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Pinzoni L, Rasotto MB, Gasparini C. Sperm performance in the race for fertilization, the influence of female reproductive fluid. ROYAL SOCIETY OPEN SCIENCE 2024; 11:240156. [PMID: 39086834 PMCID: PMC11289650 DOI: 10.1098/rsos.240156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 05/17/2024] [Indexed: 08/02/2024]
Abstract
In studies of sperm competition, particularly in external fertilizers, the importance of the fertilization environment on the paternity share among rival males often goes overlooked. The female reproductive fluid (FRF), produced and released by females, creates the microenvironment that sperm encounter on their quest for fertilization and can generate paternity biases by affecting key traits in sperm competition. Yet, whether there is a direct link between FRF effects on sperm traits and its effect on competitive fertilization dynamics remains to be explored. Here, using the zebrafish Danio rerio, we compare within-female paternity share among two competing males and predictors of fertilization success (i.e. sperm traits) in the presence/absence of FRF. Our results unequivocally reveal a direct link between the direction and magnitude of the effect of FRF on sperm traits and the change in the competitive fertilization success of each male. This study demonstrates that the FRF directly mediates post-mating female control through its differential effect on sperm performance and that the FRF's effect on sperm quality alone is sufficient to predict the magnitude of the fitness effects. These findings highlight the need to consider the role of FRF in fertilization, avoiding biases resulting from an exclusive focus on male intrinsic sperm quality.
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Affiliation(s)
- Livia Pinzoni
- Department of Biology, University of Padova, Padova 35131, Italy
| | | | - Clelia Gasparini
- Department of Biology, University of Padova, Padova 35131, Italy
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2
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Pinzoni L, Locatello L, Gasparini C, Rasotto MB. Female reproductive fluid and male seminal fluid: a non-gametic conflict for post-mating control. Biol Lett 2023; 19:20230306. [PMID: 37752852 PMCID: PMC10523087 DOI: 10.1098/rsbl.2023.0306] [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: 06/30/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023] Open
Abstract
Growing evidence shows that non-gametic components released by both males and females can significantly drive sperm competition outcomes. Seminal fluid (SF) was shown to influence paternity success by affecting rival males' sperm performance, and, in some species with male alternative reproductive tactics, to selectively decrease the fertilization success of males of the opposite tactic. Female reproductive fluid (FRF) has been proven to differentially influence ejaculates of different males and bias fertilization towards specific partners. Whether, and with what outcome, these two processes can intersect to influence sperm competition is still unknown. Here we explore this scenario in the grass goby (Zosterisessor ophiocephalus), a fish with territorial-sneaker reproductive tactics, where sneaker males can exploit the territorials' SF while penalizing territorial sperm performance with their own fluid. To test whether FRF can rebalance the ejaculate competition in favour of territorial males, we used in vitro fertilization with a SF mixture (territorial + sneaker), using increasing concentrations of FRF, to simulate the natural conditions that ejaculates encounter towards the eggs. Our findings revealed a differential effect of FRF on the different tactics' fertilization success, favouring territorial ejaculates, possibly through an attenuation of the detrimental effects of sneaker SF, and enabling females to regain control over the fertilization process.
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Affiliation(s)
- Livia Pinzoni
- Department of Biology, University of Padova, Padova 35131, Italy
| | - Lisa Locatello
- Department of Biology and Evolution of Marine Organisms (BEOM), Stazione Zoologica Anton Dohrn, Fano Marine Center, Fano 61032, Italy
| | - Clelia Gasparini
- Department of Biology, University of Padova, Padova 35131, Italy
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3
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Pinzoni L, Locatello L, Gasparini C, Rasotto MB. Female reproductive fluid concentrations affect sperm performance of alternative male phenotypes in an external fertilizer. J Evol Biol 2023; 36:1198-1207. [PMID: 37438920 DOI: 10.1111/jeb.14199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 05/05/2023] [Accepted: 05/31/2023] [Indexed: 07/14/2023]
Abstract
There is growing evidence that the female reproductive fluid (FRF) plays an important role in cryptic female choice through its differential effect on the performance of sperm from different males. In a natural spawning event, the male(s) may release ejaculate closer or further away from the spawning female. If the relative spatial proximity of competing males reflects the female pre-mating preference towards those males, then favoured males will encounter higher concentrations of FRF than unpreferred males. Despite this being a common situation in many external fertilizers, whether different concentrations of FRF can differentially influence the sperm performance of distinct male phenotypes (favoured and unfavoured by the female) remains to be elucidated. Here, we tested this hypothesis using the grass goby (Zosterisessor ophiocephalus), a fish with distinct territorial-sneaker reproductive tactics and female pre-mating preference towards territorial males, that consequently mate in an advantaged position and whose sperm experience higher concentrations of FRF. Our findings revealed a differential concentration-dependent effect of FRF over sneaker and territorial sperm motility only at low concentrations (i.e. at the distance where sneakers typically ejaculate), with increasing FRF concentrations (i.e. close to the eggs) similarly boosting the sperm performance of both sneaker and territorial males. The ability to release sperm close to the eggs is a prerogative of territorials, but FRF can likewise advantage the sperm of those sneakers that are able to get closer, allowing flexibility in the direction of female post-mating choice.
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Affiliation(s)
- Livia Pinzoni
- Department of Biology, University of Padova, Padova, Italy
| | - Lisa Locatello
- Department of Biology and Evolution of Marine Organisms (BEOM), Stazione Zoologica Anton Dohrn, Fano Marine Center, Fano, Italy
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4
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Kustra MC, Alonzo SH. The coevolutionary dynamics of cryptic female choice. Evol Lett 2023; 7:191-202. [PMID: 37475752 PMCID: PMC10355280 DOI: 10.1093/evlett/qrad025] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 07/22/2023] Open
Abstract
In contrast to sexual selection on traits that affect interactions between the sexes before mating, little theoretical research has focused on the coevolution of postmating traits via cryptic female choice (when females bias fertilization toward specific males). We used simulation models to ask (a) whether and, if so, how nondirectional cryptic female choice (female-by-male interactions in fertilization success) causes deviations from models that focus exclusively on male-mediated postmating processes, and (b) how the risk of sperm competition, the strength of cryptic female choice, and tradeoffs between sperm number and sperm traits interact to influence the coevolutionary dynamics between cryptic female choice and sperm traits. We found that incorporating cryptic female choice can result in males investing much less in their ejaculates than predicted by models with sperm competition only. We also found that cryptic female choice resulted in the evolution of genetic correlations between cryptic female choice and sperm traits, even when the strength of cryptic female choice was weak, and the risk of sperm competition was low. This suggests that cryptic female choice may be important even in systems with low multiple mating. These genetic correlations increased with the risk of sperm competition and as the strength of cryptic female choice increased. When the strength of cryptic female choice and risk of sperm competition was high, extreme codivergence of sperm traits and cryptic female choice preference occurred even when the sperm trait traded off with sperm number. We also found that male traits lagged behind the evolution of female traits; this lag decreased with increasing strength of cryptic female choice and risk of sperm competition. Overall, our results suggest that cryptic female choice deserves more attention theoretically and may be driving trait evolution in ways just beginning to be explored.
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Affiliation(s)
- Matthew C Kustra
- Corresponding author: Department of Ecology and Evolutionary Biology Coastal Biology Building, 130 McAllister Way, University of California, Santa Cruz, CA 95060, United States.
| | - Suzanne H Alonzo
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, United States
- Institute of Marine Sciences, University of California, Santa Cruz, California 95060, USA
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5
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Bernos TA, Chang SL, Giglio RM, Davenport K, Fisher J, Lowery E, Bearlin A, Simmons R, Fortin M, Day CC, Landguth EL. Evaluating the evolutionary mechanisms maintaining alternative mating strategies in a simulated bull trout ( Salvelinus confluentus) population. Ecol Evol 2023; 13:e9965. [PMID: 37038529 PMCID: PMC10082177 DOI: 10.1002/ece3.9965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 04/12/2023] Open
Abstract
The coexistence of distinct alternative mating strategies (AMS) is often explained by mechanisms involving trade-offs between reproductive traits and lifetime fitness; yet their relative importance remains poorly understood. Here, we used an established individual-based, spatially explicit model to simulate bull trout (Salvelinus confluentus) in the Skagit River (Washington, USA) and investigated the influence of female mating preference, sneaker-specific mortality, and variation in age-at-maturity on AMS persistence using global sensitivity analyses and boosted regression trees. We assumed that two genetically fixed AMS coexisted within the population: sneaker males (characterized by younger age-at-maturity, greater AMS-specific mortality, and lower reproductive fitness) and territorial males. After 300 years, variation in relative sneaker success in the system was explained by sneaker males' reproductive fitness (72%) and, to a lesser extent, the length of their reproductive lifespan (21%) and their proportion in the initial population (8%). However, under a wide range of parameter values, our simulated scenarios predicted the extinction of territorial males or their persistence in small, declining populations. Although these results do not resolve the coexistence of AMS in salmonids, they reinforce the importance of mechanisms reducing sneaker's lifetime reproductive success in favoring AMS coexistence within salmonid populations but also limit the prediction that, without any other selective mechanisms at play, strong female preference for mating with territorial males and differences in reproductive lifespan allow the stable coexistence of distinct AMS.
