A single-cell transcriptome analysis of rapidly evolving Drosophila male genitalia

One of the major challenges of evolutionary biology is to uncover the molecular mechanisms underlying morphological divergence. To address this question, we use a model system with a huge interspecific variety, Drosophila male genitalia. Male genitalia are among the most diverse and rapidly evolving organs in the animal kingdom, probably due to sexual selection. This trend extends to the model organism D. melanogaster and its close relatives, which display dramatic morphological differences that are predicted to contribute to reproductive success.

We focus on two closely related species, D. melanogaster and D. simulans, and the genetic and developmental basis of their morphological divergence. First, we generated 3D confocal microscopy images of the developing genitalia of both species at 8 different time points and demonstrated when the interspecific differences arise. Second, we performed a single-cell RNA sequencing on the D. melanogaster and D. simulans developing genitalia at the 3 most representative time points of mid pupal development and mapped the analyzed cells to different genital substructures. Thus, we revealed the expression profiles specific to each substructure in both species. These data will allow us to identify new genes that are involved in genitalia development and evolution, and the mutations that contributed to the morphological differences between these species.