ecological relations

Ecological relationships are the interactions that take place between living beings, which can occur between individuals of the same species ( intraspecific relationships ) or individuals of different species ( interspecific relationships ). They can also be harmonic or disharmonious.

Interspecific and intraspecific ecological relationships

Interspecific ecological relationships are interactions that occur between individuals of different species. Intraspecific relationships occur between individuals of the same species. The relationship known as mutualism is an example of an interspecific ecological relationship, while society is an intraspecific ecological relationship.

Bees are animals that live in society.

Harmonic and disharmonic relationships

Ecological relationships can be further classified into harmonic, also called positive, and disharmonic , also called negative . Harmonious relationships are those that, as the name suggests, do not cause harm to those involved, and these relationships are beneficial to all or even to one of those involved without harm or benefit to the other. An example of a harmonic relationship is commensalism .

When one animal kills and feeds on the other, a disharmonious interspecific relationship occurs.

Disharmonious relationships , in turn, are those in which one of those involved is not benefited by the interaction, that is, an organism is harmed. An example of a disharmonious relationship is predatism .

Examples of ecological relationships

Ecological relationships can be harmonic interspecifics, disharmonious interspecifics, harmonic intraspecifics and disharmonious intraspecifics.

Intraspecific ecological relationships


– Society: Individuals of the same species cooperate with each other and establish a division of labor. In this ecological relationship, there is no physical union between individuals. Example: bee society .

– Colony: Individuals are anatomically united, and division of labor may or may not occur. Example: Portuguese caravel.


– Cannibalism : An individual kills and feeds on another of the same species. Example: The female praying mantis feeds on the male after copulation.

– Competition : Individuals of the same species compete for resources such as food, area and partners. Example: Lions fight over territory.

Interspecific ecological relationships


– Commensalism: Individuals of different species interact and only one of them benefits from the interaction, but without causing harm to the other. Example: The vulture feeds on food leftovers thrown by humans in open environments.

– Mutualism: Individuals of different species interact and both benefit. Mutualism can be optional or mandatory. In facultative mutualism, participants can live independently; in the mandatory one, one of those involved may not survive, if the interaction is undone. Examples: Lichen (mandatory mutualism), hermit crab and sea anemone (facultative mutualism)


– Amensalism: An organism releases compounds that prevent or inhibit the development of an organism of another species. Example: Fungi release substances that cause the death of certain bacteria.

– Parasitism: One organism ( parasite ) takes from another (host) the nutrients necessary for its survival. Example: Louse living on man.

– Predatism: One organism kills and feeds on another of another species. Example: A lion feeding on a zebra.

– Competition: Individuals of different species fight for resources, such as food and space. Example: Several herbivores living in the same area.

Attention: Protocooperation and inquilinism were not presented because many authors prefer to consider protocooperation as facultative mutualism, just as inquilinism is considered a type of commensalism .

Bromeliads can be found living on another plant, a typical case of tenancy.

Exercises on ecological relationships

Question 1 – (Urca) Termites are exceptional wood eaters and become pests in urban areas, threatening sacred works, historic buildings, etc. However, they would not have this destructive power without the presence of protozoa in their intestines capable of digesting cellulose. This ecological relationship is an example of:

a) Mutualism.

b) Commensalism.

c) Amensalism.

d) Parasitism.

e) Tenancy.

Answer: Letter a. As protozoa and termites benefit from the interaction, we can say that it is a case of mutualism.

Question 2- (IFMG) In biological communities, living beings maintain different relationships with each other. These relationships can be intraspecific, when they happen between beings of the same species, or interspecific, when they happen between beings of different species. The following statements are made about the relationships between living beings. All are correct except:

a) Mutualism is a type of permanent association between living beings of two different species, with benefit to both. An example of mutualism is the association between some algae and fungi, forming lichens.

b) Bees live in groups in which the work is divided among its different members. This type of association is called protocooperation.

c) Competition is a type of ecological relationship in which individuals compete for resources in the environment. It can occur between organisms of the same species or between individuals of different species.

d) In parasitism, an individual, called a parasite, associates with another individual, called a host. The parasite takes its food from the host, causing it harm. An example of parasitism is the association between roundworms and humans.

Answer to question 2: Letter B. Bees are animals that live in society, and it is possible to observe the division of labor between individuals in the hive. In the hive, we have three castes: the workers, the queen and the drone.

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