アイテム詳細

要旨

Eukaryotes and prokaryotes have distinct genome architectures, withmarked differences in genome size, the ratio of coding/non-coding DNA,and the abundance of transposable elements (TEs). As TEs replicate inde-pendently of their hosts, the proliferation of TEs is thought to have drivengenome expansion in eukaryotes. However, prokaryotes also have TEs inintergenic spaces, so why do prokaryotes have small, streamlined genomes?Using anin silicomodel describing the genomes of single-celled asexualorganisms that coevolve with TEs, we show that TEs acquired from theenvironment by horizontal gene transfer can promote the evolution ofgenome streamlining. The process depends on local interactions and isunderpinned by rock–paper–scissors dynamics in which populations ofcells with streamlined genomes beat TEs, which beat non-streamlinedgenomes, which beat streamlined genomes, in continuous and repeatingcycles. Streamlining is maladaptive to individual cells, but improves lineageviability by hindering the proliferation of TEs. Streamlining does not evolvein sexually reproducing populations because recombination partially freesTEs from the deleterious effects they cause.This article is part of the theme issue‘The secret lives of microbial mobilegenetic elements’.