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 Dr. Jeffery Saarela |
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Canadian Museum of Nature Botanist Discovers New Lineage of Early Flowering Plants—A botanist with the Canadian Museum of Nature has used DNA evidence to help resolve a long-standing puzzle about the true identity of a tiny flowering plant. Dr. Jeffery Saarela and colleagues have now shown that a family of aquatic plants called Hydatellaceae are more closely related to water lilies, rather than grasses and rushes as previously thought. This makes it one of the most ancient lines of flowering plants. The results were published today in the journal Nature. "It was a highly unexpected result," says Saarela, who completed the work as part of his doctoral research at the University of British Columbia under the guidance of professor Dr. Sean Graham. "I was working on the evolutionary relationships of grasses and their relatives, and we wanted to examine this family because it has long been thought to be a bit of an oddball.".
Only 10 species of Hydatellaceae are known. The family had previously been grouped within a group of plants called monocots, which includes grasses. This classification was based on superficial physical characteristics. But when Saarela compared purified DNA sequences from Hydatellaceae species with DNA of other plants, he discovered that the family is much more closely related to water lilies. The results mean that Hydatellaceae plants represent one of the earliest known lines of flowering plants, which are called angiosperms. This diverse group includes garden flowers and most of our agricultural and horticultural crops. Angiosperms are thought to have diversified at least 135 million years ago, during the Early Cretaceous Period, when dinosaurs ruled the planet. For more than a century, scientists have sought to explain their rapid appearance in the fossil record and early diversification. "This discovery is making scientists rethink our understanding of early flowering plant evolution and where we place ancient angiosperm fossils on the tree of life," says Graham. "It's a major piece of the puzzle of flowering plant evolution, which Charles Darwin called an 'abominable mystery.'" Hydatellaceae are all tiny in stature (only one-to-several-centimetres tall at maturity) and they are found in freshwater seasonal pools and swamps in Australia, New Zealand and India. The plants may blossom under water at depths of up to one metre, or at the edges of drying pools. Each plant has dozens of clustered, tiny flowers that appear to the untrained eye as a single flower. Saarela and the UBC team completed the project in collaboration with researchers from Harvard University, the Royal Botanical Gardens in Sydney, Australia, the University of Zurich and the University of California. Recently hired at the Canadian Museum of Nature, Saarela is now pursuing similar research to answer questions about the origin and evolution of grasses. The Canadian Museum of Nature is a Crown corporation, and Canada's national museum of natural history. It maintains a 10-million-specimen collection and promotes awareness of Canada's natural heritage through permanent and travelling exhibitions, public education programmes, and scientific research in the life sciences and earth sciences. Media Contact
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