The living beings that share a habitat or ecosystem have different ways of relating to each other, either for mutual benefit or for that of only one. Since resources are always limited, be it territory, food or water, it is natural that there are forms of interrelation in which species cooperate (association) or on the contrary fight (competence).
The biological association
We will talk association, then, although also of cooperation, when two animal individuals allow each other to work together in order to benefit each other, taking better advantage of resources or providing an opportunity that they would not have separately. This type of beneficial relationship can occur intraspecific (between two members of the same species) or interspecific (between two members of different species).
A good example of association is the colonies, in which numerous individuals of the same species share habitat, to the degree that they are sometimes bodily fused. Thus, corals form colonies of identical individuals that cooperate to protect and feed themselves; while the bees do the same, but in a hierarchical way and by dividing the tasks, to keep the whole alive and protected.
The interspecies biological associations can be of the following types, judging by the specific relationship between the associated individuals:
- Commensalism. Both individuals live together, and one of them benefits from the other (for example, from its waste), without causing any harm to it. For example: remoras attached to a shark, which feed on their hunting spoil.
- Symbiosis. In the symbiosis both associated individuals mutually benefit, either cooperating to provide sustenance or mutual defense from predators. For example: lichen, a union of a fungus and an alga to provide mutual protection and structure.
- Parasitism. In this case, the mutual association is not so beneficial for one of the two individuals, since the other feeds on him or at his ribs and can sometimes cause harm. For example: the ticks that drink the blood of cattle.
- Tenancy. In this case, one of the two individuals seeks protection in the other, without causing harm or being injured by it. For example: the clown fish that lives among the petals of anemones, without being injured by them but being safe from predators.
On the contrary, it speaks of competence when the presence of two individuals in the same habitat causes in the other a decrease in the satisfaction of their needs, whether for food, water or territory. In other words, the competition consists of the struggle or the effort on the part of the animals involved to obtain the benefits for themselves, so it is an opposite case to the association of all kinds.
Again, this competition can occur between species or within the same species and plays a fundamental role in the natural selection, vital to the theory of evolution.
The generational predominance of the fittest individuals (and their genetic material) over the least fit or failing in the competition, then, will make species in nature have to compete with each other to adapt to the environment or, otherwise, to become extinct.
The same occurs within a species, as individuals will compete for access to resources and reproduction, which causes the most competent to reproduce more and better than the less fit.
Types of competition
There are three fundamental forms of competition, according to the mechanism by which they occur:
- Competition by interference. It occurs when an individual or a species interferes, that is, hinders the competition of the other or the other, through aggression or other methods, preventing access to food or habitat.
- Competition for exploitation. It occurs indirectly, when the use of a resource or a space to inhabit leaves others out, depriving them of their basic needs but without direct relationship with the other individual or the other species.
- Obvious competition. It is the direct competition between two species or two individuals for survival, which may imply, for example, competition to hide from one predator, leaving the other exposed.
Differences between association and competition
- In association both individuals or species cooperate and benefit more or less, while in competition one of the two will only benefit.
- Association allows the development of colonies and complex modes of interaction, while competition presses to survive or perish and rather drives the engine of selection and discard.
- The association induces to share space and resources, while competition to fight for them.
- Association allows mutual survival, while competition leads to the extinction of one of the competitors.