Removal of beneficial insertion effects prevent the long-term persistence of transposable elements within simulated asexual populations

Intracellular common gardens reveal niche differentiation in transposable element community during bacterial adaptive evolution

The distribution and abundance of transposable elements across the tree of life have significantly shaped the evolution of cellular organisms, but the underlying mechanisms shaping these ecological patterns remain elusive. Here we establish a "common garden" approach to study causal ecological interactions between a xenogeneic conditional lethal sacB gene and the community of transposable insertion sequences (ISs) in a multipartite prokaryote genome. Xenogeneic sacB of low, medium, or high GC content was individually inserted into three replicons of a model bacterium Sinorhizobium fredii, and exhibited replicon- and GC-dependent variation in genetic stability. This variation was largely attributable to multidimensional niche differentiation for IS community members. The transposition efficiency of major active ISs depended on the nucleoid-associated xenogeneic silencer MucR. Experimentally eliminating insertion activity of specific ISs by deleting MucR strongly demonstrated a dominant role of niche differentiation among ISs. This intracellular common garden approach in the experimental evolution context allows not only for evaluating genetic stability of natural and synthetic xenogeneic genes of different sequence signatures in host cells but also for tracking and testing causal relationships in unifying ecological principles in genome ecology.

Long-term TE persistence even without beneficial insertion

This correspondence responds to the critique by Butler et al. (BMC Genomics 22:241, 2021) of our recent paper on transposable element (TE) persistence. We address the three main objections raised by Butler et al. After running a series of additional simulations that were inspired by the authors’ criticisms, we are able to present a more nuanced understanding of the conditions that generate long-term persistence.