1
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Tröster M, Kotrba M, Heß M. Coevolution of spermatozoa and spermathecae in Lonchopteridae (Diptera). ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 82:101385. [PMID: 39265194 DOI: 10.1016/j.asd.2024.101385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Revised: 08/29/2024] [Accepted: 09/02/2024] [Indexed: 09/14/2024]
Abstract
Across the species of spear-winged flies (Diptera: Lonchopteridae) there is a remarkable variation in size of the female reproductive tract, especially of the spermathecae. In this family there are two tubular spermathecae, which are divided into four morphologically and histologically distinct sections of different lengths and functions. The dimensions of the spermathecae and their individual sections were examined across 11 Lonchoptera species and related to the dimensions of the respective spermatozoa. 3D reconstructions from serial sectioning made it possible to include the volume in these considerations, which is a new approach in this context. Results show that the spermathecae are always longer than the respective spermatozoa. There is a highly significant positive linear correlation between the length of the spermatozoa and the length of the spermathecae in total as well as some of the individual spermathecal sections, suggesting a coevolution of these characters. Moreover, the volume of the spermathecae is much larger in those species with longer and more voluminous spermatozoa, but the volume increase is not sufficient to keep constant the number of spermatozoa that fit within. The observed patterns are discussed with respect to their functional and evolutionary implications, including a new hypothesis on the possible selective advantage of increased spermatozoon length.
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Affiliation(s)
- Michael Tröster
- SNSB-Zoologische Staatssammlung München, Münchhausenstraße 21, D-81247, München, Germany; Ludwig-Maximilians-Universität, Biocenter, Großhaderner Straße 2, D-82152, Planegg-Martinsried, Germany.
| | - Marion Kotrba
- SNSB-Zoologische Staatssammlung München, Münchhausenstraße 21, D-81247, München, Germany
| | - Martin Heß
- Ludwig-Maximilians-Universität, Biocenter, Großhaderner Straße 2, D-82152, Planegg-Martinsried, Germany
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2
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Santhosh S, Ebert D, Janicke T. Sperm competition favours intermediate sperm size in a hermaphrodite1. J Evol Biol 2024; 37:829-838. [PMID: 38738700 DOI: 10.1093/jeb/voae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 04/22/2024] [Accepted: 05/10/2024] [Indexed: 05/14/2024]
Abstract
Sperm competition is a potent mechanism of postcopulatory sexual selection that has been found to shape reproductive morphologies and behaviours in promiscuous animals. Especially sperm size has been argued to evolve in response to sperm competition through its effect on sperm longevity, sperm motility, the ability to displace competing sperm, and ultimately fertilization success. Additionally, sperm size has been observed to co-evolve with female reproductive morphology. Theoretical work predicts that sperm competition may select for longer sperm but may also favour shorter sperm if sperm size trades-off with number. In this study, we studied the relationship between sperm size and postmating success in the free-living flatworm, Macrostomum lignano. Specifically, we used inbred isolines of M. lignano that varied in sperm size to investigate how sperm size translated into the ability of worms to transfer and deposit sperm in a mating partner. Our results revealed a hump-shaped relationship with individuals producing sperm of intermediate size having the highest sperm competitiveness. This finding broadens our understanding of the evolution of sperm morphology by providing empirical support for stabilizing selection on sperm size under sperm competition.
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Affiliation(s)
- Santhosh Santhosh
- Department of Environmental Sciences, Zoology, University of Basel, CH-4 4051 Basel, Switzerland
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, CH-4 4051 Basel, Switzerland
| | - Tim Janicke
- Centre d'Ecologie Fonctionelle et Evolutive, Univ. Montpellier, CNRS, EPHE, IRD, 34293 Montpellier Cedex 05, France
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3
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Dallai R, Mercati D, Lupetti P. The ultrastructure of the spermatheca of Mordellistena brevicauda (Coleoptera, Tenebrionoidea) and the associated bacterial cells. ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 80:101357. [PMID: 38669939 DOI: 10.1016/j.asd.2024.101357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/08/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024]
Abstract
The ultrastructural study on the female reproductive system of the beetle M. brevicauda (Mordellidae) confirmed the positive correlation between the length of the sperm and the size of the female seminal receptacle (Spermatheca). The spermatheca of the species is characterized by an apical bulb-like structure where the spermathecal duct forms numerous folds filled with sperm. At this level many bacterial cells are present intermingled with the duct folds. Some are organized in large structures, such as bacteriomes, while other are single bacteriocytes. The latter are often found near the basal lamina of duct epithelium. In addition, some bacteria are visible in the cytoplasm of the duct epithelial cells. Interestingly, bacterial cells have never been observed in the duct lumen. The possible function of the bacterial cells is discussed.
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Affiliation(s)
- Romano Dallai
- Department of Life Sciences, University of Siena, Siena, Italy.
| | - David Mercati
- Department of Life Sciences, University of Siena, Siena, Italy.
| | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Siena, Italy.
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4
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Seth RK, Yadav P, Reynolds SE. Dichotomous sperm in Lepidopteran insects: a biorational target for pest management. FRONTIERS IN INSECT SCIENCE 2023; 3:1198252. [PMID: 38469506 PMCID: PMC10926456 DOI: 10.3389/finsc.2023.1198252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/31/2023] [Indexed: 03/13/2024]
Abstract
Lepidoptera are unusual in possessing two distinct kinds of sperm, regular nucleated (eupyrene) sperm and anucleate (apyrene) sperm ('parasperm'). Sperm of both types are transferred to the female and are required for male fertility. Apyrene sperm play 'helper' roles, assisting eupyrene sperm to gain access to unfertilized eggs and influencing the reproductive behavior of mated female moths. Sperm development and behavior are promising targets for environmentally safer, target-specific biorational control strategies in lepidopteran pest insects. Sperm dimorphism provides a wide window in which to manipulate sperm functionality and dynamics, thereby impairing the reproductive fitness of pest species. Opportunities to interfere with spermatozoa are available not only while sperm are still in the male (before copulation), but also in the female (after copulation, when sperm are still in the male-provided spermatophore, or during storage in the female's spermatheca). Biomolecular technologies like RNAi, miRNAs and CRISPR-Cas9 are promising strategies to achieve lepidopteran pest control by targeting genes directly or indirectly involved in dichotomous sperm production, function, or persistence.
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Affiliation(s)
- Rakesh K. Seth
- Department of Zoology, University of Delhi, Delhi, India
| | - Priya Yadav
- Department of Zoology, University of Delhi, Delhi, India
| | - Stuart E. Reynolds
- Department of Life Sciences, University of Bath, Bath, United Kingdom
- Milner Centre for Evolution, University of Bath, Bath, United Kingdom
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5
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Dallai R, Mercati D, Fanciulli PP, Lupetti P. The Structure of the Female Genital System of the Diving Beetle Scarodytes halensis (Fabricius, 1787) (Hydroporinae, Dytiscidae), and the Organization of the Spermatheca and the Spermathecal Gland Complex. INSECTS 2023; 14:insects14030282. [PMID: 36975967 PMCID: PMC10053596 DOI: 10.3390/insects14030282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 05/29/2023]
Abstract
The fine structure of the female reproductive organs of the diving beetle Scarodytes halensis has been described, with particular attention to the complex organization of the spermatheca and the spermathecal gland. These organs are fused in a single structure whose epithelium is involved in a quite different activity. The secretory cells of the spermathecal gland have a large extracellular cistern with secretions; duct-forming cells, by their efferent duct, transport the secretions up to the apical cell region where they are discharged into the gland lumen. On the contrary, the spermatheca, filled with sperm, has a quite simple epithelium, apparently not involved in secretory activity. The ultrastructure of the spermatheca is almost identical to that described in a closely related species Stictonectes optatus. Sc. halensis has a long spermathecal duct connecting the bursa copulatrix to the spermatheca-spermathecal gland complex. This duct has a thick outer layer of muscle cells. Through muscle contractions, sperm can be pushed forwarding up to the complex of the two organs. A short fertilization duct allows sperm to reach the common oviduct where eggs will be fertilized. The different organization of the genital systems of Sc. halensis and S. optatus might be related to a different reproductive strategy of the two species.
