Evolution and diversification of living birds

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30 October 2012

First ever family tree for all living birds reveals evolution and diversification

The world’s first family tree linking all living bids and revealing when and where they evolved and diversified since dinosaurs walked the earth has been created by scientists from the University of Sheffield.

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Experts used the family tree to map out where the almost 10,000 species of birds live to show where the most diversification has taken place in the world.

Researchers, from the University of Sheffield, Yale University, University of Tasmania and Simon Fraser University, say the creation of new species has speeded-up over the last 50 million years. Surprisingly, species formation is not faster in the species rich tropics, but was found to be faster in the Western Hemisphere compared to the Eastern Hemisphere as well as on islands.

As well as being the first time scientists have created a family tree for birds, it is hoped the research could help prioritise conservation efforts in a bid to save the most diverse species from extinction.

Dr Gavin Thomas, of the University of Sheffield’s Department of Animal and Plant Sciences, said: “We have built the first ever family tree showing the evolutionary relationship among the species of birds. We used fossils and genetic data to estimate the ages of all the different branches of the bird tree so that we could assess how diversity has accumulated through time. Our work is indebted to researchers from museums and universities who have collected astounding amounts of genetic data from birds around the world.”

Despite major steps forward in modern super computers it has still taken the researchers almost five years to analyse the millions of year’s worth of fossil data, DNA, maths and maps, to create this never-before-snapshot of how the thousands of birds alive made it to where they are today.

To even enable the scientists to calculate which species were more or less diverse they had to create a new ‘species rate’ measure.

Dr Thomas added: “Diversification is the net outcome of new species arising, called speciation, and existing species going extinct. We combined this data with existing data on the geographic ranges of all living bird species so that we could map diversification across the world.

“This ‘phylogeny’ is important because it is the first that includes all living birds. It means we can ask questions about biodiversity and evolution on a global scale and gain new insight into how diversity has changed over millions of years as well as understand those changes. More widely, one way in which the phylogeny can be used, and which may not be obvious, is in helping to prioritise conservation efforts.

“We can identify where species at greatest risk of extinction are on the tree and ask how much distinct evolutionary history they represent. Some species have many close relatives and represent a small amount of distinct evolutionary history whereas others have few close relatives and their loss would represent the disappearance of vast amounts of evolutionary history that could never be recovered. Environmental change has very likely affected diversification over time. Climate change could be a part of that through its effects on the extent of different types of habitat.”

The paper - titled ‘The global diversity of birds in space and time’ – is published in the journal Nature.

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Additional information

The University of Sheffield

With nearly 25,000 students from 125 countries, the University of Sheffield is one of the UK’s leading and largest universities. A member of the Russell Group, it has a reputation for world-class teaching and research excellence across a wide range of disciplines. The University of Sheffield has been named University of the Year in the Times Higher Education Awards for its exceptional performance in research, teaching, access and business performance. In addition, the University has won four Queen’s Anniversary Prizes (1998, 2000, 2002, and 2007).

These prestigious awards recognise outstanding contributions by universities and colleges to the United Kingdom’s intellectual, economic, cultural and social life. Sheffield also boasts five Nobel Prize winners among former staff and students and many of its alumni have gone on to hold positions of great responsibility and influence around the world. The University’s research partners and clients include Boeing, Rolls-Royce, Unilever, Boots, AstraZeneca, GSK, ICI, Slazenger, and many more household names, as well as UK and overseas government agencies and charitable foundations.

The University has well-established partnerships with a number of universities and major corporations, both in the UK and abroad. Its partnership with Leeds and York Universities in the White Rose Consortium has a combined research power greater than that of either Oxford or Cambridge.

Project Sunshine

A major focus of Science research in Sheffield is on meeting the increasing food and energy needs of the world’s population in the context of an uncertain climate and global environment change. This challenge is being met through Project Sunshine, which unites scientists across the traditional boundaries in both the pure and applied sciences.

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Exhaustive family tree for birds shows recent, rapid diversification

October 31, 2012

A Yale-led scientific team has produced the most comprehensive family tree for birds to date, connecting all living bird species — nearly 10,000 in total — and revealing surprising new details about their evolutionary history and its geographic context.

Analysis of the family tree shows when and where birds diversified — and that birds’ diversification rate has increased over the last 50 million years, challenging the conventional wisdom of biodiversity experts.

“It’s the first time that we have — for such a large group of species and with such a high degree of confidence — the full global picture of diversification in time and space,” said biologist Walter Jetz of Yale, lead author of the team’s research paper, published Oct. 31 online in the journal Nature.

He continued: “The research highlights how heterogeneously fast diversifying species groups are distributed throughout the family tree and over geographic space. Many parts of the globe have seen a variety of species groups diversify rapidly and recently. All this leads to a diversification rate in birds that has been increasing over the past 50 million years.”

The researchers relied heavily on fossil and DNA data, combining them with geographical information to produce the exhaustive family tree, which includes 9,993 species known to be alive now.

“The current zeitgeist in biodiversity science is that the world can fill up quickly,” says biologist and co-author Arne Mooers of Simon Fraser University in Canada. “A new distinctive group, like bumblebees or tunafish, first evolves, and, if conditions are right, it quickly radiates to produce a large number of species. These species fill up all the available niches, and then there is nowhere to go. Extinction catches up, and things begin to slow down or stall. For birds the pattern is the opposite: Speciation is actually speeding up, not slowing down.”

The researchers attribute the growing rate of avian diversity to an abundance of group-specific adaptations. They hypothesize that the evolution of physical or behavioral innovations in certain groups, combined with the opening of new habitats, has enabled repeated bursts of diversification. Another likely factor has been birds’ exceptional mobility, researchers said, which time and again has allowed them to colonize new regions and exploit novel ecological opportunities.

In their analysis, the researchers also expose significant geographic differences in diversification rates. They are higher in the Western Hemisphere than in the Eastern, and higher on islands than mainlands. But surprisingly, they said, there is little difference in rates between the tropics and high latitudes. Regions of especially intense recent diversification include northern North American and Eurasia and southern South America.

“This was one of the big surprises,” Jetz said. “For a long time biologists have thought that the vast diversity of tropical species must at least partly be due to greater rates of net species production there. For birds we find no support for this, and groups with fast and slow diversification appear to occur there as much as in the high latitudes. Instead, the answer may lie in the tropics’ older age, leading to a greater accumulation of species over time. Global phylogenies like ours will allow further tests of this and other basic hypotheses about life on Earth.”

Other authors are G.H. Thomas of the University of Bristol in the United Kingdom; J.B. Joy of Simon Fraser University in Canada; and K. Hartmann of the University of Tasmania in Australia.

The work was supported by the National Science Foundation, NASA, the Natural Environment Research Council (U.K), the Natural Sciences and Engineering Research Council of Canada, Simon Fraser University, and the Yale Institute of Biospheric Studies.

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Yale University

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Sheffield University, & Yale University (2012).
''Evolution and diversification of living birds''
a collection of two articles :
First ever family tree for all living birds reveals evolution and diversification  SHEFFIELD University
Exhaustive family tree for birds shows recent, rapid diversification
YALE University

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