Date: August 30, 2016
Source: University of Kansas
While it is widely accepted that
songbirds originated from the Australian continent, how and when they
diversified and colonized the rest of the globe has remained a mystery.
Researchers from the University
of Kansas, Louisiana State University and three other institutions
reconstructed the evolutionary history of songbirds using thousands of DNA
sequences from majority songbird lineages and information from the fossil
record to provide answers to these questions. They found that songbirds began
diversifying about 33 million years ago and underwent extensive diversification
in Australia. Furthermore, the researchers also found that songbirds first
dispersed out of Australia about 23 million years ago through early islands in
the Indonesian archipelago into Asia and subsequently the entire globe.
This new research will be
published in Nature Communications on Aug. 30.
"One of the challenges with
deciphering songbird evolutionary history is that they diversified so rapidly
that previous studies had a difficult time estimating the branching pattern of
the songbird family tree," said lead author Rob Moyle, KU professor of
ecology and evolutionary biology and curator of ornithology at the KU
Biodiversity Institute. "With advances in DNA sequencing technology, we
were able to collect an unprecedented amount of DNA sequence data that helped
clarify songbird relationships."
Songbirds comprise the largest
group of birds, with about 5,000 species, accounting for nearly half of avian
diversity. They are found on almost all corners of the globe, with the
exception of Antarctica, and include the familiar crows and sparrows, as well
as elaborate singers like mockingbirds and lyrebirds.
With a better understanding of
the songbird family tree, Moyle and his colleagues were able to infer the
colonization history undertaken by songbird ancestors.
The dispersal of songbirds from
Australia through Indonesia, Moyle said, seems like an obvious explanation to
anyone who knows world geography; but one has to bear in mind that tens of
millions of years ago, world geography looked a lot different because of the
Earth's constant process of plate tectonic movements. "Thirty-three
million years ago, Australia was thousands of kilometers away from any
continent, and New Guinea barely existed," Moyle said.
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