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6
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Gomez RA, Mercati D, Lupetti P, Fanciulli PP, Dallai R. Morphology of male and female reproductive systems in the ground beetle Apotomus and the peculiar sperm ultrastructure of A. rufus (P. Rossi, 1790) (Coleoptera, Carabidae). ARTHROPOD STRUCTURE & DEVELOPMENT 2023; 72:101217. [PMID: 36327949 DOI: 10.1016/j.asd.2022.101217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
Relatively few studies have focused on evolutionary losses of sexually selected male traits. We use light and electron microscopy to study the male and female reproductive anatomy of Apotomus ground beetles (Coleoptera, Carabidae), a lineage that we reconstruct as likely having lost sperm conjugation, a putative sexually selected trait. We pay particular attention to the structure of the testes and spermatheca. Both of these organs share a strikingly similar shape-consisting of long blind canals arranged into several concentric overlapping rings measuring approximately 18 mm and 19.5 mm in total length, respectively. The similarity of these structures suggests a positive evolutionary correlation between female and male genital organs. Males are characterized by unifollicular testes with numerous germ cysts, which contain 64 sperm cells each, and we record a novel occurrence of sperm cyst "looping", a spermatogenic innovation previously only known from some fruit fly and Tenebrionid beetle sperm. The sperm are very long (about 2.7 mm) and include an extraordinarily long helicoidal acrosome, a short nucleus, and a long flagellum. These findings confirm the structural peculiarity of sperm, testis, and female reproductive tract (FRT) of Apotomus species relative to other ground beetles, which could possibly be the result of shifts in sexual selection.
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Affiliation(s)
- R Antonio Gomez
- Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, NY, USA.
| | - David Mercati
- Department of Life Sciences, University of Siena, Italy.
| | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Italy.
| | | | - Romano Dallai
- Department of Life Sciences, University of Siena, Italy.
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7
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Vrech DE, Peretti AV, Prendini L, Mattoni CI. Bundles of Sperm: Structural Diversity in Scorpion Sperm Packages Illuminates Evolution of Insemination in an Ancient Lineage. AMERICAN MUSEUM NOVITATES 2022. [DOI: 10.1206/3993.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- David E. Vrech
- Laboratorio de Biología Reproductiva y Evolución, Instituto de Diversidad y Ecología Animal, CONICET – FCEFyN, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Alfredo V. Peretti
- Laboratorio de Biología Reproductiva y Evolución, Instituto de Diversidad y Ecología Animal, CONICET – FCEFyN, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Lorenzo Prendini
- Arachnology Lab and Scorpion Systematics Research Group, Division of Invertebrate Zoology, American Museum of Natural History, New York
| | - Camilo I. Mattoni
- Laboratorio de Biología Reproductiva y Evolución, Instituto de Diversidad y Ecología Animal, CONICET – FCEFyN, Universidad Nacional de Córdoba, Córdoba, Argentina
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8
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Sasakawa K. Possible differences in effects on ejaculate morphology between shape and size components of the intromittent membranous part of insect male genitalia: Phylogenetic comparative analyses in Carabidae. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1032378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Male genitalia exhibit extreme morphological diversity among animals, but its diversification mechanism has not been fully elucidated. In insects, the intromittent membranous part has been barely studied. This study performed phylogenetic comparative analysis to examine the morphological associations between the intromittent membranous part (endophallus) and ejaculate characteristics in two Carabidae taxa with different endophallus diversification patterns (genus Amara and tribe Pterostichini). Endophallus morphology was analyzed using geometric morphometrics, whereby effects of shape and size components can be evaluated separately. In both taxa, no morphological associations were found between spermatophore and endophallus traits, but an association was detected between conjugated sperm length and endophallus shape. Considering the available information regarding functional morphology, the association between conjugated sperm length and endophallus shape may indicate a physical interaction between conjugated sperm and the endophallus through the spermatophore. The similarity of results between the two taxa implies functional equivalence among different endophallus types. Concerning individual sperm, several results were detected, but functional interpretation was difficult. Overall, these results imply that shape and size have different effects on ejaculate morphology, with a larger effect of shape than size. This pattern is consistent with previous results for non-intromittent and intromittent sclerotized parts, and the diversification mechanism of the intromittent membranous part may be similar to those of non-intromittent and intromittent sclerotized parts.
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9
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Laugen AT, Hosken DJ, Reinhold K, Schwarzenbach GA, Hoeck PEA, Bussière LF, Blanckenhorn WU, Lüpold S. Sperm competition in yellow dung flies: No consistent effect of sperm size. J Evol Biol 2022; 35:1309-1318. [PMID: 35972882 DOI: 10.1111/jeb.14073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 01/07/2023]
Abstract
The male competition for fertilization that results from female multiple mating promotes the evolution of increased sperm numbers and can impact sperm morphology, with theory predicting that longer sperm can at times be advantageous during sperm competition. If so, males with longer sperm should sire more offspring than competitors with shorter sperm. Few studies have directly tested this prediction, and findings are inconsistent. Here we assessed whether longer sperm provide a competitive advantage in the yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae). Initially, we let brothers with different temperature-mediated mean sperm lengths compete - thus minimizing confounding effects of genetic background - and found no clear advantage of longer sperm. We then used flies from lines subjected to bidirectional selection on phenoloxidase activity that had shown correlated evolutionary responses in sperm and female spermathecal duct lengths. This experiment also yielded no main effect of sperm size on siring success. Instead, there was a trend for a shorter-sperm advantage, but only when competing in females with longer spermathecal ducts. Our data corroborated many previously reported findings (last-male precedence, effects of copula duration and body size), suggesting our failure to find sperm size effects is not inherently due to our experimental protocols. We conclude that longer sperm are not competitively superior in yellow dung flies under most circumstances, and that, consistent with previous work, in this species competitive fertilization success is primarily determined by the relative numbers of sperm competing.
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Affiliation(s)
- Ane T Laugen
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Centre for Coastal Research, Department of Natural Sciences, University of Agder, Kristiansand, Norway
| | - David J Hosken
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Centre for Ecology and Conservation, University of Exeter in Cornwall, Penryn, UK
| | - Klaus Reinhold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Evolutionsbiologie, Universität Bielefeld, Bielefeld, Germany
| | - Gioia A Schwarzenbach
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Paquita E A Hoeck
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Luc F Bussière
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland.,Biology and Environmental Sciences, University of Gothenburg and Gothenburg Global Biodiversity Centre, Gothenburg, Sweden
| | - Wolf U Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Zurich, Switzerland
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10
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Farrow RA, Deeming DC, Eady PE. Male and female developmental temperature modulate post-copulatory interactions in a beetle. J Therm Biol 2022; 103:103155. [PMID: 35027191 DOI: 10.1016/j.jtherbio.2021.103155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/26/2021] [Accepted: 11/30/2021] [Indexed: 10/19/2022]
Abstract
Sexual selection theory has proven to be fundamental to our understanding of the male-female (sperm-egg) interactions that characterise fertilisation. However, sexual selection does not operate in a void and abiotic environmental factors have been shown to modulate the outcome of pre-copularory sexual interactions. Environmental modulation of post-copulatory interactions are particularly likely because the form and function of primary reproductive traits appears to be acutely sensitive to temperature stress. Here we report the effects of developmental temperature on female reproductive architecture and the interaction between male and female developmental temperature on the outcome of sperm competition in the bruchid beetle Callosobruchus maculatus. When females were reared at developmental temperatures above and below typical temperatures the bursa copulatrix (site of spermatophore deposition) were smaller and, were either shorter and broader (high temperatures) or longer and thinner (low temperatures) than those reared at intermediate temperatures. Males and females reared at low developmental temperatures were less likely to mate than those reared at higher temperatures. Where copulation occurred, females reared at the highest temperature copulated for longest, whilst males reared at the lowest temperature spent longer in copula. Male developmental temperature had a significant impact on the outcome of sperm competition: males reared at 17 °C were largely unsuccessful in sperm competition against control (27 °C) males, although some of the variation in the outcome of sperm competition was a product of the interaction between male and female developmental temperature. Our results demonstrate that male-female interactions that characterise pre- and post-copulatory outcomes are sensitive to developmental temperature and that plasticity in cryptic female preferences could lead to heterogeneous selection on the male reproductive phenotype.
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Affiliation(s)
- Rachel A Farrow
- Foundation Studies Centre, Janet Lane-Claypon Building, University of Lincoln, LN6 7TS, UK
| | - D Charles Deeming
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Lincoln, LN6 7DL, UK
| | - Paul E Eady
- Joseph Banks Laboratories, School of Life Sciences, University of Lincoln, Lincoln, LN6 7DL, UK.