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Affiliation(s)
- Thaïs A. Bernos
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
- Department of Biological SciencesUniversity of Toronto ScarboroughTorontoOntarioCanada
| | - Sarah L. Chang
- Department of BiologyUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
| | - Rachael M. Giglio
- Department of Ecology, Evolution, and Organismal BiologyOhio State UniversityColumbusOhioUSA
- United States Department of AgricultureNational Wildlife Research CenterOttawaOntarioUSA
| | - Kaeli Davenport
- Department of Wildlife BiologyUniversity of MontanaMissoulaMontanaUSA
| | | | | | | | | | - Marie‐Josée Fortin
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
| | - Casey C. Day
- School of Public and Community Health SciencesUniversity of MontanaMissoulaMontanaUSA
| | - Erin L. Landguth
- School of Public and Community Health SciencesUniversity of MontanaMissoulaMontanaUSA
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6
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The Use of Ovarian Fluid as Natural Fertilization Medium for Cryopreserved Semen in Mediterranean Brown Trout: The Effects on Sperm Swimming Performance. Vet Sci 2023; 10:vetsci10030219. [PMID: 36977258 PMCID: PMC10051816 DOI: 10.3390/vetsci10030219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/01/2023] [Accepted: 03/09/2023] [Indexed: 03/18/2023] Open
Abstract
D-532 fertilization solution is generally used to replace the water or ovarian fluid during artificial reproductive practices in salmonids due to its ability to boost sperm motility and increase fertilization rates compared with natural activation media. However, the maintenance of ovarian fluid in a reproductive microenvironment gives it the advantage of protecting the eggs from potential harmful factors from the external environment and simplifying the field operations related to its removal when D-532 is used alone. In light of this, the aim of the present study was to investigate in vitro, for the first time, the effect of ovarian fluid (OF 100%) on post-thaw sperm swimming performance of Mediterranean trout, comparing it with D-532 and a mixed solution of 50% D-532 and 50% ovarian fluid (OF 50%). The percentage of motile spermatozoa and movement duration was significantly increased in OF 100% and OF 50% compared with D-532. Sperm velocity was higher in D-532, but significant differences were recorded only with OF 100%. In conclusion, these results suggest that the presence of ovarian fluid alone or in combination with D-532 in an artificial microenvironment of reproduction represents a key factor in potentially increasing fertilization success when the frozen semen of Mediterranean brown trout is used.
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7
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Evaluating the Potential Fitness Effects of Chinook Salmon ( Oncorhynchus tshawytscha) Aquaculture Using Non-Invasive Population Genomic Analyses of MHC Nucleotide Substitution Spectra. Animals (Basel) 2023; 13:ani13040593. [PMID: 36830380 PMCID: PMC9951711 DOI: 10.3390/ani13040593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/27/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023] Open
Abstract
Genetic diversity plays a vital role in the adaptability of salmon to changing environmental conditions that can introduce new selective pressures on populations. Variability among local subpopulations may increase the chance that certain advantageous genes are passed down to future generations to mitigate susceptibility to novel diseases, warming oceans, loss of genetic stocks, and ocean acidification. Class I and II genes of the major histocompatibility complex (MHC) are crucial for the fitness of Chinook salmon due to the role they play in disease and pathogen resistance. The objective of this study was to assess the DNA sequence variability among wild and hatchery populations of Alaskan Chinook salmon at the class I α1 and class II β1 exons of the MHC. We hypothesized that the 96 wild samples taken from the Deshka River would display greater levels of observed heterozygosity (Ho) relative to expected heterozygosity (He) in suggesting that individuals with similar phenotypes mate with one another more frequently than would be expected under random mating patterns. Conversely, since no mate selection occurs in the William Jack Hernandez Sport Fish hatchery, we would not expect to see this discrepancy (He = Ho) in the 96 hatchery fish tested in this study. Alternatively, we hypothesized that post-mating selection is driving higher levels of observed heterozygosity as opposed to mate selection. If this is the case, we will observe higher than expected levels of heterozygosity among hatchery salmon. Both populations displayed higher levels of observed heterozygosity than expected heterozygosity at the Class I and II loci but genetic differentiation between the spatially distinct communities was minimal. Class I sequences showed evidence of balancing selection, despite high rates of non-synonymous substitutions observed, specifically at the peptide binding regions of both MHC genes.
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8
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Sperm Motility Regulation in Male and Female Bird Genital Tracts. J Poult Sci 2022; 59:1-7. [PMID: 35125908 PMCID: PMC8791776 DOI: 10.2141/jpsa.0200105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/11/2020] [Indexed: 12/02/2022] Open
Abstract
Sperm drastically change their flagellar movement in response to the surrounding physical and chemical environment. Testicular sperm are immotile; however, they gain the competence to initiate motility during passage through the male reproductive tract. Once ejaculated, the sperm are activated and promptly initiate motility. Unlike mammals, ejaculated sperm in birds are stored in specialized tubular invaginations referred to as sperm storage tubules (SSTs), located between the vagina and uterus, before fertilization. The resident sperm in the SSTs are in a quiescent state and then re-activated after release from the SSTs. It is thought that avian sperm can undergo motility change from quiescent to active state twice; however, the molecular mechanism underlying sperm motility regulation is poorly understood. In this short review, we summarize the current understanding of sperm motility regulation in male and female bird reproductive tracts. We also describe signal transduction, which regulates sperm motility, mainly derived from in vitro studies.
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9
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Kekäläinen J. Genetic incompatibility of the reproductive partners: an evolutionary perspective on infertility. Hum Reprod 2021; 36:3028-3035. [PMID: 34580729 PMCID: PMC8600657 DOI: 10.1093/humrep/deab221] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/22/2021] [Indexed: 12/18/2022] Open
Abstract
In natural fertilisation, the female reproductive tract allows only a strictly selected sperm subpopulation to proceed in the vicinity of an unfertilised oocyte. Female-mediated sperm selection (also known as cryptic female choice (CFC)) is far from a random process, which frequently biases paternity towards particular males over others. Earlier studies have shown that CFC is a ubiquitous phenomenon in the animal kingdom and often promotes assortative fertilisation between genetically compatible mates. Here, I demonstrate that CFC for genetic compatibility likely also occurs in humans and is mediated by a complex network of interacting male and female genes. I also show that the relative contribution of genetic compatibility (i.e. the male-female interaction effect) to reproductive success is generally high and frequently outweighs the effects of individual males and females. Together, these facts indicate that, along with male- and female-dependent pathological factors, reproductive failure can also result from gamete-level incompatibility of the reproductive partners. Therefore, I argue that a deeper understanding of these evolutionary mechanisms of sperm selection can pave the way towards a more inclusive view of infertility and open novel possibilities for the development of more personalised infertility diagnostics and treatments.
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Affiliation(s)
- Jukka Kekäläinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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10
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Sperm Accumulation Induced by the Female Reproductive Fluid: Putative Evidence of Chemoattraction Using a New Tool. Cells 2021; 10:cells10092472. [PMID: 34572122 PMCID: PMC8467055 DOI: 10.3390/cells10092472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 09/05/2021] [Accepted: 09/15/2021] [Indexed: 12/13/2022] Open
Abstract
There is considerable evidence that female reproductive fluid (FRF) interacts intimately with sperm, affecting several sperm traits, including sperm motility and longevity, and ultimately fertilization success. One of the first documented interactions between FRF and sperm is the ability of FRF to attract and guide sperm towards the eggs. However, most of the evidence of FRF’s chemoattraction proprieties comes from a limited number of taxa, specifically mammals and invertebrate broadcasting spawners. In other species, small FRF volumes and/or short sperm longevity often impose methodological difficulties resulting in this gap in chemoattraction studies in non-model species. One of the outcomes of sperm chemotaxis is sperm accumulation towards high chemoattractant concentrations, which can be easily quantified by measuring sperm concentration. Here, we tested sperm accumulation towards FRF in the zebrafish, Danio rerio, using an ad hoc developed, 3D printed, device (‘sperm selection chamber’). This easy-to-use tool allows to select and collect the sperm that swim towards a chemical gradient, and accumulate in a chemoattractant-filled well thus providing putative evidence for chemoattraction. We found that sperm accumulate in FRF in zebrafish. We also found that none of the sperm quality traits we measured (sperm swimming velocity and trajectory, sperm motility, and longevity) were correlated with this response. Together with the 3D printable project, we provide a detailed protocol for using the selection chamber. The chamber is optimized for the zebrafish, but it can be easily adapted for other species. Our device lays the foundation for a standardized way to measure sperm accumulation and in general chemoattraction, stimulating future research aimed at understanding the role and the mechanisms of sperm chemoattraction by FRF.
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11
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Does the Rainbow Trout Ovarian Fluid Promote the Spermatozoon on Its Way to the Egg? Int J Mol Sci 2021; 22:ijms22179519. [PMID: 34502430 PMCID: PMC8430650 DOI: 10.3390/ijms22179519] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/17/2022] Open
Abstract
The fertilization of freshwater fish occurs in an environment that may negatively affect the gametes; therefore, the specific mechanisms triggering the encounters of gametes would be highly expedient. The egg and ovarian fluid are likely the major sources of these triggers, which we confirmed here for rainbow trout (Oncorhynchus mykiss). The ovarian fluid affected significantly spermatozoa performance: it supported high velocity for a longer period and changed the motility pattern from tumbling in water to straightforward moving in the ovarian fluid. Rainbow trout ovarian fluid induced a trapping chemotaxis-like effect on activated male gametes, and this effect depended on the properties of the activating medium. The interaction of the spermatozoa with the attracting agents was accompanied by the "turn-and-run" behavior involving asymmetric flagellar beating and Ca2+ concentration bursts in the bent flagellum segment, which are characteristic of the chemotactic response. Ovarian fluid created the optimal environment for rainbow trout spermatozoa performance, and the individual peculiarities of the egg (ovarian fluid)-sperm interaction reflect the specific features of the spawning process in this species.
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12
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Ibáñez-Arancibia E, Farías JG, Valdebenito I. Use of antioxidants and time of cold storage: effects over viability parameters and enzymatic levels in semen of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792). BRAZ J BIOL 2021; 83:e245329. [PMID: 34378663 DOI: 10.1590/1519-6984.245329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 01/07/2021] [Indexed: 11/21/2022] Open
Abstract
The cold storage of milt implies potentials alterations in its quality because the storage generates as main process, free radicals that produce spermatozoa membrane lipids damage with the consequent motility and fertilising capacity disruptions. To decrease the damage generated by free radicals the cells have antioxidant defences (proteins, enzymes, and low molecular weight substances). The objective of the present study evaluated the time storage effect and different antioxidants prepared in spermatic diluents on sperm viability of O. mykiss milt stored at 4°C. The two-way ANOVA denoted that the time storage and antioxidant influence have significant effects separated or combined on viability parameters (sperm motility and viability, proteins concentrations and superoxide dismutase enzymatic activity in seminal plasma). In contrast, only the storage time affected the fertilising capacity and catalase enzymatic activity in seminal plasma. The resulting analysis can conclude that the antioxidant presence improves the viability of cold stored milt, especially the transport conditions and the antioxidants allow the fecundity despite motility decrease.
