Duke University evolutionary ecologists in Durham, N.C., are offering findings that might provide insight into how evolution operates.
The Duke study reports evidence that aggressive male western bluebirds out-compete less aggressive males for preferred breeding territories. In the process, lead researcher Renee Duckworth found more aggressive and milder-mannered birds also tended to breed in different settings that favor different body types.
"By selecting the environment in which they live, animals can actively affect the natural selection they experience," Duckworth said. "The main message of this study is that the ability of organisms to choose their environment needs to be made a more explicit part of evolutionary theory."
The full research appears online in the journal Proceedings of the Royal Society B.
Copyright 2006 by United Press International