Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
  High-Bandwidth Version
Search Evolution  
Click to return to the Evolution Home Page
darwin change extinction survival sex humans religion
Coral Reef Connections
  Reef Relationships | Predators and Prey | Competitors | Partners | Conclusion


In the never-ending challenge to survive and reproduce, living things must evolve in response to their physical environment, as well as to their fellow organisms. Under the right conditions, these pressures cause new species to arise and local biodiversity to increase. Such conditions have made the Great Barrier Reef one of the most diverse ecosystems in the world.

Inside this complex system, every organism interacts with enemies, competitors, and partners. Over scores of generations, these relationships are honed into near-perfect operations. Predators seem perfectly adapted to catching their prey, competitors know all the right moves to get their mate, and partners can't live without each other.

But this near-perfection is a mirage. The relationships are really a constant tug-of-war among organisms. When one evolves a new feature or behavior, it pulls on all of its relationships. If the other organisms can't pull back with evolutionary changes of their own, the relationship will fall apart. And so the evolutionary game continues.

  Reef Relationships | Predators and Prey | Competitors | Partners | Conclusion
  related web activities  
An Origin of Species
Witness for yourself how a new species can evolve.
Microbe Clock
Learn how deadly microbes outpace medical breakthroughs.
Sex and the Single Guppy
Learn how exhibitionism has an evolutionary payoff.
  related topics  
  Adaptation and Natural Selection  
  Evolution of Diversity  
  Why Evolution Matters  
    Source Credits    
Videos Web Activities Site Guide About the Project FAQ Glossary Site Map Feedback Help Shop