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Affiliation(s)
- E Ibáñez-Arancibia
- PhD Program in Sciences mentioning Applied Molecular and Cell Biology, La Frontera University, Temuco, Chile.,Laboratory of Engineering, Biotechnology and Applied Biochemistry - LIBBA, Department of Chemical Engineering, Faculty of Engineering and Science, La Frontera University, Temuco, Chile.,Department of Agricultural and Aquaculture Sciences, Faculty of Natural Resources, Catholic University of Temuco, Temuco, Chile
| | - J G Farías
- Laboratory of Engineering, Biotechnology and Applied Biochemistry - LIBBA, Department of Chemical Engineering, Faculty of Engineering and Science, La Frontera University, Temuco, Chile
| | - I Valdebenito
- Department of Agricultural and Aquaculture Sciences, Faculty of Natural Resources, Catholic University of Temuco, Temuco, Chile.,Nucleus of Research in Food Production, Faculty of Natural Resources, Catholic University of Temuco, Temuco, Chile
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13
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Lyons K, Kacev D, Mull CG. An inconvenient tooth: Evaluating female choice in multiple paternity using an evolutionarily and ecologically important vertebrate clade. Mol Ecol 2021; 30:1574-1593. [PMID: 33586211 PMCID: PMC8251896 DOI: 10.1111/mec.15844] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/29/2022]
Abstract
Understanding mating systems is a pillar of behavioural ecology, placing the complex interactions between females and males into a reproductive context. The field of multiple paternity, the phenomenon whereby many sires contribute to an individual litter, has traditionally viewed females as passive players in a male–male competitive framework. With the emergence of feminist perspectives in ecological fields, novel alternative mechanisms and evolutionary theories across invertebrate and vertebrate taxa recognize females are active stakeholders in the reproductive process. Despite their evolutionary significance, ecological diversity and myriad reproductive modes, elasmobranch (sharks, skates and rays) research lags behind other fields regarding complex biological processes, such as multiple paternity which is often ascribed to convenience polyandry. Here, we layout hypotheses and resynthesize multiple paternity literature from a female and life history perspective to highlight how alternative mechanisms influence the predominance of multiple paternity across elasmobranchs. We draw upon parallels in other invertebrate and vertebrate taxa to demonstrate how female elasmobranchs can influence multiple paternity outcomes that benefit their reproductive success. Our article challenges dogma that has resulted from years of dismissing the female perspective as important and provides a framework for future advancement using more holistic approaches to studying mating systems.
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Affiliation(s)
| | - Dovi Kacev
- Scripps Institution of Oceanography, San Diego, CA, USA
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14
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Lymbery RA, Berson JD, Evans JP. Indirect parental effects on offspring viability by egg-derived fluids in an external fertilizer. Proc Biol Sci 2020; 287:20202538. [PMID: 33290674 DOI: 10.1098/rspb.2020.2538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The capacity for parents to influence offspring phenotypes via nongenetic inheritance is currently a major area of focus in evolutionary biology. Intriguing recent evidence suggests that sexual interactions among males and females, both before and during mating, are important mediators of such effects. Sexual interactions typically extend beyond gamete release, involving both sperm and eggs, and their associated fluids. However, the potential for gamete-level interactions to induce nongenetic parental effects remains under-investigated. Here, we test for such effects using an emerging model system for studying gamete interactions, the external fertilizer Mytilus galloprovincialis. We employed a split-ejaculate design to test whether exposing sperm to egg-derived chemicals (ECs) from a female would affect fertilization rate and offspring viability when those sperm were used to fertilize a different female's eggs. We found separate, significant effects of ECs from non-fertilizing females on both fertilization rate and offspring viability. The offspring viability effect indicates that EC-driven interactions can have nongenetic implications for offspring fitness independent of the genotypes inherited by those offspring. These findings provide a rare test of indirect parental effects driven exclusively by gamete-level interactions, and to our knowledge the first evidence that such effects occur via the gametic fluids of females.
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Affiliation(s)
- Rowan A Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley WA 6009, Australia
| | - Jacob D Berson
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley WA 6009, Australia
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley WA 6009, Australia
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15
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Johnson SL, Borziak K, Kleffmann T, Rosengrave P, Dorus S, Gemmell NJ. Ovarian fluid proteome variation associates with sperm swimming speed in an externally fertilizing fish. J Evol Biol 2020; 33:1783-1794. [PMID: 33034086 PMCID: PMC7719593 DOI: 10.1111/jeb.13717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/02/2020] [Accepted: 09/30/2020] [Indexed: 12/27/2022]
Abstract
Sperm velocity is a key trait that predicts the outcome of sperm competition. By promoting or impeding sperm velocity, females can control fertilization via postcopulatory cryptic female choice. In Chinook salmon, ovarian fluid (OF), which surrounds the ova, mediates sperm velocity according to male and female identity, biasing the outcome of sperm competition towards males with faster sperm. Past investigations have revealed proteome variation in OF, but the specific components of OF that differentially mediate sperm velocity have yet to be characterized. Here we use quantitative proteomics to investigate whether OF protein composition explains variation in sperm velocity and fertilization success. We found that OF proteomes from six females robustly clustered into two groups and that these groups are distinguished by the abundance of a restricted set of proteins significantly associated with sperm velocity. Exposure of sperm to OF from females in group I had faster sperm compared to sperm exposed to the OF of group II females. Overall, OF proteins that distinguished between these groups were enriched for vitellogenin and calcium ion interactions. Our findings suggest that these proteins may form the functional basis for cryptic female choice via the biochemical and physiological mediation of sperm velocity.
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Affiliation(s)
- Sheri L. Johnson
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - Kirill Borziak
- Biology Department, Center for Reproductive Evolution, Syracuse University, Syracuse, NY, USA
| | - Torsten Kleffmann
- Department of Biochemistry, Centre for Protein Research, University of Otago, Dunedin, New Zealand
| | - Patrice Rosengrave
- Department of Anatomy, University of Otago, Dunedin, New Zealand
- AgResearch, Biocontrol and Biosecurity, Christchurch, New Zealand
| | - Steve Dorus
- Biology Department, Center for Reproductive Evolution, Syracuse University, Syracuse, NY, USA
| | - Neil J. Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand
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16
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Nowosad J, Kucharczyk D, Sikora M, Kupren K. Optimization of barbel (Barbus Barbus L.) fertilization and effects of ovarian fluid when there are controlled conditions for gamete activations. Anim Reprod Sci 2020; 224:106652. [PMID: 33249355 DOI: 10.1016/j.anireprosci.2020.106652] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 12/14/2022]
Abstract
Fertilization is one of the most important procedures in artificial reproduction and it directly affects the reproduction outcome. When there is optimization of fertilization, there can be a positive effect on subsequent reproductive processes and economic aspects of aquaculture. This study was conducted to determine time for which oocytes and sperm of barbel Barbus barbus retain fertilization capacity following placement in freshwater. Furthermore, the amount of ovarian fluid, excreted by fish during spawning with eggs (OFI; %) was determined, along with the chemical composition and effects on fertilization were determined. Gametes, ovarian fluid, and seminal plasma from barbel spawning specimens of the F4 generation were used to conduct the study. Ovarian fluid accounted for 14%-68% of contents of the mass released at spawning and post-spawning composition differed depending on whether hormonal treatments were utilized for control of reproduction. There was an association (R2 = 0.982; P = 0.000) between the pH of ovarian fluid and the barbel embryo survival rate. There was the greatest survival rate (>60 %) when the pH range of 7.9-8.4 and there was a lesser embryo viability when pH values were lesser or greater than values within this range (P < 0.05). The results from the study indicate that barbel eggs retain fertilization capacity longer (as long as 210 s) after activation by placement in fresh water than spermatozoa (about 30 s).
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Affiliation(s)
- Joanna Nowosad
- Department of Ichthyology and Aquaculture, Faculty of Animal Bioengineering, University of Warmia and Mazury, Olsztyn, Poland.
| | - Dariusz Kucharczyk
- Department of Ichthyology and Aquaculture, Faculty of Animal Bioengineering, University of Warmia and Mazury, Olsztyn, Poland
| | - Mateusz Sikora
- Department of Ichthyology and Aquaculture, Faculty of Animal Bioengineering, University of Warmia and Mazury, Olsztyn, Poland
| | - Krzysztof Kupren
- Department of Ichthyology and Aquaculture, Faculty of Animal Bioengineering, University of Warmia and Mazury, Olsztyn, Poland
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17
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Dittman AH, Quinn TP. Amino acid cues emanating from Pacific salmon eggs and ovarian fluid. JOURNAL OF FISH BIOLOGY 2020; 97:1408-1414. [PMID: 32829515 DOI: 10.1111/jfb.14507] [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: 06/24/2020] [Revised: 08/03/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
The eggs of salmonid fishes are an important food source for many aquatic predators that detect eggs using olfaction. Moreover, chemicals from eggs and ovarian fluid aid sperm cells in detecting and locating eggs for fertilization, and ovarian fluid is attractive to conspecific males. Thus chemicals from eggs and ovarian fluid may facilitate reproduction but may also attract egg predators. The authors sampled mature females of three Pacific salmon species - Chinook (Oncorhynchus tshawytscha), coho (Oncorhynchus kisutch) and sockeye (Oncorhynchus nerka) - and determined the proportional representation of amino acids, potent fish odorants, from their eggs and ovarian fluid (Chinook and coho salmon only). They then tested juvenile coho salmon, an egg predator, for responses to ovarian fluid and egg odours using the electro-olfactogram (EOG) recording technique. The amino acid compositions of the salmon species were significantly and positively correlated with each other, and the interspecific differences were comparable to those between individuals of the same species. The egg water samples were, on average, dominated by lysine, alanine and glutamine (12.6%, 12.4% and 10.9%, respectively). The ovarian fluid samples were dominated by lysine (20.5%), followed by threonine (9.7%), glycine (9.2%) and arginine (8.8%). EOG recordings demonstrated the ability of juvenile coho salmon to detect the chemical traces of eggs and ovarian fluid. It is concluded that salmon eggs are a potent source of odours for potential predators but likely not highly differentiated among salmon species.
