IMAGINE a newly emerged volcanic island lost in the Pacific Ocean many millions of years ago, lifeless except for a few passing seabirds. As the lava cools and weathers, a few seeds and hardy animals settle down to make a new home on this virgin speck of land. Some of the first to take hold are desert cacti, their seeds delivered by vagrant birds. As they grow and spread, the cacti eventually provide shelter for the first resident land birds and food for a few reptiles accidentally washed ashore.
And so began the relationship between the pioneering plants and animals of the Galapagos Islands. Today, without the food, water and shelter provided by the islands' numerous ...