Genome-wide patterns of transposon proliferation in an evolutionary young hybrid fish

Hybridization can induce transposons to jump into new genomic positions, which may result in their accumulation across the genome. Alternatively, transposon copy numbers may increase through non-allelic (ectopic) homologous recombination in highly repetitive regions of the genome. The relative contribution of transposition bursts versus recombination-based mechanisms to evolutionary processes remains unclear because studies on transposon dynamics in natural systems are rare. We assessed the genome-wide distribution of transposon insertions in a young hybrid lineage (“invasive Cottus”, n=11) and its parental species Cottus rhenanus (n=17) and Cottus perifretum (n=9) using a reference genome assembled from long single molecule PacBio reads. An inventory of transposable elements was reconstructed from the same data and annotated. Transposon copy numbers in the hybrid lineage increased in 120 (15.9%) out of 757 transposons studied here. The copy number increased on average by 69% (range: 10...