A Fijian crested iguana (Brachylophus vitiensis) resting on a coconut palm on the island of Fiji in the South Pacific. The four species of iguanas that inhabit Fiji and Tonga today are descended from ancestors that colonized the island within the past 34 million years, probably by rafting 5,000 miles across the Pacific Ocean from western North America. (Image Credit: Nicholas Hess)NewsletterSign up for our email newsletter for the latest science newsAbout 34 million years ago, iguanas sailed 5,000 miles from western North America and settled in Fiji. Its not uncommon for iguana species to hop a natural raft and drift to a new island, but according to new research published in Proceedings of the National Academy of Sciences, this may be the the longest known transoceanic dispersal of any terrestrial vertebrate."We found that the Fiji iguanas are most closely related to the North American desert iguanas, something that hadn't been figured out before, said lead study author Simon Scarpetta, a herpetologist, and paleontologist who is a former postdoctoral fellow at University of California Berkeley, in a press release.Iguanas and Overwater DispersalMost life that finds its way to newly-formed islands typically comes via overwater dispersal. Organisms such as plants and animals, and even humans, find their way to these new islands and take up residence. On these islands, new ecosystems and species form something that researchers such as Charles Darwin have always found fascinating.Different iguana species are found across the globe, and some are endemic to specific regions, like the Galapagos and Fiji. In previous research, scientists believed that the native Fiji iguanas were descendants of a different iguana species that had gone extinct, however, the new study suggests otherwise.Fiji Iguana LineageAccording to the study, it would appear that the iguana's arrival to Fiji coincides with the archipelagos formation. By studying the genetic divergence of Brachylophus, Fijis iguana species, from their closest relative, Dipsosaurus, North American desert iguanas, the research team determined that iguanas made it to Fiji about 30 million years to 34 million years ago.[The] lineage of Fiji iguanas split from their sister lineage relatively recently, much closer to 30 million years ago, either post-dating or at about the same time that there was volcanic activity that could have produced land," Scarpetta, who is now an assistant professor at University of South Florida in the Department of Environmental Science added in a press release.Other theories suggest that the iguanas came from other parts of South America or even Australia, but there is no fossil evidence to back this up. Its possible that a large storm swept the iguanas out to sea and they survived the journey because they could have gone long periods of time without food or water."You could imagine some kind of cyclone knocking over trees where there were a bunch of iguanas and maybe their eggs, and then they caught the ocean currents and rafted over," Scarpetta said in a press release.The study authors also note that if it were upturned trees that brought the iguanas to Fiji, the trees may have provided food.The Genetic OutliersBesides being expert sailors, it turns out that Brachylophus is an outlier among other iguana species. Theyre also endangered due to exotic animal poaching, habitat loss, and predation from an invasive rat species.To better understand where Brachylophus fits in the iguana family tree, Scarpetta analyzed genome-wide sequence DNA from genes and tissues of over 200 iguanian specimens. From there, he determined that Brachylophus and Dipsosaurus were most closely related."Iguanas and desert iguanas, in particular, are resistant to starvation and dehydration, so my thought process is if there had to be any group of vertebrate or any group of lizard that really could make an 8,000-kilometer (5,000-mile) journey across the Pacific on a mass of vegetation, a desert iguana-like ancestor would be the one," Scarpetta said in a press release.Article SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Proceedings of the National Academy of Sciences. Iguanas rafted more than 8,000 km from North America to FijiA graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.1 free article leftWant More? Get unlimited access for as low as $1.99/monthSubscribeAlready a subscriber?Register or Log In1 free articleSubscribeWant more?Keep reading for as low as $1.99!SubscribeAlready a subscriber?Register or Log In