Lecture: Keystone Species vs. Indicator Species

Professor

• Mary Penro
• Adun Professor of Biology

Key Concepts

Keystone Species

• Definition:

  • A species with a significant impact on its environment despite low population numbers.
  • Analogous to a keystone in an arch, removal can cause ecosystem collapse.

• Example:

  • California Sea Otter:
    • Almost hunted to extinction.
    • Their decline led to ecosystem disruption.
    • Role:
      • Eat sea urchins, which in turn eat kelp.
      • Without otters, sea urchin populations exploded, consuming all the kelp.
    • Impact of Kelp Loss:
      • Kelp provides protection and spawning grounds for fish.
      • Decline in sea otters led to a decline in fish populations.
    • Restoration:
      • Reintroduction of sea otters improved the ecosystem health off the California coast.

Indicator Species

• Definition:

  • Species whose presence, absence, or abundance reflects a specific environmental condition.
  • Used by scientists to infer ecosystem health.

• Example:

  • Lichens:
    • Sensitive to sulfur dioxide and ozone levels.
    • Absence or poor health indicates air pollution.
    • Useful for identifying areas with air quality issues.

Conclusion

• While all species have inherent rights to live, some species are more critical to ecosystem health and vitality.

Additional Resources

• Links for further learning on keystone and indicator species.
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