A new study from the University of the Sunshine Coast explores the remarkable genetic evolution of a bird species that has opted to stay and thrive on a tropical island resort, rather than migrate to the mainland. This fascinating story showcases the power of natural selection and the adaptability of these feathered creatures.
Avian Evolution in Action
The research, published in Nature Scientific Reports, it centered on one population of the Silvereye, The Capricorn silvereye on Lady Elliot Island in the Great Barrier Reef. The species of tiny, yellow-and-white birds quickly took on different genetic characteristics in fewer than five decades as researchers found after they voted the island home.
Dr Dominique Potvin, an animal ecologist at the University of the Sunshine Coast, said Fawceneys silvereyes were just as likely to party on in a resort-like atmosphere on the island than risk mingling with other silvereye populations back down on the mainland or nearby islands. This behaviour has seen the silvereye quickly evolve its genes too, now one of the most widespread avian species on land in New Zealand.
Staying Put for Love
The silvereyes, by comparison, are prolific breeders and form monogamous pairs. Rather than flying for miles to mix it up with others, they chose mates from across their small island – hence the genetic divide.
There are three subspecies of silvereyes throughout Queensland and its reef islands, but according to Dr. Potvin the silvereyes on Lady Elliot Island “have chosen to stick it out” on the island instead of taking flight across long distances if they could. It is consistent with previous research showing Great Barrier Reef birds are increasingly diverging from those on mainland Australia.
These fascinating insights were uncovered when the researchers compared genetic samples from birds in Maryborough, the Sunshine Coast, Lady Elliot Island and Heron Island. This research underscores the value of methods that can zoom in to a finer regional scale rather than focusing on trends across entire species ranges.
Conclusion
In this intriguing story of the Capricorn silvereyes (yes, silvereyes), we see the ways in which avian creatures are able to adapt and evolve. By remaining and flourishing on the idyllic Lady Elliot Island, these birds underwent (and continue to undergo) rapid genetic alterations, in the process diverging from their mainland relatives to become a key component of the island’s ecosystem. Although the research offers novel musings on evolutionary causes, it also illustrates that island ecosystems and biodiversity are unique bookshelves of Earth’s biodiversity.
