Shrinithi Mahadevan

Community Ecology Study Guide

The study of community ecology focuses on the processes that drive interactions between different species and the implications of those interactions.


Community ecology is the study of how communities, which are assemblages of interacting populations of species living in a certain region or habitat, are organized and operate. Let's know more structure of ecology and population interaction among them.

Community structure:

  • Community structure can be defined as the presence of organisms within an environment. It comprises species diversity, which measures both species richness and species evenness.
  • Many variables impact community structure, including abiotic influences, species interactions, disturbance levels, and random events.
  • For example, foundation species and keystone species play critical roles in shaping the structure of their ecosystems.

Community ecology Source

Species richness:

  • The amount of distinct species in a community is referred to as species richness.
  • The most diverse communities are located around the equator, with abundant solar energy (supporting high primary productivity), mild temperatures, abundant rainfall, and little seasonal variation.
  • The communities with the least diversity of species are found in the poles, which get less solar energy and are thus colder, drier, and less conducive to life.

Species diversity:

The diversity of species in a community is a measure of its complexity. It is determined by the number of distinct species in the community (species richness) and the relative abundances of those species (species evenness).

Keystone species:

A keystone species has a disproportionately great impact on community structure about its biomass or abundance. They are more likely to belong to trophic levels higher up the food chain (to be top predators)

Community interactions:

Community interactions Source

An ecological community comprises the populations of all the diverse species that coexist in a given region. Interspecific interactions are interactions between distinct species in a population. The consequences of different sorts of interspecific interactions on the two individuals might be positive (+), negative (-), or neutral (0). Competition (-/-), predation (+/-), mutualism (+ /+), commensalism (+/0), and parasitism (+ /-) are the most common interspecific interactions.


Interspecific competition occurs when individuals of two distinct species fight for the same restricted resource. Competition has a detrimental impact on both participants (-/- interaction) since if one species were gone, the other would have a greater chance of survival and reproduction.

When species have overlapping niches or ecological responsibilities and requirements for survival and reproduction, they compete. Competition can be reduced if two species with overlapping niches develop to use fewer comparable resources due to natural selection, resulting in resource partitioning.


Predation occurs when a member of one species, the predator, feeds all or part of the life or recently living the body of another species, the prey. The predator benefits from this contact, whereas the prey suffers from it (+ /- interaction). Predation can occur between two animal species, but it can also occur when an animal or insect consumes a plant's component, a type of predation known as herbivory. Predation Source

The population dynamics of predators and prey are regulated by each other. In addition, many predator-prey species have acquired adaptations—beneficial qualities resulting from natural selection—that is tied to their interactions. Mechanical, chemical, and behavioral defenses are examples of prey defenses.


Interspecific interactions in which two species live together in a long-term, close relationship are called symbiosis. We use symbiosis to describe a connection that benefits both sides in everyday life. On the other hand, Symbiosis is a larger notion in ecological terms, encompassing deep, long-term connections with a variety of good and negative impacts on the participants.


Mutualism is a long-term relationship between two species that benefits both of them ( +/+ interaction). Some fungi, for example, create mutualistic relationships with plant roots. The plant may photosynthesize and deliver sugars and other organic compounds to the fungus. The fungus extracts water and nutrients from the earth and passes them on to the plant.


Commensalism is a long-term relationship between two species that benefits one but has neither positive nor negative impact on the other ( +/0 interaction). Many of the bacteria that live in our bodies, for example, appear to have a commensal relationship with us. They gain from the shelter and nourishment they receive, and they have no obvious beneficial or detrimental influence on us.


Parasitism Source

In parasitism, two species have a tight, long-term relationship that benefits the parasite while harming the host (+ /- interaction).


  • Community ecology is the study of how communities, which are assemblages of interacting populations of species living in a certain region or habitat, are organized and operate.
  • Species richness, or the number of species present, and species diversity, which is a measure of both species richness and species evenness, may be used to define the structure of a community.
  • The amount of distinct species in a community is referred to as species richness.
  • Interspecific interactions are interactions between distinct species in a population.


1. What is an example of community ecology?

Community ecology is a broad term that refers to various ecological interactions that vary through time. The plant community, all trees, birds, squirrels, deer, foxes, fungus, fish in a forest stream, insects, and any other species dwelling or migrating seasonally make up a forest community.

2. What are the characteristics of a community in ecology?

Aside from these qualities, communities have a few things in common. Species diversity, species interactions, spatial organization, periodicity, the ecotone-edge effect, and ecological successions are all examples of these factors.

3. What are the principles of community ecology?

A community is made up of all populations that share the same habitat and are present simultaneously. Species diversity refers to the number of species that share a habitat and their relative abundance.

4. Why is it important to understand community ecology?

This branch of biology is essential because it allows scientists to understand better how communities are organized and develop through time. Furthermore, knowing the structure of a community is essential for predicting the impacts of species decline or extinction (loss of diversity).

5. What is an example of ecosystem ecology?

The interaction of living creatures with the non-living environment is referred to as an ecosystem. A food chain can be used to symbolize creatures that depend on one another for survival. Ponds and lakes, for example, are natural freshwater habitats that are stationary. Phytoplankton is among the producers.

We hope you enjoyed studying this lesson and learned something cool about Community Ecology! Join our Discord community to get any questions you may have answered and to engage with other students just like you! Don't forget to download our App to experience our fun, VR classrooms - we promise, it makes studying much more fun! 😎


  1. Community (Ecology): Definition, Structure, Theory & Examples. https://sciencing.com/community-ecology-definition-structure-theory-examples-13719217.html. Accessed 27 Dec, 2021.
  2. 4.4 Community Ecology. https://openoregon.pressbooks.pub/envirobiology/chapter/4-4-community-ecology/. Accessed 27 Dec, 2021.
  3. Community Ecology. https://www.nature.com/scitable/knowledge/community-ecology-13228209/. Accessed 27 Dec, 2021.