biostudies-literatureSyed ZANICHD NIH HHSNational Science FoundationCIHR2762https://www.ebi.ac.uk/biostudies/studies/S-EPMC8534658biostudies-literatureUnknown10(10)Postcopulatory sexual selection is credited as a principal force behind the rapid evolution of reproductive characters, often generating a pattern of correlated evolution between interacting, sex-specific traits. Because the female reproductive tract is the selective environment for sperm, one taxonomically widespread example of this pattern is the co-diversification of sperm length and female sperm-storage organ dimension. In <i>Drosophila</i>, having testes that are longer than the sperm they manufacture was believed to be a universal physiological constraint. Further, the energetic and time costs of developing long testes have been credited with underlying the steep evolutionary allometry of sperm length and constraining sperm length evolution in <i>Drosophila</i>. Here, we report on thCellsSperm Cyst "Looping": A Developmental Novelty Enabling Extreme Male Ornament Evolution.PMC8534658R21 HD088910DEB-1811805 and DEB-1655840PJT-173465Dallai RAsif ANguyen SHansen MMO'Grady PMNasirzadeh NPitnick SRice SDorus SBrill JACong SSyed ZALeef EMfalseSperm Cyst "Looping": A Developmental Novelty Enabling Extreme Male Ornament Evolution.Postcopulatory sexual selection is credited as a principal force behind the rapid evolution of reproductive characters, often generating a pattern of correlated evolution between interacting, sex-specific traits. Because the female reproductive tract is the selective environment for sperm, one taxonomically widespread example of this pattern is the co-diversification of sperm length and female sperm-storage organ dimension. In <i>Drosophila</i>, having testes that are longer than the sperm they manufacture was believed to be a universal physiological constraint. Further, the energetic and time costs of developing long testes have been credited with underlying the steep evolutionary allometry of sperm length and constraining sperm length evolution in <i>Drosophila</i>. Here, we report on th2021-01-01T00:00:00Z2021 Oct2026-06-10T03:11:35.838Z2025-04-21T21:56:16.763ZS-EPMC85346583468574610.3390/cells10102762