Disrupting the disruptors: the consequences of mutations in mobile elements for ecologically important life history traits

Transposable elements are a nearly ubiquitous component of eukaryotic genomes. While often described as parasitic genetic elements, other evidence suggests that transposable elements can become domesticated and contribute to organismal function. There is little empirical data on the positive or negative contribution of transposable elements to organismal traits. We hypothesized that mutations in transposable element genes would have less deleterious effects than mutations in other plant genes. We conducted an assay of phenotypes associated with growth and reproduction in a collection of insertion mutation lines in Arabidopsis thaliana that disrupted the sequence of a transposable element gene. The transposable element loci were from locations dispersed across the genome, and included loci from several element families. Overall, we found that mutants in transposable element genes were similar to mutants in other types of loci for the measured traits, in most cases with a distribution of effects centered on life history trait values of wild-type plants critical to population ecology processes. If transposable elements are predominantly parasitic, their deleterious effects were not uncovered by these disruptive mutations. Further characterization of the positive, negative or neutral contribution of transposable element sequences would address unresolved questions about the contribution of transposition and selection to genome evolution.