MS-LS2-4: Ecosystem Changes and Population Impact

MS-LS2-4
Ecosystem Changes and Population

Middle School

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Learning Objectives

• Define ecosystem dynamics and how disruptions can alter populations.

• Analyze evidence to support claims about how changes in an ecosystem affect populations.

• Explain how small changes can lead to large impacts on an ecosystem’s biodiversity.

• Identify major threats to biodiversity and ways humans can help mitigate them.

Key Vocabulary

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Biodiversity

Biodiversity is the wide variety of plants, animals, and other living things in a specific area.

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Ecosystem Dynamics

Ecosystem dynamics describes how the interactions between living and nonliving things in an ecosystem change over time.

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Ecosystem Disruption

A disruption is an event, either natural or human-caused, that disturbs the delicate balance of an ecosystem.

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Keystone Species

A keystone species is an organism that has a very large effect on its entire ecosystem’s health.

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Invasive Species

An invasive species is a non-native organism that is introduced to an ecosystem and causes significant harm.

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Habitat Loss

Habitat loss is the process by which a natural home of an organism is destroyed or altered.

Key Vocabulary

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Empirical Evidence

This is information gathered using the five senses, through observation and structured experiments.

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Stability and Change

This is the study of how natural and human-made systems can stay the same or change.

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Causal Relationship

This is a connection where one event, the cause, makes another event, the effect, happen.

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Ecological Footprint

This measures the amount of nature needed to support a person's or a group's lifestyle.

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What is Biodiversity?

• Biodiversity refers to the wide variety of life that exists in an area.

• All the organisms within an ecosystem are interdependent and rely on each other.

• Scientists measure it using a biodiversity index, which shows an ecosystem's health.

• Scientists have identified 1.5 million species, but many more remain undiscovered.

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Multiple Choice

What is the best definition of biodiversity?

• The variety of living things in a specific area.

• The total number of individual organisms in an area.

• The way organisms interact with non-living things.

• The number of undiscovered species on Earth.

Multiple Choice

What is the relationship between a biodiversity index and an ecosystem?

• It provides a measure of an ecosystem's health.

• It lists all 1.5 million identified species.

• It explains why all organisms are interdependent.

• It separates the living from the non-living things.

Multiple Choice

Based on the relationships described, what would most likely happen if a disease wiped out several plant species in an ecosystem?

• The ecosystem would become less stable because organisms are interdependent.

• The remaining species would no longer need to rely on each other.

• The health of the ecosystem would improve with fewer species.

• Scientists would find it easier to count the remaining species.

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Distribution of Biodiversity

High Biodiversity

• Regions near the equator have the highest concentration of different plant and animal species.

• These tropical areas are warm and receive plenty of sunlight and rain all year.

• This stable and nurturing environment provides the resources for a wide variety of life.

Low Biodiversity

• Areas with extreme weather conditions, like deserts or polar regions, support less life.

• These environments experience extreme heat or cold, and have very little available water.

• Only a small number of specially adapted species are able to survive here.

Multiple Choice

Where is the highest concentration of different plant and animal species typically found?

• In regions near the equator

• In areas with extreme weather

• In desert and polar regions

• In places with very little water

Multiple Choice

Why do tropical areas support a wide variety of life?

• They have extreme temperatures that only some species can tolerate.

• They provide a stable environment with plenty of resources like sunlight and rain.

• They have very little available water, which limits the variety of life.

• They experience dramatic seasonal changes that support different species.

Multiple Choice

If a normally warm and rainy tropical area began to experience long-term extreme cold and reduced rainfall, what would be the most likely outcome?

• Biodiversity would increase as new species move in.

• Biodiversity would decrease because fewer species could survive the extreme conditions.

• The number of species would stay the same, but they would become smaller.

• Only the plants would be affected, while the animals would adapt quickly.

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Ecosystems Change Over Time

• Ecosystems are dynamic, meaning their characteristics can and do change over time.

• Disruptions, like fires or droughts, can cause big shifts in populations.

• The arrival of invasive species is another example of a biological disruption.

• A small change can cause large, unpredictable shifts throughout the entire ecosystem.

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Multiple Choice

Which statement best describes the nature of ecosystems over time?

• They are dynamic and their characteristics can change.

• They remain stable and unchanging indefinitely.

• They only change when new animals are introduced.

• They always return to their original state immediately after a disruption.

Multiple Choice

What is the relationship between a disruption, like a fire or the arrival of an invasive species, and an ecosystem?

• A disruption can cause significant changes in the populations within the ecosystem.

• A disruption only affects the non-living parts of an ecosystem, like water and soil.

• An ecosystem is able to prevent all disruptions from occurring.

• A disruption only occurs if a new species is introduced.

Multiple Choice

If a single new plant species is introduced to a stable forest ecosystem, what is the most likely potential outcome?

• The small change of a new species could cause large, unpredictable shifts throughout the forest.

• The new species will have no effect on the overall ecosystem.

• Only the specific trees the new species eats will be affected.

• The ecosystem will immediately adapt and become more stable.

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The Role of Keystone Species

Top Predators

• Keystone species are organisms that fill a specific niche that another species cannot.

• Top predators like wolves control prey populations, which prevents overgrazing of plants.

• This allows other species like trees and beavers to thrive in the ecosystem.

Ecosystem Engineers

• Ecosystem engineers are keystone species that physically alter the environment around them.

