Sperm Competition Models Research Articles

Social Environment Influences the Temporal Dynamics of Sneak-Spawning in a Fish with Alternative Reproductive Tactics.

AbstractSeveral predictions of sperm competition theory are not well supported empirically. One potential reason is that most current theory and empirical research ignore how the social environment influence the temporal dynamics of mating. We propose that understanding these dynamics is key to understanding sexual selection and improving the predictive power of theory. To demonstrate the importance of these dynamics, we quantify how males' social role, interactions among males, and current social environment influence the timing of mating in Symphodus ocellatus, a species with three alternative male reproductive tactics. Nesting males spawn synchronously with females; sneakers and satellites sneak-spawn with some time delay. Satellites also cooperate with nesting males. We found that satellites have shorter sneak-spawning delays than sneakers, a benefit of their cooperation with nesting males. Sneak-spawning delays decreased with increasing nest activity for sneakers but not for satellites, suggesting that sneakers may benefit from increased sperm competition intensity. Current sperm competition models ignore this potential benefit, which may be why the prediction that males should decrease investment when sperm competition involves more than two males is not well supported. Our study provides insight into mechanisms that drive variation in the timing of spawning, which could explain mismatches between theoretical and empirical results.

Sperm oxidative status varies with the level of sperm competition and affects male reproductive success

Sperm competition theory predicts that males should strategically adjust the allocation of sperm in response to the level of sperm competition (i.e. the number of competing ejaculates). Predictions of sperm competition models have mostly focused on sperm numbers. However, whether males strategically adjust other important traits of their ejaculate such as sperm antioxidants in response to potential rivals and the consequences of such allocation strategies on sperm integrity (e.g. oxidative damage accumulation) and offspring viability is poorly investigated. Using an experimental design in which I manipulated the perceived level of sperm competition experienced by male field crickets, Gryllus bimaculatus , I show that besides sperm numbers, sperm oxidative status can also vary in response to the level of sperm competition. Male crickets increased the antioxidant content of their ejaculates in response to sperm competition risk, an effect that presumably led to less sperm oxidative damage, at least when the level of competition was low. Moreover, I provide evidence suggesting that such strategic adjustments can have fitness consequences for males, as eggs sired by males with increased sperm damage had lower viability. Overall, my results suggest that sperm competition drives plasticity in nonsperm components affecting sperm oxidative status and support the idea that oxidative stress may play a key role in postcopulatory sexual selection. • Male crickets adjusted sperm numbers as expected by sperm competition theory. • Males also increased sperm antioxidants in response to other potential rivals. • Males under a low level of sperm competition had reduced sperm oxidative damage. • Eggs fertilized by males with reduced sperm oxidative damage were more viable.

Cephalopod mating systems as models for the study of sexual selection and alternative reproductive tactics: a review

Cephalopods are a remarkable group for studies on sexual selection, due to their complex reproductive behavior, pronounced sexual dimorphism, polygamous behavior, as well as cumulative evidence of pre- and postcopulatory male-male competition and female choice in the group. is paper provides a review of sexual selection studies on cephalopods, with an emphasis on the loliginid squid mating system. In this system, males may adopt alternative reproductive tactics (ART) and display male intrasexual dimorphism, with each morph generally exhibiting distinct behaviors and ejaculate traits. Consort males typically transfer ejaculates to the female mantle cavity, while sneaker males typically transfer ejaculates to the female buccal region, where a sperm storage organ is located. Each site provides distinct fertilization environments for the ejaculates of each morph, differing in the availability of eggs, gamete protection, and timing between mating and fertilization. Accordingly, the ejaculates of each morph show putative adaptations for each site, differing in size, morphology, sperm release duration, and sperm behavior. Although solid evidence is lacking for most loliginids, cryptic female choice may occur in this system through, for example, spermatangia removal or egg string manipulation during fertilization. In addition, recent evidence for one loliginid species indicates that adoption of male ART is ontogenetic and may represent two alternative pathways: from immature males (i) directly to consort phenotype or (ii) going through a sneaker phase, then switching to consort morph. The second pathway would, therefore, imply striking change in behavior, physiology, and ejaculates. Moreover, data on the age of this species suggests that the adoption of sneaker tactic early in life may be associated with extending the male mating period by 25%. With such a peculiar system, loliginids should prove useful not only for comprehending the evolution of female promiscuity and ART in cephalopods, but also as an emerging nonvertebrate and nonarthropod model for testing sperm competition models.

