Lecture Notes: The Enchanted Galapagos Islands

Introduction

• The Galapagos Islands were initially called the "Enchanted Isles."
• Known for their unique creatures and disappearing terrain.
• Charles Darwin and Robinson Crusoe were notable visitors.
• Darwin's observations on finches led to groundbreaking theories on evolution.
• The islands became a scientific hub and a tourist destination.

Darwin's Observations

• Darwin found marine iguanas and finches on James Island.
• Noted the variations in finch beak sizes, which later contributed to his theory of evolution.
• Initially, the finches did not impress him until further study back in England.

Current Scientific Studies

• Peter and Rosemary Grant continue Darwin’s work on finches.
• Conducted a 20-year study observing and measuring finch populations.

Geography and Climate

• Located 621 miles west of Ecuador on the equator.
• Consist of 18 islands, only five inhabited.
• Rough living conditions for wildlife.

The Grants' Research

• Began their study on a small island called Daphne Major.
• Focused on Darwin's finches, specifically two main species: cactus and medium ground finches.
• Challenges included setting up camp and avoiding introducing foreign elements to the ecosystem.

Finch Adaptation and Evolution

• Finch species vary in beak size and shape based on food availability.
• Adaptation is island-specific with 13 species evolving distinct beak shapes.
• Grants observed evolution in action twice over 20 years.

Natural Selection Observations

• The Grants measured finches to understand the impact of climate on their survival.
• Droughts and food scarcity tested finch survival, favoring larger or smaller beaked birds depending on conditions.

The 1977 Drought Event

• Severe drought led to food scarcity.
• Larger-beaked finches survived better as they could crack tougher seeds.
• A significant natural selection event confirming evolutionary theories.

The 1983 El Niño Event

• Excessive rain from El Niño led to different selection pressures.
• Abundance of small seeds favored smaller-beaked finches.
• Another observed evolution event, reversing previous trends.

Continued Research

• The Grants continue to study hybrids and the impact of climatic changes.
• Galapagos remains a critical location for studying evolution.

Charles Darwin's Legacy

• Darwin's initial impressions formed the foundation of evolutionary biology.
• Ongoing studies build on Darwin's questions about species formation and coexistence.

Conclusion

• Darwin's finches are a symbol of evolution in action.
• The Galapagos Islands continue to be a focal point for evolutionary study.
• The future of finch evolution remains subject to environmental changes and scientific inquiry.