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11
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Fertilization mode drives sperm length evolution across the animal tree of life. Nat Ecol Evol 2021; 5:1153-1164. [PMID: 34155385 DOI: 10.1038/s41559-021-01488-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 05/12/2021] [Indexed: 01/08/2023]
Abstract
Evolutionary biologists have endeavoured to explain the extraordinary diversity of sperm morphology across animals for more than a century. One hypothesis to explain sperm diversity is that sperm length is shaped by the environment where fertilization takes place (that is, fertilization mode). Evolutionary transitions in fertilization modes may transform how selection acts on sperm length, probably by affecting postcopulatory mechanisms of sperm competition and the scope for cryptic female choice. Here, we address this hypothesis by generating a macro-evolutionary view of how fertilization mode (including external fertilizers, internal fertilizers and spermcasters) influences sperm length diversification among 3,233 species from 21 animal phyla. We show that sperm are shorter in species whose sperm are diluted in aquatic environments (that is, external fertilizers and spermcasters) and longer in species where sperm are directly transferred to females (that is, internal fertilizers). We also show that sperm length evolves faster and with a greater number of adaptive shifts in species where sperm operate within females (for example, spermcasters and internal fertilizers). Our results demonstrate that fertilization mode is a key driver in the evolution of sperm length across animals, and we argue that a complex combination of postcopulatory forces has shaped sperm length diversification throughout animal evolution.
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12
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Can Sexual Selection Drive the Evolution of Sperm Cell Structure? Cells 2021; 10:cells10051227. [PMID: 34067752 PMCID: PMC8156441 DOI: 10.3390/cells10051227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/04/2021] [Accepted: 05/14/2021] [Indexed: 02/07/2023] Open
Abstract
Sperm cells have undergone an extraordinarily divergent evolution among metazoan animals. Parker recognized that because female animals frequently mate with more than one male, sexual selection would continue after mating and impose strong selection on sperm cells to maximize fertilization success. Comparative analyses among species have revealed a general relationship between the strength of selection from sperm competition and the length of sperm cells and their constituent parts. However, comparative analyses cannot address causation. Here, we use experimental evolution to ask whether sexual selection can drive the divergence of sperm cell phenotype, using the dung beetle Onthophagus taurus as a model. We either relaxed sexual selection by enforcing monogamy or allowed sexual selection to continue for 20 generations before sampling males and measuring the total length of sperm cells and their constituent parts, the acrosome, nucleus, and flagella. We found differences in the length of the sperm cell nucleus but no differences in the length of the acrosome, flagella, or total sperm length. Our data suggest that different sperm cell components may respond independently to sexual selection and contribute to the divergent evolution of these extraordinary cells.
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13
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Vasudeva R, Deeming DC, Eady PE. Age‐specific sensitivity of sperm length and testes size to developmental temperature in the bruchid beetle. J Zool (1987) 2021. [DOI: 10.1111/jzo.12884] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- R. Vasudeva
- School of Biological Sciences Norwich Research Park University of East Anglia Norwich UK
| | - D. C. Deeming
- School of Life Sciences University of Lincoln Lincoln Lincolnshire UK
| | - P. E. Eady
- School of Life Sciences University of Lincoln Lincoln Lincolnshire UK
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14
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Dallai R, Fanciulli PP, Lupetti P, Mercati D. The ultrastructure of sperm and female sperm storage organs in the water strider Gerris lacustris L. (Heteroptera) and a possible example of genital coevolution. ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 61:101043. [PMID: 33689939 DOI: 10.1016/j.asd.2021.101043] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
The fine structural organization of the male and the female inner reproductive apparatuses of the water-strider Gerris lacustris was studied. The sperm of the species shows a long helicoidal acrosome provided with longitudinal tubules, and a short nucleus. The flagellum is characterized by crescent mitochondrial derivatives and a 9 + 9 + 2 axoneme, as occurs in all Heteroptera. The female reproductive apparatus is characterized by an extremely long spermathecal duct, filled with sperm, which plays the role of the main sperm storage organ. The duct has a thin epithelium surrounded by a complex of secretory and duct-forming cells. The spermathecal duct flows into the gynatrial sac. This region, together with the fertilization chamber, exhibits a simple epithelium with deep apical plasma membrane invaginations, and it does not show conspicuous secretions. The basal cell region shows plasma membrane infoldings forming thin cytoplasmic bands hosting mitochondria and large intercellular spaces. This organization is typical of epithelia active in fluid reabsorption. Two lateral large gynatrial glands open into the gynatrial sac. Such glands also exhibit secretory and duct forming cells. The same structure of these glands is also present along the proximal region of the fecundation canal. The duct forming cells of these regions have very wide ducts with peculiar cuticular finger-like structures at their opening into the gland duct lumen. The results of the present study suggest the occurrence of a coevolution between the sperm and the spermathecal duct lengths.
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Affiliation(s)
- Romano Dallai
- Department of Life Sciences, University of Siena, Italy.
| | | | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Italy.
| | - David Mercati
- Department of Life Sciences, University of Siena, Italy.
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15
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Dallai R, Fanciulli PP, Mercati D, Lupetti P. Coevolution between female seminal receptacle and sperm morphology in the semiaquatic measurer bug Hydrometra stagnorum L. (Heteroptera, Hydrometridae). ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 60:101001. [PMID: 33120187 DOI: 10.1016/j.asd.2020.101001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
The coevolution between sperm length and size of the female sperm-storage organs is described for the first time within Heteroptera. The long sperm of the measurer bug Hydrometra stagnorum is characterized by the unusually long acrosome with its anterior region helically arranged, and by a very short nucleus. The sperm flagellum has a 9 + 9+2 conventional axoneme and crystallized mitochondrial derivatives. The female spermatheca consists of an extraordinarily long spermathecal duct ending with an apical spermathecal bulb into which flows also the secretions of a relatively short spermathecal gland. Both spermathecal duct and gland have a thin epithelium lined by a cuticle, beneath which a complex of secretory and duct forming cells are present. The secretions of these two structures flow into the apical spermathecal bulb. A thick layer of muscle fibers surrounds the epithelium. These results confirm the opinion that the dimensions of the female reproductive sperm-storage organs are able to drive the sperm morphology.
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Affiliation(s)
- Romano Dallai
- Department of Life Sciences, University of Siena, Siena, Italy.
| | | | - David Mercati
- Department of Life Sciences, University of Siena, Siena, Italy.
| | - Pietro Lupetti
- Department of Life Sciences, University of Siena, Siena, Italy.
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16
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Ramm SA. Seminal fluid and accessory male investment in sperm competition. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200068. [PMID: 33070740 DOI: 10.1098/rstb.2020.0068] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sperm production and allocation strategies have been a central concern of sperm competition research for the past 50 years. But during the 'sexual cascade' there may be strong selection for alternative routes to maximizing male fitness. Especially with the evolution of internal fertilization, a common and by now well-studied example is the accessory ejaculate investment represented by seminal fluid, the complex mixture of proteins, peptides and other components transferred to females together with sperm. How seminal fluid investment should covary with sperm investment probably depends on the mechanism of seminal fluid action. If seminal fluid components boost male paternity success by directly enhancing sperm function or use, we might often expect a positive correlation between the two forms of male investment, whereas trade-offs seem more likely if seminal fluid acts independently of sperm. This is largely borne out by a broad taxonomic survey to establish the prevailing patterns of seminal fluid production and allocation during animal evolution, in light of which I discuss the gaps that remain in our understanding of this key ejaculate component and its relationship to sperm investment, before outlining promising approaches for examining seminal fluid-mediated sperm competitiveness in the post-genomic era. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Steven A Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
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17
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Lüpold S, de Boer RA, Evans JP, Tomkins JL, Fitzpatrick JL. How sperm competition shapes the evolution of testes and sperm: a meta-analysis. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200064. [PMID: 33070733 DOI: 10.1098/rstb.2020.0064] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Females of many species mate with multiple males, thereby inciting competition among ejaculates from rival males for fertilization. In response to increasing sperm competition, males are predicted to enhance their investment in sperm production. This prediction is so widespread that testes size (correcting for body size) is commonly used as a proxy of sperm competition, even in the absence of any other information about a species' reproductive behaviour. By contrast, a debate about whether sperm competition selects for smaller or larger sperm has persisted for nearly three decades, with empirical studies demonstrating every possible response. Here, we synthesize nearly 40 years of sperm competition research in a meta-analytical framework to determine how the evolution of sperm number (i.e. testes size) and sperm size (i.e. sperm head, midpiece, flagellum and total length) is influenced by varying levels of sperm competition across species. Our findings support the long-held assumption that higher levels of sperm competition are associated with relatively larger testes. We also find clear evidence that sperm competition is associated with increases in all components of sperm length. We discuss these results in the context of different theoretical predictions and general patterns in the breeding biology and selective environment of sperm. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Raïssa A de Boer
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, Stockholm 10691, Sweden
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences (M092), University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Joseph L Tomkins
- Centre for Evolutionary Biology, School of Biological Sciences (M092), University of Western Australia, Crawley, Western Australia 6009, Australia
| | - John L Fitzpatrick
- Department of Zoology/Ethology, Stockholm University, Svante Arrhenius väg 18B, Stockholm 10691, Sweden
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18
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Rudin-Bitterli TS, Mitchell NJ, Evans JP. Extensive geographical variation in testes size and ejaculate traits in a terrestrial-breeding frog. Biol Lett 2020; 16:20200411. [PMID: 32991823 PMCID: PMC7532705 DOI: 10.1098/rsbl.2020.0411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/08/2020] [Indexed: 11/12/2022] Open
Abstract
Ejaculate traits vary extensively among individuals and species, but little is known about their variation among populations of the same species. Here, we investigated patterns of intraspecific variation in male reproductive investment in the terrestrial-breeding frog Pseudophryne guentheri. Like most anurans, breeding activity in P. guentheri is cued by precipitation, and therefore the timing and duration of breeding seasons differ among geographically separated populations, potentially leading to differences in the level of sperm competition. We, therefore, anticipated local adaptation in sperm traits that reflect these phenological differences among populations. Our analysis of six natural populations across a rainfall gradient revealed significant divergence in testes and ejaculate traits that correspond with annual rainfall and rainfall seasonality; males from the northern and drier edge of the species range had significantly smaller testes containing fewer, smaller and less motile sperm compared with those from mesic central populations. These findings may reflect spatial variation in the strength of postcopulatory sexual selection, likely driven by local patterns of precipitation.
