Genomic study reveals New Zealand Tuatara unlike any other animal on the planet

In the evolutionary tree of life, the New Zealand lizard-like tuatara is on a branch all to itself.

In the days of the dinosaurs, this amazing animal had many relatives all over the world, and yet now there is nothing else like it on Earth.

According to the new sequencing of the tuatara’s entire genome – one of the largest on record and 50% larger than the human genome – it appears that this strange creature is neither a lizard, nor a bird, nor a mammal. Rather, it is a strange fusion of the three.

According to the authors of the new study, the animal’s genomic architecture is unlike anything previously reported.

“The tuatara genome contained about 4% jumping genes common in reptiles, about 10% in monotremes (platypuses and echidnas), and less than 1% in placental mammals such as humans,” says biologist David Adelson of the University of Adelaide. , Australia.

“It was a very unusual observation and indicated that the tuatara genome is a strange combination of mammals and reptiles. [including bird] Components.”

Scientists already knew about tuatara (Spotted Tufted Tufted) was something else, but this new research suggests it’s even more unique than we thought.

Found only in New Zealand, the tuatara – which looks a lot like a lizard to the untrained eye – is considered a taonga, or “special treasure” to local Maori. And for good reason.

These nocturnal creatures can live for a century, withstand very cold temperatures, hold their breath for up to an hour, and see light from a third “parietal eye” on their head.

Today, the species’ closest relatives are snakes and lizards, but calling them relatives is much like calling a kangaroo a relative of humans. Their common ancestor actually dates back some 250 million years.

Throughout this time, the tuatara remained the only members of the archaic reptilian order known as Rhynchocephalia.

“This species represents an important link to the now-extinct stem reptiles from which dinosaurs, modern reptiles, birds, and mammals evolved, and is therefore important to our understanding of amniote evolution,” writes L. research team in their article.

The tuatara retains the characteristics of the ancient and long-extinct animals from which all of these groups evolved. The researchers who sequenced its genome note that this species is the slowest-evolving reptile ever analyzed, more than any other lizard or snake.

As such, tuatara are a direct link to our origins, but their continued existence on our planet is not a safe bet.

Although their numbers are doing well now, as tuatara are protected on all 35 islands they are found on in New Zealand, a rapidly changing climate could spell the end.

The sex of future tuatara is highly dependent on the temperature surrounding the eggs, and global warming could cause too many males to be born, leading to an imbalance in the reproductive cycle.

The authors of the new study say tuatara “remain at risk due to their highly restricted distribution, threats imposed by disease, and climate change-induced shifts in sex ratios that could significantly affect their survival.”

Knowing more about the species is crucial for its continued survival. But this genomics research is also important for other reasons.

The research was conducted in partnership with the Ngātiwai, the Māori iwi (tribe) who hold kaitiakitanga (trusteeship) over the Tuatara populations; this type of collaboration is not always considered in conservation research.

“This partnership – which to our knowledge is unique among genome projects undertaken to date – had a strong practical focus on developing resources and information that will improve our understanding of tuatara and contribute to future conservation efforts. “, write the authors.

“It is hoped that this work will set an example for future genome initiatives that aspire to meet access and benefit-sharing obligations to indigenous communities.”

Sharing knowledge is important, as is sharing credit. The Ngātiwai Trust Board is among the authors of the article.

The study was published in Nature.

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