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Population Interaction

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The study of different Organisms, their scattered presence over different regions, and their Interaction or Communication with each other and the surrounding Environment comes under the Umbrella of Ecology.  The theory of Population Interaction is extremely crucial to be understood fundamentally prior to the understanding of the concepts and relationships between Predators and Prey, Camouflage, Competition, Mimicry, Hunting Strategies, etc.


Definition of Population Interaction

According to the Population Interaction definition, the Interaction among Populations is the Interaction between different species of Organisms in the Ecosystem. It takes into account the effects that Organisms belonging to a community have on everybody else and one another. 


There are two kinds of Factors, the abiotic one or the Physical Factor and the biological one or biotic Factor in the Environment. Some Physical Factors like nutrients of the soil, water, carbon dioxide, atmospheric pressure, wind, etc. are important for and needed by a living Organism to live. The different kinds of Populations and their Interactions can be affected a lot by these abiotic Factors, which are a part of the Ecosystem. Mentioned below are the major modes of Interaction between different Populations or the types of Population Interaction:



It is an Interaction between two or more than two species of Organisms when they compete. The competition is for limited resources, which all the competitors want control of, at the same time. These resources can be area, food, water, or any other prey. As these things are important for sustaining, these resources are mainly the ones for which competition happens.


Competition is further categorized into the following types:

  • In interference competition, Organisms interact directly by fighting for scarce resources which may be availability of mates or food etc. One example is the large aphids who defend  their feeding sites on cottonwood leaves by ejecting smaller aphids from better sites. Male-male competition in red deer during rut is another example. One key feature is that individuals often engage in aggressive behaviours with respect to the other competitor for foraging, survival and/or reproduction. They also show territorial behaviour in order to beat any competition for limiting resources. To compete aggressively, they have evolved various structures such as antlers in deer, bright colourful feathers in peacocks, etc., which lends competitive advantage over the other members of the species. In an Ecosystem, interference competition is a strategy adopted in animal species mainly by the larger and stronger Organisms within a habitat.

  • In exploitation competition, or scramble competition, both  Organisms indirectly use the common limiting resource or shared food item. Instead of fighting to win resources, they indirectly deplete the total amount available for other Organisms. These Organisms might never interact directly, but nevertheless are said to be competing as they effectively respond to changes in resource levels. Common examples of this phenomenon include plants who grow in close vicinity to each other and then compete with their neighboring plants for sunlight, soil nutrients, etc. .

  • The apparent competition occurs when two species that are otherwise unrelated end up competing with each other for survival due to a shared predator. For example, suppose there are two species (species A and species B), which are preyed upon by food-limited predator species C. Scientists observe an increase in the abundance of species A and a decline in the abundance of species B.



In a predation relationship, there is a full dependency of one kind of species over the other species for their survival and food. The one that gets preyed for food is called the prey. The species which feeds on the other kind of species is termed as a predator species.


Several instances of the food chains, food webs, etc. are based on this concept, where a predator keeps on relying on other species for food during its entire life cycle. In some cases, the predator can also become prey to some other species. All the living Organisms have their own defense and attack strategies, which they use to become safe from the stronger species or to hunt down the weaker species.


This relationship is witnessed not just within the animal kingdom but also plant kingdom. Predator and prey can also be applied to animal and plant relationships. For example, a goat feeding on grass or a panda eating bamboo.



It is an effective defense survival strategy used by various Organisms to develop structural adaptation and Physical characteristics similar to their surroundings and blend with it in order to be safe and not get found by the predators actively looking for them. Many animals like chameleons, lizards, frogs, leopards, etc. use this technique for their own advantages for hiding away from predators.



In the Greek language, symbiosis means to live together. There are situations in which many species of Organisms depend on each other for survival. They depend on each other for food in most cases. One Organism lives with another exhibiting a mutual stereotypical behaviour in this case. There are different types of Population Interactions of Symbiosis kind.


Types of Symbiosis Interaction

1) Mutualism 

It is a biological relationship or Interaction between two or more species of Organisms. In this type of Population Interaction, each species is profited in some or the other way from the other species. This is the most common type of ecological Interaction. It explains that mutual dependency is needed and is necessary for the social well-being of different species. It is prominent in most Populations of Organisms around the globe.



2) Commensalism

It is a unique kind of relationship where two or more species of Organisms depend on each other for food or survival and get benefitted, but without harming each other or anyone.

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3) Parasitism

Parasitism involves one Organism feeding off another Organism. It is a case of one-sided symbiosis. The Organism that feeds off another species is called a parasite, and the prey species is called the host. The parasites multiply, causing harm to the hosts.

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FAQs on Population Interaction

1. What are the Different Examples of Mutualism, Commensalism, and Parasitism Interaction?

There are several Population Interactions examples which can be witnessed on day to day basis, they are: 

  • Oxpecker and Zebra 

Oxpecker is a kind of bird that eats flies, insects, etc. from the zebra and other grazing animals. The animals get rid of insects in this way, and the birds get their food. This is an example of mutualism Population Interaction.

  • Tree Frog and Trees 

The frog hides under the leaves to protect itself from rain, storm, or predators. This is an example of commensalism as no species is harmed while getting benefitted from one another. 

  • Mosquitoes and Humans 

The mosquitoes are parasites here, and the humans are the hosts. Mosquitoes feed on human blood for survival, and humans, in turn, get harmed. This is an example of parasitism Population Interaction. 

2. What are the Examples of Competition and Camouflage Population Interactions? 

Herbivores like gazelles are the prey for dangerous predator species like a group of lions and a group of hyenas. Both of these groups are carnivorous predators and can compete to get the prey to themselves in order to satiate their hunger and survive. This is an example of competition population interaction. 

Stonefish adapts itself to the rocks of the ocean and camouflages with them in order to not get seen by bigger predator fishes like sharks. It also does this while hunting smaller fish as they would not be able to differentiate between the stonefish and its surroundings and fall prey to it. This is an example of camouflage population interaction.

3. What do we understand by the term “positive Interaction” among Populations?

In ecological systems, positive Interaction refers to the Interaction among various species that improves the chances of survival, growth and reproduction, leading to overall well being of all the species Population involved. One common example is that of symbiosis, in which both the Organisms involved in the Interaction benefit from the association, as they help improve food availability (between fungi and algae), provide protection against predation (sea anemone and clownfish) or helps in reproduction (bees and the plants they pollinate).

4. Explain negative Population Interaction with examples?

Negative Interaction is a type of ecological Interaction in which the two Populations of species enter in an association for better survival chances at the expense of the other. Only when one Population group is harmed while the other derives survival benefit, can it be said as negative Interaction. For example predation (where one Population group kills the other for food) or parasitism (where one derives nutrition while the health and well being of the other deteriorates and eventually dies), etc.

5. What are the differences between the terms “Population” and “community”?

Population in ecological context refers to the group of individuals that belong to the same species and can interbreed to produce fertile offspring. They may or may not live within the same niche. A Community also shares some of the characteristics of a Population but the distinct feature of a community is that they closely share a habitat or niche and are affected by the same climate and natural forces governing an area of the Ecosystem. They may not be entirely  genetically related species but due to the same ecological conditions, they face similar challenges for food, reproduction, growth and survival. 

For example, all lions (the African lions or lions of the Indian subcontinent) are genetically the same species and form a Population. But they face different conditions based upon their place of occurrence. On the other hand, within a desert, all the species of animals and plants are not related to each other genetically. They however are united by their habitat and therefore form a community.

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