SYDNEY, June 6 (Xinhua) -- A new study conducted by Australian experts has shown that insects were most likely the pollinators when the first flowers bloomed on Earth more than 140 million years ago.
According to a study published in the New Phytologist journal on Monday, most contemporary angiosperms are insect pollinated, but pollination by wind, water or vertebrates occurs in many lineages as well.
To puzzle out which kind of pollination evolved first, researchers from Australia's Botanic Gardens of Sydney, Macquarie University, Western Sydney University, and University of New South Wales collected data on the pollination system of 1,160 species, which can date back to the Cretaceous period from 145 to 66 million years ago.
They depicted the macroevolution of four pollination modes in a "family tree" that not only indicates what pollinates a plant in the present, but also shows what might have pollinated the ancestor of the plant in the past.
The research team concluded that angiosperms were ancestrally insect-pollinated, and insects have pollinated angiosperms for 86 percent of its evolutionary history.
"This is a significant discovery, revealing a key aspect of the origin of almost all plants on Earth today," said Ruby E. Stephens, lead author of the study and Ph.D. student from Macquarie University.
"Plants are the lifeblood of our planet, and our study highlights the importance of insects to plant reproduction throughout Earth's history," Stephens added.
The research team also elaborated on their findings in an article released by the media network The Conversation on Tuesday.
The species of the first pollinating insects still remain unknown to scientists, but they ruled out the possibility of bees, as most evidence has suggested that bees didn't evolve until after the first flowers.
Given that most of the early flowers have been preserved as fossils and are very small, the experts speculated that the pollinators could be tiny fly or beetle, maybe even a midge, or some extinct types of insects. ■