• Beavers are an example, as their dams create entirely new wetland habitats.

• This creates a large shift in the populations of many other different species.

Multiple Choice

What is the main characteristic of a keystone species?

• It is the most numerous species in the ecosystem.

• It physically alters the environment more than any other species.

• It helps other species by controlling the climate.

• It fills a specific role that cannot be performed by another species.

Multiple Choice

How do ecosystem engineers, such as beavers, have a major impact on their habitat?

• By controlling the population of prey animals.

• By physically changing the environment, which creates new habitats.

• By providing a food source for many different predators.

• By competing with other species for resources.

Multiple Choice

Based on the role of top predators, what would most likely happen in an ecosystem if wolves were suddenly removed?

• The population of prey animals would increase, leading to fewer plants.

• The beaver population would increase because their main predator is gone.

• The number of trees would increase due to a lack of predators.

• The ecosystem would remain stable as other species would take the wolves' place.

Threats to Biodiversity as Ecosystem Disruptions

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Habitat Loss

• ​This is the destruction or change of an organism's natural home.

• ​​It is a physical change to the environment caused by human activity.

• ​Examples include construction, farming, and clearing forests for wood.

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Invasive Species

• ​These are new organisms that humans introduce to an ecosystem.

• ​​They often outcompete native species for resources like food and water.

• ​This can cause the populations of the native species to decrease.

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Pollution & Climate Change

• ​Pollution introduces harmful chemicals and substances into the environment.

• ​​It is a physical change that can poison water, air, and soil.

• ​Climate change alters long-term weather patterns, affecting survival conditions.

Multiple Choice

Habitat loss, the introduction of invasive species, and pollution are all examples of what?

• Ecosystem disruptions caused by human activity.

• Natural cycles of environmental change.

• Ways that organisms adapt to new environments.

• Methods for increasing biodiversity in an area.

Multiple Choice

How can the introduction of an invasive species lead to a decrease in the populations of native species?

• By outcompeting them for resources like food and water.

• By physically destroying their natural homes.

• By poisoning the water, air, and soil.

• By altering long-term weather patterns.

Multiple Choice

A large forest is cleared to build a new factory and a town. Which combination of threats to biodiversity would this single event most likely cause?

• Habitat loss from clearing the forest and pollution from the factory.

• Invasive species from the new town and climate change from the factory.

• Only habitat loss from clearing the forest.

• Only pollution from the new factory and town.

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Arguing from Evidence

• Scientists support claims with evidence from observations and experiments.

• A valid argument needs evidence of the change and its effect.

• For example, data on rising temperatures and declining fish populations.

• This helps show a relationship between the cause and the effect.

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Multiple Choice

What is the main purpose of using evidence in a scientific argument?

• To support claims with facts from observations and experiments.

• To prove a scientific theory without any doubt.

• To make a scientific idea popular with the public.

• To replace a complex explanation with a simpler one.

Multiple Choice

How does showing evidence of both a change and its effect strengthen a scientific argument?

• It connects the cause of the change to the outcome that was observed.

• It proves that the change will happen again in the future.

• It describes the location where the scientific experiment took place.

• It lists all the scientists who worked on the project.

Multiple Choice

A scientist claims that pollution is harming the fish in a river. Which piece of evidence provides the strongest support for this claim?

• An article describing the different types of fish that live in the river.

• A statement from a local resident who thinks the river is dirty.

• Data showing that river pollution levels increased, followed by a decrease in the fish population.

• A report on the weather patterns in the area over the last year.

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How We Can Protect Biodiversity

• Reduce your ecological footprint to positively impact biodiversity, like restoring Mono Lake.

• Eating more plants and less meat conserves energy and natural resources.

• Follow the Reduce, Reuse, and Recycle principle to conserve materials like wood.

• Act locally by planting native species to improve your neighborhood’s biodiversity.

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Multiple Choice

What is the main purpose of actions like planting native species and following the 'Reduce, Reuse, and Recycle' principle?

• To preserve the variety of life in an ecosystem

• To increase the amount of available food

• To reduce the cost of natural resources

• To make neighborhoods look more organized

Multiple Choice

How does eating more plants and less meat help protect biodiversity?

• It helps conserve energy and natural resources.

• It directly creates new habitats for animals.

• It reduces the need for wood and paper products.

• It provides more food for native animal species.

Multiple Choice

A community wants to take direct action to improve the biodiversity within its own neighborhood. Which of the following plans would be the most effective way to achieve this specific goal?

• Start a project to plant native flowers and trees in the town's parks.

• Encourage families to eat less meat during the week.

• Organize a town-wide cleanup to recycle more plastic and paper.

• Focus on restoring a large lake in a different part of the state.

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Common Misconceptions

Misconception	Correction
A change in one part of an ecosystem only affects that part.	Ecosystems are interconnected; a small change can affect many other parts.
Extinction is a natural process that humans cannot control.	Human activities like habitat loss are causing rapid extinction rates.
Biodiversity is just about having many different types of animals.	Biodiversity includes all living things, like plants and insects, and their interactions.

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Summary

• Disruptions in a dynamic ecosystem can cause large shifts in its populations.

• The Stability and Change concept shows how small changes cause large impacts.

• Threats like habitat loss and invasive species decrease an ecosystem's biodiversity.

• Humans can protect biodiversity by reducing their ecological footprint.

Poll

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

• 1

• 2

• 3

• 4