Competition in Ecosystems

Competition in Ecosystems

Middle School

​

Learning Objectives

• Define competition and provide examples of it in various ecosystems.

• Explain the difference between competing for mates and for resources.

• Explain mutualism as a type of interaction between different organisms.

• Analyze how resource availability affects population growth, competition, and reproduction.

Key Vocabulary

​

Competition

The struggle between organisms for limited resources like food, water, or available mates in an ecosystem.

​

Rutting

The process of male deer fighting one another by fiercely locking their antlers together.

​

Alpha Leader

The dominant male in a group who wins fights and is the most likely to mate.

​

Mutualism

A relationship between two different organisms where both species benefit from helping out each other.

​

Resource Availability

The amount of necessary resources like food, mates, and water that are present in an ecosystem.

​

​

Types of Competition

For Resources

• ​Organisms compete for limited resources like food, water, and living space.

• ​​This struggle for survival limits the growth and reproduction of a population.

• ​A lack of resources can keep populations stable by limiting survival.

For Mates

• ​Members of the same species will often compete with one another to find a mate.

• ​​Some animals, like Red Deer, may engage in physical fights to prove their strength.

• ​Others use elaborate displays, like dancing, to attract a female’s attention.

Multiple Choice

Which of the following is an example of competition for mates?

• A vine growing up a tree to get more sunlight.

• Two male Red Deer fighting by locking antlers.

• Sharks and dolphins hunting the same type of fish.

• A pistol shrimp and a goby fish living in the same burrow.

​

​

Where Does Competition Happen?

Animal Competition

• Animals compete when they need the same limited resources, such as food, water, or space.

• Competition can occur between different species, like sharks and dolphins hunting the same types of fish.

• It also happens within the same species, like chimpanzees competing for the best territory.

Plant Competition

• Plants also compete with one another for the resources they need to survive and grow.

• Their primary needs include sunlight to make food, as well as water and nutrients.

• For example, some vines climb up tree trunks to reach more direct sunlight.

Multiple Choice

What is the key difference between the competition involving sharks and dolphins and the competition among chimpanzees described on the slide?

• One is for food, while the other is for territory.

• One is between different species, while the other is within the same species.

• One happens in the ocean, while the other happens on land.

• One involves animals, while the other involves plants.

Cooperation: The Power of Pairs

• Pistol shrimps and goby fish work together in a mutualistic relationship.

• The shrimp provides a shared burrow for shelter.

• The goby fish acts as a lookout, warning the shrimp of predators.

Multiple Choice

In the relationship between the pistol shrimp and the goby fish, what does the shrimp provide?

• A warning about nearby danger.

• A safe home in the burrow it builds.

• Food it has hunted.

• Protection from predators using its claws.

​

​

How Resource Availability Affects Ecosystems

• Resource availability like food and water drives changes in ecosystems.

• A change in resources directly causes a change in population size.

• Plentiful resources can lead to higher reproduction rates in a population.

• More food helps individual organisms grow faster and much stronger.

​

Multiple Choice

According to the text, what is the most likely effect of a significant increase in the food supply for a population?

• The animals will stop growing.

• The population will migrate to a new area.

• The population will likely experience a higher rate of reproduction.

• The ecosystem's dynamics will remain unchanged.

​

Common Misconceptions

Misconception	Correction
Competition only happens between different species.	Competition also occurs within the same species for mates, territory, and social rank.
All interactions between different species are competitive.	Some species cooperate in a relationship called mutualism, where both benefit.
Only animals compete for resources.	Plants constantly compete for sunlight, water, and soil nutrients.

Multiple Choice

A lion and a hyena fighting over a carcass is an example of interspecific competition. How does this differ from the intraspecific competition of two male deer fighting?

• It involves animals from different species competing for a resource, whereas the deer are from the same species competing for a mate.

• It happens on land, whereas the deer competition happens in the forest.

• One is a fight for food, while the other is a fight for territory.

• There is no difference; all competition is the same.

Multiple Choice

If a severe drought significantly reduces the amount of available food and water in an ecosystem, what is the most likely chain of effects on a population?

• Slower individual growth and less reproduction will lead to a decrease in population size.

• The population size will increase because weaker individuals are removed.

• Individual animals will grow faster to find more food, increasing the population.

• The ecosystem will remain stable, and the population size will not change.

Multiple Choice

A new, non-native plant that grows very tall and has deep roots is introduced to a forest. How could this new plant disrupt the ecosystem?

• It could outcompete native plants for sunlight and water, causing them to die and affecting animals that rely on them.

• It would provide more food for all the animals in the forest.

• It would have no effect on the existing plants or animals.

• It would immediately form mutualistic relationships with the native trees.

Multiple Choice

Imagine a disease affects the goby fish population, making them unable to see predators. What is the most likely consequence for the pistol shrimp?

• The shrimp would be more vulnerable to danger because its warning system (the goby) is compromised.

• The shrimp would be safer because it would not have to share its burrow.

• The shrimp would learn to see on its own.

• There would be no consequence for the shrimp.

​

Summary

• Organisms compete for limited resources like food, water, and mates.

• Competition can be intraspecific (within a species) or interspecific (between species).

• Available resources impact a population's size, growth, and reproduction.

• Unlike competition, mutualism is a cooperative relationship where both organisms benefit.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4