A team of researchers has cracked the code on the ancient Iguana migration puzzle, revealing that these scaly creatures crossed the Pacific Ocean to reach Fiji over 31 million years ago.
Tens of millions of years ago, a group of iguanas in North America embarked on an extraordinary journey, floating across the Pacific Ocean to reach the islands of Fiji. This remarkable feat, which may be the longest known transoceanic emigration among land vertebrates, has long been a subject of speculation and debate among researchers.
Iguanas are native to Central and South America, but they have been introduced to other regions through human activity.
They can migrate long distances in search of food, 'water' , and suitable habitats.
In the wild, iguanas typically migrate between 1-5 miles per year, but some populations have been known to travel up to 15 miles.
This migration is often driven by changes in climate, vegetation, and availability of resources.
The Origins of the Fijian Iguana
The four living iguanas species in Fiji have been a mystery to scientists, given that all other members of the iguana evolutionary family are found in the Americas. Researchers had two main hypotheses: either the iguanas drifted on vegetation rafts to Fiji from the Americas or extinct ancestors migrated a shorter distance from Asia or Australia.
Genetic Clues Uncover the Truth
A team of researchers, led by Simon Scarpetta, an evolutionary biologist at the University of San Francisco, used genetic analysis to shed light on the origins of the Fijian iguanas. By studying the evolutionary relationships of over 200 species of iguanas and related lizards, they found that Fijian iguanas are most closely related to desert iguanas (‘Dipsosaurus dorsalis‘), which live in Mexico and the American Southwest.
A Voyage Across the Ages
The genetic results, combined with the geography of where iguana fossils have previously been found, point to ancestral iguanas rafting across the ocean from the shores of North America. The team estimates that this journey took place between 31 million and 34 million years ago, covering a distance of over 8,000 kilometers, the longest move among land vertebrates.
A Suitable Species for Long-Distance Travel
Iguanas may be particularly well-suited for long trips at sea due to their herbivorous diet and ability to survive without food or water. They can also withstand heat and dehydration, making them a great choice for surviving on vegetation rafts in the open ocean.
A Rare but Possible Event
According to Ethan Gyllenhaal, an evolutionary biologist at Texas Tech University, the findings illustrate how rare events, such as iguanas successfully floating across an ocean, are more likely to occur over millions of years. ‘When you’re dealing with evolutionary time, you’ve got a lot of opportunity for these very small probability things to occur’
- sciencenews.org | The mystery of how iguanas crossed the Pacific Ocean may be solved
