1
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Richardson J, Zuk M. Meta-analytical evidence that males prefer virgin females. Ecol Lett 2024; 27:e14341. [PMID: 37988323 DOI: 10.1111/ele.14341] [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: 05/23/2023] [Revised: 10/31/2023] [Accepted: 11/03/2023] [Indexed: 11/23/2023]
Abstract
Males are often predicted to prefer virgin over non-virgin females because of the reduced risk of sperm competition. Does this prediction hold across studies? Our systematic meta-analysis of 138 studies, mainly conducted in invertebrates, confirms that males generally prefer virgin females. However, males preferred virgin females even in species with last male sperm precedence, suggesting that sperm competition alone does not drive male preferences. Furthermore, our results suggest that males may reject mated females even when no alternative exists. Preference for virgins is unlikely to influence female reproductive success since virginity cannot be selected for, but strong preference for virgin females could swamp or reinforce selection on other traits. Our results add to growing evidence that males are not indiscriminate in mating. However, given the unexplained heterogeneity in effect sizes, we urge caution in assuming that males will prefer virgins and recommend considering the natural context of mating decisions.
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Affiliation(s)
- Jon Richardson
- Department of Ecology, Evolution & Behavior, University of Minnesota, Saint Paul, Minnesota, USA
| | - Marlene Zuk
- Department of Ecology, Evolution & Behavior, University of Minnesota, Saint Paul, Minnesota, USA
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2
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Louâpre P, Muller K, Bettencourt-Amarante S, Thiery D, Moreau J. Sexual audience affects male's reproduction investment without consequences on reproductive outputs. INSECT SCIENCE 2022; 29:1170-1180. [PMID: 34897988 DOI: 10.1111/1744-7917.12990] [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: 07/08/2021] [Revised: 10/15/2021] [Accepted: 11/17/2021] [Indexed: 06/14/2023]
Abstract
Males evolved plastic strategies to respond to male-male competition and exhibit adaptive traits and behaviors maximizing their access to the females and limiting sperm competition. Mating behaviors allow males to express quick responses to current sexual audience, that is, the number of nearby conspecifics prone to mate. In contrast, physiological responses are frequently delayed because they are constrained by the time and resources having to be mobilized to produce and export sperm and associated products. This is especially critical in species for which males produce spermatophores. Here we investigated in what extend moth males (the tortricid moth Lobesia botrana) producing spermatophores exhibit plastic behavioral and physiological responses to different sexual audiences before and during mating and the consequences for their reproductive output. We found that males adjusted their mating behaviors and spermatophore size to a potentially elevated risk of sperm competition perceived before mating. In addition, males responded to the closed presence of females during mating by reducing their mating duration. Surprisingly, the various behavioral and physiological responses we highlighted here were not fully reflected in their reproductive performance as we did not reveal any effect on fecundity and fertility of their mate. The selective pressure exerted on males experiencing male-male competition could thus be sufficient to trigger adjustment in male mating behaviors but constrains physiological responses according to the perception of competition.
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Affiliation(s)
- Philippe Louâpre
- UMR CNRS 6282 Biogeosciences, Université Bourgogne Franche-Comté, Dijon, France
| | - Karen Muller
- UMR CNRS 6282 Biogeosciences, Université Bourgogne Franche-Comté, Dijon, France
| | | | - Denis Thiery
- INRA UMR 1065 Santé et Agroecologie du Vignoble, Institut des Science de la Vigne et du Vin, Villenave d'Ornon, Cedex, France
- INRA UMR 1065, Save, Université de Bordeaux, Bordeaux Sciences Agro, Villenave d'Ornon, Cedex, France
| | - Jérôme Moreau
- UMR CNRS 6282 Biogeosciences, Université Bourgogne Franche-Comté, Dijon, France
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3
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Sperm oxidative status varies with the level of sperm competition and affects male reproductive success. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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4
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Wyber BW, Dougherty LR, McNamara K, Mehnert A, Shaw J, Tomkins JL, Simmons LW. Quantifying variation in female internal genitalia: no evidence for plasticity in response to sexual conflict risk in a seed beetle. Proc Biol Sci 2021; 288:20210746. [PMID: 34229488 PMCID: PMC8261201 DOI: 10.1098/rspb.2021.0746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/09/2021] [Indexed: 11/12/2022] Open
Abstract
Sexually antagonistic coevolution can drive the evolution of male traits that harm females, and female resistance to those traits. While males have been found to vary their harmfulness to females in response to social cues, plasticity in female resistance traits remains to be examined. Here, we ask whether female seed beetles Callosobruchus maculatus are capable of adjusting their resistance to male harm in response to the social environment. Among seed beetles, male genital spines harm females during copulation and females might resist male harm via thickening of the reproductive tract walls. We develop a novel micro computed tomography imaging technique to quantify female reproductive tract thickness in three-dimensional space, and compared the reproductive tracts of females from populations that had evolved under high and low levels of sexual conflict, and for females reared under a social environment that predicted either high or low levels of sexual conflict. We find little evidence to suggest that females can adjust the thickness of their reproductive tracts in response to the social environment. Neither did evolutionary history affect reproductive tract thickness. Nevertheless, our novel methodology was capable of quantifying fine-scale differences in the internal reproductive tracts of individual females, and will allow future investigations into the internal organs of insects and other animals.
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Affiliation(s)
- Blake W. Wyber
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Liam R. Dougherty
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 7RB, UK
| | - Kathryn McNamara
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andrew Mehnert
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, Western Australia 6009, Australia
- National Imaging Facility, Brisbane, Queensland, Australia
| | - Jeremy Shaw
- Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Perth, Western Australia 6009, Australia
- National Imaging Facility, Brisbane, Queensland, Australia
| | - Joseph L. Tomkins
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Leigh W. Simmons
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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5
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Strategic adjustment of ejaculate quality in response to variation of the socio-sexual environment. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03032-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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6
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Kerwin P, von Philipsborn AC. Copulation Song in Drosophila: Do Females Sing to Change Male Ejaculate Allocation and Incite Postcopulatory Mate Choice? Bioessays 2020; 42:e2000109. [PMID: 32964470 DOI: 10.1002/bies.202000109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 08/02/2020] [Indexed: 12/14/2022]
Abstract
Drosophila males sing a courtship song to achieve copulations with females. Females were recently found to sing a distinct song during copulation, which depends on male seminal fluid transfer and delays female remating. Here, it is hypothesized that female copulation song is a signal directed at the copulating male and changes ejaculate allocation. This may alter female remating and sperm usage, and thereby affect postcopulatory mate choice. Mechanisms of how female copulation song is elicited, how males respond to copulation song, and how remating is modulated, are considered. The potential adaptive value of female signaling during copulation is discussed with reference to vertebrate copulation calls and their proposed function in eliciting mate guarding. Female copulation song may be widespread within the Drosophila genus. This newly discovered behavior opens many interesting avenues for future research, including investigation of how sexually dimorphic neuronal circuits mediate communication between nervous system and reproductive organs.
