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Syed ZA, Dallai R, Nasirzadeh N, Brill JA, O’Grady PM, Cong S, Leef EM, Rice S, Asif A, Nguyen S, Hansen MM, Dorus S, Pitnick S. Sperm Cyst "Looping": A Developmental Novelty Enabling Extreme Male Ornament Evolution. Cells 2021; 10:cells10102762. [PMID: 34685746 PMCID: PMC8534658 DOI: 10.3390/cells10102762] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 10/12/2021] [Accepted: 10/12/2021] [Indexed: 01/20/2023] Open
Abstract
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 Drosophila, 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 Drosophila. Here, we report on the discovery of a novel spermatogenic mechanism—sperm cyst looping—that enables males to produce relatively long sperm in short testis. This phenomenon (restricted to members of the saltans and willistoni species groups) begins early during spermatogenesis and is potentially attributable to heterochronic evolution, resulting in growth asynchrony between spermatid tails and the surrounding spermatid and somatic cyst cell membranes. By removing the allometric constraint on sperm length, this evolutionary innovation appears to have enabled males to evolve extremely long sperm for their body mass while evading delays in reproductive maturation time. On the other hand, sperm cyst looping was found to exact a cost by requiring greater total energetic investment in testes and a pronounced reduction in male lifespan. We speculate on the ecological selection pressures underlying the evolutionary origin and maintenance of this unique adaptation.
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Affiliation(s)
- Zeeshan A. Syed
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
- Correspondence: (Z.A.S.); (S.P.)
| | - Romano Dallai
- Department of Life Sciences, University of Siena, via Aldo Moro 2, 53100 Siena, Italy;
| | - Negar Nasirzadeh
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (N.N.); (J.A.B.)
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Julie A. Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; (N.N.); (J.A.B.)
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | | | - Siyuan Cong
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Ethan M. Leef
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Sarah Rice
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Amaar Asif
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Stephanie Nguyen
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Matthew M. Hansen
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Steve Dorus
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
| | - Scott Pitnick
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY 13244, USA; (S.C.); (E.M.L.); (S.R.); (A.A.); (S.N.); (M.M.H.); (S.D.)
- Correspondence: (Z.A.S.); (S.P.)
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