Topics Explored: Biodiversity, Ecological Tolerance, Natural Disruptions, K- and r- Selected Species, Agricultural Practices that Cause Environmental Damage, Endocrine Disruptors, Human Activity on Wetlands, Greenhouse Gases and Climate Change, Saltwater Intrusion, Invasive Species, and Endangered Species
This case study explores the story of the American alligator. It was hunted to the brink of extinction and after one of the best comeback stories of modern times, the American alligator continues to be threatened by agricultural practices, destruction of wetlands, saltwater intrusion, and an extremely aggressive invasive species, the Burmese python.   Answer key included.

Case Study: American Alligators (Teacher & Student Edition)

  • ZIP file containing 2 PDF files 
    (1 Teacher Edition and 1 Student Edition)

  • Next Generation Science Standards (NGSS):
    HS-LS2-1. Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.
    HS-LS2-2. 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.
    HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
    HS-LS2-8. Evaluate the evidence for the role of group behavior on individual and species’ chances to survive and reproduce.
    HS-LS4-6. Create or revise a simulation to test a solution to mitigate adverse impacts of human activity on biodiversity.
    HS-ESS2-2. Analyze geoscience data to make the claim that one change to Earth’s surface can create feedbacks that cause changes to other Earth systems.
    HS-ESS2-5. Plan and conduct an investigation of the properties of water and its effects on Earth materials and surface processes.
    HS-ESS3-1. Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity.

    AP® Environmental Science Learning Objectives:
    1.9 Explain how energy flows and matter cycles through trophic levels.
    1.11 Describe food chains and food webs, and their constituent members by trophic level.
    2.1 Explain levels of biodiversity and their importance to ecosystems.
    2.2 Describe ecosystem services. Describe the results of human disruption to ecosystem services.
    2.4 Describe ecological tolerance.
    2.5 Explain how natural disruptions, both short and long-term, impact an ecosystem.
    2.6 Describe how organisms adapt to their environment.
    3.2 Identify differences between K- and r-selected species.
    3.5 Explain how resource availability affects population growth.
    4.6 Describe the characteristics of a watershed.
    5.3 Describe changes in agricultural practices.
    5.4 Describe agricultural practices that cause environmental damage.
    5.9 Describe the effects of urbanization on the environment.
    5.12 Explain the concept of sustainability.
    8.2 Describe the impacts of human activities on aquatic ecosystems.
    8.3 Describe endocrine disruptors. Describe the effects of endocrine disruptors on ecosystems.
    8.4 Describe the impacts of human activity on wetlands and mangroves.
    8.7 Describe the effect of persistent organic pollutants (POPs) on ecosystems.
    9.4 Identify the threats to human health and the environment posed by an increase in greenhouse gases.
    9.5 Explain how changes in climate, both short- and long-term, impact ecosystems.
    9.6 Explain the causes and effects of ocean warming.
    9.8 Explain the environmental problems associated with invasive species and strategies to control them.
    9.9 Explain how species become endangered and strategies to combat the problem.
    9.10 Explain how human activities affect biodiversity and strategies to combat the problem.

    AP® Environmental Science Practices:
    1: Explain environmental concepts, processes, and models presented in written format. 
    2: Analyze visual representations of environmental concepts and processes. 
    3: Analyze sources of information about environmental issues. 
    4: Analyze research studies that test environmental principles. 
    5: Analyze and interpret quantitative data represented in tables, charts, and graphs.
    6: Apply quantitative methods to address environmental concepts.
    7: Propose and justify solutions to environmental problems.

    IB Environmental Systems Learning Objectives:
    2.1.7 Describe and explain population interactions using examples of named species.
    2.5.1 Explain the role of producers, consumers, and decomposers in the ecosystem.
    2.5.3 Describe and explain the transfer and transformation of energy as it flows through an ecosystem.
    2.5.4 Describe and explain the transfer and transformation of materials as they cycle within an ecosystem.
    2.6.1 Explain the concepts of limiting factors and carrying capacity in the context of population growth.
    3.2.2 Explain the dynamic nature of the concept of a resource.
    3.2.3 Explain the dynamic nature of the concept of a resource.
    3.2.5 Explain the concept of sustainability in terms of natural capital and natural income.
    3.6.2 Describe and evaluate the sustainability of freshwater resource usage with reference to a case study.
    4.1.5 Explain the relationships among ecosystem stability, diversity, succession and habitat.
    4.2.4 Describe and explain the factors that may make species more or less prone to extinction.
    4.2.7 Describe the case histories of a natural area of biological significance that is threatened by human activities.
    4.3.5 Discuss and evaluate the strengths and weaknesses of the species-based approach to conservation.
    6.1.3 Discuss qualitatively the potential effects of increased mean global temperature.


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