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Affiliation(s)
- Andrew H Dittman
- Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, USA
| | - Thomas P Quinn
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA
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18
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Gasparini C, Pilastro A, Evans JP. The role of female reproductive fluid in sperm competition. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200077. [PMID: 33070736 DOI: 10.1098/rstb.2020.0077] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The role of non-gametic components of the ejaculate (seminal fluid) in fertility and sperm competitiveness is now well established. Surprisingly, however, we know far less about female reproductive fluid (FRF) in the context of sexual selection, and insights into male-FRF interactions in the context of sperm competition have only recently emerged. Despite this limited knowledge, evidence from taxonomically diverse species has revealed insights into the effects of FRF on sperm traits that have previously been implicated in studies of sperm competition. Specifically, through the differential effects of FRF on a range of sperm traits, including chemoattraction and alterations in sperm velocity, FRF has been shown to exert positive phenotypic effects on the sperm of males that are preferred as mating partners, or those from the most compatible or genetically diverse males. Despite these tantalizing insights into the putative sexually selected functions of FRF, we largely lack a mechanistic understanding of these processes. Taken together, the evidence presented here highlights the likely ubiquity of FRF-regulated biases in fertilization success across a diverse range of taxa, thus potentially elevating the importance of FRF to other non-gametic components that have so far been studied largely in males. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Clelia Gasparini
- Department of Biology, University of Padova, Padova 35131, Italy
| | - Andrea Pilastro
- Department of Biology, University of Padova, Padova 35131, Italy
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 6009 WA, Australia
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19
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Lüpold S, Reil JB, Manier MK, Zeender V, Belote JM, Pitnick S. How female × male and male × male interactions influence competitive fertilization in Drosophila melanogaster. Evol Lett 2020; 4:416-429. [PMID: 33014418 PMCID: PMC7523561 DOI: 10.1002/evl3.193] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/02/2020] [Accepted: 08/13/2020] [Indexed: 01/01/2023] Open
Abstract
How males and females contribute to joint reproductive success has been a long‐standing question in sexual selection. Under postcopulatory sexual selection, paternity success is predicted to derive from complex interactions among females engaging in cryptic female choice and males engaging in sperm competition. Such interactions have been identified as potential sources of genetic variation in sexually selected traits but are also expected to inhibit trait diversification. To date, studies of interactions between females and competing males have focused almost exclusively on genotypes and not phenotypic variation in sexually selected traits. Here, we characterize within‐ and between‐sex interactions in Drosophila melanogaster using isogenic lines with heritable variation in both male and female traits known to influence competitive fertilization. We confirmed, and expanded on, previously reported genotypic interactions within and between the sexes, and showed that several reproductive events, including sperm transfer, female sperm ejection, and sperm storage, were explained by two‐ and three‐way interactions among sex‐specific phenotypes. We also documented complex interactions between the lengths of competing males’ sperm and the female seminal receptacle, which are known to have experienced rapid female‐male co‐diversification. Our results highlight the nonindependence of sperm competition and cryptic female choice and demonstrate that complex interactions between the sexes do not limit the ability of multivariate systems to respond to directional sexual selection.
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Affiliation(s)
- Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich CH-8057 Switzerland.,Department of Biology Syracuse University Syracuse New York 13244
| | - Jonathan Bradley Reil
- Department of Entomology Cornell University Ithaca New York 14853.,Department of Plant and Environmental Protection Sciences University of Hawaii at Mānoa Honolulu Hawaii 96822
| | - Mollie K Manier
- Department of Biology Syracuse University Syracuse New York 13244.,Department of Biological Sciences George Washington University Washington DC 20052
| | - Valérian Zeender
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich CH-8057 Switzerland
| | - John M Belote
- Department of Biology Syracuse University Syracuse New York 13244
| | - Scott Pitnick
- Department of Biology Syracuse University Syracuse New York 13244
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20
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Locatello L, Rigoni G, Soriano ME, Rasotto MB, Poli F. Going beyond conventional parameters to unveil sperm quality in fish: the use of fibre optic technology to assess mitochondrial respiratory performance. Biol Open 2020; 9:bio053306. [PMID: 32694190 PMCID: PMC7406323 DOI: 10.1242/bio.053306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/09/2020] [Indexed: 12/03/2022] Open
Abstract
Sperm fertilisation success depends on both intrinsic quality and the interactions with the surrounding reproductive fluids. In several fish species, these interactions have a variable effect on sperm performance. Although specific responses to reproductive fluids may depend on intrinsic differences in sperm quality, variations in the traditionally recorded sperm functional traits do not fully account for the observed patterns. New methods to enhance the evaluation of sperm quality may prove to be valuable at both applied and theoretical levels, by improving the breeding protocol of reared species and the understanding of mating success in sperm competition contexts. Here we develop a fibre optic-based technique, also adequate for small ejaculate samples, to test the role of mitochondrial respiratory efficiency in deciphering sperm performance variability. We purposely used as model the grass goby, Zosterisessor ophiocephalus, a fish with guard-sneaker mating tactics where the sperm in each male tactic have similar intrinsic qualities (velocity, viability, ATP content), but sneakers' sperm exploit territorial males' seminal fuid, overall displaying better fertilization ability. We found that sperm differed in their mitochondrial respiratory efficiency, which was higher in sneakers' sperm compared to territorial ones. This result draws the attention to an indicator of sperm quality that might be helpful in disentangling the mechanisms driving sperm-reproductive fluid interactions.
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Affiliation(s)
- Lisa Locatello
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35121 Padova, Italy
| | - Giovanni Rigoni
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35121 Padova, Italy
| | - Maria E Soriano
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35121 Padova, Italy
| | - Maria B Rasotto
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35121 Padova, Italy
| | - Federica Poli
- Department of Biology, University of Padova, Via Ugo Bassi 58/b, 35121 Padova, Italy
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21
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Pitnick S, Wolfner MF, Dorus S. Post-ejaculatory modifications to sperm (PEMS). Biol Rev Camb Philos Soc 2020; 95:365-392. [PMID: 31737992 PMCID: PMC7643048 DOI: 10.1111/brv.12569] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022]
Abstract
Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm 'capacitation', was discovered nearly seven decades ago and opened a window into the complexities of sperm-female interaction. Capacitation is most commonly used to refer to a specific combination of processes that are believed to be widespread in mammals and includes modifications to the sperm plasma membrane, elevation of intracellular cyclic AMP levels, induction of protein tyrosine phosphorylation, increased intracellular Ca2+ levels, hyperactivation of motility, and, eventually, the acrosome reaction. Capacitation is only one example of post-ejaculatory modifications to sperm (PEMS) that are widespread throughout the animal kingdom. Although PEMS are less well studied in non-mammalian taxa, they likely represent the rule rather than the exception in species with internal fertilization. These PEMS are diverse in form and collectively represent the outcome of selection fashioning complex maturational trajectories of sperm that include multiple, sequential phenotypes that are specialized for stage-specific functionality within the female. In many cases, PEMS are critical for sperm to migrate successfully through the female reproductive tract, survive a protracted period of storage, reach the site of fertilization and/or achieve the capacity to fertilize eggs. We predict that PEMS will exhibit widespread phenotypic plasticity mediated by sperm-female interactions. The successful execution of PEMS thus has important implications for variation in fitness and the operation of post-copulatory sexual selection. Furthermore, it may provide a widespread mechanism of reproductive isolation and the maintenance of species boundaries. Despite their possible ubiquity and importance, the investigation of PEMS has been largely descriptive, lacking any phylogenetic consideration with regard to divergence, and there have been no theoretical or empirical investigations of their evolutionary significance. Here, we (i) clarify PEMS-related nomenclature; (ii) address the evolutionary origin, maintenance and divergence in PEMS in the context of the protracted life history of sperm and the complex, selective environment of the female reproductive tract; (iii) describe taxonomically widespread types of PEMS: sperm activation, chemotaxis and the dissociation of sperm conjugates; (iv) review the occurence of PEMS throughout the animal kingdom; (v) consider alternative hypotheses for the adaptive value of PEMS; (vi) speculate on the evolutionary implications of PEMS for genomic architecture, sexual selection, and reproductive isolation; and (vii) suggest fruitful directions for future functional and evolutionary analyses of PEMS.
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Affiliation(s)
- Scott Pitnick
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
| | - Mariana F. Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Steve Dorus
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
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22
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Myers JN, Bradford AJ, Hallas VS, Lawson LL, Pitcher TE, Dunham RA, Butts IAE. Channel catfish ovarian fluid differentially enhances blue catfish sperm performance. Theriogenology 2020; 149:62-71. [PMID: 32247214 DOI: 10.1016/j.theriogenology.2020.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/24/2020] [Accepted: 03/12/2020] [Indexed: 12/12/2022]
Abstract
For externally fertilizing fishes, interactions between male and female gametes have been shown to have remarkable impacts on sperm performance. Ovarian fluid (OF) and its ability to alter the swimming behavior of fish sperm makes it a determining factor of fertility. With the expansion of channel catfish (Ictalurus punctatus) ♀ × blue catfish (Ictalurus furcatus) ♂ hybrid aquaculture, it is essential to understand the impacts during fertilization and the magnitude such gametic interactions have on sperm performance and subsequent male fertility potential. This study was conducted to address the following: 1) activate blue catfish sperm with/without channel catfish OF to determine impacts on sperm performance and 2) assess if sperm behave differently when activated in the OF from individual females. Sperm (n = 4 males) were activated without OF (control) and with diluted OF from unique females (n = 6), creating 24 experimental crosses. Sperm motility (%), velocity (VCL), and longevity were analyzed using computer assisted sperm analyses software. With OF incorporated in the activation media, sperm velocity was significantly higher than the control at 10, 20, and 30 s post-activation. OF did not have an impact on motility for any females at 10 s and 20 s post-activation but became significantly higher than the control at 30 s. In all cases, OF treatments greatly increased longevity. Male × female interactions were highly significant, such that motility, velocity, and longevity were dependent on specific male-female pairs. This information shows that OF should be incorporated in aquatic media to simulate natural spawning conditions and accurately assess the fluid mechanics of sperm propulsion for each male. Additionally, there are mechanisms that drive gamete interactions that need to be explored further, which may improve selection of male-female pairs for in-vitro fertilization. On a broad scale, our results also help to shed light on the complexities of fertilization and fish reproduction overall, which may have implications for recruitment variability and recovery strategies of threatened and/or endangered freshwater species.
