Ancient birds from North America colonized the South

Jul 13, 2010
The American Robin is an example of the species studied in this research. Credit: Dr. Christian Hof

Scientists studying ancient species migration believe northern birds had the ability to colonise continents that southern species lacked. The research, published in Ecography, reveals how the ancient 'land bridge' of Panama, which first connected North and South America, caused an uneven species migration, leading to a new understanding of species diversity today.

The continents of North and South America were historically isolated until they were abruptly joined three million years ago through the tectonic uplift of Central America and the formation of a land corridor in modern day Panama, creating a .

"This connection allowed an unprecedented degree of intercontinental exchange between species that had been isolated for millions of years," said lead author Brian Tilston Smith from the University of Nevada. "However the relatively poor has prevented us from understanding how the land bridge shaped New World bird communities."

Using molecular data and phylogenetic evidence from 11 orders, 34 families, and over 100 genera of the team applied a 'molecular clock' to estimate the historical timing of the migration, giving a unique insight into how the ancient history of American led to present day species diversity across the equator.

The results reveal that while ancient birds could fly most species did not cross the water between the two isolated continents, so were subject to the same constraints as their land based mammalian counterparts. The land bridge was therefore crucial in facilitating cross continental migration.

"This inter-continental migration was far from even. While within the tropics around the equator exchange was equal in both directions, between the temperate zones of North and South America it was not," said Smith. "Avian lineages from the northern Nearctic regions have repeatedly invaded the tropics and radiated throughout South America. In contract species with South American tropical origins remain largely restricted to the confines of the tropical regions."

Existing studies show that in mammals 50% of modern South American species have Northern origins whereas only 10% of species from the North originated in the South. The team found that this pattern is also reflected in birds. When considering the perching birds oscine and suboscine the team found that despite having northern ancestral origins, 55% of New World oscine species now breed in South America, many of them in tropical habitats. In contrast, only 2.4% of suboscines have secondarily adapted to North American temperate zone habitats.

"Our study suggests the formation of the Panama land bridge was crucial for allowing cross continental bird migration," concluded Smith. "We believe that the ability of species to colonise and radiate across this area represents an important and underappreciated factor to the distribution of species around the equator."

Explore further: Science casts light on sex in the orchard

More information: Smith. BT, Klicka.J, “The profound influence of the Late Pliocene Panamanian uplift on the exchange, diversification, and distribution of New World birds,” Ecography, Wiley-Blackwell, 2010. DOI: 10.1111/J.1600-0587.2009.0633

Related Stories

Extinct giant shark nursery discovered in Panama

May 17, 2010

The six-foot-long babies of the world's biggest shark species, Carcharocles megalodon, frolicked in the warm shallow waters of an ancient shark nursery in what is now Panama, report paleontologists workin ...

Extinct moa rewrites New Zealand's history

Nov 18, 2009

(PhysOrg.com) -- The evolutionary history of New Zealand's many extinct flightless moa has been re-written in the first comprehensive study of more than 260 sub-fossil specimens to combine all known genetic, ...

Recommended for you

'Divide and rule'—raven politics

6 hours ago

Mythology has attributed many supernatural features to ravens. Studies on the cognitive abilities of ravens have indeed revealed that they are exceptionally intelligent. Ravens live in complex social groups ...

Science casts light on sex in the orchard

Oct 30, 2014

Persimmons are among the small club of plants with separate sexes—individual trees are either male or female. Now scientists at the University of California, Davis, and Kyoto University in Japan have discovered ...

Four new dragon millipedes found in China

Oct 30, 2014

A team of speleobiologists from the South China Agriculture University and the Russian Academy of Sciences have described four new species of the dragon millipedes from southern China, two of which seem to ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.