Coconut Tales

Genetic analysis reveals secrets of the domestication of a key fruit

Kenneth Olsen, a plant evolutionary biologist, didn’t expect to find much geographical structure to coconut genetics when he and his colleagues set out to examine the DNA of more than 1,300 coconuts from all over the world. “I thought it would be mostly a mish-mash,” he says. He was in for a surprise. It turned out that there are two clearly differentiated populations of coconut, a finding that strongly suggests the coconut was brought under cultivation in two separate locations, one in the Pacific basin and the other in the Indian Ocean basin. What’s more, coconut genetics also preserve a record of prehistoric trade routes and of the colonisation of the Americas.

The discoveries of the team, which included Bee Gunn, now of the Australian National University in Australia, and Luc Baudouin of the Centre International de Recherches en Agronomie pour le Développement in Montpellier, France, as well as Olsen, associate professor of biology at Washington University in St Louis, are available in the journal PLoS One.

The most striking finding is that Pacific and Indian Ocean coconuts are quite distinct genetically. “About a third of the total genetic diversity can be partitioned between two groups that correspond to the Indian Ocean and Pacific Ocean. That’s a very high level of differentiation within a single species, and provides pretty conclusive evidence that there were two origins of cultivation of the coconut,” says Olsen.

In the Pacific, coconuts were likely first cultivated on islands of Southeast Asia, meaning the Philippines, Malaysia, Indonesia, and perhaps the continent as well. In the Indian Ocean, the likely centre of cultivation was the southern periphery of India, including Sri Lanka, the Maldives and Laccadives.

Olsen and his colleagues believe that Pacific coconuts were introduced to the Indian Ocean a couple of thousand years ago by ancient Austronesians establishing trade routes connecting Southeast Asia to Madagascar and coastal east Africa. Much later, the Indian Ocean coconut was transported to the New World by Europeans. The Portuguese carried coconuts from the Indian Ocean to the West Coast of Africa, Olsen says, and the plantations established there were a source of material that made it into the Caribbean and also to coastal Brazil.

Courtesy: Washington University in St Louis

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