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Affiliation(s)
- J N Myers
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - A J Bradford
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - V S Hallas
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - L L Lawson
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - T E Pitcher
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9B 3P4, Canada; Department of Biological Sciences, University of Windsor, Windsor, ON N9B 3P4, Canada.
| | - R A Dunham
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
| | - I A E Butts
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
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23
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Purchase CF, Rooke AC. Freezing ovarian fluid does not alter how it affects fish sperm swimming performance: creating a cryptic female choice 'spice rack' for use in split-ejaculate experimentation. JOURNAL OF FISH BIOLOGY 2020; 96:693-699. [PMID: 31985071 DOI: 10.1111/jfb.14263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
Cryptic female choice is often mediated chemically in external fertilizers by ovarian fluid (OF), which can change sperm swimming performance and bias paternity under sperm competition. Assessing cryptic female choice is hindered by the necessity of using fresh gametes and the short time window available to obtain diverse samples from wild animals. Using split-ejaculate experimental designs and samples from lake trout, brown trout and Atlantic salmon, we evaluated whether freezing OF alters the way in which it modifies sperm swimming. Sperm had improved swimming performance in the presence of OF over plain water, and the effect did not depend on whether the OF had previously been frozen. Freezing OF does not seem to alter the way it influences sperm. This allows the researcher to create a 'spice rack' of OF samples that can be used in studies on cryptic female choice, and opens up the possibility to compare animals mating under large spatial and temporal variability.
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Affiliation(s)
- Craig F Purchase
- Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, Canada
| | - Anna C Rooke
- Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, Canada
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24
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Orbach DN, Rooke AC, Evans JP, Pitcher TE, Purchase CF. Assessing the potential for post-ejaculatory female choice in a polyandrous beach-spawning fish. J Evol Biol 2020; 33:449-459. [PMID: 31860764 DOI: 10.1111/jeb.13579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 11/27/2022]
Abstract
In species with limited opportunities for pre-ejaculatory sexual selection (behavioural components), post-ejaculatory mechanisms may provide opportunities for mate choice after gametes have been released. Recent evidence from a range of taxa has revealed that cryptic female choice (i.e., female-mediated differential fertilization bias), through chemical cues released with or from eggs, can differentially regulate the swimming characteristics of sperm from various males and ultimately determine male fertilization success under sperm competition. We assessed the potential role that such female-modulated chemical cues play in influencing sperm swimming characteristics in beach-spawning capelin (Mallotus villosus), an externally fertilizing fish that mates as couples (one male and one female) or threesomes (two males and one female) with presumably limited opportunities for pre-ejaculatory sexual selection. We assayed sperm swimming characteristics under varying doses and donor origins of egg cues and also examined the possibility of assortative mating based on body size. We found mating groups were not associated by size, larger males did not produce better quality ejaculates, and egg cues (regardless of dosage or donor identity) did not influence sperm swimming characteristics. Our findings suggest that intersexual pre-ejaculatory sexual selection and cryptic female choice mediated by female chemical cues are poorly developed in capelin, possibly due to unique natural selection constraints on reproduction.
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Affiliation(s)
- Dara N Orbach
- Department of Life Sciences, Texas A&M University-Corpus Christi, Corpus Christi, TX, USA.,Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | - Anna C Rooke
- Department of Biology, Memorial University, St. John's, NL, Canada
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia
| | - Trevor E Pitcher
- Great Lakes Institute for Environmental Research and Department of Integrative Biology, University of Windsor, Windsor, ON, Canada
| | - Craig F Purchase
- Department of Biology, Memorial University, St. John's, NL, Canada
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25
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Poli F, Immler S, Gasparini C. Effects of ovarian fluid on sperm traits and its implications for cryptic female choice in zebrafish. Behav Ecol 2019. [DOI: 10.1093/beheco/arz077] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
AbstractIn polyandrous mating systems, females maintain the opportunity to bias male fertilization success after mating in a process known as cryptic female choice. Mechanisms of cryptic female choice have been described both in internal and external fertilizers, and may affect fertilization processes at different stages before, during, and after fertilization. In internal fertilizers, females have substantial control over sperm storage and fertilization, whereas in external fertilizers, female control is limited. A key factor proposed to mediate cryptic female choice is the fluid surrounding the eggs, the ovarian fluid, as it may directly affect sperm performance. Here, we studied the role of ovarian fluid in post-mating sexual selection using the zebrafish, Danio rerio. Firstly, we assessed how ovarian fluid affects sperm swimming performance compared with freshwater. We focused on sperm motility, velocity, swimming trajectory, and longevity, all traits associated with competitive fertilization success in externally fertilizing fish. In a second step, we used a North Carolina II design to explore female, male, and female x male effects by testing sperm motility of 2 males in the ovarian fluid of 2 females in a total of 11 blocks. Our results indicate that the ovarian fluid affects sperm performance differently from freshwater. Specifically, sperm velocity, motility, and longevity were higher in the ovarian fluid than in freshwater, whereas sperm linearity and beat cross frequency showed the opposite pattern. Moreover, these effects varied according to male, female, and male x female identities, supporting the potential for cryptic female choice mediated by ovarian fluid in this species.
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Affiliation(s)
- Federica Poli
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Australia
- Department of Biology, University of Padova, Padova, Italy
| | - Simone Immler
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
| | - Clelia Gasparini
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Australia
- Department of Biology, University of Padova, Padova, Italy
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26
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Zadmajid V, Myers JN, Sørensen SR, Ernest Butts IA. Ovarian fluid and its impacts on spermatozoa performance in fish: A review. Theriogenology 2019; 132:144-152. [PMID: 31022604 DOI: 10.1016/j.theriogenology.2019.03.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 03/24/2019] [Indexed: 12/11/2022]
Abstract
Factors such as gamete quality can profoundly affect fertility, but the spawning micro-environment that surrounds the spermatozoa and eggs during gamete contact has largely been neglected. In fishes, understanding these gametic interactions is crucial because each female creates a unique spawning environment by simultaneously expelling her distinct ovarian fluid (OF) along with an egg batch. In turn, OF has been shown to influence spermatozoa performance traits by modifying spermatozoa behaviors and fertilization outcomes. Here, we shed light on these gametic interactions by overviewing literature on OF and how it impacts spermatozoa performance traits. Fish OF is clear or has slight coloration and can constitute ≤10-30% of egg mass. Viscosity of the OF is ∼2- to 3-fold higher than water and its pH ranges 6.2 to 8.8. Osmolality of the OF is lower in freshwater (190-322 mOsmol/kg) than marine species (289-514 mOsmol/kg). Na+ (98.3-213.7 mmol/L) and Cl- (89.8-172.7 mmol/L) are predominant ions in OF, while K+ (1.7-19.3 mmol/L), Mg2+ (0.4-8.1 mmol/L), and Ca2+(0.5-9.7 mmol/L) ions are detected at lower concentrations. Protein levels can be high in OF and exhibit intra- and inter-species variation (54-826 mg/100 mL). Fish OF also contains a series of organic components and substances that enhance and/or attract sperm towards the vicinity of an egg. OF can also differentially impact sperm based on genetic relatedness of mates, male phenotype (i.e. alternative reproductive tactics), or geographic origin. To conclude, when testing further reproductive paradigms, we suggest a shift from classic spermatozoa activation medium (water only) to more natural spawning media, which encompass OF-spermatozoa interactions.
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Affiliation(s)
- Vahid Zadmajid
- Department of Fisheries Science, Faculty of Natural Resources, University of Kurdistan, P.O. Box 416, Sanandaj, Iran
| | - Jaelen Nicole Myers
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, United States
| | - Sune Riis Sørensen
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs., Lyngby, Denmark
| | - Ian Anthony Ernest Butts
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, United States.
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27
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Johnson SL, Zellhuber-McMillan S, Gillum J, Dunleavy J, Evans JP, Nakagawa S, Gemmell NJ. Evidence that fertility trades off with early offspring fitness as males age. Proc Biol Sci 2019; 285:rspb.2017.2174. [PMID: 29367392 DOI: 10.1098/rspb.2017.2174] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 12/21/2017] [Indexed: 12/29/2022] Open
Abstract
Models of ageing predict that sperm function and fertility should decline with age as sperm are exposed to free radical damage and mutation accumulation. However, theory also suggests that mating with older males should be beneficial for females because survival to old age is a demonstration of a male's high genetic and/or phenotypic quality. Consequently, declines in sperm fitness may be offset by indirect fitness benefits exhibited in offspring. While numerous studies have investigated age-based declines in male fertility, none has taken the integrated approach of studying age-based effects on both male fertility and offspring fitness. Here, using a cohort-based longitudinal study of zebrafish (Danio rerio), we report a decline in male mating success and fertility with male age but also compensating indirect benefits. Using in vitro fertilization, we show that offspring from older males exhibit superior early survival compared to those from their youngest counterparts. These findings suggest that the high offspring fitness observed for the subset of males that survive to an old age (approx. 51% in this study) may represent compensating benefits for declining fertility with age, thus challenging widely held views about the fitness costs of mating with older males.
