Intraspecific Competition

The animal world is a fantastic world full of surprises, adventures and curiosities. But we also know that this world has a dark side, of competition for survival. These competitions and struggles are in various sectors, there is sexual competition, between species, within the same species and so on.

In this article, we’re going to talk about a very common type of competition, called intraspecific competition. In other articles, we’ll talk about the other types of competition that exist, so stay tuned and subscribe to the newsletter for news when these articles go live.

Intraspecific competition, what is it?

Intraspecific competition is nothing more than competition between members of the same species. This competition can be for different types of resources. These resources can be mating, space, food, and so on.

It’s a very common type of competition in nature, and sometimes brutal. In many species, this type of competition exists to formulate a dominance hierarchy, where the strongest will be the dominant of the whole pack. This happens in Gorillas, for example, where the alpha male will have all the females.

This is a huge example of how intraspecific competition formulates and shapes species. This competition is completely based on natural selection. In other words, if we follow the method in which this competition takes place, we can see that the strongest will most often win, just as natural selection predicts.

It is worth noting that intraspecific competition arises in two different ways. It can be direct competition between individuals of the same species. For example, a fight between two males of the same species in order to mate. But it can also arise indirectly, if one animal feeds on something, another may not eat that food, so they are competing for the same resource but indirectly.

But that’s not all, as there are methods adopted by individuals to avoid this type of competition. One such method is migration. If there is a dominant male in an area that is stronger than another male, that other male may choose to migrate to another location.

In that other location, he may find a population with a weaker alpha male, and thus, if he wins, become the alpha male. Through migration, there is the possibility of becoming dominant in your field, even if you are not always the strongest.

But evolution also creates curious things to avoid deadly competition. As in the case of the Anolis.

In this curious case, there is a method to avoid competition, through radiative evolution. Where populations of the same species inhabit different niches in the same terrain. For example, in the case of lizards, some may be more in the sun, others more in the shade, some higher up in the trees, others in the bushes, and so on.

In this way, as the populations inhabit different microhabitats, they never compete directly. By not competing directly, they don’t need to share resources with each other, which is the basis for this type of competition. They will only compete again in the event of a disaster or if they inhabit the same place again.

In this case, individuals reduce competition, allowing several populations to coexist. New species can emerge over many generations.

Although we associate competition with animals, both this type of competition and interspecific competition occur in plants. Two oak trees that grow very close to each other will compete for sunlight and nutrients in the soil, for example.

Population dynamics

Nowadays, there are many studies on population dynamics that revolve around intraspecific and interspecific competition. We can therefore understand that the larger the population, the greater the competition between individuals. This is because resources are scarcer.

Here we can see how populations self-regulate. This is not just about intraspecific competition, other factors such as diseases and predators come into play. But what I want to explain here is that the larger the population, the fewer the resources available, so competition will increase to obtain these scarce resources.

In an overpopulated world, the strongest will win, and eliminate or expel the weakest. The opposite is also true: if there are fewer individuals in a population, intraspecific competition will be much lower. There will be no stress created and there will be plenty of resources that can be divided between them all.

Silverback Gorillas: Examples of intraspecific competition

As I mentioned earlier, these animals compete with each other for females. They have a whole hierarchy among themselves, with the dominant male, the so-called alpha male, at the top. His aim is to protect the entire population from predators, from other males, and ultimately to reproduce. So we can see that despite the benefits, being the dominant male brings a lot of stress for them.

The constant fear of another male challenging him and causing him to lose his entire harem, or the fear of being seriously injured when fighting a predator.

Intraspecific competition in these animals takes the form of fierce combats between challengers who want the throne and the alpha male who defends it. This fierce fighting can often lead to the death of one or both of the fighters. It is therefore a risk for the entire population, but a necessary one.

For the challenger, an opportunity, a chance to conquer everything he’s never had before. And for the alpha male, defending his ground is extremely important, as he has everything to lose.

Fighting over territory or females is very common in the animal kingdom. Lions, gorillas, seal species, etc.

So for my second and final example, I’ll talk about plants.

Interspecific Competition In Plants

It’s not just animals that get into fierce battles for land. Plants also fight each other for growth, the chance to sunbathe and much more. There is very brutal competition between different plant species, but more on that in another article. Now, talking about competition between plants of the same species, we have the example of the Oaks.

In the case of these plants, one will always try to grow more to catch the sun, winning in this different type of competition. The plant that gets more sun and nutrients in its development will grow much more than the other, and the other, malnourished, may even die. This is the great danger of having plants close to each other: they will compete for resources, even though they are sessile living beings (without the capacity for self-movement)¹.

With all this, we end the article on intraspecific competition. We know that this is a very common type of competition that influences the entire dynamics of populations and is essential for their control. Now you know what intraspecific competition is, how it happens and examples. As well as ways in which species try to avoid this type of competition. Remember, in competition the strongest survives, but in nature the most capable survives.

Footnotes

1. Kula, A.A.R., Hey, M.H., Couture, J.J. et al. Intraspecific competition reduces plant size and quality and damage severity increases defense responses in the herbaceous perennial, Asclepias syriaca. Plant Ecol 221, 421–430 (2020). https://doi.org/10.1007/s11258-020-01021-4 ↩︎

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