Mutualism in Biology - Meaning and Examples

Author: Peter Berry
Date Of Creation: 19 February 2021
Update Date: 21 December 2024
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10 Mutualism Examples
Video: 10 Mutualism Examples

Content

At relationships between different living beings remain one of the main subjects of study in science. In particular, mutualism has been studied extensively and, nowadays, really surprising cases of animal mutualism keep appearing. If until recently it was believed that there were cases in which only one species benefited from the other, today we know that there is always reciprocity in this type of relationship, that is, with gains on both sides.

In this PeritoAnimal article, we will explain the meaning of mutualism in biology, the types that exist and we'll also see some examples. Discover everything about this form of relationship between animals. Good reading!

What is mutualism?

Mutualism is a kind of symbiotic relationship. In this relationship, two individuals of different species benefit of the relationship between them, obtaining something (food, refuge, etc.) that they could not obtain without the presence of the other species. It is important not to confuse mutualism with symbiosis. THE difference between mutualism and symbiosis resides in that mutualism is a kind of symbiosis between two individuals.


It is quite possible that every organism on planet Earth is in some way associated with at least one other organism of a different species. Furthermore, it seems that this type of relationship has been fundamental in the history of evolution, for example, they were a consequence of mutualism to origin of the eukaryotic cell, O plant appearance over the earth's surface or the angiosperm diversification or flowering plants.

The costs of mutualism

Originally it was thought that mutualism was a selfless action by the organisms. Nowadays, it is known that this is not the case, and that the fact of taking from someone else something that you cannot produce or obtain has costs.

This is the case for flowers that produce nectar to attract insects, so that the pollen adheres to the animal and disperses. Another example is that of plants with fleshy fruits in which frugivorous animals pick up the fruit and disperse the seeds after passing through their digestive tract. For plants, creating a fruit is a considerable energy expenditure that benefits them little directly.


Nevertheless, studying and getting meaningful results about how big the costs are for an individual is a difficult task. The important thing is that at the species level and at the evolutionary level, mutualism is a favorable strategy.

Types of Mutualism

To classify and better understand the different mutualist relationships in biology, these relationships have been typified into several groups:

  • Mandatory mutualism and optional mutualism: within mutualist organisms there is a range in which a population can be obligatory mutualist in which, without the presence of the other species, it cannot fulfill its vital functions, and facultative mutualists, which can survive without interacting with another mutualist.
  • Trophic Mutualism: In this type of mutualism, the individuals involved obtain or degrade the nutrients and ions they need to live. Normally, in this type of mutualism, the organisms involved are, on the one hand, a heterotrophic animal and, on the other, an autotrophic organism. We must not confuse mutualism and commensalism. In commensalism, one of the organisms gets benefits and the other gets absolutely nothing from the relationship.
  • defensive mutualism: defensive mutualism occurs when one of the individuals involved obtains some reward (food or refuge) through the defense of another species that is part of the mutualism.
  • dispersive mutualism: this mutualism is the one that occurs between animal and vegetable species, so that the animal species obtains food and, the vegetable, the dispersion of its pollen, seeds or fruits.

Examples of mutualism

Within the different mutualist relationships there may be species that are obligatory mutualist and facultative mutualist species. It may even happen that during one stage there is obligatory mutualism and, during another stage, it is optional. The other mutualisms (trophic, defensive or dispersive) can be mandatory or optional, depending on the relationship. Check out some examples of mutualism:


Mutualism between leaf-cutting ants and fungi

Leaf-cutting ants do not feed directly on the plants they collect, instead, create gardens in their anthills where they place the cut leaves and on these they place the mycelium of a fungus, which will feed on the leaf. After the fungus grows, the ants feed on their fruit bodies. This relationship is an example of trophic mutualism.

Mutualism between rumen and ruminant microorganisms

Another clear example of trophic mutualism is that of ruminant herbivores. These animals mainly feed on grass. This type of food is extremely rich in cellulose, a type of polysaccharide impossible to degrade by ruminants without the collaboration of certain beings. The microorganisms housed in the rumen degrade the cellulose walls from plants, obtaining nutrients and releasing other nutrients that can be assimilated by the ruminant mammal. This kind of relationship is a mandatory mutualism, both ruminants and rumen bacteria cannot live without each other.

Mutualism between termites and actinobacteria

Termites, to increase the termite mound's immune level, build their nests with their own feces. These bundles, when solidifying, have a thickened appearance that allows the proliferation of actinobacteria. These bacteria make barrier against the proliferation of fungi. Thus, termites get protection and bacteria get food, exemplifying a case of defensive mutualism.

Mutualism between ants and aphids

Some ants feed on the sugary juices that the aphids expel. While aphids feed on the sap of plants, ants drink the sugary juice. If any predators try to disturb the aphids, the ants will not hesitate to defend the aphids, source of your main food. It's a case of defensive mutualism.

Mutualism between frugivorous animals and plants

The relationship between the frugivorous animals and the feeding plants is so strong that, according to several studies, if some of these animals go extinct or decrease in number, the fruits of the plants will decrease in size.

The frugivorous animals select the more fleshy and eye-catching fruits, therefore, there is a selection of the best fruits by these animals. Due to the lack of animals, plants do not develop such large fruit or, if they do, there will be no animal interested in it, so there will not be a positive pressure for this fruit to be a tree in the future.

In addition, some plants, to develop large fruits, require a partial pruning of these fruits. O dispersive mutualism it's really necessary not only for those species involved, but also for the ecosystem.

If you want to read more articles similar to Mutualism in Biology - Meaning and Examples, we recommend that you enter our Curiosities section of the animal world.