New findings from zoologists working with birds in Southeast Asia are shining fresh light on the connections between animal behaviour, geology, and evolution — underlining that species can diversify surprisingly quickly under certain conditions.
The zoologists, from Trinity College Dublin’s School of Natural Sciences, sequenced DNA and took measurements and song recordings from Sulawesi Babblers (Pellorneum celebense), shy birds that live in the undergrowth on Indonesian islands.
Although these islands were connected by land bridges just tens of thousands of years ago, and although the babblers look so similar that they are currently all considered a single subspecies, the new study shows that their DNA, body size and song have all changed in what is a very brief period of time from an evolutionary perspective.
The zoologists believe that this evolutionary divergence is likely facilitated by the babblers’ understorey lifestyle, which limits the birds’ movements even though they could easily fly between the islands if they chose to.
In the short time these islands have been isolated, the babbler subspecies have evolved to vary genetically from each other by as much as 1/3 as they do from more distantly related bird species that separated millions of years ago.
Fionn Ó Marcaigh, first author on the paper and a PhD Candidate in Trinity’s School of Natural Sciences, said:
“Everyone has heard of Darwin’s finches evolving completely different bill shapes on the Galápagos islands. The Galápagos are isolated out in the Pacific, so the birds there have had millions of years to evolve