"The similarities between the lice living in specific habitats on the bodies of birds are really striking," Johnson said. "But it appears that those similarities are the result of what we call 'convergent evolution': The lice independently arrived at the same, or similar, solutions to common ecological problems. This occurred only after they had colonized a particular type of bird."
In the new analysis, Johnson and his colleagues drew up two family trees of feather lice. The first tree grouped the lice according to physical traits; the second mapped their genetic relationships.
The two trees looked significantly different from one another, Johnson said. The genetic tree showed that different types of feather lice living on the same type of bird were often closely related, whereas lice that had evolved to survive on specific bird parts, such as the wing, were only distantly related across bird groups, he said.
The history of feather lice turns out to be a very robust example of convergent evolution, Johnson said.
"Here we see how evolution repeats itself on different bird types," he said. "The lice are converging on similar solutions to the problem of survival in different microhabitats on the bird."
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign