title: Group-level events are catalysts in the evolution of cooperation.
abstract: Group-level events, like fission and extinction, catalyze the evolution of cooperation in group-structured populations by creating new paths from uncooperative population states to more cooperative states. Group-level events allow cooperation to thrive under unfavorable conditions such as low intra-group assortment and moderate rates of migration, and can greatly speed up the evolution of cooperation when conditions are more favorable. The time-dependent effects of fission and extinction events are studied and illustrated here using a PDE model of a group-structured population based loosely on populations of hunter-gatherer tribes. By solving the PDE numerically we can compare models with and without group-level events, and explicitly calculate quantities associated with dynamics, like how long it takes a small population of cooperators to become a majority, as well as equilibrium population densities.
authors.affiliation: Department of Mathematical and Statistical Sciences, University of Colorado Denver, United States. Electronic address: burt.simon@ucdenver.edu.
authors.forename: Burton
authors.initials: B
authors.lastname: Simon
authors.affiliation: Department of Mathematical and Statistical Sciences, University of Colorado Denver, United States. Electronic address: michael.pilosov@ucdenver.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Pilosov
mesh_terms: D005075:Biological Evolution; D008954:Models, Biological
keywords: Associative splitting; Group extinction; Group fission; Group selection; Group-structured populations; Hunter-gatherer model; Population assortment; Population dynamics; Selective extinction