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Affiliation(s)
- Peter Kerwin
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, 8000, Denmark
| | - Anne C von Philipsborn
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, 8000, Denmark
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7
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Lemaître JF, Gaillard JM, Ramm SA. The hidden ageing costs of sperm competition. Ecol Lett 2020; 23:1573-1588. [PMID: 32906225 DOI: 10.1111/ele.13593] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/30/2020] [Accepted: 07/22/2020] [Indexed: 12/16/2022]
Abstract
Ageing and sexual selection are intimately linked. There is by now compelling evidence from studies performed across diverse organisms that males allocating resources to mating competition incur substantial physiological costs, ultimately increasing ageing. However, although insightful, we argue here that to date these studies cover only part of the relationship linking sexual selection and ageing. Crucially, allocation to traits important in post-copulatory sexual selection, that is sperm competition, has been largely ignored. As we demonstrate, such allocation could potentially explain much diversity in male and female ageing patterns observed both within and among species. We first review how allocation to sperm competition traits such as sperm and seminal fluid production depends on the quality of resources available to males and can be associated with a wide range of deleterious effects affecting both somatic tissues and the germline, and thus modulate ageing in both survival and reproductive terms. We further hypothesise that common biological features such as plasticity, prudent sperm allocation and seasonality of ejaculate traits might have evolved as counter-adaptations to limit the ageing costs of sperm competition. Finally, we discuss the implications of these emerging ageing costs of sperm competition for current research on the evolutionary ecology of ageing.
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Affiliation(s)
- Jean-François Lemaître
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, F-69622, France
| | - Jean-Michel Gaillard
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, F-69622, France
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, Bielefeld, 33615, Germany
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8
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Trade-offs of strategic sperm adjustments and their consequences under phenotype–environment mismatches in guppies. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.06.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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9
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Haneke-Reinders M, Mazur AP, Zyma O, Ramm SA, Reinhold K. Disentangling a shared trait: male control over mate guarding duration revealed by a mate exchange experiment. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02832-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract
Shared behavioural traits result from the interaction of two or more individuals, making it difficult to discern which individual is in control of the behaviour of interest. Especially in the case of shared reproductive traits such as mating duration or mate guarding duration is this an important issue to resolve, because these are potentially closely connected to fitness and are likely to exhibit sexual conflict. Here, we sought to disentangle which sex controls mate guarding duration in the tropical house cricket Gryllodes sigillatus, a species in which mate guarding and nuptial feeding by the male have been proposed to prevent premature removal of the transferred spermatophore by the female. To do so, we performed a series of mating experiments in a paired design, in which the first mating dyad was allowed to start mating some time before the second dyad. Once both dyads were in the mate guarding phase, we then interrupted them and exchanged partners, enabling us to determine whether the remaining guarding duration depended more on the duration of guarding already performed by the male in the new dyad (implying male control) or on the guarding already received by the female (implying female control). We found that the time a female was guarded overall was significantly affected by how long the exchanged male had already engaged in mate guarding with the previous female, but conversely, the total time males guarded both females was unaffected by the duration of guarding that the exchanged female had previously received. Our data thus clearly demonstrate that males rather than females control mate guarding duration and adjust the duration according to females’ weight.
Significance statement
It is not easy to determine which individual is in control of a shared behavioural trait (SBT). This information could provide insight into selection pressure on one sex and could help us understand differences in SBTs between related species or between different dyads of one species. We used a relative novel but simple method to disentangle a SBT in a cricket. We performed mating experiments and exchanged the mating partners after copulation within the mate guarding phase and measured the total guarding duration. Our analyses showed males were not influenced by the exchange and guarded as long as expected regardless how long the female were guarded before by another male. Our data suggest males are likely in control of mate guarding duration, and they have no ability to recognize post-copulatory mate exchange.
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10
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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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11
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Vincent A, Head ML, Iglesias-Carrasco M. Sexual conflict and the environment: teasing apart effects arising via males and females. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Tuni C, Mizerakis V, Dingemanse NJ. Experimental evidence that winning or losing a fight does not affect sperm quality in a field cricket. Ethology 2019. [DOI: 10.1111/eth.12943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Cristina Tuni
- Behavioural Ecology, Department of Biology Ludwig Maximilian University of Munich Munich Germany
| | | | - Niels J. Dingemanse
- Behavioural Ecology, Department of Biology Ludwig Maximilian University of Munich Munich Germany
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13
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Tourmente M, Archer CR, Hosken DJ. Complex interactions between sperm viability and female fertility. Sci Rep 2019; 9:15366. [PMID: 31653962 PMCID: PMC6814814 DOI: 10.1038/s41598-019-51672-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 10/03/2019] [Indexed: 12/03/2022] Open
Abstract
Sperm viability is a major male fitness component, with higher sperm viability associated with enhanced sperm competitiveness. While many studies have focussed on sperm viability from the male fitness standpoint, its impact on female fitness is less clear. Here we used a panel of 32 isogenic Drosophila simulans lines to test for genetic variation in sperm viability (percentage of viable cells). We then tested whether sperm viability affected female fitness by mating females to males from low or high sperm viability genotypes. We found significant variation in sperm viability among genotypes, and consistent with this, sperm viability was highly repeatable within genotypes. Additionally, females mated to high sperm viability males laid more eggs in the first seven hours after mating, and produced more offspring in total. However, the early increase in oviposition did not result in more offspring in the 8 hours following mating, suggesting that mating with high sperm-viability genotypes leads to egg wastage for females shortly after copulation. Although mating with high sperm-viability males resulted in higher female fitness in the long term, high quality ejaculates would result in a short-term female fitness penalty, or at least lower realised fitness, potentially generating sexual conflict over optimal sperm viability.