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Affiliation(s)
| | | | - Jonathan P. Evans
- School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia
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19
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Fitzpatrick JL, Bridge CD, Snook RR. Repeated evidence that the accelerated evolution of sperm is associated with their fertilization function. Proc Biol Sci 2020; 287:20201286. [PMID: 32752988 PMCID: PMC7575512 DOI: 10.1098/rspb.2020.1286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Spermatozoa are the most morphologically diverse cell type, leading to the widespread assumption that they evolve rapidly. However, there is no direct evidence that sperm evolve faster than other male traits. Such a test requires comparing male traits that operate in the same selective environment, ideally produced from the same tissue, yet vary in function. Here, we examine rates of phenotypic evolution in sperm morphology using two insect groups where males produce fertile and non-fertile sperm types (Drosophila species from the obscura group and a subset of Lepidoptera species), where these constraints are solved. Moreover, in Drosophila we test the relationship between rates of sperm evolution and the link with the putative selective pressures of fertilization function and postcopulatory sexual selection exerted by female reproductive organs. We find repeated evolutionary patterns across these insect groups—lengths of fertile sperm evolve faster than non-fertile sperm. In Drosophila, fertile sperm length evolved faster than body size, but at the same rate as female reproductive organ length. We also compare rates of evolution of different sperm components, showing that head length evolves faster in fertile sperm while flagellum length evolves faster in non-fertile sperm. Our study provides direct evidence that sperm length evolves more rapidly in fertile sperm, probably because of their functional role in securing male fertility and in response to selection imposed by female reproductive organs.
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Affiliation(s)
- John L Fitzpatrick
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, SE-10691, Sweden.,Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - C Daisy Bridge
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - Rhonda R Snook
- Department of Zoology, Stockholm University, Svante Arrhenius väg 18B, SE-10691, Sweden
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20
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Carballo L, Battistotti A, Teltscher K, Lierz M, Bublat A, Valcu M, Kempenaers B. Sperm morphology and evidence for sperm competition among parrots. J Evol Biol 2019; 32:856-867. [PMID: 31245887 PMCID: PMC6852422 DOI: 10.1111/jeb.13487] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/10/2019] [Accepted: 05/13/2019] [Indexed: 11/28/2022]
Abstract
Sperm competition is an important component of post‐copulatory sexual selection that has shaped the evolution of sperm morphology. Previous studies have reported that sperm competition has a concurrently directional and stabilizing effect on sperm size. For example, bird species that show higher levels of extrapair paternity and larger testes (proxies for the intensity of sperm competition) have longer sperm and lower coefficients of variation in sperm length, both within and between males. For this reason, these sperm traits have been proposed as indexes to estimate the level of sperm competition in species for which other measures are not available. The relationship between sperm competition and sperm morphology has been explored mostly for bird species that breed in temperate zones, with the main focus on passerine birds. We measured sperm morphology in 62 parrot species that breed mainly in the tropics and related variation in sperm length to life‐history traits potentially indicative of the level of sperm competition. We showed that sperm length negatively correlated with the within‐male coefficient of variation in sperm length and positively with testes mass. We also showed that sperm is longer in sexually dichromatic and in gregarious species. Our results support the general validity of the hypothesis that sperm competition drives variation in sperm morphology. Our analyses suggest that post‐copulatory sexual selection is also important in tropical species, with more intense sperm competition among sexually dichromatic species and among species that breed at higher densities.
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Affiliation(s)
- Luisana Carballo
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Alessandra Battistotti
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany.,Department of Biology, University of Padua, Padova, Italy
| | - Kim Teltscher
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Michael Lierz
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus-Liebig University, Giessen, Germany
| | - Andreas Bublat
- Clinic for Birds, Reptiles, Amphibians and Fish, Justus-Liebig University, Giessen, Germany
| | - Mihai Valcu
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Bart Kempenaers
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Seewiesen, Germany
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21
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Rojas Mora A, Meniri M, Ciprietti S, Helfenstein F. Is sperm morphology functionally related to sperm swimming ability? A case study in a wild passerine bird with male hierarchies. BMC Evol Biol 2018; 18:142. [PMID: 30231935 PMCID: PMC6146611 DOI: 10.1186/s12862-018-1260-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 09/11/2018] [Indexed: 11/21/2022] Open
Abstract
Background Sexual selection continues after copulation via either sperm competition or cryptic female choice, and favors sperm traits that maximize sperm competitiveness. Both sperm swimming velocity and longevity are important determinants of the outcome of sperm competition. Theoretically, sperm morphology can influence sperm velocity at least in three different non-exclusive ways: (i) longer sperm may generate more propelling thrust, (ii) bigger midpieces may produce more energy, and/or (iii) larger flagella or mid-pieces relative to the head size may compensate for the drag forces around the head. A growing number of studies have investigated the relationship of sperm morphology with sperm performance, which remains equivocal at both the inter- and intra-specific levels. Here, we used House Sparrows to test the functional relationship between sperm morphology with sperm velocity and longevity. Based on a previous study showing that sperm swimming ability covaries with social rank, we predicted that —if a functional relationship exists—1) sperm morphology should differ across social ranks, and 2) correlations between sperm morphology and sperm velocity and/or sperm longevity should be constant across social ranks. Results We found no differences in sperm morphology across social ranks. Moreover, we found that sperm morphology may be correlated with sperm velocity, but such relationship varied across social ranks. This result contradicts the hypothesis of a functional relationship between sperm morphology and sperm performance. Finally, after experimentally manipulating social ranks, we observed that relationships between sperm morphology and sperm velocity and/or sperm longevity disappeared or changed direction. Conclusions We suggest that in species with internal fertilization, while sperm morphology is likely constrained by the morphology of the female sperm storage organs, selection may act upon physiological traits that enhance sperm performance. Hence, these two selection forces could decouple sperm performance from sperm morphology. Electronic supplementary material The online version of this article (10.1186/s12862-018-1260-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alfonso Rojas Mora
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland. .,Present Address: Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, Faculty of Sciences, University of Neuchatel, Rue Emile-Argand 11, 2000, Neuchatel, Switzerland.
| | - Magali Meniri
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
| | - Sabrina Ciprietti
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
| | - Fabrice Helfenstein
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
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22
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Poidatz J, Bressac C, Bonnard O, Thiéry D. Delayed sexual maturity in males of Vespa velutina. INSECT SCIENCE 2018; 25:679-689. [PMID: 28248003 DOI: 10.1111/1744-7917.12452] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 01/03/2017] [Accepted: 01/24/2017] [Indexed: 06/06/2023]
Abstract
Vespa velutina var nigrithorax (Lepelletier, 1835) is an invasive predator of bees accidentally introduced in France in 2004, and it is having a serious impact on apiculture and ecosystems. Studying the reproduction of an invasive species is key to assess its population dynamic. This study explores the sexual maturation of V. velutina males and the evolution of their fertility. The main studied parameters were physiologic (spermiogenesis, spermatogenesis) and anatomic (testes size and structure, head width). Two populations of males were described based on their emergence period: early males in early summer or classic males in autumn. Each testis has an average of 108 testicular follicles. Spermatogenesis is synchronous, with only 1 sperm production wave, and completed, on average, at 10.3 d after emergence with the degeneration of the testes. The sperm counts in seminal vesicles of mature males are 3 × 106 in October/November and 0.8 × 106 in June. In comparison, females store 0.1 × 106 sperm in their spermathecae. The early males emerged from colonies made by fertilized queens. The reproductive potential of these early males seemed limited, and their function in the colony is discussed. The sperm stock evolution in autumn males suggests the occurrence of a reproductive pattern of male competition for the access to females and a single copulation per male. The synchronicity of male and foundress emergences and sexual maturation is of primary importance for the mating success and the future colony development.
