Researchers have long debated how iguanas reached Fiji, a remote island group in the South Pacific. Most modern iguana species inhabit the Americas, separated from Fiji by thousands of miles of ocean. Early theories suggested that iguanas might have migrated through Asia or Australia before geological changes moved Fiji farther away. However, recent research proposes that iguanas achieved this journey by floating on rafts of vegetation over 5,000 miles (8,000 kilometers) of open ocean, which would mark the longest recorded ocean voyage by a land-dwelling vertebrate. Genetic analysis of 14 iguana species from the Americas, the Caribbean, and Fiji revealed that Fijian iguanas are closely related to desert iguanas from North America, with their evolutionary split estimated to have occurred around 31 million years ago. This discovery supports the theory that these reptiles drifted across the ocean rather than migrating by land.

To support this theory, researchers used a statistical model that combined genetic data, current iguana distribution patterns, and environmental factors. The results indicated that the most plausible explanation was that iguanas floated to Fiji from North America. Desert iguanas are believed to have survived the lengthy voyage due to their ability to resist dehydration and consume plant material found on the vegetation rafts. Understanding the origins of Fijian iguanas is crucial, as several native species face endangerment, while invasive green iguanas threaten local ecosystems. Identifying the evolutionary history of these reptiles may assist conservation efforts in protecting Fiji’s native iguana population. The study’s findings appeared in the journal Proceedings of the National Academy of Sciences, providing valuable insights into the evolutionary journey of Fijian iguanas and their remarkable ocean crossing.