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Affiliation(s)
- Maximiliano Tourmente
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom.
| | - C Ruth Archer
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom.,Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - David J Hosken
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom
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14
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Wilson KM, Walker SE. Age at mating and male quality influence female patterns of reproductive investment and survival. Ecol Evol 2019; 9:5440-5449. [PMID: 31110692 PMCID: PMC6509372 DOI: 10.1002/ece3.5137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 02/06/2019] [Accepted: 03/15/2019] [Indexed: 01/28/2023] Open
Abstract
The trade-off between the allocation of resources toward somatic maintenance or reproduction is one of the fundamentals of life history theory and predicts that females invest in offspring at the expense of their longevity or vice versa. Mate quality may also affect life history trade-offs through mechanisms of sexual conflict; however, few studies have examined the interaction between mate quality and age at first mating in reproductive decisions. Using house crickets (Acheta domesticus), this study examines how survival and reproductive trade-offs change based on females' age at first reproduction and exposure to males of varying size. Females were exposed to either a large (presumably high-quality) or small male at an early (young), middle (intermediate), or advanced (old) age, and longevity and reproductive investment were subsequently tracked. Females mated at a young age had the largest number of eggs but the shortest total lifespans while females mated at older ages produced fewer eggs but had longer total lifespans. The trade-off between age at first mating and eggs laid appears to be mediated through higher egg-laying rates and shorter postmating lifespans in females mated later in life. Exposure to small males resulted in shorter lifespans and higher egg-laying rates for all females indicating that male manipulation of females, presumably through spermatophore contents, varies with male size in this species. Together, these data strongly support a trade-off between age at first reproduction and lifespan and support the role of sexual conflict in shaping patterns of reproduction.
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Affiliation(s)
- Kerianne M. Wilson
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineCalifornia
| | - Sean E. Walker
- Department of Biological SciencesCalifornia State UniversityFullertonCalifornia
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15
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Sloan NS, Lovegrove M, Simmons LW. Social manipulation of sperm competition intensity reduces seminal fluid gene expression. Biol Lett 2018; 14:rsbl.2017.0659. [PMID: 29367215 DOI: 10.1098/rsbl.2017.0659] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/05/2018] [Indexed: 11/12/2022] Open
Abstract
A considerable body of evidence supports the prediction that males should increase their expenditure on the ejaculate in response to sperm competition risk. The prediction that they should reduce their expenditure with increasing sperm competition intensity is less well supported. Moreover, most studies have documented plasticity in sperm numbers. Here we show that male crickets Teleogryllus oceanicus exhibit reduced seminal fluid gene expression and accessory gland mass in response to elevated sperm competition intensity. Together with previous research, our findings suggest that strategic adjustments in seminal fluid composition contribute to competitive fertilization success in this species.
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Affiliation(s)
- Nadia S Sloan
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| | - Maxine Lovegrove
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
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16
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Herrera-Cruz M, Abraham S, Nuñez-Beverido N, Flores-Estévez N, Reyes-Hernández M, Alvarado M, Pérez-Staples D. Male age and strain affect ejaculate quality in the Mexican fruit fly. INSECT SCIENCE 2018; 25:703-711. [PMID: 28217884 DOI: 10.1111/1744-7917.12446] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/23/2016] [Accepted: 01/11/2017] [Indexed: 06/06/2023]
Abstract
Aging in all organisms is inevitable. Male age can have profound effects on mating success and female reproduction, yet relatively little is known on the effects of male age on different components of the ejaculate. Furthermore, in mass-reared insects used for the Sterile Insect Technique, there are often behavioral differences between mass-reared and wild males, while differences in the ejaculate have been less studied. The ejaculate in insects is composed mainly of sperm and accessory gland proteins. Here, we studied how male age and strain affected (i) protein quantity of testes and accessory glands, (ii) the biological activity of accessory gland products injected into females, (iii) sperm viability, and (iv) sperm quantity stored by females in wild and mass-reared Anastrepha ludens (Diptera: Tephritidae). We found lower protein content in testes of old wild males and lower sperm viability in females mated with old wild males. Females stored more sperm when mated to young wild males than with young mass-reared males. Accessory gland injections of old or young males did not inhibit female remating. Knowledge of how male age affects different ejaculate components will aid our understanding on investment of the ejaculate and possible postcopulatory consequences on female behavior.
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Affiliation(s)
- Mariana Herrera-Cruz
- Cátedra CONACYT- Facultad de Medicina y Cirugía, Universidad Autónoma "Benito Juárez" de Oaxaca, Oaxaca, México
| | - Solana Abraham
- Laboratorio de Investigaciones Ecoetológicas de Moscas de la Fruta y sus Enemigos Naturales (LIEMEN), PROIMI, Tucumán, Argentina
- CONICET, Argentina
| | - Nicolas Nuñez-Beverido
- INBIOTECA, Universidad Veracruzana, Xalapa, Veracruz, Mexico
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico
| | | | | | - Mayvi Alvarado
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, Mexico
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17
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Metzler S, Schrempf A, Heinze J. Individual- and ejaculate-specific sperm traits in ant males. JOURNAL OF INSECT PHYSIOLOGY 2018; 107:284-290. [PMID: 29273326 DOI: 10.1016/j.jinsphys.2017.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 12/07/2017] [Accepted: 12/17/2017] [Indexed: 06/07/2023]
Abstract
Sperm cells are the most morphologically diverse cells across animal taxa. Within species, sperm and ejaculate traits have been suggested to vary with the male's competitive environment, e.g., level of sperm competition, female mating status and quality, and also with male age, body mass, physiological condition, and resource availability. Most previous studies have based their conclusions on the analysis of only one or a few ejaculates per male without investigating differences among the ejaculates of the same individual. This masks potential ejaculate-specific traits. Here, we provide data on the length, quantity, and viability of sperm ejaculated by wingless males of the ant Cardiocondyla obscurior. Males of this ant species are relatively long-lived and can mate with large numbers of female sexuals throughout their lives. We analyzed all ejaculates across the individuals' lifespan and manipulated the availability of mating partners. Our study shows that both the number and size of sperm cells transferred during copulations differ among individuals and also among ejaculates of the same male. Sperm quality does not decrease with male age, but the variation in sperm number between ejaculates indicates that males need considerable time to replenish their sperm supplies. Producing many ejaculates in a short time appears to be traded-off against male longevity rather than sperm quality.
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Affiliation(s)
- Sina Metzler
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany; IST Austria (Institute of Science and Technology Austria), Am Campus 1, A-3400 Klosterneuburg, Austria.
| | - Alexandra Schrempf
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany
| | - Jürgen Heinze
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany
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18
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Iglesias-Carrasco M, Jennions MD, Zajitschek SRK, Head ML. Are females in good condition better able to cope with costly males? Behav Ecol 2018. [DOI: 10.1093/beheco/ary059] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Maider Iglesias-Carrasco
- Division of Evolution, Ecology and Genetics, Australian National University, Research School of Biology, Canberra, Australia
| | - Michael D Jennions
- Division of Evolution, Ecology and Genetics, Australian National University, Research School of Biology, Canberra, Australia
| | - Susanne R K Zajitschek
- Doñana Biological Station – CSIC, Seville, Spain
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Megan L Head
- Division of Evolution, Ecology and Genetics, Australian National University, Research School of Biology, Canberra, Australia
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19
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Simmons LW, Lovegrove M. Socially cued seminal fluid gene expression mediates responses in ejaculate quality to sperm competition risk. Proc Biol Sci 2018; 284:rspb.2017.1486. [PMID: 28855372 DOI: 10.1098/rspb.2017.1486] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Accepted: 07/20/2017] [Indexed: 01/29/2023] Open
Abstract
There is considerable evidence that males will increase the number of sperm ejaculated in response to sperm competition risk. However, whether they have the capacity to adjust seminal fluid components of the ejaculate has received less attention. Male crickets (Teleogryllus oceanicus) have been shown to adjust the viability of sperm in their ejaculate in response to sperm competition risk. Here we show that socially mediated plasticity in sperm viability is probably due, at least in part, to male adjustments in the protein composition of the seminal fluid. Seven seminal fluid protein genes were found to have an increased expression in males exposed to rival calls. Increased expression of these genes was correlated with increased sperm viability in whole ejaculates, and gene knockdown confirmed that at least one of these proteins promotes sperm viability. Our results lend support for recent theoretical models that predict complex responses in male allocation to seminal fluid composition in response to sperm competition risk.
