Independent origin of sperm heteromorphism in the Drosophilidae

Sperm heteromorphism, the production multiple discrete sperm types (or \"morphs\"), occurs in diverse animal and plant taxa. This phenomenon represents a division of labor by male gametes, with one morph participating in fertilization and the other morph(s) specialized to perform some other reproductive function. One of the most intensively investigated systems is the Drosophila obscura species group, for which sperm heteromorphism evolved once in the common ancestor to the group, with all examined descendent species exhibiting sperm length heteromorphism. The absence of additional sperm heteromorphism origins among drosophilids has precluded comparative evolutionary analyses. Here, we report the discovery of a second origin within the Drosophilidae, with Chymomyza procnemis exhibiting the most extreme sperm length heteromorphism known (> 15-fold difference). Males produced and transferred to females approximately twice as many short sperm as long sperm. Shortly after insemination, fem..., , # Independent origin of sperm heteromorphism in the Drosophilidae

Dataset DOI: [10.5061/dryad.crjdfn3m1](https://doi.org/10.5061/dryad.crjdfn3m1)

## Description of the data and file structure

To quantify sperm morphometry and the production of heteromorphic sperm, the seminal vesicles of sexually mature males were dissected in phosphate-buffer saline (PBS) on subbed microscope slides. One seminal vesicle was then ruptured to release the contents, and fine pins were used to isolate individual sperm in the PBS. Preparations were then dried in a 60 °C oven, fixed in 3:1 methanol:acetic acid, treated with the blue-fluorescent DNA stain 4',6-diamidino-2-phenylindole (DAPI), then mounted with glycerol:PBS (9:1) with ProLong Gold Antifade (Thermo Fisher) under a glass coverslip and sealed with nail polish. Using an Olympus DP-71 camera mounted on an Olympus BX60 microscope (Olympus America Inc., Melville, NY), digital images of sperm heads were obtained using epifluorescence at 400X magnifi..., ,