Supporting data for: "A natural mechanism of eukaryotic horizontal gene transfer"

Horizontal gene transfer (HGT) is an important process impacting the evolutionary trajectory of eukaryotic species. Yet to date, the mechanism of HGT among eukaryotes has remained a mystery. Here, we demonstrate that <i>Starships</i>, a newly discovered group of cargo-mobilizing transposable elements, are active vectors of horizontally transferred DNA among eukaryotic species. We find that multiple <i>Starships</i> simultaneously transfer themselves and their cargo within and between fungal genera separated by upwards of 100 million years of evolution. Transferred <i>Starships</i> are recovered in strains with and without selection for particular <i>Starship</i>-encoded phenotypes. Using whole genome sequencing, we exclude alternative hypotheses such as heterokaryosis, parasex or the random uptake of exogenous DNA by showing that only <i>Starship </i>DNA is precisely transferred. Furthermore, we demonstrate that the introduction of the <i>Hephaestus</i> <i>Starship </i>into a new species increases metal resistance due to the genes carried by this element. Between 18-33% of all <i>Starships </i>in our focal genus, <i>Paecilomyces,</i> have evidence of horizontal transfer under natural conditions, including between fungal genera, revealing <i>Starship</i>-mediated HGT to be a widespread and frequent phenomenon across filamentous fungi. This study identifies the first active genetic mechanism for HGT between eukaryotic species.