The evolution of cooperation by the Hankshaw effect

Authored by Sarah P Hammarlund, Brian D Connelly, Katherine J Dickinson, Benjamin Kerr

Date Published: 2016

DOI: 10.1111/evo.12928

Sponsors: United States National Science Foundation (NSF)

Platforms: Python

Model Documentation: Other Narrative Mathematical description

Model Code URLs: https://figshare.com/articles/Model_Data_and_Analysis_Scripts_for_The_Evolution_of_Cooperation_by_the_Hankshaw_Effect/2056563

Abstract

The evolution of cooperationcostly behavior that benefits othersfaces one clear obstacle. Namely, cooperators are always at a competitive disadvantage relative to defectors, individuals that reap the benefits, but evade the cost of cooperation. One solution to this problem involves genetic hitchhiking, where the allele encoding cooperation becomes linked to a beneficial mutation, allowing cooperation to rise in abundance. Here, we explore hitchhiking in the context of adaptation to a stressful environment by cooperators and defectors with spatially limited dispersal. Under such conditions, clustered cooperators reach higher local densities, thereby experiencing more mutational opportunities than defectors. Thus, the allele encoding cooperation has a greater probability of hitchhiking with alleles conferring stress adaptation. We label this probabilistic enhancement the Hankshaw effect after the character Sissy Hankshaw, whose anomalously large thumbs made her a singularly effective hitchhiker. Using an agent-based model, we reveal a broad set of conditions that allow the evolution of cooperation through this effect. Additionally, we show that spite, a costly behavior that harms others, can evolve by the Hankshaw effect. While in an unchanging environment these costly social behaviors have transient success, in a dynamic environment, cooperation and spite can persist indefinitely.

Tags

Adaptation selection ecology niche construction Altruism Prisoners-dilemma Life-history Pseudomonas-aeruginosa Bacterial-populations Species range