Nature does an about turn on evolution islands - article


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Posted by GoatWorld on January 13, 2003 at 17:16:01:

Nature does an about turn on evolution islands

ESPANOLA ISLAND, Ecuador: The squat, brown owl sits immobile under the lee of a lava rock and stares unblinkingly as a dozen camera-toting tourists scramble on a ridge in front to get a better view.

"He'll take off soon," says naturalist Ramiro Tomala, squinting in the morning sunshine. "It's his hunting time."

A surprising assertion for visitors to Ecuador's Galapagos Islands from North America, Europe and Asia -- as well as mainland Latin America -- where any self-respecting owl will only fly by night. But the day-owl is only one of many quirks of nature on these volcanic outcrops straddling the Equator in the southern Pacific. The unique wildlife of the Galapagos helped Charles Darwin more than 150 years ago to shape the principle of evolution through natural selection that today is the bedrock of scientific thought on the origins of life.

Across the islands birds, reptiles and marine animals showing no fear of man parade within a hand's length as if to drive home the message that here, things are different. On the island of Genovesa, blue-beaked booby birds miraculously wrap their bright red webbed feet around the branches of the scrub trees where they build their nests. On other islands, their more conventional blue-footed cousins nest on the ground.

On Isabela, the largest island in the archipelago where man first made a recorded landing in 1535, grass-munching goats brought in by 19th century fishermen to provide fresh food on the hoof, have adapted their diet to include turtle eggs. On Wolf island to the northwest, a "Dracula" finch has emerged since Darwin discovered 13 species of the bird, marked by varying beak shapes, during his five-week voyage around the islands in 1835 on the British survey ship Beagle.

Abandoning the seed diet maintained by its cousins on other islands, the local ground finch now feeds on the blood of larger birds, pecking exposed skin at the base of their feathers with a sharp beak perfectly adapted for the purpose.

Herons and gulls hunt by day, right? Well, even on the Galapagos most do. But not all.

Varieties of both sea birds, adapting over generations to the heavy competition in the daylight struggle for existence, have evolved larger eyes and catch their fish by night. "And where else," muses naturalist Tomala as a gaggle of scarlet-streaked marine iguanas snort out the salt they have swallowed with their water at his feet, "do you find lizards that swim in the sea?".




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