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Affiliation(s)
- Sheri L Johnson
- Department of Zoology, University of Otago, Dunedin 9054, New Zealand .,Department of Anatomy, University of Otago, Dunedin 9054, New Zealand.,Allan Wilson Centre, University of Otago, Dunedin 9054, New Zealand
| | | | - Joanne Gillum
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - Jessica Dunleavy
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand
| | - Jonathan P Evans
- Centre for Evolutionary Biology, University of Western Australia, Crawley 6009, Australia
| | - Shinichi Nakagawa
- Department of Zoology, University of Otago, Dunedin 9054, New Zealand.,Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, Australia
| | - Neil J Gemmell
- Department of Anatomy, University of Otago, Dunedin 9054, New Zealand.,Allan Wilson Centre, University of Otago, Dunedin 9054, New Zealand
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28
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Kleppe SA, Nordeide JT, Rudolfsen G, Figenschou L, Larsen B, Reiss K, Folstad I. No support for cryptic choice by ovarian fluid in an external fertilizer. Ecol Evol 2018; 8:11763-11774. [PMID: 30598774 PMCID: PMC6303707 DOI: 10.1002/ece3.4628] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 09/17/2018] [Accepted: 09/19/2018] [Indexed: 12/01/2022] Open
Abstract
Whether the ovarian fluid (OF) represents a selective environment influencing cryptic female choice was tested using an external fertilizer experiencing intense sperm competition and large effects of OF on sperm swimming behavior-the Arctic charr (Salvelinus alpinus). We physically separated the OF from the eggs of reproductively active females and reintroduced either their own OF or fluid from another female to the eggs. The eggs were then fertilized in vitro in a replicated split-brood design with sperm from two males under synchronized sperm competition trials, while also measuring sperm velocity of the individual males in the individual OFs. We found large effects of males, but no effect of females (i.e., eggs) on paternity, determined from microsatellites. More important, we found no effect of OF treatments on the relative paternity of the two competing males in each pair. This experimental setup does not provide support for the hypothesis that OF plays an important role as medium for cryptic female choice in charr. Power analyses revealed that our sample size is large enough to detect medium-sized changes in relative paternity (medium-sized effect sizes), but not large enough to detect small changes in relative paternity. More studies are needed before a conclusion can be drawn about OF's potential influence on paternity under sperm competition-even in charr.
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Affiliation(s)
| | | | - Geir Rudolfsen
- Faculty of Bioscience, Fishery and EconomyUiT The Arctic University of NorwayTromsøNorway
| | - Lars Figenschou
- University Library, UiT The Arctic University of NorwayTromsøNorway
| | | | - Katrin Reiss
- Faculty of Biosciences and AquacultureNord UniversityBodøNorway
| | - Ivar Folstad
- Faculty of Bioscience, Fishery and EconomyUiT The Arctic University of NorwayTromsøNorway
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29
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Kekäläinen J, Evans JP. Gamete-mediated mate choice: towards a more inclusive view of sexual selection. Proc Biol Sci 2018; 285:20180836. [PMID: 30051836 PMCID: PMC6083266 DOI: 10.1098/rspb.2018.0836] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 06/26/2018] [Indexed: 12/23/2022] Open
Abstract
'Sperm competition'-where ejaculates from two or more males compete for fertilization-and 'cryptic female choice'-where females bias this contest to suit their reproductive interests-are now part of the everyday lexicon of sexual selection. Yet the physiological processes that underlie these post-ejaculatory episodes of sexual selection remain largely enigmatic. In this review, we focus on a range of post-ejaculatory cellular- and molecular-level processes, known to be fundamental for fertilization across most (if not all) sexually reproducing species, and point to their putative role in facilitating sexual selection at the level of the cells and gametes, called 'gamete-mediated mate choice' (GMMC). In this way, we collate accumulated evidence for GMMC across different mating systems, and emphasize the evolutionary significance of such non-random interactions among gametes. Our overall aim in this review is to build a more inclusive view of sexual selection by showing that mate choice often acts in more nuanced ways than has traditionally been assumed. We also aim to bridge the conceptual divide between proximal mechanisms of reproduction, and adaptive explanations for patterns of non-random sperm-egg interactions that are emerging across an increasingly diverse array of taxa.
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Affiliation(s)
- Jukka Kekäläinen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia
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30
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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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31
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Firman RC. Postmating sexual conflict and female control over fertilization during gamete interaction. Ann N Y Acad Sci 2018. [DOI: 10.1111/nyas.13635] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Renée C. Firman
- Centre for Evolutionary Biology University of Western Australia Western Australia Australia
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32
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Geßner C, Johnson SL, Fisher P, Clarke S, Rutherford K, Symonds J, Gemmell NJ. Male-female relatedness at specific SNP-linkage groups influences cryptic female choice in Chinook salmon ( Oncorhynchus tshawytscha). Proc Biol Sci 2018; 284:rspb.2017.0853. [PMID: 28747474 DOI: 10.1098/rspb.2017.0853] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 06/13/2017] [Indexed: 12/14/2022] Open
Abstract
In a range of taxa, the relatedness between mates influences both pre- and post-mating processes of sexual selection. However, relatively little is known about the genetic loci facilitating such a bias, with the exception of the major histocompatibility complex. Here, we performed tightly controlled replicated in vitro fertilization trials to explore the impact of relatedness on two possible mechanisms of cryptic female choice (CFC) in Chinook salmon (Oncorhynchus tshawytscha). We tested (i) whether relatedness of mates, assessed using 682 single nucleotide polymorphisms (SNPs) on 29 SNP-linkage groups (LGs), biases a male's sperm velocity in ovarian fluid (a parameter previously shown to predict male fertilization success), and (ii) whether relatedness of mates governs fertilization success via other mechanisms, probably via sperm-egg interactions. We found that relatedness on three LGs explained the variation in sperm velocity, and relatedness on two LGs explained fertilization success, which might indicate the presence of genes important in sperm-ovarian fluid and sperm-egg interactions in these genomic regions. Mapping of the SNPs on these LGs to the rainbow trout genome revealed two genes that affect fertility in humans and represent candidate genes for further studies. Our results thereby provide a novel contribution to the understanding of the mechanism of CFC.
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Affiliation(s)
- Cornelia Geßner
- Allan Wilson Centre, Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand
| | - Sheri L Johnson
- Allan Wilson Centre, Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand.,Department of Zoology, University of Otago, 340 Great King Street, Dunedin 9016, New Zealand
| | - Paul Fisher
- AgResearch, Invermay Agricultural Centre, Puddle Alley, Mosgiel 9053, New Zealand
| | - Shannon Clarke
- AgResearch, Invermay Agricultural Centre, Puddle Alley, Mosgiel 9053, New Zealand
| | - Kim Rutherford
- Allan Wilson Centre, Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand
| | - Jane Symonds
- National Institute of Water and Atmospheric Research, Bream Bay Aquaculture Park, Station Road, Ruakaka 0116, New Zealand
| | - Neil J Gemmell
- Allan Wilson Centre, Department of Anatomy, University of Otago, 270 Great King Street, Dunedin 9016, New Zealand
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33
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Horváth B, Kalinka AT. The genetics of egg retention and fertilization success in Drosophila: One step closer to understanding the transition from facultative to obligate viviparity. Evolution 2018; 72:318-336. [PMID: 29265369 DOI: 10.1111/evo.13411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 10/16/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait. Here, we develop a novel microscope-based method for measuring egg retention in Drosophila females and determine the range of phenotypic variation in mated female egg retention in a subset of 91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the genetic basis of egg retention using a genome-wide association study (GWAS). Further, the scoring of more than 95,000 stained, staged eggs enabled estimates of fertilization success for each line. We found evidence that ovary- and spermathecae-related genes as well as genes affecting olfactory behavior, male mating behavior, male-female attraction and sperm motility may play a crucial role in post-mating physiology. Based on our findings we also propose potential evolutionary routes toward obligate viviparity. In particular, we propose that the loss of fecundity incurred by viviparity could be offset by benefits arising from enhanced mate discrimination, resource specialization, or modified egg morphology.
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Affiliation(s)
- Barbara Horváth
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Vienna Graduate School of Population Genetics, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Current Address: Barbara Ellis, Institutionen för ekologi och genetik, Evolutionsbiologiskt Centrum (EBC), Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Alex T Kalinka
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria
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34
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Eckel BA, Guo R, Reinhardt K. More Pitfalls with Sperm Viability Staining and a Viability-Based Stress Test to Characterize Sperm Quality. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00165] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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35
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Monro K, Marshall DJ. Unravelling anisogamy: egg size and ejaculate size mediate selection on morphology in free-swimming sperm. Proc Biol Sci 2017; 283:rspb.2016.0671. [PMID: 27412273 DOI: 10.1098/rspb.2016.0671] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/20/2016] [Indexed: 01/28/2023] Open
Abstract
Gamete dimorphism (anisogamy) defines the sexes in most multicellular organisms. Theoretical explanations for its maintenance usually emphasize the size-related selection pressures of sperm competition and zygote survival, assuming that fertilization of all eggs precludes selection for phenotypes that enhance fertility. In external fertilizers, however, fertilization is often incomplete due to sperm limitation, and the risk of polyspermy weakens the advantage of high sperm numbers that is predicted to limit sperm size, allowing alternative selection pressures to target free-swimming sperm. We asked whether egg size and ejaculate size mediate selection on the free-swimming sperm of Galeolaria caespitosa, a marine tubeworm with external fertilization, by comparing relationships between sperm morphology and male fertility across manipulations of egg size and sperm density. Our results suggest that selection pressures exerted by these factors may aid the maintenance of anisogamy in external fertilizers by limiting the adaptive value of larger sperm in the absence of competition. In doing so, our study offers a more complete explanation for the stability of anisogamy across the range of sperm environments typical of this mating system and identifies new potential for the sexes to coevolve via mutual selection pressures exerted by gametes at fertilization.
