Evolutionary Dynamics and Genomic Impact of Prokaryote Transposable Elements

Transposable elements (TEs) are one of the major forces that drive prokaryote genome evolution. Analyses of TE evolutionary dynamics revealed extensive variability in TE density between prokaryote genomes, even closely related ones. To explain this variability, a model of recurrent invasion/proliferation/extinction cycles has been proposed. In this chapter, we examine different parameters that influence these cycles in two of the simplest TE classes: insertion sequences and group II introns. In particular, we discuss TE transposition efficiency (mechanisms and regulation), ability to transfer horizontally (through plasmids and phages), and impact on genome evolution (gene activation/inactivation and structural variation). Finally, we describe TE dynamics in bacterial endosymbionts, especially in Wolbachia, to illustrate the importance of host population size in prokaryote TE evolution.