Brinkmanship in intragenomic conflict.

Abstract

When the Darwinian interests of genes in the genome collide, intragenomic conflicts evolve. Recent advances in social evolution predict that intragenomic conflicts shape diverse phenotypes. However, principles governing which side wins remain unresolved. Here, we use game theory to predict that power asymmetries arise from differences in appetite for risk between rival genes in 'wars of nerve'. We focus on 'genomic imprinting': differing expression between alleles inherited from mothers and fathers. Escalating conflict is commonly believed to risk damaging the whole organism. We show that genes can exploit risk strategically: genes prepared to take greater risks with the body's vulnerability to disorders and mortality gain coercive advantages, deterring countermoves. Kin selection generates differences in appetite for risk: for instance, if harm to the body frees resources for maternal siblings, genes from mothers have less to lose from gambling with the current body than do genes from fathers. Seemingly maladaptive developmental risks can be adaptively useful for higher-nerve genes, much as political states manipulate risk to coerce rivals. Our results suggest a determinant of power alongside the 'loudest voice prevails' principle, and call for empirical investigation of the extent and means by which risks of imprinting-related disorders are amplified by intragenomic brinkmanship.