title: Cooperative boundary populations: the evolution of cooperation on mortality risk gradients.
abstract: Cooperative or altruistic behavior is known to be vulnerable to destructive exploitation in the absence of spatial segregation and perceptual discrimination on the part of cooperators. In this study, a non-standard, agent-based, spatially explicit model of the evolution of cooperation shows that spatial gradients of increasing individual mortality risk can allow cooperative subpopulations to persist among players randomly matched for one-shot Prisoner's Dilemma. Further, the dynamically stable cooperator population formed on the gradient at the boundary of the survivable non-cooperative range provides ideal conditions for the evolution of discriminating strategies such as tit-for-tat. It is suggested that such gradients may commonly exist at the boundaries of the ranges of existing populations, providing a new basic mechanism for the evolution of cooperation.
authors.affiliation: Centre for Applied Ethics, University of British Columbia, Vancouver, Canada. billharms@billharms.com
authors.forename: W
authors.initials: W
authors.lastname: Harms
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003198:Computer Simulation; D003299:Cooperative Behavior; D005716:Game Theory; D008954:Models, Biological; D009026:Mortality; D012306:Risk