Factors affecting biodiversity and populations in ecosystems of different scales. HS-LS2-6. Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem

Standards Alignment

• HS-LS2-2 primary
  Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales. HS-LS2-6. Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.

Lesson Overview

This Grade 10 science lesson explores how complex interactions in ecosystems maintain relatively consistent numbers and types of organisms under stable conditions, and how changing conditions can lead to new ecosystems. Students will use mathematical representations and evidence to evaluate claims about biodiversity and population dynamics in ecosystems of various scales, aligned with NGSS standards HS-LS2-2 and HS-LS2-6.

Learning Objectives

• Use mathematical representations to analyze factors affecting biodiversity and populations in ecosystems of different scales.
• Evaluate claims, evidence, and reasoning about how complex interactions maintain ecosystem stability under stable conditions.
• Explain how changing conditions can lead to the development of new ecosystems.

Success Criteria

• Students can interpret and create graphs or charts showing population changes in ecosystems.
• Students can identify and explain evidence supporting ecosystem stability or change.
• Students can compare biological processes or outcomes using evidence.
• Students can revise explanations based on new or conflicting evidence.

Prerequisite Knowledge

Students should understand basic ecological concepts such as ecosystems, populations, biodiversity, and the roles of biotic and abiotic factors. Familiarity with interpreting graphs and basic mathematical representations is also needed.

Key Vocabulary

• Ecosystem
• Biodiversity
• Population
• Carrying Capacity
• Resilience
• Disturbance
• Anthropogenic
• Mathematical Representation
• Evidence
• Claim
• Reasoning

Materials and Resources

• Graphing tools or software (e.g., graph paper, spreadsheet software)
• Case study data sets on ecosystem populations and biodiversity
• Models or diagrams of ecosystems
• Whiteboard or chart paper for group work
• Access to scientific articles or texts on ecosystem changes

Teacher Preparation

• Prepare data sets showing population trends in different ecosystems under stable and changing conditions.
• Select case studies illustrating ecosystem resilience and shifts due to disturbances.
• Prepare guiding questions to prompt evidence-based reasoning.
• Set up materials for graphing and modeling activities.
• Review NGSS standards HS-LS2-2 and HS-LS2-6 to align lesson activities.

Detailed Lesson Notes

Ecosystem Stability and Biodiversity

Ecosystems consist of interacting organisms and their physical environment. Biodiversity refers to the variety of species within an ecosystem. Under stable conditions, complex interactions among organisms and environmental factors maintain relatively consistent numbers and types of organisms. This stability is due to factors like resource availability, competition, predation, and symbiotic relationships that balance populations.

Mathematical Representations in Ecology

Mathematical tools such as graphs, charts, and averages help visualize and analyze changes in populations and biodiversity over time. For example, population growth curves or biodiversity indices can show trends and fluctuations. Using these representations, students can support or revise explanations about ecosystem dynamics based on evidence.

Ecosystem Resilience and Disturbances

Resilience is an ecosystem's ability to return to its original state after a disturbance. Disturbances can be biological (e.g., moderate hunting) or physical (e.g., seasonal floods). Modest disturbances may not change the ecosystem significantly, but extreme events (e.g., volcanic eruptions, sea level rise) can alter resource availability and habitat, leading to new ecosystem structures and species compositions.

Human Impacts on Ecosystems

Human activities such as habitat destruction, pollution, introduction of invasive species, and climate change can disrupt ecosystem stability. These anthropogenic changes may reduce biodiversity and alter population dynamics, sometimes causing ecosystems to shift to new states or collapse.

Evaluating Claims, Evidence, and Reasoning

Scientific argumentation involves assessing claims by examining the supporting evidence and reasoning. Students should learn to identify the strength of evidence, recognize gaps or inconsistencies, and revise explanations accordingly. This critical thinking skill is essential for understanding complex ecological interactions and the effects of changing conditions.

Worked Examples

Classroom Activity

Students work individually or in groups to graph the data, identify trends, and note any fluctuations or shifts in populations and biodiversity.

Guided Practice

Independent Practice

1. Foundational: What does biodiversity mean in an ecosystem?
2. Developing: How can mathematical graphs help us understand changes in populations within an ecosystem?
3. Application: Using a provided data set of species counts before and after a flood, explain how the flood affected biodiversity and whether the ecosystem is resilient.
4. Analysis: Compare two ecosystems: one with stable populations over 5 years and one with declining populations due to pollution. Use evidence to explain the differences in their stability.
5. Challenge: Evaluate a claim that moderate hunting does not change an ecosystem's biodiversity. Use evidence from population graphs and reasoning about ecosystem interactions to support or refute this claim.

