NZ was never underwater - scientists

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HIGH AND DRY: Evolutionary geneticist Peter Lockhart and his team say DNA taken from native kauri contradicts the notion that New Zealand sank underwater 26 million years ago.

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Scientists have uncovered strong evidence, hidden deep within the genes of native kauri, that New Zealand was never underwater.

Though it is accepted New Zealand's landmass broke away from the super-continent Gondwanaland more than 80 million years ago, some scientists have argued it was completely submerged around the Oligocene "drowning" period 26 million years ago.

But Massey University evolutionary geneticist Peter Lockhart says dna taken from native kauri contradicts the notion that New Zealand sank.

When dna from local kauri was compared with its Australian counterparts, molecular dating showed the plants genetically diverged at least 40 million and up to 90 million years ago.

"The results with the kauri are very difficult to explain if New Zealand was completely submerged [as] all flora and fauna would have been extinguished," he said.

"The simplest explanation is that New Zealand has existed ever since it rafted away from Gondwana. If this is so, [our] kauri may well have a whakapapa that traces back to 90 million-year-old South Island fossils."

The drowning theory was also contradicted by the tuatara, which was genetically unique and could be up to 100 million years old.

Wellington geologist Hamish Campbell said it was widely accepted large parts of the country were underwater during the Oligocene but there was a good geological and biological case for the landmass being completely submerged about 23 million years ago.

"So few animals and plants are older than 20 million years, the kauri must be the only one. It's an anomaly, so one has to question the data," he said. "It's an interesting result, which will tease the mind of researchers. It's important to have it out there."

With many "native" plants coming to New Zealand across oceans, Professor Lockhart said the finding also anchored the kauri's iconic status.

"People are curious and want to know where we came from. The kauri has a lot of importance to us, it's a strong symbol, and it's good to find out it hasn't just blown in from Australia."

Professor Lockhart said further study of native flora and fauna's genetic diversity was needed to unearth exactly how life in New Zealand had developed and was important for conservation and climate change issues.