Phenotypic and genomic analysis of P elements in natural populations of Drosophila melanogaster

TheDrosophila melanogaster Ptransposable element provides one of the best cases of horizontal transfer of a mobile DNA sequence in eukaryotes. Invasion of natural populations by thePelement has led to a syndrome of phenotypes known as “P-M hybrid dysgenesis” that emerges when strains differing in theirPelement composition mate and produce offspring. Despite extensive research on many aspects ofPelement biology, questions remain about the stability and genomic basis of variation in P-M dysgenesis phenotypes. Here we report the P-M status for a number of populations sampled recently from Ukraine that appear to be undergoing a shift in theirPelement composition. Gondal dysgenesis assays reveal that Ukrainian populations ofD. melanogasterare currently dominated by the P’ cytotype, a cytotype that was previously thought to be rare in nature, suggesting that a new active form of thePelement has recently spread in this region. We also compared gondal dysgenesis phenotypes and genomicPelement predictions for isofemale strains obtained from three worldwide populations ofD. melanogasterin order to guide further work on the molecular basis of differences in cytotype status across populations. We find that the number of euchromaticPelements per strain can vary significantly across populations but that totalPelement numbers are not strongly correlated with the degree of gondal dysgenesis. Our work shows that rapid changes in cytotype status can occur in natural populations ofD. melanogaster, and informs future efforts to decode the genomic basis of geographic and temporal differences inPelement induced phenotypes.