Aug. 6 (UPI) -- Though New Zealand's tuatara looks very much like a lizard, it's not. The tuatara is the last of its kind, the sole living member of the reptilian order of Rhynchocephalia.
New research, published this week in the journal Nature, suggests the tuatara shares genetic heritage with both reptiles and mammals.
Scientists knew tuatara's genetic lineage was ancient and quite unique. Until now, however, researchers weren't sure whether the lizard-like reptile was most closely related to birds, crocodiles and turtles, or if it diverged from an ancestor of lizards and snakes.
To find out, an international team of scientists spent several years sequencing the tuatara's genome. The scientists focused on repetitive DNA sequences called "jumping genes."
"So-called repetitive elements are important for evolution as they have many important functions, such as transcription regulation, gene duplication, de novo gene evolution and serve important functions in genome architecture," study co-author Stefan Prost, postdoctoral researcher in comparative genomics at the Senckenberg Society for Nature Research in Germany, told UPI.
The research confirmed that tuatara diverged some 250 million years ago from the ancestor of lizards and snakes.
But when scientists compared the species' jumping gene patterns with those of several mammalian and reptilian genomes, they were surprised by the diversity of the tuatara's genetic heritage.
"The Tuatara shows ancient amniote genome features," Prost said. "Among the most striking features is the high percentage of repetitive elements that they share with mammals."
Researchers were also surprised by tuatara's remarkably slow rates of evolution. The tuatara's genes and appearance are much as they were millions of years ago.
"Contrary to previous studies, we showed that Tuatara shows one of the slowest molecular evolutionary rates known for Lepidosauria [reptiles]," Prost said.
The tuatara does a lot of things quite slowly, including sexual maturation. The also live upwards of 100 years, and rarely suffer from disease.
Researchers said they plan to investigate the relationship between the tuatara's genes and the reptile's physiological idiosyncrasies in followup studies.
"We plan to take a closer look at genes important for phenotypes such as longevity or temperature-dependent sex-determination, and also support conservation measures using genetic analyses," Prost said.