About the Authors

Martin Willensdorfer

To whom correspondence should be addressed. E-mail: ma.wi@gmx.at

Affiliations Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts, United States of America , Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America

Reinhard Bürger

Affiliations Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts, United States of America , Department of Mathematics, University of Vienna, Vienna, Austria

Martin A Nowak

Affiliations Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts, United States of America , Department of Mathematics, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

MW, RB, and MAN conceived and designed the experiments and wrote the paper. MW performed the experiments. MW and RB analyzed the data.