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Affiliation(s)
- Juliette Poidatz
- INRA, UMR1065 Santé et Agroécologie du Vignoble, ISVV, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | | | - Olivier Bonnard
- INRA, UMR1065 Santé et Agroécologie du Vignoble, ISVV, Bordeaux Sciences Agro, Villenave d'Ornon, France
| | - Denis Thiéry
- INRA, UMR1065 Santé et Agroécologie du Vignoble, ISVV, Bordeaux Sciences Agro, Villenave d'Ornon, France
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23
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Mendonca T, Birkhead TR, Cadby AJ, Forstmeier W, Hemmings N. A trade-off between thickness and length in the zebra finch sperm mid-piece. Proc Biol Sci 2018; 285:rspb.2018.0865. [PMID: 30051869 PMCID: PMC6083248 DOI: 10.1098/rspb.2018.0865] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/29/2018] [Indexed: 01/22/2023] Open
Abstract
The sperm mid-piece has traditionally been considered to be the engine that powers sperm. Larger mid-pieces have therefore been assumed to provide greater energetic capacity. However, in the zebra finch Taeniopygia guttata, a recent study showed a surprising negative relationship between mid-piece length and sperm energy content. Using a multi-dimensional approach to study mid-piece structure, we tested whether this unexpected relationship can be explained by a trade-off between mid-piece length and mid-piece thickness and/or cristae density inside the mitochondrial helix. We used selective plane illumination microscopy to study mid-piece structure from three-dimensional images of zebra finch sperm and used high-resolution transmission electron microscopy to quantify mitochondrial density. Contrary to the assumption that longer mid-pieces are larger and therefore produce or contain a greater amount of energy, our results indicate that the amount of mitochondrial material is consistent across mid-pieces of varying lengths, and longer mid-pieces are simply proportionately ‘thinner’.
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Affiliation(s)
- Tania Mendonca
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK .,Department of Physics and Astronomy, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Tim R Birkhead
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Ashley J Cadby
- Department of Physics and Astronomy, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Wolfgang Forstmeier
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, Eberhard-Gwinner-Straße, 82319 Seewiesen, Germany
| | - Nicola Hemmings
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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24
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Lüpold S, Pitnick S. Sperm form and function: what do we know about the role of sexual selection? Reproduction 2018; 155:R229-R243. [DOI: 10.1530/rep-17-0536] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/19/2018] [Indexed: 12/20/2022]
Abstract
Sperm morphological variation has attracted considerable interest and generated a wealth of predominantly descriptive studies over the past three centuries. Yet, apart from biophysical studies linking sperm morphology to swimming velocity, surprisingly little is known about the adaptive significance of sperm form and the selective processes underlying its tremendous diversification throughout the animal kingdom. Here, we first discuss the challenges of examining sperm morphology in an evolutionary context and why our understanding of it is far from complete. Then, we review empirical evidence for how sexual selection theory applies to the evolution of sperm form and function, including putative secondary sexual traits borne by sperm.
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25
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Maroto-Morales A, García-Álvarez O, Ramón M, Martínez-Pastor F, Fernández-Santos MR, Soler AJ, Garde JJ. Current status and potential of morphometric sperm analysis. Asian J Androl 2017; 18:863-870. [PMID: 27678465 PMCID: PMC5109877 DOI: 10.4103/1008-682x.187581] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology arose during speciation and what role the different specializations play in sperm function, however, remain incompletely characterized. This work reviews the hypotheses proposed to explain sperm morphological evolution, with a focus on some aspects of sperm morphometric evaluation; the ability of morphometrics to predict sperm cryoresistance and male fertility is also discussed. For this, the evaluation of patterns of change of sperm head morphometry throughout a process, instead of the study of the morphometric characteristics of the sperm head at different stages, allows a better identification of the males with different sperm cryoconservation ability. These new approaches, together with more studies employing a greater number of individuals, are needed to obtain novel results concerning the role of sperm morphometry on sperm function. Future studies should aim at understanding the causes of sperm design diversity and the mechanisms that generate them, giving increased attention to other sperm structures besides the sperm head. The implementation of scientific and technological advances could benefit the simultaneous examination of sperm phenotype and sperm function, demonstrating that sperm morphometry could be a useful tool for sperm assessment.
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Affiliation(s)
| | - Olga García-Álvarez
- SaBio IREC (CSIC - UCLM - JCCM), Albacete, Spain.,Biomedical Center, Medical Faculty in Pilsen, Charles University in Prague, Pilsen, Czech Republic
| | - Manuel Ramón
- Regional Center of Animal Selection and Reproduction (CERSYRA) JCCM, Valdepeñas, Spain
| | - Felipe Martínez-Pastor
- Institute for Animal Health and Cattle Development, University of León, León, Spain.,Department of Molecular Biology, University of León, León, Spain
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26
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Rojas Mora A, Meniri M, Ciprietti S, Helfenstein F. Social dominance explains within-ejaculate variation in sperm design in a passerine bird. BMC Evol Biol 2017; 17:66. [PMID: 28259157 PMCID: PMC5336654 DOI: 10.1186/s12862-017-0914-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 02/15/2017] [Indexed: 11/10/2022] Open
Abstract
Background Comparative studies suggest that sperm competition exerts stabilizing selection towards an optimal sperm design – e.g., the relative size and covariation of different sperm sections or a quantitative measure of sperm shape - that maximizes male fertility, which results in reduced levels of within-male variation in sperm morphology. Yet, these studies also reveal substantial amounts of unexplained within-ejaculate variance, and the factors presiding to the maintenance of such within-male variation in sperm design at the population level still remain to be identified. Sperm competition models predict that males should progressively invest more resources in their germline as their mating costs increase, i.e., the soma/germline allocation trade-off hypothesis. When access to fertile females is determined by social dominance, the soma/germline allocation trade-off hypothesis predicts that dominant males should invest less in the control of spermatogenesis. Hence, dominance should positively correlate with within-male variance in sperm design. Results In support of this hypothesis, we found that dominant house sparrow males produce ejaculates with higher levels of within-ejaculate variation in sperm design compared to subordinate males. However, after experimentally manipulating male social status, this pattern was not maintained. Conclusions Our results suggest that males might control variation in sperm design according to their social status to some extent. Yet, it seems that such within-ejaculate variation in sperm design cannot be rapidly adjusted to a new status. While variation in sperm design could result from various non-exclusive sources, we discuss how strategic allocation of resources to the somatic vs. the germline functions could be an important process shaping the relationship between within-male variation in sperm design and social status. Electronic supplementary material The online version of this article (doi:10.1186/s12862-017-0914-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alfonso Rojas Mora
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchatel, Switzerland
| | - Magali Meniri
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchatel, Switzerland
| | - Sabrina Ciprietti
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchatel, Switzerland
| | - Fabrice Helfenstein
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, University of Neuchatel, Rue Emile-Argand 11, Neuchatel, Switzerland.
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27
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Smith RJ, Matzke-Karasz R, Kamiya T. Sperm length variations in five species of cypridoidean non-marine ostracods (Crustacea). Cell Tissue Res 2016; 366:483-497. [PMID: 27449928 DOI: 10.1007/s00441-016-2459-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/17/2016] [Indexed: 11/25/2022]
Abstract
Spermatozoa of the ostracod superfamily Cypridoidea include some of the longest in the animal kingdom, but unlike other so-called giant spermatozoa, they are aflagellate, probably evolved only once, and represent an exceptionally old trait. Sperm length variations within cypridoidean species remain poorly known, a lack that hinders the development of hypotheses to explain their length and variation. For this study, the lengths of 500 spermatozoa from each of five species of freshwater cypridoidean ostracods, Candonopsis tenuis (Brady, 1886), Fabaeformiscandona subacuta (Yang, 1982), Heterocypris rotundata (Bronshtein, 1928), Ilyocypris japonica Okubo, 1990, and Notodromas trulla Smith and Kamiya, 2014, were measured, including the lengths of the posterior and anterior regions. No overall pattern in sperm variation was discernible. Length variations between species, between males of the same species, and within individual males varied from low (Candonopsis tenuis) to extraordinarily large (Notodromas trulla and Fabaeformiscandona subacuta). Sperm competition, cryptic female choice, sperm heteromorphism, and testis size are unlikely to explain all of the variations observed. Age structures of the populations sampled might play a role in explaining some intraspecific variation. The differing amounts of variation in sperm characters revealed in this study suggest that multiple evolutionary trends and pressures shape sperm lengths in this superfamily.
