Population Interaction

Population Interaction

When a certain group of species lives in a certain ecosystem, they have effects on one another. This phenomenon affecting nearby living and nonliving beings are called Population Interaction. This is also termed as Biological or Species Interactions in Ecology.

Ecology is a vast arena in Biology, which is a study of organisms, their distribution and interaction with each other and the environment. To study the relationship between prey, predators, other interactions and phenomenon like Competition, Camouflage, Mimicry etc., it is mandatory to study the theory of population interaction.

Let’s discuss each of them in detail.

Population Interaction in the Ecosystem

The environment consists of both abiotic (physical) and biotic (biological) factors. Nutrients in the Soil, Carbon Dioxide, Water, Temperature, Atmospheric Pressure, the Wind and Osmotic Balances are some of the physical aspects required for a living being.

Along with these abiotic factors of the ecosystem, the populations can be very much affected by their interactions.

Here are the main modes of interaction between population


As the name suggests, it is a relationship when two or more species attempt to consume the same limited resources at the same time, which may be food, water, light, or any prey. All these things are crucial for any organism’s growth and survival.


This is a relationship where one species depends entirely on other for its food and survival. The species which feeds on another one is called predator whereas the one that is fed upon is called as the prey. This entire relationship is called Predation.  Predator is usually stronger than that of the prey, and hence it consumes preys during its entire life cycle. In some food chains and webs, a predator can also fall as a prey as all living organisms develop a kind of defense mechanisms after a certain period of time.

Another important aspect of this concept is that the words ‘predator’ and ‘prey’  is not always limited to animals as it applies to the relationship of animal and plants as well. For example – Rabbit eating a carrot, Bear preying on Berry & Grasshopper and leaf.


Camouflage literally means ‘to disguise’. In biology, the phenomena where an organism or a species develops structural adaptation that helps them to blend with their surroundings. This lets them avoid getting detected by predators.


It is a Greek term which means “living together.” In various relationships among two or more species or organisms, both the parties depend on each other for food and survival. It is a relationship where one organism lives on another with mutual stereotypic behavior.

There are three types of Symbiosis:

  1. Mutualism – where both species are benefitted.
  2. Commensalism – where one species benefits without harming the other.
  3. Parasitism – where one species benefits by harming the other.


Symbiosis is a mutual long-term relationship between different species, where both of them depends on each other for survival, but Parasitism is one-sided symbiosis, that is only one species live off the host by mostly harming it. The one who feeds on the host is called the parasite. A parasite survives because of the host; it may harm it also but doesn’t kill it unlike in the process of Predation. Also, parasites are usually weaker and smaller than the host.

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Practise This Question

Which of the following options are correct regarding given assertion and reason?

Assertion [A]: Fossil fuels causes air pollution.

Reason [R] : Fossil fuels contain small amount of nitrogen and sulphur in it.