The baobab’s journey from Madagascar to Africa and Australia
The baobab tree is a distinctive sight on the landscape. When its contorted branches are lea ess during the dry season, they resemble jumbled roots emanating from a thick trunk, making it appear as if someone had yanked the tree from the ground, ipped it on its head, and jammed it back into the earth.
But the origins and history of the baobab, found in Madagascar and parts of Africa and Australia, have been something of a mystery. A new study has resolved this based on genomic analyses of all eight recognised species as well as ecological and geological data.
The baobab lineage originated in Madagascar roughly 21 million years ago and reached Africa and Australia sometime in the past 12 million years, the researchers found. Madagascar, an island o Africa’s southeastern coast, is a biodiversity hot spot and home to unusual ora and fauna.
Two baobab lineages went extinct in Madagascar, but not before establishing themselves elsewhere, one in Africa and one in Australia, the study found.
The tale of how a tree crossed the Indian Ocean to put down roots in two distant destinations is dramatic. It appears baobab seed pods oated from
The dispersal to Australia was probably facilitated by the Indian Ocean gyre which likely picked up baobab seed pods as it moved past Madagascar
Madagascar to mainland Africa, located about 400 km to the west, and to Australia, situated more than nearly
7,000 km to the east.
“The plants almost certainly got to Africa and Australia oating on or with vegetation rafts,” said botanist Tao Wan of the Wuhan Botanical Garden in China, one of the authors of the study published on May 14 in the journal Nature.
“The long-distance dispersal to Australia was probably facilitated by the Indian Ocean gyre, which is an oceanic current that circulates south past Madagascar, where it probably picked up baobab seed pods, before the current swings east to Australia, where it delivered the pods. The current then circulates north and then swings west past Mauritius and to Africa once again, where it completes the gyre,” Dr. Wan added.
Baobabs, found in dry savannah habitats, provide food, shelter and nesting sites for wildlife. Their fruits also provide nutrients and medicines for people, and the leaves are edible. The trees produce large, sweet-smelling
owers whose sugary nectar attracts nocturnal pollinators as well as two types of primates, lemurs in Madagascar and bush babies in Africa.
“They can reach huge dimensions ... in both height and diameter, and are reported to live for thousands of years. The root systems are also massive, which are considered to play an important ecological role, helping to slow down soil erosion and enabling nutrient recycling,” plant geneticist and study co-author Ilia Leitch of the Royal Botanic Gardens Kew in London said.
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