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Affiliation(s)
- Robin J Smith
- Lake Biwa Museum, Oroshimo 1091, Kusatsu, Shiga Prefecture, 525-0001, Japan.
| | - Renate Matzke-Karasz
- Department of Earth and Environmental Sciences, Palaeontology, Ludwig-Maximilians-Universität München and GeoBio-Center LMU, 80333, Munich, Germany.
| | - Takahiro Kamiya
- College of Science and Engineering, School of Natural System, University of Kanazawa, Kakuma, Kanazawa, 920-1192, Japan
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28
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What makes a good mate? Factors influencing male and female reproductive success in a polyphagous moth. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.07.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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29
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Droge-Young EM, Belote JM, Perez GS, Pitnick S. Resolving mechanisms of short-term competitive fertilization success in the red flour beetle. JOURNAL OF INSECT PHYSIOLOGY 2016; 93-94:1-10. [PMID: 27343847 DOI: 10.1016/j.jinsphys.2016.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
Postcopulatory sexual selection occurs when sperm from multiple males occupy a female's reproductive tract at the same time and is expected to generate strong selection pressures on traits related to competitive fertilization success. However, knowledge of competitive fertilization success mechanisms and characters targeted by resulting selection is limited, partially due to the difficulty of discriminating among sperm from different males within the female reproductive tract. Here, we resolved mechanisms of competitive fertilization success in the promiscuous flour beetle Tribolium castaneum. Through creation of transgenic lines with fluorescent-tagged sperm heads, we followed the fate of focal male sperm in female reproductive tracts while tracking paternity across numerous rematings. Our results indicate that a given male's sperm persist and fertilize eggs through at least seven rematings. Additionally, the proportion of a male's sperm in the bursa (the site of spermatophore deposition), which is influenced by both timing of female's ejecting excess sperm and male size, significantly predicted paternity share in the 24h following a mating. Contrary to expectation, proportional representation of sperm within the female's specialized sperm-storage organ did not significantly predict paternity, though spermathecal sperm may play a role in fertilization when females do not have access to mates for longer time periods. We address the adaptive significance of the identified reproductive mechanisms in the context of T. castaneum's unique mating system and ecology.
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Affiliation(s)
| | - John M Belote
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Giselle S Perez
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Scott Pitnick
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
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30
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Gottardo M, Dallai R, Mercati D, Hörnschemeyer T, Beutel RG. The evolution of insect sperm − an unusual character system in a megadiverse group. J ZOOL SYST EVOL RES 2016. [DOI: 10.1111/jzs.12136] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Marco Gottardo
- Department of Life Sciences; Università degli Studi di Siena; Siena Italy
| | - Romano Dallai
- Department of Life Sciences; Università degli Studi di Siena; Siena Italy
| | - David Mercati
- Department of Life Sciences; Università degli Studi di Siena; Siena Italy
| | | | - Rolf Georg Beutel
- Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum; Friedrich-Schiller-Universität Jena; Jena Germany
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Schmera D, Pizá J, Reinartz E, Ursenbacher S, Baur B. Breeding system, shell size and age at sexual maturity affect sperm length in stylommatophoran gastropods. BMC Evol Biol 2016; 16:89. [PMID: 27130818 PMCID: PMC4850656 DOI: 10.1186/s12862-016-0661-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/18/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sperm size and quality are key factors for fertilization success. There is increasing empirical evidence demonstrating that sperm form and function are influenced by selective pressures. Theoretical models predict that sperm competition could favour the evolution of longer sperm. In hermaphrodites, self-fertilizing species are expected to have shorter sperm than cross-fertilizing species, which use sperm stored from several mating partners for the fertilization of their eggs and thus are exposed to intense sperm competition. We tested this hypothesis by comparing original data on sperm length in 57 species of simultaneously hermaphroditic stylommatophoran gastropods from Europe and South America with respect to the species' breeding system. We used 28S rRNA nuclear and COI mitochondrial sequence data to construct a molecular phylogeny. Phylogenetic generalized linear models were applied to examine the potential influence of morphological and life-history characters. RESULTS The best-fit model revealed that the breeding system and age at sexual maturity influence sperm length in gastropods. In general, species with predominant cross-fertilization had longer sperm than species with predominant self-fertilization or a mixed breeding system. Across species with shells (snails), sperm length also increased with shell size. CONCLUSIONS Our study provides evidence that sperm length in stylommatophoran gastropods is influenced by the risk of sperm competition, as well as by age at sexual maturity and shell size. This finding extends present knowledge of sperm evolution to a group of so far poorly studied simultaneous hermaphrodites.
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Affiliation(s)
- Dénes Schmera
- Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland.
- MTA Centre for Ecological Research, Balaton Limnological Institute, Klebelsberg Kuno 3, 8237, Tihany, Hungary.
| | - Julia Pizá
- Departamento de Biología, Bioquímica y Farmacia, Laboratorio de Zoología de Invertebrados 1, Universidad Nacional del Sur, San Juan 670, 8000, Bahía Blanca, Argentina
| | - Ellen Reinartz
- Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland
| | - Sylvain Ursenbacher
- Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland
| | - Bruno Baur
- Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, 4056, Basel, Switzerland
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McLennan HJ, Lüpold S, Smissen P, Rowe KC, Breed WG. Greater sperm complexity in the Australasian old endemic rodents (Tribe: Hydromyini) is associated with increased levels of inter-male sperm competition. Reprod Fertil Dev 2016; 29:RD15425. [PMID: 26922469 DOI: 10.1071/rd15425] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/08/2016] [Indexed: 12/12/2022] Open
Abstract
Spermatozoa exhibit considerable interspecies morphological variation across mammals, especially among murid rodents. In Australasia, most murids in the tribe Hydromyini have a spermatozoon with a highly complex head exhibiting an apical hook, characteristic of most murids, and two projections that extend from its upper concave surface, the ventral processes. In the present study we performed a phylogenetically controlled comparison of sperm morphology across 45 species of hydromyine rodents to test the hypothesis that the length and angle of both the apical hook and ventral processes, as well as the length of the sperm tail, increase with relative testes mass as a proxy for differences in levels of inter-male sperm competition. Although both sperm head protrusions exhibited considerable variation in their length and angle across species, only the angles increased significantly in relation to relative testes mass. Further, the length of the sperm flagellum was positively associated with relative testes mass. These results suggest that, in hydromyine rodents, the angle of the apical hook and ventral processes of the sperm head, as well as the sperm tail length, are likely to be sexually selected traits. The possible functional significance of these findings is briefly discussed.
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Abstract
Sperm competition, in which the ejaculates of multiple males compete to fertilize a female's ova, results in strong selection on sperm traits. Although sperm size and swimming velocity are known to independently affect fertilization success in certain species, exploring the relationship between sperm length, swimming velocity and fertilization success still remains a challenge. Here, we use the zebra finch (Taeniopygia guttata), where sperm size influences sperm swimming velocity, to determine the effect of sperm total length on fertilization success. Sperm competition experiments, in which pairs of males whose sperm differed only in length and swimming speed, revealed that males producing long sperm were more successful in terms of (i) the number of sperm reaching the ova and (ii) fertilizing those ova. Our results reveal that although sperm length is the main factor determining the outcome of sperm competition, complex interactions between male and female reproductive traits may also be important. The mechanisms underlying these interactions are poorly understood, but we suggest that differences in sperm storage and utilization by females may contribute to the outcome of sperm competition.
