New Zealand Sea Lion is a Relative Newcomer to its Prehistoric Counterpart

The modern New Zealand sea lion may be somewhat of a newcomer, according to a recent study conducted by biologists from the University of Otago. In fact, they estimate that the now-extinct unique prehistoric New Zealand sea-lion died out as recently as 600 years ago.

"It is estimated that the mainland sea-lions became extinct between 1300 and
1500AD, soon after Polynesian settlement, and midden remains suggest they were hunted extensively. The extinction apparently created an opportunity for the subantarctic lineage to colonise New Zealand's mainland," said study author Catherine Collins, via a press release. Collins is also a zoology Ph.D. student at the university.

Researchers estimate that this prehistoric mainland sea-lion was replaced by a lineage limited to primarily cold waters of the subantarctic. Furthermore, they also identified a previously unknown sea-lion lineage that dominated the South Island shores just a few hundred years ago, according to the release, which they determined using the ancient DNA samples from prehistoric bones.

"We found that the extinct mainland population was clearly genetically distinct from the modern subantarctic population that arrived more recently," Collins added, via the release. 

These findings also mirror a prehistoric extinction-replacement event of the yellow-eyed penguins, according to lead study author Jon Waters, who is a professor at the university. 

"Our findings demonstrate that our current sea-lion population is not a declining remnant of an original mainland population, but rather represents a new arrival from the subantarctic," he added, via the release. "Competition between the two lineages may have previously prevented the subantarctic lineage from expanding northwards to the mainland of New Zealand."

With further studies, researchers hope to find out more about the prehistoric sea-lion. As the team finds that modern and prehistoric sea-lions carried different attributes, much is left undetermined about the biology of the now-extinct creature.

More information regarding the findings can be seen via the international biological research journal Proceedings of the Royal Society B: Biological Sciences.