Fiji is home to four species of iguana, including this crested iguana (Brachylophus vitiensis), but all are thought to have descended from ancient iguanas that made the long journey across the ocean. (Photo by Nicholas Hess)
About 34 million years ago, iguanas made the longest known transoceanic journey of any land species, swimming about a fifth of the way around the globe from North America to settle in Fiji, according to a new study.
Scientists believe the iguanas traveled more than 5,000 miles (8,000 kilometers) on rafts made from vegetation, arriving in Fiji shortly after the islands formed. “You can imagine some kind of cyclone knocking down trees containing many iguanas and possibly eggs, and then they were caught in ocean currents and transported,” lead author Simon Scarpetta, an associate professor of ecology at the University of San Francisco, said in a statement.
The bright green Fiji lizards are the only iguanas outside the Western Hemisphere, and how they got there has long been a mystery. In a new genetic study published Monday (March 17) in the journal PNAS, scientists have found that Fiji iguanas are much more closely related to their Western Hemisphere cousins than previously thought, having traveled directly from the west coast of the United States to Fiji about 34 million years ago.
“That they came to Fiji directly from North America seems unlikely,” study co-author Jimmy McGuire, a professor of biology at the University of California, Berkeley, said in a statement. “However, alternative models that involve colonization from nearby areas don’t really explain that time frame, since we know they got to Fiji within the last 34 million years or so.”
Previously, some biologists had suggested that the Fijian lizards of the genus Brachylophus descended from a now-extinct family of iguanas that once lived in the Pacific Ocean. Others hypothesized that the lizards may have traveled shorter distances from South America via Antarctica or Australia before ending up in the Pacific Ocean.
However, these ideas were based on previous genetic analyses that failed to clearly demonstrate how closely Fijian iguanas are related to other iguanas.
Sourse: www.livescience.com