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Omotoriogun TC, Albrecht T, Hořák D, Laskemoen T, Ottosson U, Rowe M, Sedláček O, Lifjeld JT. Sperm size evolution in African greenbuls (Passeriformes: Pycnonotidae). Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12663] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Taiwo C. Omotoriogun
- Natural History Museum; University of Oslo; Oslo Norway
- AP Leventis Ornithological Research Institute; University of Jos; Jos Nigeria
| | - Tomas Albrecht
- Institute of Vertebrate Biology; Academy of Sciences of the Czech Republic; Brno Czech Republic
- Department of Zoology; Faculty of Science; Charles University in Prague; Prague Czech Republic
| | - David Hořák
- Department of Ecology; Faculty of Science; Charles University in Prague; Prague Czech Republic
| | | | - Ulf Ottosson
- AP Leventis Ornithological Research Institute; University of Jos; Jos Nigeria
| | - Melissah Rowe
- Natural History Museum; University of Oslo; Oslo Norway
- Centre for Ecological and Evolutionary Synthesis; Department of Biosciences; University of Oslo; Oslo Norway
| | - Ondřej Sedláček
- Department of Ecology; Faculty of Science; Charles University in Prague; Prague Czech Republic
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Ramón M, Jiménez-Rabadán P, García-Álvarez O, Maroto-Morales A, Soler AJ, Fernández-Santos MR, Pérez-Guzmán MD, Garde JJ. Understanding Sperm Heterogeneity: Biological and Practical Implications. Reprod Domest Anim 2014; 49 Suppl 4:30-6. [DOI: 10.1111/rda.12404] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 07/14/2014] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - AJ Soler
- SaBio IREC (UCLM-CSIC-JCCM); Albacete Spain
| | | | | | - JJ Garde
- SaBio IREC (UCLM-CSIC-JCCM); Albacete Spain
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36
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Dallai R. Overview on spermatogenesis and sperm structure of Hexapoda. ARTHROPOD STRUCTURE & DEVELOPMENT 2014; 43:257-290. [PMID: 24732045 DOI: 10.1016/j.asd.2014.04.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 03/28/2014] [Accepted: 04/01/2014] [Indexed: 06/03/2023]
Abstract
The main characteristics of the sperm structure of Hexapoda are reported in the review. Data are dealing with the process of spermatogenesis, including the aberrant models giving rise to a reduced number of sperm cells. The sperm heteromorphism and the giant sperm exceeding the usual sperm size for length and width are considered. The characteristics of several components of a typical insect sperm are described: the plasma membrane and its glycocalyx, the nucleus, the centriole region and the centriole adjunct, the accessory bodies, the mitochondrial derivatives and the flagellar axoneme. Finally, a detailed description of the main sperm features of each hexapodan group is given with emphasis on the flagellar components considered to have great importance in phylogenetic considerations. This study may be also useful to those requiring an introduction to hexapod reproduction.
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Affiliation(s)
- Romano Dallai
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
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Zeng Y, Lou SL, Liao WB, Jehle R. Evolution of sperm morphology in anurans: insights into the roles of mating system and spawning location. BMC Evol Biol 2014; 14:104. [PMID: 24884745 PMCID: PMC4030069 DOI: 10.1186/1471-2148-14-104] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 05/02/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The degree of postcopulatory sexual selection, comprising variable degrees of sperm competition and cryptic female choice, is an important evolutionary force to influence sperm form and function. Here we investigated the effects of mating system and spawning location on the evolution of sperm morphology in 67 species of Chinese anurans. We also examined how relative testes size as an indicator of the level of sperm competition affected variation in sperm morphology across a subset of 29 species. RESULTS We found a significant association of mating system and spawning location with sperm morphology. However, when removing the effects of body mass or absolute testes mass for species for which such data were available, this effect became non-significant. Consistent with predictions from sperm competition theory, we found a positive correlation between sperm morphology and relative testes size after taking phylogeny into account. CONCLUSIONS Our findings suggest that sexual selection in Chinese anurans favors longer sperm when the level of sperm competition is high. Pre-copulatory male-male competition and spawning location, on the other hand, do not affect the evolution of sperm morphology after taking body mass and absolute testes mass into account.
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Affiliation(s)
- Yu Zeng
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, P. R. China
- China Three Gorges Corporation, Beijing 100038, China
| | - Shang Ling Lou
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, P. R. China
| | - Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, P. R. China
| | - Robert Jehle
- School of Environment & Life Sciences, University of Salford, Salford M5 4WT, UK
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Vrech DE, Olivero PA, Mattoni CI, Peretti AV. Testes mass, but not sperm length, increases with higher levels of polyandry in an ancient sex model. PLoS One 2014; 9:e94135. [PMID: 24736525 PMCID: PMC3988103 DOI: 10.1371/journal.pone.0094135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 03/14/2014] [Indexed: 11/26/2022] Open
Abstract
There is strong evidence that polyandrous taxa have evolved relatively larger testes than monogamous relatives. Sperm size may either increase or decrease across species with the risk or intensity of sperm competition. Scorpions represent an ancient direct mode with spermatophore-mediated sperm transfer and are particularly well suited for studies in sperm competition. This work aims to analyze for the first time the variables affecting testes mass, ejaculate volume and sperm length, according with their levels of polyandry, in species belonging to the Neotropical family Bothriuridae. Variables influencing testes mass and sperm length were obtained by model selection analysis using corrected Akaike Information Criterion. Testes mass varied greatly among the seven species analyzed, ranging from 1.6 ± 1.1 mg in Timogenes dorbignyi to 16.3 ± 4.5 mg in Brachistosternus pentheri with an average of 8.4 ± 5.0 mg in all the species. The relationship between testes mass and body mass was not significant. Body allocation in testes mass, taken as Gonadosomatic Index, was high in Bothriurus cordubensis and Brachistosternus ferrugineus and low in Timogenes species. The best-fitting model for testes mass considered only polyandry as predictor with a positive influence. Model selection showed that body mass influenced sperm length negatively but after correcting for body mass, none of the variables analyzed explained sperm length. Both body mass and testes mass influenced spermatophore volume positively. There was a strong phylogenetic effect on the model containing testes mass. As predicted by the sperm competition theory and according to what happens in other arthropods, testes mass increased in species with higher levels of sperm competition, and influenced positively spermatophore volume, but data was not conclusive for sperm length.
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Affiliation(s)
- David E. Vrech
- Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina
| | - Paola A. Olivero
- Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina
| | - Camilo I. Mattoni
- Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina
| | - Alfredo V. Peretti
- Institute of Animal Diversity and Ecology (IDEA), Laboratory of Reproductive Biology and Evolution, CONICET - The National University of Cordoba, Cordoba, Argentina
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40
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Sharma MD, Minder AM, Hosken DJ. No association between sperm competition and sperm length variation across dung flies (Scathophagidae). J Evol Biol 2013; 26:2341-9. [PMID: 24016061 DOI: 10.1111/jeb.12232] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 07/03/2013] [Accepted: 07/04/2013] [Indexed: 11/29/2022]
Abstract
Sperm length is extremely variable across species, but a general explanation for this variation is lacking. However, when the risk of sperm competition is high, sperm length is predicted to be less variable within species, and there is some evidence for this in birds and social insects. Here, we examined intraspecific variation in sperm length, both within and between males, and its potential associations with sperm competition risk and variation in female reproductive tract morphology across dung flies. We used two measures of variation in sperm size, and testis size was employed as our index of sperm competition risk. We found no evidence of associations between sperm length variation and sperm competition or female reproductive tract variation. These results suggest that variation in sperm competition risk may not always be associated with variation in sperm morphology, and the cause(s) of sperm length variation in dung flies remains unclear.
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Affiliation(s)
- M D Sharma
- Centre for Conservation & Ecology, College of Life and Environmental Sciences, University of Exeter, Tremough, Penryn, UK
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41
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42
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Abstract
Females frequently mate with several males, whose sperm then compete to fertilize available ova. Sperm competition represents a potent selective force that is expected to shape male expenditure on the ejaculate. Here, we review empirical data that illustrate the evolutionary consequences of sperm competition. Sperm competition favors the evolution of increased testes size and sperm production. In some species, males appear capable of adjusting the number of sperm ejaculated, depending on the perceived levels of sperm competition. Selection is also expected to act on sperm form and function, although the evidence for this remains equivocal. Comparative studies suggest that sperm length and swimming speed may increase in response to selection from sperm competition. However, the mechanisms driving this pattern remain unclear. Evidence that sperm length influences sperm swimming speed is mixed and fertilization trials performed across a broad range of species demonstrate inconsistent relationships between sperm form and function. This ambiguity may in part reflect the important role that seminal fluid proteins (sfps) play in affecting sperm function. There is good evidence that sfps are subject to selection from sperm competition, and recent work is pointing to an ability of males to adjust their seminal fluid chemistry in response to sperm competition from rival males. We argue that future research must consider sperm and seminal fluid components of the ejaculate as a functional unity. Research at the genomic level will identify the genes that ultimately control male fertility.
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Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, , School of Animal Biology (M092), The University of Western Australia, Crawley, Western Australia 6009, Australia.
