A little yellow-and-white bird that prefers to date its mates in an idyllic island lifestyle rather than fly to the mainland to mingle is an example of avian species evolution in action, according to new Australian research.
The University of the Sunshine Coast paper, published in Nature Scientific Reports, investigated the genetic divergence of the Capricorn silvereye population on Lady Elliot Island since the species was first observed there in the 1980s.
The study found that the species, known for fast breeding and monogamy, had already developed genetic distinction in less than five decades on the southern Great Barrier Reef island.
UniSC animal ecologist Dr Dominique Potvin said genetic markers indicated the bird chose to stay and play on the resort side of the island for its lifespan rather than seek out other silvereye populations.
“This is a rapid rate of genetic divergence, with the zosterops lateralis silvereye now one of the island’s most common land-dwelling avian species,” she said.
“It can easily fly long distances but chooses not to visit the Queensland mainland or other islands.”
Dr Potvin, who supervised the collaborative study led by UniSC Honours graduate Annika Radu, said there were three subspecies of silvereyes across Queensland and its reef islands.
“Many individuals migrate from Tasmania to Queensland and back every year, so it’s not like they can’t get places,” she said.
“This study supports previous research showing that Great Barrier Reef birds are slowly evolving away from the mainland species.
“Silvereyes are notorious for this, but most studies have looked at them on a species level – such as throughout the South Pacific – rather than a local level.
“We are seeing species divergence/evolution in action,” Dr Potvin said.
Ms Radu said the study compared samples from birds at Maryborough, the Sunshine Coast, Lady Elliot Island and Heron Island northeast of Gladstone.
September is breeding season for the bird with a distinct white ring around the eye, which nests in trees and feeds on invertebrates and fruit. There are 17 subspecies of silvereye across Australia and the South Pacific.
The paper Genetic patterns reveal geographic drivers of divergence in silvereyes was co-supervised by UniSC Associate Professor Kathy Townsend and co-authored by UniSC Senior Research Fellow Christine Dudgeon, UniSC Dr Alexis Levengood, University of Oxford’s Sonya Clegg and Ashley Sendell-Price, and University of Otago’s Yasmin Foster.
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