William H. Durham - Exuberant Life

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Library of Congress Control Number: 2020952645

ISBN 9780197531518

eISBN 9780197531532

DOI: 10.1093/oso/9780197531518.001.0001

To Ryan

celebrating your place in the tree of life

The natural history of this archipelago is very remarkable: it seems to be a little world within itself; the greater number of its inhabitants, both vegetable and animal, being found nowhere else.

Charles Darwin ( Narrative of the Surveying Voyages of His Majestys Ships Adventure and Beagle)

The book before you is a contemporary synthesis of what we know about the evolution of the curiously wonderful organisms of Galpagos, of how they are faring in the tumultuous world of human-induced change, and how evolution can guide our efforts today for their conservation. The book stems from the conviction that the more people know and appreciate the story Galpagos tells, with key subplots told by a diverse set of the archipelagos species, the better our chances of successfully managing the challenges facing the archipelago and ensuring its sustainable future.

The books impetus runs back to events earlier in my life. In 1975, while a graduate student, I wrote a proposal to the Smithsonian Tropical Research Institute to join their expedition to Galpagos. I proposed to study a potential mutual relationship between giant tortoises and their key food, the prickly pear cacti of the genus Opuntia.I wanted to ask whether tortoises, who readily consume the large, fleshy fruits of the cactus, thereby enhance its seed dispersal, building on the suggestion of ). The expedition was never reorganized, but still I dreamed of getting to Galpagos.

Meanwhile, educational tourism in Galpagos was flourishing, and the chance to visit finally came when Stanford Universitys Travel-Study Program invited me to lead a tour. Arriving at last, I found Galpagos even more fascinating than I had imagined. Happily, evidence today confirms my earlier curiosity: tortoises do enhance Opuntiaseed dispersal and, indeed, they do much more, as described in a sunflower to a whopping 6.5 ft (2 m)it took first place at the county fair. What a surprise, years later, to find in Galpagos a closely related speciesan endemic daisygrowing 10 times higher (to 65 ft or 20 m) in a genuine forestof daisies! With that I was convinced that something very special about Galpagos had shaped its flora and fauna in ways that seemed to break all records.

That trip taught me another key lesson about Galpagos. Because organisms adapted to this little world within itself, per Darwin above, free of terrestrial predators or competitors, they live their lives fully in the open with their many wonderful details on display. Todays visitors can have a field day using principles of evolution and ecology to make sense of it all. For example, the wonderful adaptations of plants and animals to the islands consistently illustrate the principle of reproductive advantage. No matter how curious the adaptationsflightlessness, seaweed-eating, giant proportions, and more all of themhave some net survival and reproduction advantage to individual bearers in their Galpagos environment.