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43
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Mi ZP, Liao WB, Jin L, Lou SL, Cheng J, Wu H. Testis Asymmetry and Sperm Length inRhacophorus omeimontis. Zoolog Sci 2012; 29:368-72. [DOI: 10.2108/zsj.29.368] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Female reproductive tract form drives the evolution of complex sperm morphology. Proc Natl Acad Sci U S A 2012; 109:4538-43. [PMID: 22323584 DOI: 10.1073/pnas.1111474109] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The coevolution of female mate preferences and exaggerated male traits is a fundamental prediction of many sexual selection models, but has largely defied testing due to the challenges of quantifying the sensory and cognitive bases of female preferences. We overcome this difficulty by focusing on postcopulatory sexual selection, where readily quantifiable female reproductive tract structures are capable of biasing paternity in favor of preferred sperm morphologies and thus represent a proximate mechanism of female mate choice when ejaculates from multiple males overlap within the tract. Here, we use phylogenetically controlled generalized least squares and logistic regression to test whether the evolution of female reproductive tract design might have driven the evolution of complex, multivariate sperm form in a family of aquatic beetles. The results indicate that female reproductive tracts have undergone extensive diversification in diving beetles, with remodeling of size and shape of several organs and structures being significantly associated with changes in sperm size, head shape, gains/losses of conjugation and conjugate size. Further, results of Bayesian analyses suggest that the loss of sperm conjugation is driven by elongation of the female reproductive tract. Behavioral and ultrastructural examination of sperm conjugates stored in the female tract indicates that conjugates anchor in optimal positions for fertilization. The results underscore the importance of postcopulatory sexual selection as an agent of diversification.
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Michalska K. Daily production of spermatophores, sperm number and spermatophore size in two eriophyoid mite species. EXPERIMENTAL & APPLIED ACAROLOGY 2011; 55:349-359. [PMID: 21751036 DOI: 10.1007/s10493-011-9479-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 07/02/2011] [Indexed: 05/31/2023]
Abstract
Under dissociated sperm transfer, (non-pairing) males deposit spermatophores on a substrate, while females seek spermatophores and pick up sperm on their own. Spermatophore expenditures of non-pairing males should be high, due to the increased uncertainty of sperm uptake by a female. In this study I examined spermatophore expenditures in two eriophyoid species that differed in the degree of dissociation between sexes: (1) Aculus fockeui (Nalepa and Trouessart) males rarely visit quiescent female nymphs (QFNs), and mostly deposit spermatophores all over the leaves, whereas (2) Aculops allotrichus (Nalepa) males guard QFNs for many hours and deposit several spermatophores beside them. Males of both species were collected from the field and tested in solitude. Aculus fockeui males deposited on average 19.1 spermatophores per day, whereas A. allotrichus deposited only 3.6 spermatophores per day, and had a very large coefficient of variation. Males and spermatophores of A. allotrichus were significantly smaller and contained less sperm than those of A. fockeui. In both eriophyoids, spermatophore size was fitted to the size of female genitalia and the height of females. The ratio between the diameter of spermatophore head and the width of a female genital coverflap was 0.6, whereas the ratio between the female leg and the length of spermatophore stalk was 0.5. Several factors could be responsible for the discrepancy in spermatophore expenditures between species. Among other factors, the effects of male size, male reproductive strategy and female genitalia size on spermatophore output and size of spermatophores are discussed.
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Affiliation(s)
- Katarzyna Michalska
- Department of Applied Entomology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland.
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Noguchi T, Koizumi M, Hayashi S. Sustained elongation of sperm tail promoted by local remodeling of giant mitochondria in Drosophila. Curr Biol 2011; 21:805-14. [PMID: 21549602 DOI: 10.1016/j.cub.2011.04.016] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 02/22/2011] [Accepted: 04/11/2011] [Indexed: 01/01/2023]
Abstract
BACKGROUND Sperm length in Drosophilidae varies from a few hundred microns to 6 cm as a result of evolutionary selection. In postcopulatory competition, longer sperm have an advantage in positioning their head closer to the egg. Sperm cell elongation can proceed in the absence of an axoneme, suggesting that a mechanism besides intraflagellar transport emerged to sustain it. RESULTS Here we report that sperm elongation in Drosophila melanogaster is driven by the interdependent extension of giant mitochondria and microtubule array that is formed around the mitochondrial surface. In primary cultures of elongating spermatids, we demonstrated that the mitochondrial integrity and local dynamics of microtubules at the tail tip region are essential for uniaxial elongation of the sperm tail. Mitochondria-microtubule linker protein Milton accumulated on mitochondria near the tail tip and is required for the sliding movement of microtubules. Disruption of Milton and its associated protein dMiro, and of potential microtubule crosslinkers Nebbish and Fascetto, caused strong elongation defects, indicating that mitochondria-microtubule association and microtubule crosslinking are required for spermatid tail elongation. CONCLUSIONS Mitochondria play unexpected roles in sperm tail elongation in Drosophila by providing a structural platform for microtubule reorganization to support the robust elongation taking place at the tip of the very long sperm tail. The identification of mitochondria as an organizer of cytoskeletal dynamics extends our understanding of mechanisms of cell morphogenesis.
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Affiliation(s)
- Tatsuhiko Noguchi
- Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Kobe, Hyogo 650-0047, Japan
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Thüler K, Bussière LF, Postma E, Ward PI, Blanckenhorn WU. Genetic and environmental sources of covariance among internal reproductive traits in the yellow dung fly. J Evol Biol 2011; 24:1477-86. [PMID: 21545422 DOI: 10.1111/j.1420-9101.2011.02280.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Substantial inter- and intraspecific variation is found in reproductive traits, but the evolutionary implications of this variation remain unclear. One hypothesis is that natural selection favours female reproductive morphology that allows females to control mating and fertilization and that diverse male reproductive traits arise as counter adaptations to subvert this control. Such co-evolution predicts the establishment of genetic correlations between male and female reproductive traits that closely interact during mating. Therefore, we measured phenotypic and genetic correlations between male and female reproductive tract characteristics in the yellow dung fly, Scathophaga stercoraria (Diptera: Scathophagidae), using a nested half-sib breeding experiment. We found significant heritabilities for the size of most reproductive tract traits investigated in both females (spermathecae and their ducts, accessory glands and their ducts) and males (testis size but not sperm length). Within the sexes, phenotypic and genetic correlations were mostly nil or positive, suggesting functional integration of or condition-dependent investment in internal reproductive traits. Negative intrasexual genetic correlations, potentially suggestive of resource allocation trade-offs, were not evident. Intersexual genetic correlations were mostly positive, reflecting expected allometries between male and female morphologies. Most interestingly, testis size correlated positively with female accessory gland size and duct length, potentially indicative of a co-evolutionary arms race. We discuss these and alternative explanations for these patterns of genetic covariance.
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Affiliation(s)
- K Thüler
- Zoological Museum, Institute for Evolutionary Biology and Environmental Studies, Winterthurerstrasse, University of Zurich, Zurich, Switzerland
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Ultrastructure of spermatozoa of Onthophagus taurus (Coleoptera, Scarabaeidae) exhibits heritable variation. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2011; 98:213-23. [PMID: 21279320 DOI: 10.1007/s00114-011-0763-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 12/15/2010] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Sperm competition is thought to be an important selective pressure shaping sperm form and function. However, few studies have moved beyond gross examinations of sperm morphology. Sperm length is subject to sexual selection via sperm competition in the scarab beetle Onthophagus taurus. Here, the structure and ultrastructure of spermatozoa in this species were investigated using light and electron microscopy. Spermatozoa were found to be filiform, measuring about 1,200 mm in length. The sperm head consists of a three-layered acrosome and a nuclear region bearing the anterior extension of the centriole adjunct. Acrosome and nuclear regions are bilaterally symmetric, with their axes of symmetry being orthogonal to each other. Head and flagellar structures are connected by a well-developed centriole adjunct. The sperm heads are asymmetrically surrounded by accessory material and embedded into the cytoplasm of the spermatocyst cell. The accessory material is produced inside the spermatids and then transferred to the outside due to a new membrane formed around the sperm's organelles. The old spermatid membrane separates the accessory material from the cyst cell. The flagellum contains a 9+9+2 axoneme, two accessory bodies, and two mitochondrial derivatives of unequal size. The major mitochondrial derivative is significantly larger than the minor one. The axoneme is arranged in a sinusoidal manner parallel along the major mitochondrial derivative. The spermatozoa show no progressive motility when released in buffer solution which is likely to be the result of the flagellar arrangement and the structure of the major mitochondrial derivative. The cross-sectional area of the minor and the major mitochondrial derivatives show different patterns of genetic variation. The data provide the first estimates of genetic variation in sperm ultrastructure for any species, and give evidence for the persistence of genetic variation in ultrastructure required for the rapid and divergent evolution that characterizes spermatozoa generally.
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50
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Sperm number and velocity affect sperm competition success in the guppy (Poecilia reticulata). Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-010-1085-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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