obstruct the required sunlight to the small plants under them.
  • Penicillin commonly called bread mold produces a chemical substance called penicillin. This penicillin is an antibiotic, i.e. kills bacteria.

Antibiosis

Vuillemin gave the term antibiosis. Certain species of plants produce harmful substances that are dreadful to animals.
For example –  

  • Roots of Tagetes species commonly called marigold produce terthienyls. These terthienlys inhibit the growth of nematodes and fungi.
  • Green, red, and blue algae form algal blooms and produce toxic chemicals that are harmful to fish. This process is termed antibiosis.
  • Antibiotics that restrict bacterial growth, penicillin produced by Penicillium notatum fungus, restricts bacterial growth. 

Conceptual Questions

Question 1: What is Allelopathy?

Answer: 

Allelopathy- There are certain species of  plants which  makes chemical substances that hinder the germination process  and growth of other plants. This chemical phenomenon is termed as  allelopathy,

ExamplesChemical produced by Chamise plant, Juglone produced from the roots of Juglans nigra, Pencilin from Penicillium notatum are best examples of Allelopathy 

Question 2: What is Antibiosis?

Answer:

Antibiosis- Some species of plants secrete poisonous substances that are dreadful to animals this process is called Antibiosis.Vuillemin gave the term antibiosis.

Example – Terthinyls are produced from the roots of the Marigold plant, chemicals produced by algal blooms.

Question 3: What is Amensalism?

Answer: 

Amensalism is a 0/- relationship between species in contact.

This single-sided association between two species is called Amensalism. This type of association is detrimental to one species and neither detrimental nor beneficial to another.

Question 4: What are the various interspecific competitions that exist in nature?

Answer: 

  • Mutualism: Here both species benefit from each other 
  • Competition:  In this interaction, both species will lose to each other. 
  • Predation and Parasitism: Here only one species is benefitted (i.e predator and parasite) and the interaction is destructive to the other species (i.e host and prey). 
  • Commensalism: This is +/0 interaction. Here one species is benefitted and another is neither benefitted nor harmed. 
  • Ammesalism: If one species is harmed and the other is neither harmed nor benefitted from the interaction is termed Ammensalism.

Question 5: What are interspecific interactions?

Answer: 

The interaction of populations of two different species leads to interspecific interactions. These interspecific interactions could be either beneficial,  neutral, or destructive to other species.

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