1. Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada.
2. Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario M5S 3B2, Canada.
3. Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
4. The Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M3S 3E1, Canada.
5. Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada.
6. Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
7. Department of Computer Science, University of Toronto, Toronto, Ontario M5S 2E4, Canada.
8. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada.