HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

Environmental changes can have significant impacts on ecosystems and the species within them. These changes can lead to variations in species populations, the emergence of new species, and even the extinction of others. This review sheet explores the evidence supporting these claims and examines how different environmental factors affect species distribution and survival.

Main Concepts

Impact of Environmental Changes: Environmental changes, whether gradual or sudden, can affect species in various ways. Changes such as deforestation, pollution, climate change, and the introduction of invasive species can alter habitats, resources, and interactions among species.

Increases in Species Numbers: Changes in environmental conditions can lead to increases in the number of individuals of certain species. For example, a reduction in predators or an increase in available resources can result in population growth for species that benefit from these changes.

Emergence of New Species: Over time, environmental changes can lead to the emergence of new species through processes such as speciation. This can occur when populations become isolated and adapt to different environmental conditions, leading to the development of new species.

Extinction of Species: Environmental changes can also result in the extinction of species that cannot adapt quickly enough to the new conditions. Factors such as habitat loss, pollution, and climate change can lead to decreased survival rates and eventually extinction.

Cause and Effect Relationships: To understand how environmental changes affect species, it is important to evaluate the cause-and-effect relationships between environmental factors and species dynamics. Evidence can include changes in population sizes, distribution patterns, and the presence or absence of species in response to environmental changes.

NGSS Aligned Testing Question

Dinosaurs: Some Live and Some Die - Avian (bird-like) and non-avian dinosaurs in the northern hemisphere lived in extreme heat. The average summer temperature could range from 81° to 104°F. Winters were mild and wet, averaging around 59oF. There was no polar ice at this time. Most non-avian dinosaurs had a mass of about 7700 pounds. Most avian dinosaurs weighed significantly less and most mammals that coexisted with the dinosaurs weighed less than a pound.

A giant asteroid struck just off the coast of Mexico 66 million years ago. The asteroid impact event is referred to as the K-T extinction. Enormous amounts of dust, sulfur, and carbon dioxide entered the atmosphere. It caused Earth's average surface air temperatures to drop by as much as 47o F. Dust from the impact blocked the Sun’s radiation for an extended amount of time, and photosynthesis was drastically reduced. Many dinosaurs were immediately killed while others managed to survive for a period of time. All of the non-avian dinosaurs went extinct. The mammals that survived the impact increased in number. They continued to survive and evolve.

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Review Questions and Answers

1. How can changes in environmental conditions lead to an increase in the number of individuals of some species?

Environmental changes that provide more resources or reduce threats such as predation can lead to population growth for certain species. For example, a decrease in predator numbers or an increase in food supply can result in higher birth rates and survival rates for those species.

2. What is speciation, and how can environmental changes contribute to it?

Speciation is the process by which new species are formed. Environmental changes can contribute to speciation by causing populations to become isolated or adapt to different conditions. Over time, these isolated populations may develop distinct traits and eventually become separate species.

3. How can environmental changes lead to the extinction of species?

Environmental changes such as habitat destruction, pollution, or climate change can reduce the availability of resources or suitable habitats, making it difficult for species to survive. If species cannot adapt quickly enough, they may face extinction due to decreased survival and reproductive success.

4. What types of evidence can be used to evaluate the impact of environmental changes on species?

Evidence can include data on population sizes, distribution patterns, changes in species presence or absence, and observations of how species interact with their environment. Statistical analyses, historical records, and field studies also provide valuable insights.

5. How do factors such as deforestation and pollution impact species populations?

Deforestation can lead to habitat loss, which reduces the space and resources available for species. Pollution can contaminate food and water sources, harming species and reducing their survival rates. Both factors can result in decreased population sizes or local extinctions.

6. What role do invasive species play in affecting native species?

Invasive species can outcompete native species for resources, spread diseases, and disrupt ecological balances. This can lead to declines in native species populations and sometimes cause local extinctions if native species cannot adapt or compete effectively.

7. How can changes in climate contribute to shifts in species distributions?

Climate change can alter temperature, precipitation patterns, and seasonal conditions, affecting the availability of suitable habitats and resources. Species may migrate to new areas or face challenges in their current locations, leading to shifts in distribution or declines in populations.

8. What is the significance of monitoring changes in species populations in response to environmental changes?

Monitoring changes in species populations helps scientists understand the effects of environmental changes and assess the health of ecosystems. It provides crucial information for conservation efforts and helps predict future impacts of ongoing environmental changes.

9. How can human activities impact the rate of environmental change and its effects on species?

Human activities such as urbanization, industrialization, and agriculture can accelerate environmental changes, leading to faster and more severe impacts on species. Activities like deforestation, pollution, and climate change contribute to habitat loss and altered ecosystems, affecting species survival and adaptation.

10. Why is it important to study the relationships between environmental changes and species dynamics?

Studying these relationships is crucial for understanding how ecosystems function and how species adapt or face threats. It informs conservation strategies, helps manage natural resources, and supports efforts to mitigate negative impacts on biodiversity.

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Disclaimer: The information provided is intended to serve as a study guide based on a contextual analysis of the NGSS standards for the Life Science Biology assessment. These study guides should be used as a supplement to your overall study strategy, and their alignment to the actual test format is not guaranteed. We recommend that you consult with your instructor for additional guidance on exam preparation.