The interspecific competition it is a type of interaction where members of different species pursue a limited common resource. Competition is a type of interaction that not only applies to animals, it also applies to other living beings.
Many times the competition does not occur due to a direct fight between the species (combats, aggressions, among others). It can also occur indirectly. Competition is a very important factor - in addition to other biotic and abiotic components - that is responsible for shaping the structures of communities. In general, interactions between species have ecological and evolutionary consequences.
Interspecific competition is opposed to the concept of intraspecific competition, where the members of the interaction remain the same species.
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Organisms live in what we call “ecological community”. The nature of the interaction is determined by the evolutionary context and the environmental conditions in which it occurs..
For these reasons, ecological interactions between organisms are difficult to define, since they depend on the scale in which they want to be quantified and the context in which the interaction takes place..
In these associations, individuals of different species interact directly or indirectly. In addition, interactions can either favor both parties or be antagonistic..
Competition is considered as an interaction between individuals who pursue a particular common resource, and in this circumstance the resource is in limited quantities.
In a more general view, competition is a direct or indirect interaction between organisms that leads to change in the fitness of these when the organisms share the resource in question. The result of the interaction is negative, particularly for the “weaker” part of the interaction.
Competition is classified in several ways, and one of the most common is to separate it according to the species that are involved. If competition occurs between members of the same species it is intraspecific, and if it occurs between different species it is interspecific.
Competition is classified into three types: interference, exploitation, and apparent. The latter is not considered as a type of real competition.
Competition for interference occurs between individuals directly, while the remaining two occur indirectly. We will expand these concepts a little further below.
It occurs when an individual directly alters the obtaining of another's resource. For example, when a male of a certain species alters access to females for the rest of the males in the group.
This can be done through aggressive behavior and fighting. In this case, the dominant male restricts the other males.
It occurs when different individuals interact indirectly through the same resource. In this way, the use of the resource by one of the species affects indirectly to the other species involved in the interaction.
Suppose two species of birds feed on the same fruit. Consumption of the fruit by species A will affect species B
The same thought applies to lions and hyenas. Both species consume similar prey and mutually affect their populations - even if the fight is not "hand to hand".
It occurs when two individuals that are not competing directly for a resource are mutually affected, since they are prey to the same predator. I mean, they have enemies in common.
Suppose that predator A (it can be an owl or an eagle) has two prey targets Y and X (it can be small mammals such as mice or squirrels).
If the population of Y increases, it will favor the population of X, since now Y will be the prey of A in greater proportion. Similarly, an increase in Y also leads to an increase in A (the predator), negatively affecting X.
The same reasoning applies to the decline in the populations of Y and X. Therefore, the interaction depends on the ecological context. This type of competitive scenario is difficult to identify in nature, as it is complex and involves multiple species.
If you want to predict the outcome of the competition, you can apply the Lotka-Volterra mathematical model. The model relates the population density and the carrying capacity of the members of the competitive interaction.
The model has several possible outcomes: species A excludes species B; species B excludes species A, either species wins due to its population density or the two species can coexist.
Species can survive in the same context if intraspecific competition is greater than interspecific competition. The model predicts that two species cannot compete stably if they both pursue the same ecological resources..
This means that each species must inhibit its own population before inhibiting the population of the species with which they are competing, and the result is coexistence..
In the case where one species excludes the other, it is an event called competitive exclusion or Gause's rule. Indicates that one species remains in the wild and the other is locally extinct, due to competition.
This principle is summed up in the phrase: “total competitors cannot coexist”. Natural selection seeks to reduce competition and one way to achieve this is by developing alternative life histories and exploiting other types of resources. In other words, the species must be separated in at least one axis of the ecological niche..
The most iconic example in the literature involves Darwin's finches from the Galapagos Islands. The evolution of the beak size has been exhaustively studied and has been shown to comply with the exclusion principle..
When two species that consume the same seeds live on separate islands, the peaks are similar to each other. However, when the species coexist on the same island, the peaks exhibit morphological differences to avoid competition and separate the type of seeds they consume..
The separation may not be morphological, it may also be temporary (use the resource at different times, such as birds and insectivorous bats) or spatial (occupy different spatial regions, such as birds that disperse in different areas of the same tree).
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