Timeshare nests
The researchers studied petrels at the the Galapagos Islands
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Sunday, 14, Oct 2007 03:07
It is not just humans who take advantage of timeshare properties abroad but certain species of animals as well, scientists claim.
A team from Queen's University, California, discovered that different birds can breed in the same nests at different times of the year.
They say this proves Charles Darwin's theory of evolution that species can arise, unhindered, in the same place.
The team studied a small seabird, the band-rumped storm petrel, which nests on desert islands in the tropics and sub-tropics.
They found that one set of petrels will breed in burrows, raise their chicks, and leave for the winter. A different set will then move in and repeat the breeding pattern before leaving when the season changes again.
"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," said Dr Vicki 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."
After observing the 'timeshare' nest habits of the petrels, the researchers studied DNA samples from birds breeding in the Azores, Madeira, Cape Verde and the Galapagos.
This revealed that petrels breeding in different seasons but from the same burrows differed genetically.
Writing in the journal Proceedings of the National Academy of Science (PNAS), the researchers say that the seasonal species had not bred with each other for periods ranging from around 1,000 to 180,000 years.
"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," said Dr Friesen.
"It's also exciting to be able to verify Darwin's original theory."