The Tuatara , Sphenodon punctatus, is a unique reptile found in New Zealand. New research suggests that the species has two mitochondrial genomes.
The tuátaras constitute the only species of the Sphenodontia order that has survived to the present day, practically unchanged since the Mesozoic Era . The meaning of its common name comes from the Maori and means "spiny back".
All animals have nuclear DNA found in the nucleus of the cell and mitochondrial DNA, located in the so-called cellular ‘powerhouse’, the mitochondria . Mitochondrial DNA (mtDNA) or mitochondrial genome, then, is a genetic material of the mitochondria, the elements of the cell that generate energy for it.
However, after analyzing the existing tuatara DNA sequences and comparing them with the DNA of other reptiles, they soon realized that the genome was not as incomplete as scientists initially thought. In reality, there were too many mysterious and leftover DNA sequences in the reptile’s mitochondrial genome.
After an exhaustive study, thanks to new data from the whole sequenced genome, they identified a second complete mitochondrial genome that is 10% different from the ‘typical’ tuatara mitochondrial genome .
Although the discovery of a second mitochondrial genome was only confirmed in a single sample, its presence remains surprising. If scientists discover that double mitochondrial genomes are common in tuataras, they could use these multiple genomes to figure out when each genome appeared and when it separated from the other . The research could help zoologists understand what exactly makes the species so genetically different from all other reptiles.