How did iguanas reach tiny Pacific islands?
Scientists have long puzzled over how iguanas, a group of lizards mostly found in the Americas, came to inhabit the isolated Pacific islands of Fiji and Tonga. For years, the leading explanation has been that progenitors of the island species must have rafted there, riding across the Pacific on a mat of vegetation or floating debris. But new research in the January issue of The American Naturalist suggests a more grounded explanation. Using the latest genetic, geological and fossil data, biologists Brice Noonan of the University of Mississippi and Jack Sites of Brigham Young University have found that iguanas may have simply walked to Fiji and Tonga when the islands were still a part of an ancient southern supercontinent. The two islands, located about 2000 miles east of Australia, are home to several iguana species, and their presence there is “one of the most perplexing scenarios in island biogeography,” Noonan says. The other islands in the region, and closest continental landmass,