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Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
| | - Maxine Lovegrove
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Australia
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20
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Turnell BR, Shaw KL, Reeve HK. Modeling strategic sperm allocation: Tailoring the predictions to the species. Evolution 2018; 72:414-425. [PMID: 29331038 DOI: 10.1111/evo.13423] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 12/06/2017] [Accepted: 12/14/2017] [Indexed: 12/01/2022]
Abstract
Two major challenges exist when empirically testing the predictions of sperm allocation theory. First, the study species must adhere to the assumptions of the model being tested. Unfortunately, the common assumption of sperm allocation models that females mate a maximum of once or twice does not hold for many, if not most, multiply and sequentially mating animals. Second, a model's parameters, which dictate its predictions, must be measured in the study species. Common examples of such parameters, female mating frequency and sperm precedence patterns, are unknown for many species used in empirical tests. Here, we present a broadly applicable model, appropriate for multiply, sequentially mating animals, and test it in three species for which data on all the relevant parameter values are available. The model predicts that relative allocation to virgin females, compared to nonvirgins, depends on the interaction between female mating rate and the sperm precedence pattern: relative allocation to virgins increases with female mating rate under first-male precedence, while the opposite is true under later-male precedence. Our model is moderately successful in predicting actual allocation patterns in the three species, including a cricket in which we measured the parameter values and performed an empirical test of allocation.
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Affiliation(s)
- Biz R Turnell
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853.,Current Address: Department of Biology, Technische Universität Dresden, 01062 Dresden, Germany
| | - Kerry L Shaw
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
| | - H Kern Reeve
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14853
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21
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Bertram SM, Loranger MJ, Thomson IR, Harrison SJ, Ferguson GL, Reifer ML, Corlett DH, Gowaty PA. Choosy males in Jamaican field crickets. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.09.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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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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23
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SCHREMPF A, MOSER A, DELABIE J, HEINZE J. Sperm traits differ between winged and wingless males of the antCardiocondyla obscurior. Integr Zool 2016; 11:427-432. [DOI: 10.1111/1749-4877.12191] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Alexandra SCHREMPF
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
| | - Astrid MOSER
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
| | - Jacques DELABIE
- Myrmecological Laboratory; Cocoa Research Center CEPLAC; Itabuna Brazil
| | - Jürgen HEINZE
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
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24
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Chaudhary DD, Mishra G, Omkar. Last male wins the egg fertilization fight: A case study in ladybird, Menochilus sexmaculatus. Behav Processes 2016; 131:1-8. [PMID: 27476769 DOI: 10.1016/j.beproc.2016.07.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 10/21/2022]
Abstract
Sexual selection and the mechanisms involved in sperm competition have not been greatly explored in ladybird beetles. The present study was conducted to investigate the processes of sperm competition and the role of mate guarding behaviour in its regulation in ladybird beetles. We investigated these questions in polyandrous females of the ladybird, Menochilus sexmaculatus (Coleoptera: Coccinellidae) using a phenotypic marker (typical and intermediate morph) to assess paternity of offspring; to determine sperm competition. We conducted two double mating experiments: (i) complete first and second matings, and (ii) disrupted first and complete second matings each using homomorphic and heteromorphic pairing in alternation. Males which mated last were found to sire up to 72% of the offspring produced, indicating last male sperm precedence. Morph itself, independent of mating order, did not have a significant effect on proportion of offspring sired. Paternity share of the last male was negatively associated with mating duration of the first male; mating duration of the first male being indicative of mate guarding. This therefore indicates that prolonged matings by first males are essentially examples of post-copulatory mate guarding to prevent last male sperm precedence.
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Affiliation(s)
- Desh Deepak Chaudhary
- Ladybird Research Laboratory Department of Zoology, University of Lucknow, Lucknow Uttar Pradesh, 226 007, India.
| | - Geetanjali Mishra
- Ladybird Research Laboratory Department of Zoology, University of Lucknow, Lucknow Uttar Pradesh, 226 007, India.
| | - Omkar
- Ladybird Research Laboratory Department of Zoology, University of Lucknow, Lucknow Uttar Pradesh, 226 007, India.
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25
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Worthington AM, Kelly CD. Direct costs and benefits of multiple mating: Are high female mating rates due to ejaculate replenishment? Behav Processes 2016; 124:115-22. [DOI: 10.1016/j.beproc.2015.12.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 12/22/2015] [Indexed: 01/22/2023]
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26
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Ala-Honkola O, Ritchie MG, Veltsos P. Postmating-prezygotic isolation between two allopatric populations of Drosophila montana: fertilisation success differs under sperm competition. Ecol Evol 2016; 6:1679-91. [PMID: 27087932 PMCID: PMC4801965 DOI: 10.1002/ece3.1995] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/17/2016] [Accepted: 01/18/2016] [Indexed: 12/23/2022] Open
Abstract
Postmating but prezygotic (PMPZ) interactions are increasingly recognized as a potentially important early‐stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population (Vancouver) to penetrate the eggs of the other population (Colorado). As the natural mating system of D. montana is polyandrous (females remate rapidly), we set up double matings of all possible crosses between the same populations to test whether competitive effects between ejaculates influence this PMPZ isolation. We measured premating isolation in no‐choice tests, female fecundity, fertility and egg‐to‐adult viability after single and double matings as well as second‐male paternity success (P2). Surprisingly, we found no PMPZ reproductive isolation between the two populations under a competitive setting, indicating no difficulty of sperm from Vancouver males to fertilize Colorado eggs after double matings. While there were subtle differences in how P2 changed over time, suggesting that Vancouver males’ sperm are somewhat less competitive in a first‐male role within Colorado females, these effects did not translate into differences in overall P2. Fertilisation success can thus differ dramatically between competitive and noncompetitive conditions, perhaps because the males that mate second produce higher quality ejaculates in response to sperm competition. We suggest that unlike in more divergent species comparisons, where sperm competition typically increases reproductive isolation, ejaculate tailoring can reduce the potential for PMPZ isolation when recently diverged populations interbreed.
