In a tale that sounds almost mythical, ancient iguanas embarked on an extraordinary journey across the Pacific Ocean. These reptiles set sail on natural rafts formed by clumps of vegetation. Their voyage began in North America over 30 million years ago and ended on the remote islands of Fiji, Science News reports.

The trip spanned more than 8,000 kilometers, marking the longest known oceanic dispersal event among land vertebrates, according to Live Science.

The discovery shakes up our understanding of how species colonize new lands. Researchers have pieced together the journey using genomic data and evolutionary timelines. Their findings reveal that the closest living relatives of Fiji’s iguanas are North American desert iguanas. This genetic link challenges previous ideas that the reptiles might have migrated from nearby continents or through now-vanished island chains, PNAS reports.

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Ancient iguanas once set sail from North America.

Riding the Currents of Change

The journey was not an act of intentional migration but a series of chance events. A violent cyclone or a sudden storm may have dislodged trees filled with iguanas and their eggs. These natural rafts then floated along powerful ocean currents.

“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,” Simon Scarpetta, an expert in herpetology, told Discover Magazine.

The randomness of nature allowed a group of iguanas to eventually reach a safe haven on a newly formed island.

This mechanism of overwater dispersal is not rare in the animal kingdom. Plants, insects, and even other reptiles have been documented riding the waves to distant shores. However, the distance covered by the iguanas is unparalleled among terrestrial vertebrates, Scientific American reports. The fact that these reptiles could survive such a long journey speaks volumes about their resilience and adaptability.

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They journeyed over 5000 miles to Fiji.

Survival at Sea

Iguanas possess a unique set of traits that made them ideal candidates for an ocean voyage. They can endure long periods without food or water and may slow their metabolism when resources are scarce. Such abilities would have proven vital during a journey that lasted weeks, if not months. Floating on a mass of vegetation allowed them to nibble on the food available as they drifted across the sea. The possibility that they sustained themselves on parts of their makeshift rafts underlines the importance of physiological adaptations in survival.

Studies show that the Fijian iguanas share a close evolutionary relationship with desert iguanas from North America. This link is based on thousands of genetic markers that reveal a split between the groups around 34 million years ago. Researchers argue that the rafting event coincided with the volcanic formation of the Fijian archipelago.

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They traveled on natural vegetation rafts.

Genetic Clues and New Perspectives

The research into the iguanas’ voyage has unlocked new perspectives on how species colonize islands. Detailed genomic studies have allowed scientists to pinpoint the origins of Fiji’s iguanas with remarkable precision. By comparing over 200 iguana specimens, researchers found that the Fijian lineage branched off from the North American desert iguanas. This breakthrough supports the idea that a singular, unlikely event led to a major biogeographic expansion.

Simon Scarpetta and his team emphasize the role of chance in evolutionary history.

“When you’re dealing with evolutionary time, you’ve got a lot of opportunity for these very small probability things to occur,” he told Science News. The genetic data not only reveal the past but also raise questions about how other species might have taken similar risks.

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Fiji’s iguanas share DNA with North American desert iguanas.

Legacy and Future Research

The story of these wandering iguanas adds a new chapter to the field of biogeography. It underscores the impact of rare events on the course of evolution. The dispersal of iguanas over thousands of miles reshaped the biodiversity of the Pacific islands.

The findings encourage scientists to reexamine how isolated ecosystems develop. As islands continue to serve as natural laboratories, the lessons from Fiji’s iguanas remind us of nature’s unpredictability. The interplay between geology, climate, and biology remains a fertile ground for discovery. Researchers now hope to use similar genetic techniques to unravel other ancient mysteries of species dispersal.

Ancient iguanas did not set sail with maps or compasses. They were at the mercy of the wind and the waves. Their journey, dictated by chance and survival, resulted in a colonization event that reshaped an entire ecosystem. The revelation of their past offers a glimpse into the dramatic processes that have molded life on Earth. This account stands as one of the most remarkable chapters in the history of animal migration.