By PHILIP ENGLISH
University of Auckland scientists have discovered that the New Zealand pohutukawa is one of the world's great plant travellers.
In a research project that began in 1996, they have concluded that species spread throughout the Pacific north to Hawaii all originated from New Zealand.
The researchers collected 60 pohutukawa family
species from across the Pacific Basin to extract DNA and track their evolutionary origin.
Project Crimson, which has worked for 10 years to restore the country's declining pohutukawa and rata populations, helped to finance the research, which links the spread of the tree to the Pacific's changing weather over 10 million years.
The DNA testing showed that the tiny seeds of our ancestor pohutukawa were blown to western parts of the South Pacific - Fiji, Vanuatu and Samoa - 7 to 10 million years ago, consistent with other research showing wind flows were predominantly southeasterly at the time.
In the eastern Pacific - Rarotonga, Tahiti and Hawaii - the species were less than a million years old. Weather patterns over this period were predominantly powerful El Nino events causing strong westerly winds.
The research also showed that seeds from New Caledonia reached central and western Pacific countries such as Fiji, the Solomon Islands and the Bonin Islands near Japan, but no trees of this origin were found in the southern or eastern Pacific.
One of the researchers, Dr Shane Wright, of the university's School of Biological Sciences, said the team had discovered two new species.
"Pohutukawa and its relatives are evolving and mutating all the time, leading to new species. Some are very rare and in one case our field team took several attempts to find a tiny population of plants on a remote mountain ledge in New Caledonia."
The forest on Rangitoto in the Hauraki Gulf showed how tenacious a coloniser the species was.
