Evolution, driven by “survival of the fittest”, allows the best, most suited organisms to survive in an environment. These organisms are “fit” and survive because of a behavioral or physical trait that makes them superior to other competing individuals or species. But what does being “fit” really mean? Is it just about being the best within themselves? Or is being “fit” also tied in to the role that that organism plays in an ecosystem?
Being fit has as much to do with being able to survive the environmental pressures as it has to do with the role that an organism plays in an ecosystem. You see, Nature is remarkably efficient. No organism is present in a place without a reason. This is, of course, only in the case of an undisturbed ecosystem. The organisms present are those that can survive in that ecosystem and also play a role in maintaining the balance of that ecosystem. The role that they play, defines the niche of that organism.
Let us look at this with an example. Dung beetles are a fascinating set of creatures that perform a very, very unique (albeit disgusting) role in the ecosystem. They are responsible for decomposing the dung of animals. They play a critical role in the nutrient cycling process by allowing nutrients to go back into the soil, so that they can be taken up by plants again. Decomposition of dung is thus, the broad niche of dung beetles.
(Within dung beetles, there are many different species that decompose different types of dung, different PARTS of dung, etc. The niches present within dung beetles are truly staggering.)
How did dung beetles take up this role that ensured their continued, indispensable existence in the ecosystems of the world? The answer is evolution.
Some ancestor of the current dung beetles must have faced severe competition to survive in the ecosystem. The “job” that they had the ecosystem, must have had many other contenders as well. So, some dung beetles must have developed the ability to break down and help in the decomposition of the dung; a “job” that probably had vacancies. This allowed these dung beetles to survive, and ensured that their innate ability was carried by their progeny. In time, dung beetles took over a part of this decomposition “industry” and became the dominant and important species we know them to be today.
The process of the development of niches through evolution has a trend in it.
- First of all, this can only happen in an ecosystem that is unstable and disturbed.
- The instability can be in two ways. One, it could be because the ecosystem is still new and developing, and many niches are empty. In effect, this means that the “job market” is young and there are “many vacancies” for every kind of role that the “job market” supports.
- Or, the instability could be because of the introduction of new species in a stable ecosystem. Influx of graduates into a job market is analogous to this. Now, there is intense competition between the new species and the existing species. A species that used to enjoy a large realized niche is now in a position where there are new contenders for their niche space.
- In the face of this instability, species that could come up with a new way to meet the demands would quickly establish themselves in a niche that is available in the ecosystem.
- These successful species would pass on their special traits, the traits that allow them to survive in their niches, to their progeny. The other species would find it difficult to even produce progeny. This is the process of natural selection.
- In time, the established species would flourish, and all individuals of that species would possess the characteristics that allow them to fulfill the duties of the niche they occupy.
So when you think about it, evolution has a huge role to play in how a species fills niches in an ecosystem and how that niche could change in the future. All of this is done with only one goal in mind; stability and order in nature.
(It is actually shocking to see how similar this process is to the way human society functions in the economy today!)
Categories: Fundamentals of Ecology