Molecular identification of polymorphic transposable elements in populations of the invasive ant cardiocondyla obscurior

Transposable elements (TEs) are found in virtually every eukaryotic genome and are important for generating de novo genetic variation. However, outside of costly and time-consuming whole-genome sequencing approaches, the set of available methods to study TE polymorphisms in non-model species is very limited. The Transposon Display (TD) is a simple yet effective technique to characterize polymorphisms across samples by identifying amplified fragment length polymorphisms using primers targeting specific TE families. So far, this technique has almost exclusively been used in plants. Here, we present an optimized TD protocol for insect species with small genomes such as ants (ca. 200-600 Mb). We characterized TE polymorphisms between two distinct genetic lineages of the invasive ant Cardiocondyla obscurior, as well as between neighboring populations of the New World lineage. We found active LTR/Ty3 retrotransposons, that contributed to the genetic diversification of populations in this species.