Amensalism: What it is and Examples

He Amensalism Or antagonism is an interaction between species where one of them - without being affected - impedes the growth and survival of the other.

The interaction between species, from the biological point of view, may be negative (-) or have no effect. This interaction is important, since it allows to study the relationships between predators and prey within the food chain .

Eucalyptus is one of the plants that produce amensalism.

It also helps to see the impacts that pests can have on the agriculture process, plant growth (noxious or not) and species that can generate positive and / or negative changes within watersheds

The factors that define populations are also defined as communities. These are defined by the nature of the interactions between populations in the association or by the place where associations often occur.

They are characterized by unique interrelated properties: structure and function. The structure is composed of the number of species, called riches of the species, the species present and their relative abundances, the characteristics of the vegetation and the trophic relationships between the interaction of the populations in the community.

Ecosystems have plant and animal species that can interact with each other, either negatively or neutrally through amensalism. These relationships can occur naturally or through the incorporation of species within specific geographic areas.

Examples of amensalism

1- Mushrooms

According to Arenas (1993) all fungi are characterized by the absence of chlorophyll, which prevents them from performing the photosynthesis . Therefore, they must be fed with organic matter. They also have a cell wall formed by chitin, which is a strongly rigid compound (polysaccharide).

Therefore, this type of microorganisms must absorb the simple and soluble nutrients, instead of decomposing the food cells (Arias, 2008).

Fungi take nutrients from other populations for the purpose of secreting their substances that inhibit the growth of them. In this way, the fungi have a negative relationship, are strengthened and other populations can be weakened or neutralized, which would compromise their existence by losing their nutrients.

The strongest population when interacting by amensalism with another, secretes a chemical component of its metabolism to the detriment of the other population. An example of this is the fungus Penicillium notatum. It secretes a substance - discovered by Alexander Fleming - capable of destroying bacteria, penicillin.

The Pencils Are common molds that grow on a variety of substrates: grains, straw, hides, fruits, etc. Its morphological identification has always been very difficult until Pitt (1980) harmonized the conditions of cultivation and Frisvad (1981) began to take into account the formation of secondary metabolites in the description of these species.

The importance of these molds in human and animal food is due to the fact that, besides causing deterioration, they produce toxins (Carrillo, 2008).

In foods, fungi can take in the nutrients of other populations, so that the former can grow and secrete specific harmful toxic substances for the latter, causing deterioration and damage. It is a negative relationship.

2 plants

Black walnut produces a toxin, called"junglone"that prevents the growth of other plants around it, thus reducing competition in survival.

The substance deprives weaker plants of the energy required for photosynthesized production. The symptoms of the affected plants are the yellowing in the leaf and wilting, that lead to the death of the same ones. The largest sources of junglone are found in the cocoons, roots and hulls of their nuts.

The eucalyptus tree, Eucalyptus globulus labill, Is a plant native to Australia and occurs in soils rich in boron and phosphorus. It grows at a temperature between 10.80 and 16.80 ° C.

Amensalism occurs when beetles defoliate their leaves and fungi Diplodiasp Y Armillariasp Produce chancres, rot in the roots and death of the tree. The living beings mentioned are those that generate damage by their voracity and the chemicals they secrete.

The blue grass is found in cool, moist places and comes from the United States. It grows on humus rich soils and limestone material. It is one of the dominant herbaceous species and susceptible to rust, may present microtoxin-producing fungi.

In the Amazon jungle, there are 390,000 million trees, distributed in 116,000 species of trees, of which 227 species concentrate 50% of them.

These last ones are those that take all the solar energy and more oxygen. In this way, they can more easily perform the photosynthesis process while the smaller trees receive their nutrients only from the soil and river water.

3- Animals

Wild pigs, when transferred to new habitats, take all the nutrients they find in their path, resulting in their excretion processes being able to contaminate the wetlands or rivers, plants and soils destined for agriculture without the swine Be affected.

Rabbits, when introduced into Australia to serve as hunters and ended up being a pest, affected the habitat without being affected.

Elephants are a population that is negatively related to plant species, since with substances excreted by urine and fecal material, they bring pathogens capable of reducing or killing other species, polluting rivers and relief.

Knowing amensalism through its definition and some examples, make it possible to improve the knowledge of this point of biology to the non-specialized public in this area.


  1. Amensalism. Retrieved from:
  2. Arias, E. (2008). Isolation and Identification of Filamentous Fungi of Soil Samples from Guasca and Cruz Verde Moors . Bogotá, Pontificia Universidad Javeriana.
  3. Microbial Associations. Recovered from:
  4. Biosecurity of Genetically Modified Organisms. Rome Italy. Retrieved from:
  5. [Links] The Wetland: An Element of the Natural Landscape, as a Teaching Strategy for the Teaching of the Natural Sciences in Students of Cycle II . Bogotá, National University of Colombia.
  6. Commensalism, Amensalism and Parasitism. Retrieved from:
  7. Echium vulgare. (Common Viper's Bugloss). Retrieved from:
  8. Ecology and Environment. Retrieved from:
  9. Ecology and Environment. Recovered from:
  10. Eucalyptus Globulus Labill. Retrieved from:
  11. History of Production of Penicillin. Retrieved from:
  12. Juglans Nigra (Black Walnut). Retrieved from
  13. Fungi of Food and Forage. Retrieved from

Loading ..

Recent Posts

Loading ..