{"title":"Discovery of a novel ejaculation mechanism in danceflies (Diptera: Empididae), with implications for genital elongation","authors":"Tomoki Hirose, Kazunori Yoshizawa","doi":"10.1007/s00114-024-01938-0","DOIUrl":null,"url":null,"abstract":"<div><p>Genitalia are known to evolve rapidly and are among the most variable structures in insect morphology, making them a target of active research. However, function and evolutionary significance of internal genital structures remain less well understood. Here, we report the morphology and mechanism of a novel ejaculatory system that has evolved in the dancefly genus <i>Rhamphomyia</i> (Insecta: Diptera: Empididae). Using synchrotron µCT technology, we examined the male genitalia of five dancefly species and identified an ejaculatory system resembling a leverage hydraulic jack, which is thought to have derived from a plunger-like pumping system. This jacking system amplifies the applied muscle power by up to 4.2 times, allowing the system to produce the same pumping power with much smaller muscles. However, the volume of the pumping muscle in the jacking system is comparable to that of the plunger system, indicating a significant increase in ejaculation power in this genus. We hypothesize that the greater pumping power evolved through sexual selection favoring strong ejaculation to rapidly pass semen through a thin and elongated phallus and spermathecal duct.</p></div>","PeriodicalId":794,"journal":{"name":"The Science of Nature","volume":null,"pages":null},"PeriodicalIF":2.1000,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Science of Nature","FirstCategoryId":"6","ListUrlMain":"https://link.springer.com/article/10.1007/s00114-024-01938-0","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MULTIDISCIPLINARY SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Genitalia are known to evolve rapidly and are among the most variable structures in insect morphology, making them a target of active research. However, function and evolutionary significance of internal genital structures remain less well understood. Here, we report the morphology and mechanism of a novel ejaculatory system that has evolved in the dancefly genus Rhamphomyia (Insecta: Diptera: Empididae). Using synchrotron µCT technology, we examined the male genitalia of five dancefly species and identified an ejaculatory system resembling a leverage hydraulic jack, which is thought to have derived from a plunger-like pumping system. This jacking system amplifies the applied muscle power by up to 4.2 times, allowing the system to produce the same pumping power with much smaller muscles. However, the volume of the pumping muscle in the jacking system is comparable to that of the plunger system, indicating a significant increase in ejaculation power in this genus. We hypothesize that the greater pumping power evolved through sexual selection favoring strong ejaculation to rapidly pass semen through a thin and elongated phallus and spermathecal duct.
期刊介绍:
The Science of Nature - Naturwissenschaften - is Springer''s flagship multidisciplinary science journal. The journal is dedicated to the fast publication and global dissemination of high-quality research and invites papers, which are of interest to the broader community in the biological sciences. Contributions from the chemical, geological, and physical sciences are welcome if contributing to questions of general biological significance. Particularly welcomed are contributions that bridge between traditionally isolated areas and attempt to increase the conceptual understanding of systems and processes that demand an interdisciplinary approach.