Interactions Between Organisms – Lesson Summary

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Learning Objective

In this lesson we will learn about different types of interactions that occur between organisms.

Learning Outcomes

By the end of this lesson you will be able to:

  • Distinguish between intraspecific and interspecific interactions.
  • Describe predation, herbivory and competition, with examples.
  • Define ‘symbiosis’.
  • Differentiate between mutualism, commensalism and parasitism, with examples.
  • Discuss how the different types of interactions affect the organisms involved.

 
interactions between organisms lesson contents

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Lesson Topics

1 | Ecological Interactions

2 | Predation and Herbivory

3 | Competition

4 | Symbiosis

5 | Mutualism

6 | Commensalism

7 | Parasitism

8 | Summary

Lesson Summary

  • Interactions between organisms of the same species are called intraspecific interactions.
  • Interactions between organisms of different species are called interspecific interactions.
  • Ecological interactions can have positive (+), negative (–) or neutral (0) outcomes for the organisms involved.
  • The main types of ecological interactions are:
  • Predation and herbivory
  • Competition
  • Symbiosis, including mutualism, commensalism and parasitism.
  • Predation involves an animal (the predator) killing and eating another animal (the prey).
  • Herbivory involves an animal feeding on a plant.
  • Predation and herbivory both have positive consequences for one organism at the expense of the other.
  • Therefore, they can be represented as +/–.
  • Competition involves two organisms vying for the same resource.
  • Competition has negative consequences for both organisms involved.
  • Therefore, it can be represented as –/–.
  • Symbiosis refers to any close, long-term association between organisms of different species.
  • Symbiosis always benefits at least one of the organism involved.
  • There are three main types of symbiosis, which differ in their consequences for the second organism involved.
  • Mutualism is a symbiosis that has positive consequences for both organisms.
  • It can be represented as +/+.
  • Commensalism is a symbiosis that has positive consequences for one organism while the other organism is unaffected.
  • It can be represented as +/0.
  • Parasitism is a symbiosis that has positive consequences for one organism (the parasite) at the expense of the other (the host).
  • It can be represented as +/–.

 
macaque monkeys grooming

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