Competition in Ecosystems

Competition in Ecosystems

Middle School

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Learning Objectives

• Define competition and give examples of it in different ecosystems.

• Explain the difference between competition 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

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Competition

The struggle between organisms for limited resources like food, water, or mates.

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Rutting

Rutting – A seasonal period when male animals compete for mates, often involving displays, fighting, or other behaviors to attract females.

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Alpha Leader

The dominant male who wins fights and is the one most likely to mate.

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Mutualism

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

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Resource Availability

The amount of necessary resources like food and water present in an ecosystem.

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Types of Competition

For Resources

• Competition happens when organisms need the same limited resources like food, water, or living space.

• This struggle for survival directly limits how large a population can grow and reproduce.

• If there is not enough food, some individuals may not survive, keeping populations stable.

For Mates

• Members of the same species will often compete with each other to find a mate.

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

• Others use elaborate displays, like dancing or creating patterns, to attract a female's attention.

Multiple Choice

What is competition?

• A struggle between organisms for the same limited resources.

• A process where animals help each other find food.

• A relationship where one organism hunts another for food.

• A situation where organisms have everything they need.

Multiple Choice

What is the most likely effect of a limited food supply on a population?

• The population size is limited by the lack of food.

• The organisms will learn to share the food equally.

• The population will grow larger and reproduce more.

• The organisms will stop competing for mates.

Multiple Choice

Which scenario describes two different types of competition happening at the same time?

• A lion and a hyena fighting over a dead animal.

• Two male deer fighting over a mate, while the herd struggles to find enough water.

• A bird building a nest, while a squirrel gathers nuts for the winter.

• A plant growing tall to get more sunlight than the plants around it.

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Competition for Resources

Animal Competition

• Animals compete when they need the same limited resource, like food, water, or territory.

• For example, sharks and dolphins compete with each other (interspecific) to hunt the same fish.

• Chimpanzee groups may compete within their species (intraspecific) for access to the best fig trees.

Plant Competition

• Plants also compete with one another to get the resources they need to survive.

• Their primary needs include sunlight to make food, water, and nutrients from the soil.

• For example, vines climb up tree trunks to reach the top for more direct sunlight.

Multiple Choice

Under what condition does competition occur between organisms?

• When they live in the same habitat but eat different foods.

• When they are active during different times of the day.

• When they both require the same limited resources to survive.

• When one organism helps another organism find food.

Multiple Choice

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

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

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

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

• One involves animals, while the other involves plants.

Multiple Choice

If a large number of new, young trees are planted close together in a sunny field, what is the most likely long-term outcome?

• The trees will grow taller but not wider.

• Competition between the trees for sunlight and water will increase.

• The trees will begin to share nutrients through their roots.

• Animals will stop competing for territory beneath the trees.

Cooperation: The Power of Pairs

• Pistol shrimps and goby fish live together in a burrow.

• The goby fish watches for danger and warns the nearly blind shrimp.

• The shrimp provides a safe home for the goby fish in return.

Multiple Choice

Based on the information, what is cooperation?

• A relationship where two animals help each other.

• A relationship where one animal hunts another animal.

• A relationship where animals fight for the same food.

• A relationship where animals ignore one another.

Multiple Choice

What is the specific relationship between the pistol shrimp and the goby fish?

• The goby fish cleans the burrow, and the shrimp finds food.

• The goby fish warns the shrimp of danger, and the shrimp provides a safe home.

• The shrimp protects the goby from predators, and the goby digs the burrow.

• The shrimp shares its food, and the goby helps it see.

Multiple Choice

What would most likely happen if the goby fish left the burrow?

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

• The shrimp would be more vulnerable to danger because it is nearly blind.

• The shrimp would have to find a new goby fish to help it dig.

• The shrimp would learn to watch for danger on its own.

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How Resource Availability Affects Ecosystems

• The availability of resources like food and water drives changes in ecosystems.

• A change in available resources leads to a direct change in population size.

• More available food can help an individual organism grow much faster.

• Plentiful resources can support a higher rate of reproduction in a population.

Multiple Choice

What is a key driver of an ecosystem's dynamics?

• The availability of resources like food and water.

• The number of predators in the area.

• The daily weather and temperature patterns.

• The specific types of plants in the ecosystem.

Multiple Choice

What is the most likely effect of a significant increase in the food supply for a population?

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

• The population will likely decrease in size.

• Individual animals in the population will likely stop growing.

• The animals in the population will likely migrate to a new area.

Multiple Choice

If a severe drought significantly reduces the amount of available food and water in an ecosystem, what is the most likely outcome for a population of animals living there?

• The population size will likely decrease due to slower growth and less reproduction.

• Individual animals will likely grow much faster to find more food.

• The rate of reproduction will likely increase to save the population.

• The ecosystem's dynamics will likely remain stable and unchanged.

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Common Misconceptions

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

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Summary

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

• Competition occurs within a species or between different species.

• In mutualism, a cooperative relationship, both organisms benefit.

• Resource availability affects an ecosystem's population size, growth, and reproduction.

Poll

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

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