Horizontal Transposon Transfer and Their Ecological Drivers: The Case of Flower-breeding Drosophila

Understanding the mechanisms that shape the architecture, diversity, and adaptations of genomes and their ecological and genetic interfaces is of utmost importance to understand biological evolution. Transposable elements (TEs) play an important role in genome evolution, due to their ability to transpose within and between genomes, providing sites of nonallelic recombination. Here we investigate patterns and processes of TE-driven genome evolution associated with niche diversification. Specifically, we compared TE content, TE landscapes, and frequency of horizontal transposon transfers (HTTs) across genomes of flower-breeding Drosophila (FBD) with different levels of specialization on flowers. Further, we investigated whether niche breadth and ecological and geographical overlaps are associated with a potential for HTT rates. Landscape analysis evidenced a general phylogenetic pattern, in which species of the D. bromeliae group presented L-shaped curves, indicating recent transposition bursts, whereas D. lutzii showed a bimodal pattern. The great frequency of highly similar sequences recovered for all FBD suggests that these species probably experienced similar ecological pressures and evolutionary histories that contributed to the diversification of their mobilomes. Likewise, the richness of TEs superfamilies also appears to be associated with ecological traits. Furthermore, the two more widespread species, the specialist D. incompta and the generalist D. lutzii, presented the highest frequency of HTT events. Our analyses also revealed that HTT opportunities are positively influenced by abiotic niche overlap but are not associated with phylogenetic relationships or niche breadth. This suggests the existence of intermediate vectors promoting HTTs between species that do not necessarily present overlapping biotic niches.

Automated summary

Understanding the mechanisms that shape genomes and their interfaces is crucial for biological evolution. Transposable elements (TEs) play a significant role in genome evolution by providing sites for nonallelic recombination. In this study, the patterns and processes of TE-driven genome evolution related to niche diversification in flower-breeding Drosophila were investigated. The results showed that ecological traits and abiotic niche overlap influence TE content and horizontal transposon transfers (HTTs).