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Affiliation(s)
- Outi Ala-Honkola
- Department of Biological and Environmental Science University of Jyvaskyla PO Box 35 FI- 40014 Jyvaskyla Finland
| | - Michael G Ritchie
- Centre for Biological Diversity School of Biology University of St Andrews St Andrews KY16 9TS UK
| | - Paris Veltsos
- Department of Ecology and Evolution University of Lausanne Biophore Building Lausanne 1015 Switzerland
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Bunning H, Rapkin J, Belcher L, Archer CR, Jensen K, Hunt J. Protein and carbohydrate intake influence sperm number and fertility in male cockroaches, but not sperm viability. Proc Biol Sci 2016; 282:rspb.2014.2144. [PMID: 25608881 DOI: 10.1098/rspb.2014.2144] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
It is commonly assumed that because males produce many, tiny sperm, they are cheap to produce. Recent work, however, suggests that sperm production is not cost-free. If sperm are costly to produce, sperm number and/or viability should be influenced by diet, and this has been documented in numerous species. Yet few studies have examined the exact nutrients responsible for mediating these effects. Here, we quantify the effects of protein (P) and carbohydrate (C) intake on sperm number and viability in the cockroach Nauphoeta cinerea, as well as the consequences for male fertility. We found the intake of P and C influenced sperm number, being maximized at a high intake of diets with a P : C ratio of 1 : 2, but not sperm viability. The nutritional landscapes for male fertility and sperm number were closely aligned, suggesting that sperm number is the major determinant of male fertility in N. cinerea. Under dietary choice, males regulate nutrient intake at a P : C ratio of 1 : 4.95, which is midway between the ratios needed to maximize sperm production and pre-copulatory attractiveness in this species. This raises the possibility that males regulate nutrient intake to balance the trade-off between pre- and post-copulatory traits in this species.
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Affiliation(s)
- Harriet Bunning
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK
| | - James Rapkin
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK
| | - Laurence Belcher
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK
| | - C Ruth Archer
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK Max Planck Institute for Demographic Research, Konrad-Zuse-Strasse 1, 18057 Rostock, Germany
| | - Kim Jensen
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK Department of Entomology, North Carolina State University, Gardner Hall, Raleigh, NC 27695-7613, USA
| | - John Hunt
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Tremough Campus, Penryn TR10 9EZ, UK
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28
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Men Ejaculate Larger Volumes of Semen, More Motile Sperm, and More Quickly when Exposed to Images of Novel Women. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2015. [DOI: 10.1007/s40806-015-0022-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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29
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Louâpre P, Fauvergue X, van Baaren J, Martel V. The male mate search: an optimal foraging issue? CURRENT OPINION IN INSECT SCIENCE 2015; 9:91-95. [PMID: 32846715 DOI: 10.1016/j.cois.2015.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/22/2015] [Accepted: 02/24/2015] [Indexed: 06/11/2023]
Abstract
Male insects must find and mate females to have some descendants; male fitness therefore depends on the number of females they inseminate. Males are for this reason expected to optimize the behaviors related to mate location, orientation and copulation. Although optimization of the reproductive behavior of males has long been neglected in the literature, recent studies suggest a renewed interest for this idea. Here we discuss the parallel between male mate-finding and mating strategies in insects and optimal foraging theory (OFT), a class of models which formalize the behavior of organisms seeking and exploiting resources, generally food. We highlight the different facets of male mating systems allowing such a parallel, and claim for a unifying approach of foraging behavior. Finally, we discuss novel research perspective emerging from the application of OFT to male reproductive behavior.
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Affiliation(s)
- Philippe Louâpre
- University of Burgundy, UMR CNRS 6282 Biogeosciences, 6 bd Gabriel, 21000 Dijon, France.
| | - Xavier Fauvergue
- Institut Sophia Agrobiotech, UMR INRA-CNRS-UNS 1355, 400 route des Chappes, BP 167, 06903 Sophia Antipolis Cedex, France
| | - Joan van Baaren
- University of Rennes 1, UMR CNRS 6553 Ecobio, Avenue du Général Leclerc, 35042 Rennes Cedex, France
| | - Véronique Martel
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 rue du P.E.P.S, P.O. Box 10380, Stn. Ste-Foy, Québec, Québec, Canada
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30
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Abraham S, Vera MT, Pérez-Staples D. Current Sperm Competition Determines Sperm Allocation in a Tephritid Fruit Fly. Ethology 2015. [DOI: 10.1111/eth.12355] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Solana Abraham
- Laboratorio de Investigaciones Ecoetológicas de Moscas de la Fruta y sus Enemigos Naturales (LIEMEN); PROIMI; Tucumán Argentina
- CONICET; Buenos Aires Argentina
| | - M. Teresa Vera
- CONICET; Buenos Aires Argentina
- Cátedra de Terapéutica Vegetal; Departamento de Sanidad Vegetal de la Facultad de Agronomía y Zootecnia de la UNT; Tucumán Argentina
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31
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Uma R, Sevgili H. Spermatophore allocation strategy over successive matings in the bushcricketIsophya sikorai(Orthoptera Phaneropterinae). ETHOL ECOL EVOL 2014. [DOI: 10.1080/03949370.2014.896830] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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32
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Simmons LW, Lovegrove M, Almbro M. Female effects, but no intrinsic male effects on paternity outcome in crickets. J Evol Biol 2014; 27:1644-9. [PMID: 24836498 DOI: 10.1111/jeb.12418] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/17/2014] [Accepted: 04/21/2014] [Indexed: 11/30/2022]
Abstract
Competitive fertilization success can depend on the relative abilities of competing males to fertilize available ova, and on mechanisms of cryptic female choice that moderate paternity. Competitive fertilization success is thus an emergent property of competing male genotypes, female genotype and their interactions. Accurate estimates of intrinsic male effects on competitive fertilization success are therefore problematic. We used a cross-classified nonbreeding design in which rival male family background was standardized to partition variation in competitive fertilization success among male and female family backgrounds in the field cricket Teleogryllus oceanicus. Male effects were close to zero, supporting previous quantitative genetic designs in which male competitors were assigned at random. In contrast, some 22% of the variance in competitive fertilization success was explained by female effects, suggesting that paternity in this species is influenced strongly by cryptic female choice.
