It is in the scientific journal PNAS that the researchers present their theory: Iguanas floated more than 8,000 kilometers from North America to Fiji.
"'Floating' refers to mats of floating vegetation, including uprooted trees or entangled smaller plants, which move with the sea or rivers from one place to another," explains Simon Scarpetta, evolutionary biologist at the University of San Francisco, in an email interview.
Similar teeth
Often, these floats can form after hurricanes and floods. Already during Darwin's time, experiments showed that seeds could spread long distances and take root, even if they had been underwater.
It is on this type of float that Scarpetta believes iguanas in North America boarded around 31-34 million years ago, and traveled across the sea to reach present-day Fiji, which had emerged from volcanic activity at the time. Through DNA analysis, the researchers found that the closest relatives of the Fijian iguanas are found in the North American desert.
The desert iguanas are brown or white, while their cousins in Fiji are green and have adapted to a tropical climate. Despite the differences, they are surprisingly close relatives, according to Scarpetta.
"Both are relatively slender in body shape, and they have some similarities in their skeletons, such as their teeth."
May have been surprised
How many individuals must have boarded the float to create a viable colony on the other side of the earth is difficult to answer. But in 1995, researchers discovered that 15 green iguanas had floated 300 kilometers on trees felled in a hurricane from a Caribbean island to Anguilla, where they had not existed before, and that they managed to establish themselves there.
Simon Scarpetta believes that it was a pure coincidence that the iguanas made the journey across the Pacific Ocean over 30 million years ago. They may have sat on trees that were torn up by a storm. The three-four months the journey is estimated to have taken may have coincided with their winter hibernation, or they may have eaten the floating plants.
"I imagine that the situation surprised the iguanas!"
Iguanas are a lizard family with 750 species, living in large parts of North and South America, as well as the Galapagos Islands, Madagascar, Fiji, and Tonga.
They mainly eat plants. Some lay eggs, while others give birth to live young.
Fijian iguanas (Brachyʹlophus) live in trees and can grow to almost one meter long. The desert iguana (Dipsosaurus dorsalis) lives mainly in the desert in southwestern USA and northwestern Mexico and grows to about 40 centimeters long.
Sources: NE, Nevada Department of Wildlife, Arizona-Sonora Desert Museum.
