Gene Mobility and the Concept of Relatedness

Abstract

Social behaviour is widespread in the microbial world, yet social evolution theory was mostly developed with multicellular animals in mind. One difference between multicellular organisms and microbes is the prevalence of mobile genetic elements, such as plasmids, in microbial populations. Plasmids are often implicated in the production of so-called public goods, and relatedness may be at the heart of this phenomenon. However, gene mobility introduces a temporal aspect to relatedness: because genotypes can change over the life cycle, two bacteria may share a gene at one time point, but not at some earlier or later time point. This chapter argues that the best concept of relatedness in this context is a diachronic concept that captures the association between actor genotypes at the moment of gene expression and recipient genotypes at the end of the life cycle.