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Affiliation(s)
- L W Simmons
- Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia
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33
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Moatt JP, Dytham C, Thom MDF. Sperm production responds to perceived sperm competition risk in male Drosophila melanogaster. Physiol Behav 2014; 131:111-4. [PMID: 24769021 DOI: 10.1016/j.physbeh.2014.04.027] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 04/07/2014] [Accepted: 04/14/2014] [Indexed: 11/19/2022]
Abstract
Postcopulatory sexual selection arising from female multiple mating leads to the evolution of ejaculates that maximize a male's reproductive success under sperm competition. Where the risk of sperm competition is variable, optimal fitness may be achieved by plastically altering ejaculate characteristics in response to the prevailing sperm competition environment. In the model species Drosophila melanogaster, males expecting to encounter sperm competition mate for longer and transfer more accessory proteins and sperm. Here we show that after being housed with a single rival for one week, the seminal vesicles of male D. melanogaster contain a significantly greater proportion of live sperm than those of males maintained alone, indicating adaptive adjustment of sperm quality in response to the perceived risk of sperm competition. This effect is due to an increase in the number of live sperm produced, indicating that males upregulate sperm production in response to the presence of rivals. Our data suggest that males show plasticity in the rate of spermatogenesis that is adaptive in the context of a fluctuating sperm competition environment.
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Affiliation(s)
- Joshua P Moatt
- Department of Biology, University of York, York YO10 5DD, UK
| | - Calvin Dytham
- Department of Biology, University of York, York YO10 5DD, UK
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34
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McNamara KB, van Lieshout E, Simmons LW. The effect of maternal and paternal immune challenge on offspring immunity and reproduction in a cricket. J Evol Biol 2014; 27:1020-8. [DOI: 10.1111/jeb.12376] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/19/2014] [Accepted: 03/14/2014] [Indexed: 01/01/2023]
Affiliation(s)
- K. B. McNamara
- Centre for Evolutionary Biology; School of Animal Biology (M092); the University of Western Australia; Crawley Australia
| | - E. van Lieshout
- Centre for Evolutionary Biology; School of Animal Biology (M092); the University of Western Australia; Crawley Australia
| | - L. W. Simmons
- Centre for Evolutionary Biology; School of Animal Biology (M092); the University of Western Australia; Crawley Australia
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35
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Paynter E, Baer-Imhoof B, Linden M, Lee-Pullen T, Heel K, Rigby P, Baer B. Flow cytometry as a rapid and reliable method to quantify sperm viability in the honeybeeApis mellifera. Cytometry A 2014; 85:463-72. [DOI: 10.1002/cyto.a.22462] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Revised: 02/27/2014] [Accepted: 03/04/2014] [Indexed: 11/08/2022]
Affiliation(s)
- Ellen Paynter
- Centre for Integrative Bee Research (CIBER), ARC CoE Plant Energy Biology, MCS Building M316, The University of Western Australia; 6009 Crawley Australia
| | - Barbara Baer-Imhoof
- Centre for Integrative Bee Research (CIBER), ARC CoE Plant Energy Biology, MCS Building M316, The University of Western Australia; 6009 Crawley Australia
| | - Matthew Linden
- Centre for Microscopy, Characterisation and Analysis, QEII Medical Centre M510, The University of Western Australia; 6009 Crawley Australia
| | - Tracey Lee-Pullen
- Centre for Microscopy, Characterisation and Analysis, QEII Medical Centre M510, The University of Western Australia; 6009 Crawley Australia
| | - Kathy Heel
- Centre for Microscopy, Characterisation and Analysis, QEII Medical Centre M510, The University of Western Australia; 6009 Crawley Australia
- The School of Pathology and Laboratory Medicine M504; The University of Western Australia; 6009 Crawley Australia
| | - Paul Rigby
- Centre for Microscopy, Characterisation and Analysis, QEII Medical Centre M510, The University of Western Australia; 6009 Crawley Australia
| | - Boris Baer
- Centre for Integrative Bee Research (CIBER), ARC CoE Plant Energy Biology, MCS Building M316, The University of Western Australia; 6009 Crawley Australia
- Centre for Evolutionary Biology, School of Animal Biology M092; The University of Western Australia; 6009 Crawley Australia
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36
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Engel KC, von Hoermann C, Eggert AK, Müller JK, Steiger S. When males stop having sex: adaptive insect mating tactics during parental care. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.02.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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37
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Maroja LS, McKenzie ZM, Hart E, Jing J, Larson EL, Richardson DP. Barriers to gene exchange in hybridizing field crickets: the role of male courtship effort and cuticular hydrocarbons. BMC Evol Biol 2014; 14:65. [PMID: 24678642 PMCID: PMC4137559 DOI: 10.1186/1471-2148-14-65] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 03/17/2014] [Indexed: 11/10/2022] Open
Abstract
Background Pre-zygotic barriers often involve some form of sexual selection, usually
interpreted as female choice, as females are typically the choosier sex.
However, males typically show some mate preferences, which are increasingly
reported. Here we document previously uncharacterized male courtship
behavior (effort and song) and cuticular hydrocarbon (CHC) profiles in the
hybridizing crickets Gryllus firmus and G. pennsylvanicus.
These two species exhibit multiple barriers to gene exchange that act
throughout their life history, including a behavioral barrier that results
in increased time to mate in heterospecific pairs. Results We demonstrated that male mate choice (as courtship effort allocation) plays
a more important role in the prezygotic behavioral barrier than previously
recognized. In gryllids females ultimately decide whether or not to mate,
yet we found males were selective by regulating courtship effort intensity
toward the preferred (conspecific) females. Females were also selective by
mating with more intensely courting males, which happened to be
conspecifics. We report no differences in courtship song between the two
species and suggest that the mechanism that allows males to act
differentially towards conspecific and heterospecific females is the
cuticular hydrocarbon (CHC) composition. CHC profiles differed between males
and females of both species, and there were clear differences in CHC
composition between female G. firmus and G. pennsylvanicus
but not between the males of each species. Conclusion Although many barriers to gene exchange are known in this system, the
mechanism behind the mate recognition leading to reduced heterospecific
mating remains unknown. The CHC profiles might be the phenotypic cue that
allow males to identify conspecifics and thus to adjust their courtship
intensity accordingly, leading to differential mating between species.
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Affiliation(s)
- Luana S Maroja
- Department of Biology, Williams College, 31 Morley Drive, 01267 Williamstown, MA, USA.
