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

Abstract

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 non-allelic 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 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 appear 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.

“Embryonic piRNAs target horizontally transferred vertebrate transposons in assassin bugs”

“…Since the discovery of horizontally transmitted P-elements in Drosophila species, a wealth of studies have reported the exchange of transposable elements between non-hybridizing insect species 5,12,34 . The piRNA pathway has been proposed to coordinate an adaptive defense mechanism against newly invading transposons 35 .…”

Horizontal transfer and the widespread presence of Galileo transposons in Drosophilidae (Insecta: Diptera)

“…Horizontal transposon transfer (HTT) is the phenomenon in which a given TE “jumps” to the genome of a non-closely related species, i.e., sexually isolated organisms ( Panaud, 2016 ). The role of HTT in shaping diversity as an endogenous source of evolution is widely recognized ( Pace et al, 2008 ; Gilbert and Feschotte, 2018 ; Carvalho et al, 2023 ), and its frequency is much higher than previously thought ( Schaack et al, 2010 ; Panaud, 2016 ; Peccoud et al, 2017 ; Melo and Wallau, 2020 ).…”