How did sugar-eating birds co-evolve with plants that produce nectar?
Research led by the University of Adelaide has shown, for the first time, that the digestive systems of nectar-eating birds co-evolved with the nectar-composition in flowers.
Scientists have long suspected the digestive systems of nectar-eating birds, such as honeyeaters, co-evolved with the nectar-composition in flowers.
To document whether this theory is accurate, in a paper published in iScience, researchers at the University of Adelaide studied the ability of birds to digest different sugars, and looked at whether they matched the nectar sugars found in plants used by families of birds in different parts of the world.
“The plants specialised for pollination by nectar-feeding birds produce the sugars that those birds can use very efficiently, and the birds’ digestive ability has evolved to match.”- Dr Todd McWhorter
The study involved 50 different bird species, including 20 nectarivores (mainly consume nectar and pollen), such as hummingbirds, sunbirds, honeyeaters, flower-piercers, and lorikeets.
“We’ve been collecting data on the abilities of these birds to digest a nectar diet for many years and on multiple continents – honeyeaters in Australia, sunbirds in Africa, hummingbirds in North America,” said lead author Dr Todd McWhorter, Senior Lecturer in the University of Adelaide’s School of Veterinary Sciences.
The researchers found that the digestive abilities of birds match the sugars found in the plant nectars that they use. Birds that only occasionally feed on nectar are not as good at digesting sucrose, and the plants they usually feed on tend to have mostly the sugars glucose and fructose in their nectar, which are simpler to digest. [...]