About 34 million years ago, the ancestors of the modern iguanas probably performed the longest ocean crossing already made by a non -human terrestrial vertebrate.
Starting from the west coast of North America, these iguanas traveled almost 8,000 km – the equivalent of one fifth of the earth’s circumference – through the Pacific Ocean, finally even Fiji, according to a new study.
Based on genetic evidence, researchers suggest that these iguanas made the incredible journey floating in natural rafts of vegetation, possibly composed of trees or torn plants.
For decades, scientists debated how the iguanas arrived at Fiji. Previous theories suggested that an extinct species of Iguana would have crossed the ocean in natural rafts from the Americas, without a definite period, while other hypotheses proposed that the lizards migrated by land from Asia or Australia, explained the main author of the study, Dr. Simon Scarpetta, assistant professor at San Francisco.
Scarpetta conducted this research during his postdoctoral degree from the National Science Foundation at the University of California, Berkeley, and in his current position.
The results, published Monday in the Proceedings of the National Academy of Sciences, help to clarify the old mystery of how these reptiles have reached such remote islands.
Scarpetta and his team sought to test both raft ocean crossing theory and earthly migration, as well as other hypotheses about the biogeographic origin of Fiji’s iguanas, including antarctic dispersion or the Bering Earth Bridge. Scarpetta pointed out that understanding this type of dispersion about water can offer new perspectives on as other species colonized isolated areas over time.
Tracking genetics
Iguanas have already shown the ability to survive long ocean trips. A October 1998 study reported that in 1995 at least 15 green iguanas arrived at the beaches of Anguilla, in the Caribbean, in torn trees. Researchers concluded that the lizards probably floated about 322 km from Guadalupe after a hurricane.
Scarpetta explained that this type of ocean dispersion is often called “Draw Dispersion” (Sweepstakes), a rare event that allows the colonization of inaccessible areas. Great climate phenomena, such as hurricanes or floods, can detach vegetation and transport animals along with it.
To determine when the iguanas arrived in Fiji, the researchers analyzed the genes of 14 living species. The study revealed that the liver relative closest to Fiji’s iguanas is Diposaurus, a type of iguana of the native desert of the southwest of the United States and northwest of Mexico.
Fossil evidence reinforces the hypothesis that these iguanas originated in North America, as no fossils of desert’s iguanas were found in any other part of the world.
The analysis also suggests that the Fijian iguanas separated from their American ancestors between 34 and 30 million years ago, a period that coincides with the volcanic formation of the Fiji Archipelago, according to Scarpetta.
This timeline challenges previous theories that suggested that the iguanas could have done a complex terrestrial journey of South America via Antarctic, which would have happened much later in history, explained study co -author Dr. Jimmy McGuire, professor of integrative biology at California University, Berkeley.
“In phylogenetic analyzes, there is always a certain degree of uncertainty in trying to predict the moment of divergence between species,” said Dr. Shane Campbell-Staton, an associate professor of Ecology and Evolutionary Biology at Princeton University, who did not participate in the study.
“In this case, the authors were extremely thorough, collecting different types of genetic data and using multiple models to test their hypothesis, finding widely agreement results.”
How was this journey possible?
Although a Pacific month crossing seems impossible, the iguanas have amazing features that make them well prepared for extreme travel.
“If we had to choose a group of vertebrates capable of surviving a journey of thousands of kilometers over the ocean on a natural raft, the iguanas would be an excellent option,” said Scarpetta.
Many species of iguanas, especially those living in desert environments, are highly resistant to extreme heat, hunger and dehydration he added.
“Because they are ectothermic, they do not spend many food resources or fat reserves to maintain a high body temperature,” McGuire explained. “Ectothermal can be about 25 times more efficient in this respect than endothermic (warm -blooded animals), which means they need to feed much less frequently.”
Some estimates suggest that the Oceanic crossing of North America to Fiji could have lasted four to 12 months. However, more recent simulations indicate that the trip may have been shorter, between two and a half and four months, said Scarpetta.
Despite the basic challenges of survival, the food scarcity was probably not a major obstacle . If necessary, these herbivorous reptiles could have fed on the vegetation of the floating rafts themselves, McGuire explained.
Scientists hope that by studying dispersion events, they can predict which species have the ability to survive long -distance ocean travel, offering new perspectives on how animals spread across the planet.
“Now we know that dispersion about water is not only possible, but probably played a crucial role in the diversification of species In islands around the world, ”said Campbell-Staton by email.
This content was originally published in Iguanas traveled 8,000 km to Fiji on vegetation rafts, says study on the CNN Brazil website.
Source: CNN Brasil
Charles Grill is a tech-savvy writer with over 3 years of experience in the field. He writes on a variety of technology-related topics and has a strong focus on the latest advancements in the industry. He is connected with several online news websites and is currently contributing to a technology-focused platform.
