Ecological niche: how it helps to understand nature


Ecological niche : To this day, scientists theorize that there are an average of 7.77 million animal species in the world, of which 953,434 have already been cataloged. From both a theoretical and a practical point of view, there must be a certain order between each of the members included in these figures, since the physical space on Earth is finite.

Ecology, a branch of biology that focuses its effort and interest in the relationships of living beings with each other and with their environment, is responsible for exactly discovering this order “invisible” to the human eye. From the prey-hunter relationship to the effects of climatic variables on organisms, this branch of science leaves no question to chance in nature.

Today we come to show you a term as exciting as it is abstract, which is key to understanding ecology as a scientific discipline: the ecological niche. We assure you that, after reading these lines, you will never see a walk through the countryside in the same way as before.

What is an ecological niche?

This abstract concept has undergone many conceptual modifications since it was coined in the early 20th century. Although many of its meanings are valid, in general the ecological niche can be defined as follows: “a multidimensional hypervolume that includes all the biotic and abiotic factors with which the organism is related”.

To present the term in a more friendly way to the reader, even if we are reductionist, it can also be generalized by saying that the niche is the range of environmental, physical and biotic conditions (conditioned by living beings) in which a species, or rather a population, can develop and endure over time successfully. The description of an ecological niche tries to explain, taking into account many variables, the reason for the adaptations of living beings to their environment and their viability in the short and long term.

Although we are facing a fairly abstract term, various scientific publications have established certain bases in relation to it. We show you some of them in the following list:

  • The niche must be understood in a functional sense, understanding as a function all organism-environment interaction. It cannot be confused with habitat.
  • Organism-environment interactions can be quantified through records and experiments based on statistical inference.
  • The concept of niche should not be founded solely on direct observations.
  • The niche is an attribute of the individuals of a population belonging to a particular community and ecosystem.
  • The niche reports information at the individual level but this is not relevant: it seeks to understand the dynamics at the population level.

So the niche allows us to directly relate the geographic space through the notion of an abstract multidimensional space composed of “n variables”, where a species develops or could potentially do so. We know, all this conglomerate is a bit complex to understand, but in the following lines we assure you that everything will be clearer.

What is referred to by this term in Biology?

Ecological niche : Intertwined with natural selection, the concept of niche allows us to postulate a blunt but irrefutable reality, at least in a theoretical framework: two species competing for the same resources cannot coexist locally unless they occupy different niches. Therefore, ecologically identical species cannot coexist in the same ecosystem, because by force one of them will end up being displaced or suffering an extinction. Let’s take a completely fictitious but functional example:

If we understand a resource such as food in a region along the X axis of a graph, each of the “curves” drawn will represent the exploitation of that resource by a given species. Animals are “interested” in having the greatest possible distance between the curves of different species, because if they overlap, intense competition occurs that, in the long run, benefits no one.

Take, for example, the insectivorous birds and bats of a region. They are both flying, small in size and have the same diet: if both species coexisted in the same time space, the “resource exploitation curves” or their niches would come dangerously close, right? Therefore, the solution may be to promote the reproduction of nocturnal individuals in bat populations by natural selection.

Thus, bats would begin to exploit a nocturnal niche throughout their evolutionary history, with all the peculiarities and adaptations that this requires. While the birds sleep, these winged mammals can develop so, despite having similar needs, both species avoid overlapping. We do not want to say that this example is real, but it is certainly a “book” case that allows us to understand in a simple way what an ecological niche is.

Types of ecological niche

Ecological niche :Once the term has become clear to us, we must also point out that there are two main types of ecological niche: the realized and the fundamental.

The realized niche specifies the geographic range based on the variables already described that allows a population to develop at a practical level, that is, the place where a population of a species actually lives at this time. Although it seems that we are circumscribing the term to a “place”, this is not the case: we are still talking about an abstract term that does not refer to a fixed position.

On the other hand, the fundamental niche explores the places that a species could occupy in the absence of other competing species. Thus, a fundamental niche becomes a realized niche when we take into account predator-prey interactions, disease, parasitism, or competition for resources among living things. Perhaps a fish could live in the upper part of a river depending on its biological adaptations, but a piscivorous species may develop there that has been successfully evolving and exploiting its niche for thousands of years.

Meanings of this term

Ecological niche : Again, we want to emphasize that the concept of a niche does not refer solely to a physical place, tempting as it may seem to treat it indistinguishable from a habitat. Here are a series of meanings based on the niche that must be taken into account:

  • Niche as habitat: The early ideas of the niche were based on the physical place that the animals exploited and which they developed.
  • Niche as role: other authors postulate that the niche is more conditioned by the trophic relationships between species than by the physical space itself.
  • Niche as an “N-dimensional hypervolume”: a quantitative description of the range of conditions that allow a population to persist somewhere.

Of course, the third meaning is the most accepted today. We are before a combination of physical place and role, because both the climatic conditions and the trophic chain and other relationships with living beings are just as important when it comes to predicting or knowing the distribution area of ​​the population of a species.

Criticisms of this construct

Searching for a scientific current or an idea that is free from criticism in the research community is a true chimera. The ecological niche could not be different, since almost no application is untouchable today.

The difficulty in quantifying an exact ecological niche is that, for each variable, it is necessary to ideally record how each one of them affects the population growth rate. For example, if a species survives at X temperature, it would be necessary to experiment in the laboratory with all the possible environmental combinations that allow its development as far as this parameter is concerned. As you can imagine, this is practically impossible.

Even so, we want to make it clear that the operational difficulty in measuring a parameter does not underestimate the value of its estimate at all. As is often said in the scientific community, in many cases it is better to approximate than to know nothing and, sometimes, recording the uncertainty or recording negatives is as important as any other discovery.

Ecological niche : Summary

Ecological niche : As you may have seen in these lines, the ecological niche is a complex, abstract term with multiple meanings. If we want something to be clear after reading this space, it is the following: the niche is the set of all the parameters that come to mind that make a population be present in a specific place and not in another. That complex, that simple.

The next time you walk in the field, ask yourself why that beautiful bird flies higher than another or why one insect lives on the leaves and another under the stones. Each living being occupies its space and specializes in it: in the niches lies the key to the ordering of life in nature.

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  1. November 26, 2020

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