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Environmental Change and Species Survival — Reading Comprehension

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MS-LS4-4
MS-LS4-6

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This middle school science passage explores how environmental changes, such as climate change, habitat destruction, the introduction of new predators, disease, and natural disasters, create selection pressures that affect species survival. Students will learn the mechanisms behind adaptation, migration, and extinction, and how the rate of environmental change impacts a species’ ability to survive. The passage includes real-world examples like polar bears facing Arctic ice loss, coral bleaching, and the impact of invasive species. Designed for grades 6-8 and aligned to NGSS standards MS-LS4-4 and MS-LS4-6, the resource supports science literacy by integrating cause-and-effect reasoning and scientific thinking. Audio integration ensures accessibility for diverse learners. Activities include a quiz, writing prompts, vocabulary support, and graphic organizers to deepen understanding and critical thinking.

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Underwater shot of a colorful reef teeming with marine life and vivid corals. — Environmental change is putting immense pressure on coral reefs. Image by Francesco Ungaro / Pexels.

Environmental change can disrupt entire ecosystems, affecting which species thrive and which may disappear. Scientists observe that rapid changes in climate or habitat can cause significant shifts in species populations. The survival of a species depends on how well it can respond to new selection pressures created by changing environments. These pressures include climate change, habitat destruction, new predators or competitors, disease, and natural disasters. Understanding these mechanisms helps explain why some species adapt, some migrate to new areas, and others become extinct.

How Environmental Changes Create Selection Pressures

When the environment changes, it can alter the conditions that species rely on for survival. For example, rising temperatures in the Arctic reduce the amount of sea ice, affecting polar bears’ ability to hunt for seals. This is a selection pressure because only bears with specific traits, such as strong swimming ability or efficient fat storage, may survive. If the change is gradual and there is enough genetic variation within the species, natural selection can favor individuals with traits that help them survive. Over generations, these traits become more common, and the species adapts. However, if the change is too fast or drastic, species may not have time to adapt and could face extinction.

Different Types of Environmental Change and Species Responses

There are several types of environmental changes that create new challenges for species. Climate change can cause droughts, floods, or shifts in temperature. Habitat destruction, such as deforestation, removes essential resources and living space. The arrival of new predators or invasive species can disrupt food webs. Disease outbreaks can wipe out populations with low resistance. For example, coral reefs are threatened by rising sea temperatures, which cause coral bleaching. Invasive species like the brown tree snake in Guam have caused the extinction of many native birds. Species can respond by adapting, migrating to more suitable habitats, or, in some cases, becoming extinct if they cannot survive the new conditions.

The Rate of Change: Adaptation or Extinction?

The speed of environmental change is a critical factor. Gradual changes allow for adaptation through natural selection, as there is enough time for beneficial traits to spread in the population. However, rapid changes, such as sudden habitat loss from a wildfire or a new disease, often outpace a species’ ability to adapt. Human-caused changes, like pollution or climate change, are happening at rates much faster than most natural changes in the past. This increases the risk of extinction for many species. Scientists use data on population trends, genetic diversity, and environmental conditions to predict which species are most at risk and to guide conservation efforts.

In conclusion, environmental change is a powerful force shaping the survival of species. The process of natural selection determines whether a species adapts, migrates, or goes extinct, depending on the type and speed of change. Understanding these interactions helps people protect biodiversity and make decisions that support healthy ecosystems for the future.

Interesting Fact: Coral reefs support about 25% of all marine life, even though they cover less than 1% of the ocean floor!

What is a selection pressure?

A force in the environment that affects survival and reproductionA change in weather every dayThe number of animals in a habitatA type of new species entering an ecosystem

According to the passage, what is one example of environmental change?

Habitat destructionPhotosynthesisGravityEvaporation

What does the term 'genetic variation' mean in this passage?

Different traits within a speciesThe number of species in an ecosystemA type of diseaseA kind of habitat

What does 'coral bleaching' refer to?

Corals losing color and vital algae due to stressCorals growing largerThe process of coral reproductionThe formation of new coral reefs

Based on the passage, why is the rate of environmental change important?

Slow changes allow adaptation, but fast changes can cause extinctionFast changes help all species surviveRate of change has no effect on species survivalSlow changes cause more extinctions

How might a species respond if it cannot adapt to a new environment?

It may become extinctIt will always adaptIt will turn into a new habitatIt becomes a predator

What is one consequence of introducing invasive species to a new habitat?

Native species may go extinctThe environment always improvesNo change occursAll species become invasive

Which of the following is an example of adaptation?

Polar bears developing better swimming abilityCoral reefs dying from heatSudden wildfire destroying a forestHumans polluting the ocean

True or False: Most environmental changes caused by humans happen slower than natural changes.

TrueFalse

True or False: Coral reefs cover more than half of the ocean floor.

TrueFalse