Researchers have long pondered the mystery of how iguanas arrived in Fiji, a remote group of islands in the South Pacific. Most present-day iguanas are found in the Americas, a considerable distance across the Pacific Ocean.
The earlier hypothesis suggested iguanas might have migrated to Fiji through regions like Asia or Australia, from which geological shifts then isolated the islands.
However, new findings propose that millions of years ago, iguanas undertook a remarkable journey measuring approximately 5,000 miles, traveling on rafts of floating vegetation, consisting of uprooted trees and small plants. This is believed to be the longest recorded oceanic journey by any land-dwelling vertebrate.
Scientists believe this is also the means by which iguanas reached the Galapagos Islands near Ecuador and moved between islands in the Caribbean. Although initially considered too far for iguanas to travel in this manner, a recent study examined the genetic makeup of 14 iguana species from the Americas, the Caribbean, and Fiji. The results revealed that the Fijian iguanas share the closest genetic link with desert iguanas from North America, diverging from them roughly 31 million years ago.
Utilizing these genetic insights and knowledge of current iguana habitats, researchers developed a statistical model. This model compellingly suggests that iguanas likely floated to Fiji from North America.
Kevin de Queiroz, an evolutionary biologist at the Smithsonian National Museum of Natural History, noted, “Given what we know now, their result is by far the most strongly supported.” De Queiroz was not involved in this specific study.
The research findings were published in the journal Proceedings of the National Academy of Sciences. The proposed journey from North America to Fiji might have spanned several months. Desert iguanas, well-suited for such a voyage, can resist dehydration and would have found food sources in the plants along their route.
Simon Scarpetta from the University of San Francisco, one of the study’s authors, stated, “If you had to pick a vertebrate to survive a long trip on a raft across an ocean, iguanas would be the one.”
Today, many Fijian iguana species face endangerment, exacerbated by the presence of an invasive green iguana species on the islands. Robert Fisher of the United States Geological Survey, another study author, emphasized the importance of understanding their origins to bolster conservation efforts for these unique creatures.
