Germline proliferation trades off with lipid metabolism in Drosophila

Evolutionary theory predicts that energy allocation to reproduction occurs at the expense of investment into somatic maintenance and survival. Notably, lipids are thought to be a central energetic currency in which such "costs of reproduction" are paid but still little is understood about the underlying mechanisms. Previous work in the nematode worm and the fruit fly has found that loss of proliferating germ cells (and hence curtailed reproduction) alters hormonal signaling and extends lifespan; in the worm, germline removal also leads to excess fat stores. Here, we sought to test whether the lack of a proliferating germline in the fly also impacts fat metabolism as observed in the worm. Using gene expression and lipid measurements we show that-similar to the worm-germline-ablated flies exhibit profound changes in lipid metabolism and excess fat storage. Our findings confirm that lipids play a central role in mediating costs of reproduction and suggest that the regulatory principles governing reproductive trade-offs are evolutionarily conserved.