About the Authors
Department of Genetics, University of Cambridge, Cambridge, United Kingdom
The authors have declared that no competing interests exist.
The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: PGS SMD PH AMA. Performed the experiments: PGS SMD TB FWP PH AMA. Analyzed the data: PGS SMD TB FWP PH AMA. Contributed reagents/materials/analysis tools: PGS SMD TB FWP PH AMA. Wrote the paper: PGS SMD AMA.