Tracking a recent horizontal transfer event: The P-element reaches Brazilian populations of Drosophila simulans

The "cut-and-paste" P-element present in some Diptera illustrates two important transposable elements abilities: to move within genomes and to be transmitted between non-mating species, a phenomenon known as horizontal transposon transfer (HTT). Recent studies reported a HTT of the P-element from Drosophila melanogaster to D. simulans. P-elements first appeared in D. simulans European samples collected in 2006 and spread across several populations from Europe, Africa, North America and Japan within seven years. Nevertheless, no P-element was found in South American populations of D. simulans collected between 2002 and 2009. We investigated the presence of the P-element in D. simulans collected in five Brazilian localities between 2018 and 2019, using a combination of methodologies such as PCR, DNA sequencing and FISH on chromosomes. Our experiments revealed the presence of the P-element in all sampled individuals from the five localities. The number of P-elements per individual varied from 11 to 20 copies and truncated copies were also observed. Altogether, our results showed that P-element invasion in D. simulans is at an advanced stage in Brazil and, together with other recent studies, confirms the remarkable rapid invasion of P-elements across worldwide D. simulans populations.