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Affiliation(s)
- Keyne Monro
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Dustin J Marshall
- Centre for Geometric Biology, School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
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36
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Lymbery RA, Kennington WJ, Evans JP. Egg chemoattractants moderate intraspecific sperm competition. Evol Lett 2017; 1:317-327. [PMID: 30283659 PMCID: PMC6121861 DOI: 10.1002/evl3.34] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/10/2017] [Indexed: 12/20/2022] Open
Abstract
Interactions among eggs and sperm are often assumed to generate intraspecific variation in reproductive fitness, but the specific gamete-level mechanisms underlying competitive fertilization success remain elusive in most species. Sperm chemotaxis-the attraction of sperm by egg-derived chemicals-is a ubiquitous form of gamete signaling, occurring throughout the animal and plant kingdoms. The chemical cues released by eggs are known to act at the interspecific level (e.g., facilitating species recognition), but recent studies have suggested that they could have roles at the intraspecific level by moderating sperm competition. Here, we exploit the experimental tractability of a broadcast spawning marine invertebrate to test this putative mechanism of gamete-level sexual selection. We use a fluorescently labeled mitochondrial dye in mussels to track the real-time success of sperm as they compete to fertilize eggs, and provide the first direct evidence in any species that competitive fertilization success is moderated by differential sperm chemotaxis. Furthermore, our data are consistent with the idea that egg chemoattractants selectively attract ejaculates from genetically compatible males, based on relationships inferred from both nuclear and mitochondrial genetic markers. These findings for a species that exhibits the ancestral reproductive strategy of broadcast spawning have important implications for the numerous species that also rely on egg chemoattractants to attract sperm, including humans, and have potentially important implications for our understanding of the evolutionary cascade of sexual selection.
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Affiliation(s)
- Rowan A. Lymbery
- School of Biological SciencesThe University of Western AustraliaCrawleyWA 6009Australia
| | - W. Jason Kennington
- School of Biological SciencesThe University of Western AustraliaCrawleyWA 6009Australia
| | - Jonathan P. Evans
- School of Biological SciencesThe University of Western AustraliaCrawleyWA 6009Australia
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37
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Bartlett MJ, Steeves TE, Gemmell NJ, Rosengrave PC. Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid. eLife 2017; 6:e28811. [PMID: 29084621 PMCID: PMC5669631 DOI: 10.7554/elife.28811] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 09/13/2017] [Indexed: 12/15/2022] Open
Abstract
In many species, males can make rapid adjustments to ejaculate performance in response to sperm competition risk; however, the mechanisms behind these changes are not understood. Here, we manipulate male social status in an externally fertilising fish, chinook salmon (Oncorhynchus tshawytscha), and find that in less than 48 hr, males can upregulate sperm velocity when faced with an increased risk of sperm competition. Using a series of in vitro sperm manipulation and competition experiments, we show that rapid changes in sperm velocity are mediated by seminal fluid and the effect of seminal fluid on sperm velocity directly impacts paternity share and therefore reproductive success. These combined findings, completely consistent with sperm competition theory, provide unequivocal evidence that sperm competition risk drives plastic adjustment of ejaculate quality, that seminal fluid harbours the mechanism for the rapid adjustment of sperm velocity and that fitness benefits accrue to males from such adjustment.
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Affiliation(s)
- Michael J Bartlett
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | - Tammy E Steeves
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | - Neil J Gemmell
- Department of AnatomyUniversity of OtagoDunedinNew Zealand
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38
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Lehnert SJ, Butts IAE, Flannery EW, Peters KM, Heath DD, Pitcher TE. Effects of ovarian fluid and genetic differences on sperm performance and fertilization success of alternative reproductive tactics in Chinook salmon. J Evol Biol 2017; 30:1236-1245. [PMID: 28387056 DOI: 10.1111/jeb.13088] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 03/03/2017] [Accepted: 03/30/2017] [Indexed: 12/20/2022]
Abstract
In many species, sperm velocity affects variation in the outcome of male competitive fertilization success. In fishes, ovarian fluid (OF) released with the eggs can increase male sperm velocity and potentially facilitate cryptic female choice for males of specific phenotypes and/or genotypes. Therefore, to investigate the effect of OF on fertilization success, we measured sperm velocity and conducted in vitro competitive fertilizations with paired Chinook salmon (Oncorhynchus tshawytscha) males representing two alternative reproductive tactics, jacks (small sneaker males) and hooknoses (large guarding males), in the presence of river water alone and OF mixed with river water. To determine the effect of genetic differences on fertilization success, we genotyped fish at neutral (microsatellites) and functional [major histocompatibility complex (MHC) II ß1] markers. We found that when sperm were competed in river water, jacks sired significantly more offspring than hooknoses; however, in OF, there was no difference in paternity between the tactics. Sperm velocity was significantly correlated with paternity success in river water, but not in ovarian fluid. Paternity success in OF, but not in river water alone, was correlated with genetic relatedness between male and female, where males that were less related to the female attained greater paternity. We found no relationship between MHC II ß1 divergence between mates and paternity success in water or OF. Our results indicate that OF can influence the outcome of sperm competition in Chinook salmon, where OF provides both male tactics with fertilization opportunities, which may in part explain what maintains both tactics in nature.
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Affiliation(s)
- S J Lehnert
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada
| | - I A E Butts
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, USA
| | - E W Flannery
- Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - K M Peters
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada.,Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - D D Heath
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada.,Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - T E Pitcher
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON, Canada.,Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
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39
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Fenkes M, Fitzpatrick JL, Ozolina K, Shiels HA, Nudds RL. Sperm in hot water: direct and indirect thermal challenges interact to impact on brown trout sperm quality. ACTA ACUST UNITED AC 2017; 220:2513-2520. [PMID: 28455440 DOI: 10.1242/jeb.156018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/24/2017] [Indexed: 01/31/2023]
Abstract
Climate change alters the thermal habitat of aquatic species on a global scale, generating novel environmental challenges during all life stages, including reproduction. Changes in water temperature profoundly influence the performance of ectothermic aquatic organisms. This is an especially crucial issue for migratory fish, because they traverse multiple environments in order to reproduce. In externally fertilizing migratory fish, gametes are affected by water temperature indirectly, within the reproductive organ in which they are produced during migration, as well as directly, upon release into the surrounding medium at the spawning grounds. Both direct (after release) and indirect (during production) thermal impacts on gamete quality have been investigated, but never in conjunction. Here, we assessed the cumulative influence of temperature on brown trout, Salmo trutta, sperm quality during sperm production (male acclimation temperature) as well as upon release (sperm activation water temperature) on two consecutive dates during the brown trout spawning season. Early in the season, warm acclimation of males reduced their fertilization probability (lower sperm velocity) when compared with cold-acclimated males, especially when the activation water temperature was also increased beyond the thermal optimum (resulting in a lower proportion of motile sperm with lower velocity). Later in the season, sperm quality was unaffected by acclimation temperature and thermal sensitivity of sperm was reduced. These results give novel insights into the complex impacts of climate change on fish sperm, with implications for the reproduction and management of hatchery and wild trout populations in future climate scenarios.
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Affiliation(s)
- Miriam Fenkes
- University of Manchester, Faculty of Biology, Medicine and Health, Manchester M13 9PL, UK
| | - John L Fitzpatrick
- Stockholm University, Department of Zoology, Ethology division, Stockholm 106 91, Sweden
| | - Karlina Ozolina
- University of Manchester, Faculty of Biology, Medicine and Health, Manchester M13 9PL, UK
| | - Holly A Shiels
- University of Manchester, Faculty of Biology, Medicine and Health, Manchester M13 9PL, UK
| | - Robert L Nudds
- University of Manchester, Faculty of Biology, Medicine and Health, Manchester M13 9PL, UK
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40
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Lewis JA, Pitcher TE. Tactic-specific benefits of polyandry in Chinook salmon Oncorhynchus tshawytscha. JOURNAL OF FISH BIOLOGY 2017; 90:1244-1256. [PMID: 27873318 DOI: 10.1111/jfb.13223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
This study examined whether polyandrous female Chinook salmon Oncorhynchus tshawytscha obtain benefits compared with monandrous females through an increase in hatching success. Both of the alternative reproductive tactics present in male O. tshawytscha (large hooknoses and small, precocious jacks) were used, such that eggs were either fertilized by a single male (from each tactic) or multiple males (using two males from the same or different tactics). The results show that fertilized eggs from the polyandrous treatments had a significantly higher hatching success than those from the monandrous treatments. It is also shown that sperm speed was positively related with offspring hatching success. Finally, there were tactic-specific effects on the benefits females received. The inclusion of jacks in any cross resulted in offspring with higher hatching success, with the cross that involved a male from each tactic providing offspring with the highest hatching success than any other cross. This study has important implications for the evolution of multiple mating and why it is so prevalent across taxa, while also providing knowledge on the evolution of mating systems, specifically those with alternative reproductive tactics.
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Affiliation(s)
- J A Lewis
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - T E Pitcher
- Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
- Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
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41
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Sexual selection for genetic compatibility: the role of the major histocompatibility complex on cryptic female choice in Chinook salmon (Oncorhynchus tshawytscha). Heredity (Edinb) 2017; 118:442-452. [PMID: 28051059 DOI: 10.1038/hdy.2016.116] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 10/28/2016] [Accepted: 11/01/2016] [Indexed: 12/17/2022] Open
Abstract
Cryptic female choice (CFC), a form of sexual selection during or post mating, describes processes of differential sperm utilization by females to bias fertilization outcomes towards certain males. In Chinook salmon (Oncorhynchus tshawytscha) the ovarian fluid surrounding the ova of a given female differently enhances the sperm velocity of males. Sperm velocity is a key ejaculate trait that determines fertilization success in externally fertilizing fishes, thus the differential effect on sperm velocity might bias male fertilization outcomes and represent a mechanism of CFC. Once sperm reach the oocyte, CFC could potentially be further facilitated by sperm-egg interactions, which are well understood in externally fertilizing marine invertebrates. Here, we explored the potential genetic basis of both possible mechanisms of CFC by examining whether the genotypic combinations of mates (amino-acid divergence, number of shared alleles) at the major histocompatibility complex (MHC) class I and II explain the variation in sperm velocity and/or male fertilization success that is not explained by sperm velocity, which might indicate MHC-based sperm-egg interactions. We recorded sperm velocity in ovarian fluid, employed paired-male fertilization trials and evaluated the fertilization success of each male using microsatellite-based paternity assignment. We showed that relative sperm velocity was positively correlated with fertilization success, confirming that the differential effect on sperm velocity may be a mechanism of CFC in Chinook salmon. The variation in sperm velocity was independent of MHC class I and II. However, the MHC class II divergence of mates explained fertilization success, indicating that this locus might influence sperm-egg interactions.
