March 16, 2010

Humans Alter Wings of Songbirds

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It’s almost impossible to think of evolution without thinking about birds. Since Charles Darwin traveled to the Galapagos Islands, where he studied the diversity of island finches, birds have fascinated scientists with their ability to adapt to surroundings.

A recent study of North American songbirds found that their wings have evolved into significantly pointier shapes in the past 100 years as a result of human influence in forests.  The study, which examined 851 specimens from 21 species at the Cornell Museum of Vertebrates and the Canadian Museum of Nature in Ottawa, was published in the journal Ecology on Feb 1.

Due to deforestation and clear-cutting, birds must travel further distances to find food, mates and nesting places. In order to fly the longer distances, birds, like the Cape May Warbler, developed aerodynamic, pointy wings.  Evolution may favor alternative wings, as well, and birds inhabiting highly dense forests throughout New England have developed relatively less pointy wings.

To research this, the Lab of Ornithology works on The Warbler Tree of Life project to map the evolution of the more than 100 species of wood warblers.  The lab is led by Prof. Irby Lovette, ecology and evolutionary biology, and it collaborates with various universities across the nation.

According to Lovette, the main goal of generating this evolutionary tree aims to clarify “our understanding of evolutionary relationships. For example, our research has already shown that a number of species of birds long considered to be warblers are not closely related to the ‘true’ warblers.”

The second goal of the tree, however, aims to conduct other types of evolutionary analysis, such as the current study of bird wings and deforestation.  According to the team at the Lab of Ornithology, in order to test the hypothesis that deforestation causes evolutionary changes in wing morphology, they require a good evolutionary tree.  With this tree, they believe that they may see when traits actually change over evolutionary time.

Original Author: Maria Minsker