Some Animals Are More Equal than Others: Keystone Species and Trophic Cascades

Introduction

• This educational resource explores the concept of keystone species and trophic cascades within ecosystems.
• The film specifically delves into the research of ecologists Robert Paine and James Estes.

Key Concepts

Keystone Species

• Keystone species play critical roles in maintaining the structure of an ecosystem.
• Their presence or absence can significantly alter the population sizes and overall diversity within the ecosystem.

Trophic Cascades

• Trophic cascades are ecological processes that start at the top of the food chain and cascade down to affect multiple trophic levels.
• They demonstrate the interconnectedness of species and their influence on nutrient cycles and energy flow.

Case Studies

Robert Paine's Experiment

• Conducted experiments by removing starfish from tidal pools.
• Found that the absence of starfish led to a significant decline in species diversity.

James Estes' Research

• Focused on the kelp forest ecosystems in the North Pacific.
• Sea otters act as a keystone species by feeding on sea urchins, which in turn consume kelp.
• The presence of sea otters helps maintain the balance and health of kelp forests.

Student Learning Targets

• Students should be able to use evidence to explain the significance of keystone species in ecosystems.
• Students should understand and explain the concept of trophic cascades with real-world examples.

Related Scientific Literature

• Dyer, Lee A., and Deborah K. Letourneau, "Trophic cascades in a complex terrestrial community."
• Estes, James A. et al., "Killer whale predation on sea otters linking oceanic and nearshore ecosystems."

Curriculum Connections

Educational Standards

• NGSS (2013): HS-LS2.A, HS-LS2.B, HS-LS2.C, HS-LS4.C
• AP Biology (2019): ENE-1, ENE-4, SYI-1, SYI-2, SYI-3
• IB Biology (2016): 4.1, 4.2, C.1, C.2, C.3, C.4, C.5
• AP Environmental Science (2020): Topics 1.1, 1.11, 2.7
• IB Environmental Systems and Societies (2017): 2.2, 2.3, 2.4, 3.3
• Vision and Change (2009): CC4, CC5

Resources and Materials

• Downloadable video and transcript resources available in multiple formats and languages.
• Additional activities and interactive media resources to supplement learning.

Educator Tips

• Includes insights from educators on implementing this resource in the classroom.
• Features strategies such as claim-evidence-reasoning activities related to key ecological experiments.

Additional Resources

• Links to related films, activities, and interactive lessons on keystone species and ecosystem dynamics.

Conclusion

• Understanding the roles of keystone species and trophic cascades is crucial for comprehending ecological balance and biodiversity conservation.