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42
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Kekäläinen J, Evans JP. Female-induced remote regulation of sperm physiology may provide opportunities for gamete-level mate choice. Evolution 2016; 71:238-248. [DOI: 10.1111/evo.13141] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 11/10/2016] [Accepted: 11/15/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Jukka Kekäläinen
- Centre for Evolutionary Biology, School of Animal Biology; University of Western Australia; Crawley WA 6009 Australia
- Department of Environmental and Biological Sciences; University of Eastern Finland; Joensuu Finland
| | - Jonathan P. Evans
- Centre for Evolutionary Biology, School of Animal Biology; University of Western Australia; Crawley WA 6009 Australia
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43
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Makiguchi Y, Torao M, Kojima T, Pitcher TE. Reproductive investment patterns and comparison of sperm quality in the presence and absence of ovarian fluid in alternative reproductive tactics of masu salmon, Oncorhynchus masou. Theriogenology 2016; 86:2189-2193.e2. [DOI: 10.1016/j.theriogenology.2016.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 06/13/2016] [Accepted: 07/10/2016] [Indexed: 12/19/2022]
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44
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Egeland TB, Rudolfsen G, Nordeide JT, Folstad I. Status Specific Tailoring of Sperm Behavior in an External Fertilizer. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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45
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Siddique MAM, Linhart O, Kujawa R, Krejszeff S, Butts IAE. Composition of seminal plasma and ovarian fluid in IdeLeuciscus idusand Northern pikeEsox lucius. Reprod Domest Anim 2016; 51:960-969. [DOI: 10.1111/rda.12773] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 08/02/2016] [Indexed: 01/06/2023]
Affiliation(s)
- MAM Siddique
- Faculty of Fisheries and Protection of Waters; University of South Bohemia in Ceske Budejovice; South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses; Research Institute of Fish Culture and Hydrobiology; Vodňany Czech Republic
| | - O Linhart
- Faculty of Fisheries and Protection of Waters; University of South Bohemia in Ceske Budejovice; South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses; Research Institute of Fish Culture and Hydrobiology; Vodňany Czech Republic
| | - R Kujawa
- Department of Lake and River Fisheries; Warmia and Mazury University; Olsztyn Poland
| | - S Krejszeff
- Department of Lake and River Fisheries; Warmia and Mazury University; Olsztyn Poland
| | - IAE Butts
- DTU Aqua-National Institute of Aquatic Resources; Section for Marine Ecology and Oceanography; Technical University of Denmark; Charlottenlund Denmark
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46
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Lehnert SJ, Heath DD, Devlin RH, Pitcher TE. Post-spawning sexual selection in red and white Chinook salmon (Oncorhynchus tshawytscha). Behav Ecol 2016. [DOI: 10.1093/beheco/arw142] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Alonzo SH, Stiver KA, Marsh-Rollo SE. Ovarian fluid allows directional cryptic female choice despite external fertilization. Nat Commun 2016; 7:12452. [PMID: 27529581 PMCID: PMC4990696 DOI: 10.1038/ncomms12452] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 07/04/2016] [Indexed: 12/11/2022] Open
Abstract
In species with internal fertilization, females can favour certain males over others, not only before mating but also within the female's reproductive tract after mating. Here, we ask whether such directional post-mating (that is, cryptic) female mate choice can also occur in species with external fertilization. Using an in vitro sperm competition experiment, we demonstrate that female ovarian fluid (ovarian fluid) changes the outcome of sperm competition by decreasing the importance of sperm number thereby increasing the relative importance of sperm velocity. We further show that ovarian fluid does not differentially affect sperm from alternative male phenotypes, but generally enhances sperm velocity, motility, straightness and chemoattraction. Under natural conditions, female ovarian fluid likely increases the paternity of the preferred parental male phenotype, as these males release fewer but faster sperm. These results imply females have greater control over fertilization and potential to exert selection on males in species with external fertilization than previously thought possible.
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Affiliation(s)
- Suzanne H. Alonzo
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, Connecticut 06520, USA
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA
| | - Kelly A. Stiver
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, Connecticut 06520, USA
- Psychology Department, Southern Connecticut State University, 501 Crescent Street, New Haven, Connecticut 06515, USA
| | - Susan E. Marsh-Rollo
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA
- Department of Psychology, Neuroscience, and Behaviour, McMaster University, 1280 Main Street W, Hamilton, Ontario, Canada L8S4K1
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Devigili A, Di Nisio A, Grapputo A, Pilastro A. Directional postcopulatory sexual selection is associated with female sperm storage in Trinidadian guppies. Evolution 2016; 70:1829-43. [PMID: 27345870 DOI: 10.1111/evo.12989] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 05/23/2016] [Accepted: 06/06/2016] [Indexed: 12/17/2022]
Abstract
Female sperm storage (FSS) is taxonomically widespread and often associated with intense sperm competition, yet its consequences on postcopulatory sexual selection (PCSS) are poorly known. Theory predicts that FSS will reduce the strength of PCSS, because sperm characteristics favored before and after FSS may be traded-off, and opportunities for nondirectional PCSS should increase. We explored these questions in the guppy (Poecilia reticulata), by allowing females to mate multiply and by comparing the paternity pattern in two successive broods. Contrary to predictions, the variance in male fertilization success increased after FSS, driven by a change in male paternity share across broods. This change was positively associated with sperm velocity (measured before FSS) but not with the duration of FSS, indirectly suggesting that faster sperm were better in entering female storage organs, rather than in persisting within them. Other male traits, such as male size and orange color, heterozygosity, and relatedness to the female, did not influence paternity after FSS. These results indicate that processes associated with FSS tend to reinforce the strength of PCSS in guppies, rather than weaken it. Further work is necessary to test whether this pattern changes in case of more prolonged FSS.
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Affiliation(s)
| | - Andrea Di Nisio
- Department of Biology, University of Padua, I-35131, Padova, Italy
| | | | - Andrea Pilastro
- Department of Biology, University of Padua, I-35131, Padova, Italy.
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Rosengrave P, Montgomerie R, Gemmell N. Cryptic female choice enhances fertilization success and embryo survival in chinook salmon. Proc Biol Sci 2016; 283:20160001. [PMID: 27009221 PMCID: PMC4822462 DOI: 10.1098/rspb.2016.0001] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 02/24/2016] [Indexed: 12/27/2022] Open
Abstract
In this study, we investigated two potentially important intersexual postcopulatory gametic interactions in a population of chinook salmon (Oncorhynchus tshawytscha): (i) the effect of female ovarian fluid (OF) on the behaviour of spermatozoa during fertilization and (ii) the effects of multilocus heterozygosity (MLH) (as an index of male quality) and female-male genetic relatedness on sperm behaviour and male fertilization success when there is sperm competition in the presence of that OF. To do this, we conducted a series of in vitro competitive fertilization experiments and found that, when ejaculates from two males are competing for access to a single female's unfertilized eggs, fertilization success was significantly biased towards the male whose sperm swam fastest in the female's OF. Embryo survival--a measure of fitness--was also positively correlated with both sperm swimming speed in OF and male MLH, providing novel evidence that cryptic female choice is adaptive for the female, enhancing the early survival of her offspring and potentially influencing her fitness.
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Affiliation(s)
- Patrice Rosengrave
- Department of Anatomy, University of Otago, Dunedin, New Zealand Allan Wilson Centre for Molecular Ecology and Evolution, Department of Anatomy University of Otago, Dunedin, New Zealand
| | - Robert Montgomerie
- Department of Biology, Queen's University, Kingston, Ontario, Canada K7 L 3N6
| | - Neil Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand Allan Wilson Centre for Molecular Ecology and Evolution, Department of Anatomy University of Otago, Dunedin, New Zealand
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50
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Naud MJ, Sauer WHH, McKeown NJ, Shaw PW. Multiple Mating, Paternity and Complex Fertilisation Patterns in the Chokka Squid Loligo reynaudii. PLoS One 2016; 11:e0146995. [PMID: 26872354 PMCID: PMC4752281 DOI: 10.1371/journal.pone.0146995] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 12/28/2015] [Indexed: 11/18/2022] Open
Abstract
Polyandry is widespread and influences patterns of sexual selection, with implications for sexual conflict over mating. Assessing sperm precedence patterns is a first step towards understanding sperm competition within a female and elucidating the roles of male- and female-controlled factors. In this study behavioural field data and genetic data were combined to investigate polyandry in the chokka squid Loligo reynaudii. Microsatellite DNA-based paternity analysis revealed multiple paternity to be the norm, with 79% of broods sired by at least two males. Genetic data also determined that the male who was guarding the female at the moment of sampling was a sire in 81% of the families tested, highlighting mate guarding as a successful male tactic with postcopulatory benefits linked to sperm deposition site giving privileged access to extruded egg strings. As females lay multiple eggs in capsules (egg strings) wherein their position is not altered during maturation it is possible to describe the spatial / temporal sequence of fertilisation / sperm precedence There were four different patterns of fertilisation found among the tested egg strings: 1) unique sire; 2) dominant sire, with one or more rare sires; 3) randomly mixed paternity (two or more sires); and 4) a distinct switch in paternity occurring along the egg string. The latter pattern cannot be explained by a random use of stored sperm, and suggests postcopulatory female sperm choice. Collectively the data indicate multiple levels of male- and female-controlled influences on sperm precedence, and highlights squid as interesting models to study the interplay between sexual and natural selection.
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Affiliation(s)
- Marie-Jose Naud
- School of Biological Sciences, Royal Holloway University of London, Egham, United Kingdom
| | - Warwick H. H. Sauer
- Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa
| | - Niall J. McKeown
- Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Paul W. Shaw
- Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown, South Africa
- Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
- * E-mail:
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