Post by warriorwitch on Jun 29, 2006 11:32:41 GMT
Great tits challenge evolutionary theory
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News
6 January 2005
A team of Oxford zoologists involved in the world’s longest continuous bird population study have shed new light on the evolution of one of Britain’s most common birds, the great tit. Researchers from the Edward Grey Institute of Field Ornithology (EGI) at the University of Oxford have discovered that contrary to standard evolutionary theory, wild birds living only a short distance apart are evolving differently.
Evolutionary theory predicts that the diversity of local animal population depends on a balance between two factors: the diversifying effect of selection and the homogenising effect upon the gene pool of dispersal. According to this theory, dispersal amongst the animal population in a small area will cancel out genetic variation. The Oxford team’s findings, published today in Nature, challenge this theory by demonstrating evolutionary differentiation amongst the great tit population of Wytham, Oxfordshire.
Researchers at the EGI have been studying great tits in Wytham, Oxfordshire, since 1947. For the purposes of this study, the researchers analysed the weight of nestlings at Wytham over a 36-year period. The team found that over time, birds in different parts of the same woodland had evolved in different directions, getting heavier in one part and lighter in another.
Professor Ben Sheldon, Luc Hoffmann Professor of Field Ornithology and Director of the EGI, led the study. He said: ‘Our data show that dispersal of birds is not a random process, and that evolutionary differentiation can be rapid and can occur over surprisingly small spatial scales. Our findings have important implications for questions of scale of adaptation and speciation, and challenge the usual treatment of dispersal as a force opposing evolutionary differentiation.’
The researchers expect that their findings could apply to animals in many different situations. ‘Human intervention has caused a mosaic of different habitats across the UK,’ Professor Sheldon commented. ‘This may lead to evolutionary differentiation within species, as animals with particular characteristics settle in the habitats that best suit them.’
For more information contact the Press Office on 01865 280528, or email press.office@admin.ox.ac.uk
Notes to Editors:
The paper, entitled ‘Evolution driven by differential dispersal within a wild bird population’ is published in Nature on 6 January 2005.
The Edward Grey Institute, established in 1938, is part of the Department of Zoology at the University of Oxford. It conducts research in behaviour, ecology, evolution and conservation of birds, with a strong emphasis on understanding organisms in their natural environments. For more information visit egizoosrv.zoo.ox.ac.uk/EGI/EGIhome.htm
Members of the EGI have been studying great tits in the woods at Wytham, Oxfordshire, since 1947. This is the longest continuous bird population study in the world. Studies of the great tit population at Wytham have allowed researchers to answer questions about the ecology and reproduction of wild birds, and to track the effects of climate change over time.
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