Independent Practice Teacher Answer Key

1. 1. Biodiversity is the variety of different species living in an ecosystem.
2. 2. Graphs show trends and changes in population sizes over time, helping us see if populations are stable, increasing, or decreasing.
3. 3. If species counts drop after the flood but return to previous levels later, the flood caused a disturbance but the ecosystem is resilient. If counts stay low, the ecosystem may have changed.
4. 4. The stable ecosystem shows consistent population data indicating balanced interactions and resource availability. The polluted ecosystem shows declining populations, evidence that pollution disrupts interactions and reduces stability.
5. 5. If population graphs show temporary declines but recovery after moderate hunting, the claim is supported because the ecosystem is resilient. If populations decline permanently, the claim is refuted because hunting disrupts stability.

Guiding Questions

• What factors help maintain ecosystem stability?
• How can disturbances affect populations and biodiversity?
• What evidence supports ecosystem resilience?
• How do human activities disrupt ecosystems?
• How can we use data to evaluate claims about ecosystems?

Common Misconceptions

• Ecosystems always return to their original state after any disturbance.
• Human activities only have minor effects on ecosystems.
• Population sizes always increase if resources are available.
• Mathematical representations are too complex to understand ecosystem dynamics.
• Biodiversity means just the number of species, not their interactions.

Differentiation

Assessment

• Students create graphs from data sets and explain trends.
• Class discussions where students cite evidence for ecosystem stability.
• Group analysis of case studies evaluating human impacts.
• Compare two ecosystems using evidence to explain which is more stable.
• Explain how a disturbance can lead to a new ecosystem.
• Describe how mathematical representations support understanding of biodiversity.
• Write an essay evaluating claims about ecosystem resilience using multiple data sources.
• Design a model showing factors affecting population changes in an ecosystem.
• Develop a presentation on human activities impacting biodiversity and propose solutions.

Answer Guide

• What does biodiversity mean in an ecosystem?
  Answer: Biodiversity is the variety of different species living in an ecosystem.
• How can mathematical graphs help us understand changes in populations within an ecosystem?
  Answer: Graphs show trends and changes in population sizes over time, helping us see if populations are stable, increasing, or decreasing.
• Using a provided data set of species counts before and after a flood, explain how the flood affected biodiversity and whether the ecosystem is resilient.
  Answer: If species counts drop after the flood but return to previous levels later, the flood caused a disturbance but the ecosystem is resilient. If counts stay low, the ecosystem may have changed.
• Compare two ecosystems: one with stable populations over 5 years and one with declining populations due to pollution. Use evidence to explain the differences in their stability.
  Answer: The stable ecosystem shows consistent population data indicating balanced interactions and resource availability. The polluted ecosystem shows declining populations, evidence that pollution disrupts interactions and reduces stability.
• Evaluate a claim that moderate hunting does not change an ecosystem's biodiversity. Use evidence from population graphs and reasoning about ecosystem interactions to support or refute this claim.
  Answer: If population graphs show temporary declines but recovery after moderate hunting, the claim is supported because the ecosystem is resilient. If populations decline permanently, the claim is refuted because hunting disrupts stability.

Real-Life Application

Encourage students to observe a nearby natural area or garden and note any signs of biodiversity and changes over time. They can discuss with family members how human activities might impact these ecosystems and share what they learned about ecosystem stability and resilience.

Homework or Home Connection

• Encourage students to observe a nearby natural area or garden and note any signs of biodiversity and changes over time. They can discuss with family members how human activities might impact these ecosystems and share what they learned about ecosystem stability and resilience.

Lesson Summary

This lesson helps students understand how complex interactions in ecosystems maintain stability in populations and biodiversity under stable conditions, and how disturbances—both natural and human-induced—can lead to changes or new ecosystems. Using mathematical representations and evidence-based reasoning, students evaluate claims about ecosystem dynamics, developing critical scientific skills aligned with NGSS standards HS-LS2-2 and HS-LS2-6.

Teacher Notes

Use the exact standards alignment and retrieved-source provenance stored with this enrichment.

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