Why Are There So Many Species? 2

In 1989, our team of American and Filipino biologists briefly visited Sibuyan Island, which lies near the center of the Philippines. Even for the generally mountainous Philippines, Sibuyan is a rugged place, with a saw-toothed peak that dominates the view from nearly every point. It is small, only 463 square kilometers. Although the soil in the flat lowlands is rich, the lowlands form a narrow ring around the mountain, and the deep waters surrounding the island, although productive, are not rich enough to feed the ever-growing population. The island's inhabitants are poor, and economic opportunities have been few. They laughingly say that their primary export is people, and until recently the island received little attention from outsiders.
     Most of the island consists of steep hillsides where most crops grow very poorly, and so the lower slopes have been planted with coconut. The upper slopes, with their original cover of rain forest, have been slowly and illegally deforested, with most of the lumber going to an adjacent island for use in several large mines. Flooding during the typhoon season had been gradually increasing, as had droughts during the dry season. A pattern of increasing poverty seemed to be in place.
      We had worked only a few days in the island's rain forest when, amazingly, we discovered a new species of small fruit bat, and a second trip a few years later produced four more species of small mammals that had never before been seen by a biologist— new species that were unknown to all but a few of the local people.Although all the animals are small, and none has any special economic value, they are evidence that Sibuyan is a "center of endemism," a place that supports the world's only populations of a series of species. Finding five new, unique species of mammals on such a small island was astonishing—no other island of this size anywhere in the world is known to have so many.
     Subsequently we learned that Sibuyan harbors several unique species of flowering plants, including an orchid, a palm, and a ginger plant. The beetles and lizards of Sibuyan have yet to be studied, but it would be a good bet that more new species remain to be discovered by biologists; where one or two groups show concentrations, other groups are likely to do the same.
     In recognition of the need for both watershed and wildlife protection, the mountains of Sibuyan now form the core of one of the newest national parks in the country, officially designated in 1996. Almost all of the logging has ceased, giving hope that the floods and droughts will abate. An internationally supported program is developing alternative means of livelihood for the people of the island, giving them greater hope for the future. Environmental stability and survival are within reach for both people and wildlife.
     But why are there so many unique species on Sibuyan? What quirk of nature has given it more unique species of mammals than any country in Europe? The answer lies in the unusual geological history of thePhilippines.

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