Raft or bridge: 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.