Cornell researchers have identified 544 genes that have been shaped by positive selection over millions of years of evolution by comparing the genomes of humans and five other mammals.
‘To our knowledge this is the largest and most comprehensive analysis of positive selection to date,’ write the researchers in the 1 August 2008 issue of the journal PLoS Genetics, reporting on research mainly funded by the National Science Foundation. Natural selection (favourable traits becoming more common over successive generations) that tends to favour new forms of genes is known as positive selection.
Previously, the Cornell group compared the genomes of humans, chimpanzees and the Rhesus macaque. By extending the analysis to mice, rats and dogs, the researchers were able to find 'stronger signals' of change by going back up to 80 million years on the evolutionary tree. Other studies have found signatures of positive selection using population genetics methods - comparing genomes across many members of the same species - but those focus on changes over just the last tens of thousands of years.
The researchers - including Adam Siepel, Cornell assistant professor, Carlos Bustamante, Cornell associate professor, both of biological statistics and computational biology, and Cornell postdoctoral researchers Carolin Kosiol and Tomas Vinar - used a high-performance computer cluster at the Cornell Center for Advanced Computing to study 16,500 human genes that are also found, with some differences, in at least two of the other five species.