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38
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Zhuang JY, Zhang S, Xu J, Hu D. Discriminating males and unpredictable females: males differentiate self-similar facial cues more than females in the judgment of opposite-sex attractiveness. PLoS One 2014; 9:e90493. [PMID: 24594644 PMCID: PMC3940898 DOI: 10.1371/journal.pone.0090493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 01/13/2014] [Indexed: 11/18/2022] Open
Abstract
Attractiveness judgment in the context of mate preferences is thought to reflect an assessment of mate quality in relation to an absolute scale of genetic fitness and a relative scale of self-similarity. In this study, subjects judged the attractiveness and trustworthiness of faces in composite images that were manipulated to produce self-similar (self-resemblance) and dissimilar (other-resemblance) images. Males differentiated between self- and other-resemblance as well as among different degrees of self-resemblance in their attractiveness ratings; females did not. Specifically, in Experiment 1, using a morphing technique, we created previously unseen face images possessing different degrees (0%, 30%, 40%, or 50%) of incorporation of the subject's images (different degrees of self-resemblance) and found that males preferred images that were closer to average (0%) rather than more self-similar, whereas females showed no preference for any degree of self-similarity. In Experiment 2, we added a pro-social question about trustworthiness. We replicated the Experiment 1 attractiveness rating results and further found that males differentiated between self- and other-resemblance for the same degree of composites; women did not. Both males and females showed a similar preference for self-resemblances when judging trustworthiness. In conclusion, only males factored self-resemblance into their attractiveness ratings of opposite-sex individuals in a manner consistent with cues of reproductive fitness, although both sexes favored self-resemblance when judging trustworthiness.
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Affiliation(s)
- Jin-Ying Zhuang
- Key Laboratory of Brain Functional Genomics (MOE & STCSM), School of Psychology and Cognitive Science, East China Normal University, Shanghai, China
| | - Sen Zhang
- Key Laboratory of Brain Functional Genomics (MOE & STCSM), School of Psychology and Cognitive Science, East China Normal University, Shanghai, China
| | - Jing Xu
- Key Laboratory of Brain Functional Genomics (MOE & STCSM), School of Psychology and Cognitive Science, East China Normal University, Shanghai, China
| | - Die Hu
- Key Laboratory of Brain Functional Genomics (MOE & STCSM), School of Psychology and Cognitive Science, East China Normal University, Shanghai, China
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39
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Dhole S, Pfennig KS. Age-dependent male mating investment in Drosophila pseudoobscura. PLoS One 2014; 9:e88700. [PMID: 24586373 PMCID: PMC3929311 DOI: 10.1371/journal.pone.0088700] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 01/10/2014] [Indexed: 11/24/2022] Open
Abstract
Male mating investment can strongly influence fitness gained from a mating. Yet, male mating investment often changes with age. Life history theory predicts that mating investment should increase with age, and males should become less discriminatory about their mate as they age. Understanding age-dependent changes in male behavior and their effects on fitness is important for understanding how selection acts in age-structured populations. Although the independent effects of male or female age have been studied in many species, how these interact to influence male mating investment and fitness is less well understood. We mated Drosophila pseudoobscura males of five different age classes (4-, 8-, 11-, 15-, 19-day old) to either young (4-day) or old (11-day) females, and measured copulation duration and early post-mating fecundity. Along with their independent effects, we found a strong interaction between the effects of male and female ages on male mating investment and fitness from individual matings. Male mating investment increased with male age, but this increase was more prominent in matings with young females. Male D. pseudoobscura made smaller investments when mating with old females. The level of such discrimination based on female age, however, also changed with male age. Intermediate aged males were most discriminatory, while the youngest and the oldest males did not discriminate between females of different ages. We also found that larger male mating investments resulted in higher fitness payoffs. Our results show that male and female ages interact to form a complex pattern of age-specific male mating investment and fitness.
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Affiliation(s)
- Sumit Dhole
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Karin S. Pfennig
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
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40
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Leivers S, Simmons LW. Human Sperm Competition. ADVANCES IN THE STUDY OF BEHAVIOR 2014. [DOI: 10.1016/b978-0-12-800286-5.00001-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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41
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Zizzari ZV, van Straalen NM, Ellers J. Male-male competition leads to less abundant but more attractive sperm. Biol Lett 2013; 9:20130762. [PMID: 24307528 DOI: 10.1098/rsbl.2013.0762] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Males employ complex strategies to optimize their reproductive success when faced with male-male competition; for instance, they can adjust the ejaculate characteristics. In copulating species, a male may also strategically adjust his ejaculate expenditure according to female quality. Quantifying the relative contribution of ejaculate plasticity in male reproductive success is often difficult, especially when females exert postcopulatory cryptic choice. One way to quantify the functional significance of ejaculate plasticity is offered by mating systems in which the reproductive partners do not meet each other during insemination. In the collembolan Orchesella cincta, males deposit their ejaculates (spermatophores) irrespective of the presence of females. We tested whether Orchesella males adjust spermatophore number when exposed to the presence of another male and whether changes in spermatophore production influence female choice. We found that Orchesella males display plasticity in spermatophore allocation. Males decreased the spermatophore number when exposed to a rival male. Moreover, females preferentially took up spermatophores of males that were exposed to a competitor. The reduction in spermatophore number suggests, besides an adaptive response to the risk of ejaculate removal by rival males, an optimization strategy owing to the costs of more attractive spermatophores.
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Affiliation(s)
- Z Valentina Zizzari
- Department of Ecological Science, Animal Ecology, VU University Amsterdam, , De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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42
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Worthington AM, Gress BE, Neyer AA, Kelly CD. Do male crickets strategically adjust the number and viability of their sperm under sperm competition? Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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43
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Experience affects mating behavior, but does not impact parental reproductive allocation in a lizard. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1523-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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44
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Fitzsimmons LP, Bertram SM. No relationship between long-distance acoustic mate attraction signals and male fertility or female preference in spring field crickets. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1511-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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45
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Gray B, Simmons LW. Acoustic cues alter perceived sperm competition risk in the field cricket Teleogryllus oceanicus. Behav Ecol 2013. [DOI: 10.1093/beheco/art009] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Simmons LW, Tan YF, Millar AH. Sperm and seminal fluid proteomes of the field cricket Teleogryllus oceanicus: identification of novel proteins transferred to females at mating. INSECT MOLECULAR BIOLOGY 2013; 22:115-130. [PMID: 23211034 DOI: 10.1111/imb.12007] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Reproductive proteins are amongst the most evolutionarily divergent proteins known, and research on genetically well-characterized species suggests that postcopulatory sexual selection might be important in their evolution; however, we lack the taxonomic breadth of information on reproductive proteins that is required to determine the general importance of sexual selection for their evolution. We used transcriptome sequencing and proteomics to characterize the sperm and seminal fluid proteins of a cricket, Teleogryllus oceanicus, that has been widely used in the study of postcopulatory sexual selection. We identified 57 proteins from the sperm of these crickets. Many of these had predicted function in glycolysis and metabolism, or were structural, and had sequence similarity to sperm proteins found across taxa ranging from flies to humans. We identified 21 seminal fluid proteins, some of which resemble those found to be involved in postmating changes to female reproduction in other species. Some 27% of sperm proteins and 48% of seminal fluid proteins were of unknown function. The characterization of seminal fluid proteins in this species will allow us to explore their adaptive significance, and to contribute comparative data that will facilitate a general appreciation of the evolution of reproductive proteins within and among animal taxa.
