A bee trapped by a glob of sap inside a come-hither orchid up to 20 million years ago has rewritten the evolutionary tale of a flower with the most fanatical following of any plant in the world.
PARIS: A bee trapped by a glob of sap inside a come-hither orchid up to 20 million years ago has rewritten the evolutionary tale of a flower with the most fanatical following of any plant in the world.
In a study published on Wednesday, biologists say the most recent common ancestor to all modern-day orchids lived in the twilight of the dinosaurs, in the Late Cretaceous period some 80 million years ago. The finding settles a century-old hothouse debate. Previous estimates, based on mainly circumstantial evidence, ranged from 26 to 110 million years ago. What killed the dinosaurs - wiped out, apparently when an asteroid whacked into Earth - may also have helped orchids.
The flowers spread dramatically across the globe shortly after this mass extinction and just before the rise of mammals, say the team, led by Harvard researcher Santiago Ramirez. The Orchidaceae family is the largest in the plant kingdom, numbering at least 25,000 species.
Hundreds more are brought to light every year to feed a lucrative market, and orchid hunters are known for venturing into remote, often dangerous jungle in search of ever more exotic gems.
Writing in the British journal Nature, Ramirez reports on grains of orchid pollen found on the back of a bee in the Dominican Republic. The insect was trapped for eternity in amber, dropped from a tree, after it was lured to the flower by the prospect of nectar some 15-20 million years ago. "It is the first identifiable fossil orchid ever found," Ramirez said.
"And it is the first case in which an insect-orchid interaction has been observed in the fossil record." The new orchid species, identified from the DNA of the pollen, has been dubbed Meliorchis caribea. Dating the fossil enabled Ramirez to calibrate a "molecular clock" which uses the DNA mutations to estimate the time of divergence between living organisms.
By building a 'family tree' of orchids, the scientists could move back in time to see when the species first appeared and where and how it spread. The luckless bee has become a timeless testament to the orchid's seductive power, for there was probably nothing for the insect to eat.
Biologists have long been fascinated by the evolutionary adaptations of orchids for attracting, deceiving, and manipulating insects to achieve cross-pollination. For romantics, too, nothing beats the orchid - as a love offering.
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