21 EFTA02690250 Page 7 of 9 Submitted to Biology Letters 1 Jacques, Haunt, Traulsen, & Milinski 2 3 3 Ostrom, E. 1990 Governing the Commons: The Evolution of Institutions for Collective Action 4 5 6 Cambridge, United Kingdom: Cambridge University Press. 7 8 4 Hardin, G. 1968 The tragedy of the commons Science 162, 1243. 9 10 5 Wat