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Affiliation(s)
- L W Simmons
- Centre for Evolutionary Biology, The University of Western Australia, Crawley, WA, Australia.
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47
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Price TAR, Lizé A, Marcello M, Bretman A. Experience of mating rivals causes males to modulate sperm transfer in the fly Drosophila pseudoobscura. JOURNAL OF INSECT PHYSIOLOGY 2012; 58:1669-1675. [PMID: 23085556 DOI: 10.1016/j.jinsphys.2012.10.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/08/2012] [Accepted: 10/09/2012] [Indexed: 06/01/2023]
Abstract
Male responses to risk of sperm competition play an important role in sexual selection, sexual conflict, and the evolution of mating systems. Such responses can combine behavioural and physiological processes, and can be mediated through different components of the ejaculate such as sperm numbers and seminal proteins. An additional level of ejaculate complexity is sperm heteromorphism, with the inclusion of non-fertilising parasperm in the ejaculate. We now test the response to rivals in a sperm heteromorphic species, Drosophila pseudoobscura, measuring the behavioural response and sperm transfer and, crucially, relating these to short-term fitness. Males respond to exposure to conspecific rivals by increasing mating duration, but do not respond to heterospecific rivals. In addition, after exposure to a conspecific rival, males increased the transfer of fertilising eusperm, but not non-fertilising parasperm. Males exposed to a conspecific rival also achieve higher offspring production. This suggests that the evolution of parasperm in flies was not driven by sperm competition and adds to the increasing evidence that males can make extremely sophisticated responses to mating competition.
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Affiliation(s)
- Tom A R Price
- Biosciences, University of Exeter, Cornwall Campus, UK
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48
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Abstract
Females frequently mate with several males, whose sperm then compete to fertilize available ova. Sperm competition represents a potent selective force that is expected to shape male expenditure on the ejaculate. Here, we review empirical data that illustrate the evolutionary consequences of sperm competition. Sperm competition favors the evolution of increased testes size and sperm production. In some species, males appear capable of adjusting the number of sperm ejaculated, depending on the perceived levels of sperm competition. Selection is also expected to act on sperm form and function, although the evidence for this remains equivocal. Comparative studies suggest that sperm length and swimming speed may increase in response to selection from sperm competition. However, the mechanisms driving this pattern remain unclear. Evidence that sperm length influences sperm swimming speed is mixed and fertilization trials performed across a broad range of species demonstrate inconsistent relationships between sperm form and function. This ambiguity may in part reflect the important role that seminal fluid proteins (sfps) play in affecting sperm function. There is good evidence that sfps are subject to selection from sperm competition, and recent work is pointing to an ability of males to adjust their seminal fluid chemistry in response to sperm competition from rival males. We argue that future research must consider sperm and seminal fluid components of the ejaculate as a functional unity. Research at the genomic level will identify the genes that ultimately control male fertility.
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Affiliation(s)
- Leigh W Simmons
- Centre for Evolutionary Biology, , School of Animal Biology (M092), The University of Western Australia, Crawley, Western Australia 6009, Australia.
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49
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Galeotti P, Bernini G, Locatello L, Sacchi R, Fasola M, Rubolini D. Sperm traits negatively covary with size and asymmetry of a secondary sexual trait in a freshwater crayfish. PLoS One 2012; 7:e43771. [PMID: 22916304 PMCID: PMC3423389 DOI: 10.1371/journal.pone.0043771] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/25/2012] [Indexed: 11/29/2022] Open
Abstract
In species where females mate promiscuously, the reproductive success of males depends both on their ability to acquire mates (pre-copulatory sexual selection) and ability of their ejaculates to outcompete those of other males (post-copulatory sexual selection). Sperm competition theory predicts a negative relationship between investment in body traits favouring mate acquisition (secondary sexual characters, SSCs) and investment in ejaculate size or quality, due to the inherent costs of sperm production. In contrast, the phenotype-linked fertility hypothesis posits that male fertilizing efficiency is reliably reflected by the phenotypic expression of male SSCs, allowing females to obtain direct benefits by selecting more ornamented males as copulation partners. In this study, we investigated the relationships between male SSCs and size and quality (viability and longevity) of ejaculates allocated to females in mating trials of the freshwater crayfish Austropotamobius italicus. We showed that the relative size of male weapons, the chelae, was negatively related to ejaculate size, and that chelae asymmetry, resulting from regeneration of lost chelipeds, negatively covaried with sperm longevity. Moreover, males allocated more viable sperm to mates from their own rather than different stream of origin. Our findings thus suggest that, according to sperm competition theory, pre-copulatory sexual selection for large weapons used in male fighting may counteract post-copulatory sperm competition in this crayfish species, and that investment in cheliped regeneration may impair ejaculate quality.
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Affiliation(s)
- Paolo Galeotti
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Pavia, Italy
| | - Guido Bernini
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Pavia, Italy
| | - Lisa Locatello
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
| | - Roberto Sacchi
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Pavia, Italy
| | - Mauro Fasola
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Pavia, Italy
| | - Diego Rubolini
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
- * E-mail:
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50
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Radhakrishnan P, Fedorka KM. Immune activation decreases sperm viability in both sexes and influences female sperm storage. Proc Biol Sci 2012; 279:3577-83. [PMID: 22696524 DOI: 10.1098/rspb.2012.0654] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
All animals are under the constant threat of pathogenic infection. However, little is known regarding the influence of acute infection on sperm viability, particularly in female insects. This information is crucial for our understanding of mating and immune system coevolution, considering that females store sperm and serve as the site of sperm competition. Using the fruitfly, Drosophila melanogaster, we examined the influence of infection on sperm viability and storage. Twenty-four hours after haemocoel inoculation with a pathogen mimic (peptidoglycan, PGN) both sexes exhibited reduced sperm viability, indicating that systemic immune activation played a significant role in gamete survival. Surprisingly, sperm death did not appear to result from a reproductive-immune system trade-off, considering that sperm survived 24 h in vitro once removed from their somatic resources. Instead, our results are most consistent with death owing to immune effector collateral damage. We also examined the potential for sexually transmitted pathogens to influence sperm storage. Females mated with 'infected' males (created by dipping genitalia into a PGN solution) exhibited a higher proportion of empty sperm stores 48 h after mating compared to their controls. Remarkably, these data indicate that females may increase their fitness by removing 'infected' ejaculates from storage over time.
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Affiliation(s)
- Preethi Radhakrishnan
- Department of Biology, University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816, USA
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