Chuck Landis at his home in Otago, New Zealand. He believes New Zealand sank beneath the waves before being re-colonised by drifting species.

Credit: Bill Morris

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However, improvements in DNA sequencing and molecular analysis have allowed scientists to determine more accurately how long divergent species have been separated. This has overthrown many of the old assumptions about species being torn apart by continental drift and evolving on their own. It turns out many forms of life, isolated by oceans, have diverged too recently to have simply ridden the break-up of land-masses.

Matt McGlone, a palaeoecologist with Landcare Research, a government owned institute, has written a paper entitled "Goodbye Gondwana," in which he roundly criticises those who claim New Zealand's evolutionary heritage is uniquely Gondwanan.

"Let's think about it," he says. "The transformations New Zealand's gone through. We started almost in the polar circle, albeit with a mild climate. Then we floated north, and there were coconut trees and corals here. Later we developed into a cool-temperate oceanic land-mass. "What are the chances a species could survive all that?"

Eleven years ago, Kiwi botanist Mike Pole, now at the University of Queensland, presented a paper in which he argued it was entirely plausible New Zealand's entire flora and fauna arrived via dispersal. He pointed out that DNA analysis of the now-flightless kiwi suggests it diverged from its closest relatives, the Australian emus and cassowaries, less than 45 million years ago, long after the continents split. This would suggest its ancestors must have flown, floated, or at least 'island-hopped' to New Zealand.

Nothofagus, the beech tree that clothes New Zealand's southern mountains, is often termed 'Gondwanan', as its relatives are found in Tasmania and Chile. Yet one species of Nothofagus pollen turns up in Australia's geological record after the two separated, indicating the tree reseeded itself in the Australia despite the widening ocean barrier. Indeed, according to Mike Pole, the fossil records of Australia and New Zealand point to a continuous flow of plant species from west to east across the Tasman Sea.

"30 or 40 million years ago, Australia was completely covered in rainforest," he says. "And there were huge rivers, huge piles of vegetation flooding out there, and it just floated across to New Zealand."

Punctuating the Pacific, volcanic islands have never been connected to continental landmasses. The fauna of Lord Howe Island, in the Tasman Sea, includes such landlubbers as tortoises (now extinct) and snails. This place was sizzling lava emerging from the brine just three million years ago, yet its sides are now dense with trees and plants. Of similar age, nearby Norfolk Island inherited its eponymous pine from across the waves, which means the seeds had to travel at least 470 kilometres to get there. How these things arrived is a mystery, but if islands like Lord Howe, Norfolk and the Fiji group can be readily colonised, why not New Zealand?

And then there's Hawaii, alone in the Pacific, 4000 kilometres from any large land-mass. When the intrepid Captain got there, native Hawaiians built houses and tools from 'Ohi'a lehua, the most plentiful tree on the islands. The scarlet blooms must have looked familiar to Cook - the seeds of its ancestors came from New Zealand, probably utilising the unusually strong wind patterns of the ice age to traverse the massive ocean and populate the volcanic domes of Hawaii thousands of years earlier.

Proponents of the vicarious dispersal theory of continents drifting apart are now being criticised for underestimating the importance of wind and water-borne dispersal. A kind of counter-revolution in biogeography is at hand. Chuck Landis and others are taking an axe to the pillar of knowledge that has explained New Zealand's evolutionary heritage since the advent of plate tectonics theory. In arguing New Zealand could well have been colonised by species that drifted or blew in from elsewhere, they're fighting an easy assumption of biogeography that has prevailed for over forty years.

Inland from Chuck's house on the Otago coast of New Zealand's South Island, a wide river valley hangs between broad, flat-topped hills. These hills, says the textbook, are remnants of the Otago peneplain - a flat surface left behind after New Zealand was ground down by millions of years of erosion. Chuck has never believed it. He suspects the 'peneplain' is a wave-cut platform, shaped by the sea as it marched steadily inland, on its way to an overwhelming extinction.

Chuck Landis doesn't really expect to prove New Zealand went under the waves 30 million years ago. He does, however, want to challenge the idea that New Zealand's ecological inheritance is uniquely 'Gondwanan'. He's got a big job ahead.

As Matt McGlone wryly observes, abandoning 'Time Capsule of the South Seas' for 'Fly-paper of the Pacific' could well be a wrench.