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(Bio) Bird Flies 2.5K Miles for Baby's Food (Bird)
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adedios
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Joined: 06 Jul 2005
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Location: Angel C. de Dios

PostPosted: Thu Nov 01, 2007 11:25 am    Post subject: Ancient and Modern Condors Co-Existed, Fossils Suggest Reply with quote

Ancient and Modern Condors Co-Existed, Fossils Suggest
By Andrea Thompson, LiveScience Staff Writer

posted: 01 November 2007 08:15 am ET

New comparisons of modern California condor bones to those found in Los Angeles’ La Brea Tar Pits show that two distinct species of these large vultures roamed the skies before the end of the last ice age, providing a compelling answer to a long-standing question.

At the end of the Pleistocene epoch about 10,000 years ago, when Earth was thawing out from the Ice Age, two types of condors competed over resources in what is now California, but it has been unclear if they were distinct species. The California condor seen in the skies today ultimately triumphed (though it is currently listed as Critically Endangered), while the others perished.

For the full article:

http://www.livescience.com/ani.....roots.html
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adedios
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Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Wed Nov 14, 2007 3:29 pm    Post subject: “Time-sharing” birds key to evolutionary mystery Reply with quote

“Time-sharing” birds key to evolutionary mystery
November 13, 2007
Queen's University

Whereas most birds are sole proprietors of their nests, some tropical species “time share” together – a discovery that helps clear up a 150-year-old evolutionary mystery, says Biology professor Vicki Friesen.

The Queen’s-led international study confirms one of Charles Darwin’s more controversial theories – first put forward in 1859 and since disputed by many experts – that different species can arise, unhindered, in the same place. Others believe that a geographic barrier such as a mountain or a river is required to produce two separate species. Although focused on how species change over time through natural selection, Darwin’s landmark book, The Origin of Species, also speculates that it is possible for different species to develop in the same place.

The team’s findings will appear in the international journal, Proceedings of the National Academy of Sciences (PNAS).

With PhD student Andrea Smith and an international team of researchers, Dr. Friesen studied a small seabird called the band-rumped storm petrel, which nests on desert islands in the tropics and sub-tropics. They observed that one set of petrels will breed in burrows, raise their chicks, and leave for the winter. Then a different set of birds moves in – similar to a vacation “time share” – and repeats the pattern in the very same burrows. When the season changes again, the first set of birds will return.

“We’re taught today that new species generally emerge as a result of a geographic barrier such as a mountain range or river, creating two separate populations that can’t easily move from one place to the other,” says Dr. Friesen, an expert in evolutionary biology. “While that model fits for many parts of the natural world, it doesn’t explain why some species appear to have evolved separately, within the same location, where there are no geographic barriers to gene flow.”

The evidence for this happening in certain types of plants, insects and fish has led to a number of scientific explanations, such as salmon spawning in the same location at different times of year. Until now, however, there have only been two documented cases that such a pattern might occur in birds, and no clear evidence as to how it happens in any warm-blooded creature.

Using DNA samples retrieved from birds breeding in the Azores, Madeira, Cape Verde and the Galapagos, the researchers determined that petrels breeding in different seasons but from the same burrows did indeed differ genetically. They also learned that the seasonal species had not bred with each other for periods ranging from around 1,000 to 180,000 years, providing a series of “time shots” of divergence, Dr. Friesen explains.

“This is important for us to know, not just as an explanation for how new species can arise, but also because biodiversity is part of a healthy ecosystem and each bird species is part of our natural heritage,” she says, noting that the European Union is now elevating the conservation status of band-rumped storm petrels.

“It’s also exciting to be able to verify Darwin’s original theory!” Dr. Friesen adds.

Other members of the research team include: Elena Gomez-Diaz and Jacob Gonzalez-Solis from the University of Barcelona; Mark Bolton and the late Luis Monteiro from the University of Azores; and Robert Furness from the University of Glasgow.

Among funders of the study are: the American Museum of Natural History, the American Ornithologists’ Union, the European Economic Union LIFE program, the Natural Sciences and Engineering Research Council of Canada, and Queen’s School of Graduate Studies.
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