Delayed male maturity is a cost of producing large sperm in Drosophila.

TLDR

Drosophila species exhibit extreme sperm length variation, with some producing sperm over ten times body length, and many males experience a prolonged nonreproductive adult phase. We measured sperm length, body size, and sex‑specific reproductive maturity ages across 42 Drosophila species and tested phylogeny‑controlled hypotheses on sexual maturation rates. We discuss a physiological mechanism linking long sperm production to delayed male maturity. Our results indicate that delayed male maturity is a cost of producing long sperm.

Abstract

Among fruit-fly species of the genus Drosophila there is remarkable variation in sperm length, with some species producing gigantic sperm (e.g., > 10 times total male body length). These flies are also unusual in that males of some species exhibit a prolonged adult nonreproductive phase. We document sperm length, body size, and sex-specific ages of reproductive maturity for 42 species of Drosophila and, after controlling for phylogeny, test hypotheses to explain the variation in rates of sexual maturation. Results suggest that delayed male maturity is a cost of producing long sperm. A possible physiological mechanism to explain the observed relationship is discussed.