Male spiders reduce pre- and postmating sexual investment in response to sperm competition risk

The interplay between pre- and postmating responses to intrasexual competition remains enigmatic. Sperm competition models often assume a trade-off between pre- and postmating traits that enhance mate acquisition and fertilization success, respectively. However, when males court females through food donations (i.e., nuptial gifts), pre- and postmating responses may be aligned, as nuptial gifts have the dual function of facilitating both mate acquisition and sperm transfer. In the spider Pisaura mirabilis, nuptial gifts consist of silk-wrapped prey. We tested whether males respond to a competitor by altering: 1) premating investment in the gift, 2) postmating sperm investment, and 3) whether pre- and postmating responses are coupled and respond to competition in the same direction or not. Under competition risk males silk-wrapped their gifts for significantly shorter time and transferred less sperm to females, pointing to a reduction of both pre- and postmating responses. Because silk is not a target of female choice, reducing gift construction may speed up mate acquisition. In accordance with models of sperm allocation, perceived high levels of competition and/or sperm priority patterns may explain the reduced patterns of sperm transfer found in our study. Overall, our findings suggest that in competitive environments pre- and postmating traits are coupled and respond in the same direction.

Social dominance explains within-ejaculate variation in sperm design in a passerine bird

BackgroundComparative studies suggest that sperm competition exerts stabilizing selection towards an optimal sperm design – e.g., the relative size and covariation of different sperm sections or a quantitative measure of sperm shape - that maximizes male fertility, which results in reduced levels of within-male variation in sperm morphology. Yet, these studies also reveal substantial amounts of unexplained within-ejaculate variance, and the factors presiding to the maintenance of such within-male variation in sperm design at the population level still remain to be identified. Sperm competition models predict that males should progressively invest more resources in their germline as their mating costs increase, i.e., the soma/germline allocation trade-off hypothesis. When access to fertile females is determined by social dominance, the soma/germline allocation trade-off hypothesis predicts that dominant males should invest less in the control of spermatogenesis. Hence, dominance should positively correlate with within-male variance in sperm design.ResultsIn support of this hypothesis, we found that dominant house sparrow males produce ejaculates with higher levels of within-ejaculate variation in sperm design compared to subordinate males. However, after experimentally manipulating male social status, this pattern was not maintained.ConclusionsOur results suggest that males might control variation in sperm design according to their social status to some extent. Yet, it seems that such within-ejaculate variation in sperm design cannot be rapidly adjusted to a new status. While variation in sperm design could result from various non-exclusive sources, we discuss how strategic allocation of resources to the somatic vs. the germline functions could be an important process shaping the relationship between within-male variation in sperm design and social status.

Sperm competition and the evolution of precopulatory weapons: Testis size and amplexus position, but not arm strength, affect fertilization success in a chorusing frog.

Trade-offs between pre- and postcopulatory traits influence their evolution, and male expenditure on such traits is predicted to depend on the number of competitors, the benefits from investing in weapons, and the risk and intensity of sperm competition. Males of the chorusing frog Crinia georgiana use their arms as weapons in contest competition. Previously, we showed that increased numbers of rivals elevated the risk and intensity of sperm competition due to multimale amplexus, and caused a reversal in the direction of precopulatory selection on arm girth. Here, we focused on the factors affecting postcopulatory fertilization success during group spawning, using paternity data from natural choruses. Competitive fertilization success depended on the time spent amplexed and amplexus position. Relative testes size but not arm girth, contributed to fertilization success, but the effect of testes size depended on amplexus position. Our findings offer within species empirical support for recent sperm competition models that incorporate precopulatory male-male competition, and show why an understanding of the evolution of animal weapons requires a consideration of both pre- and postcopulatory episodes of sexual selection.

Alternative reproductive tactics, sperm mobility and oxidative stress in Carollia perspicillata (Seba’s short-tailed bat)

In social systems with alternative reproductive tactics, sneakers face a higher level of sperm competition than harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we assessed, for harem and sneaker males, four sperm mobility traits, blood and ejaculate markers of the redox balance and the ejaculate to blood ratios of the redox markers. Under higher sperm competition, sneaker males should allocate proportionally more antioxidant resources to the protection of sperm than harem males. In contrast, harem males should favour pre-copulatory functions, which comprise the protection of blood. We found significantly higher sperm velocity and sperm survival in sneakers. There was no correlation between sperm mobility and sperm enzymatic antioxidant activity or ejaculate levels of lipid peroxidation (oxidative damage). Ejaculate levels of lipid peroxidation and sperm survival showed a significantly positive correlation, which could be attributed to the role of reactive oxygen species for sperm capacitation. Harem and sneaker males showed similar levels of redox balance markers in ejaculate and blood. However, harem males showed a higher ratio of oxidized over reduced glutathione in blood, which may indicate higher cellular stress due to higher metabolism. Overall, our findings suggest that sneakers of C. perspicillata compensate for a higher level of sperm competition by higher sperm mobility. In social systems with alternative reproductive tactics, sneakers face higher level of sperm competition than harem males and hence are predicted to allocate more resources to ejaculates. Antioxidants can protect sperm against oxidative stress, and thus, their allocation to the ejaculate may depend on mating tactic. In this study on the frugivorous bat Carollia perspicillata, we found sperm swimming significantly faster and longer in sneaker males compared to harem males. However, traits other than the investigated antioxidant may favour higher sperm mobility. Measured redox pattern in blood of harem males may indicate higher cellular stress due to higher metabolism. Our results provide support to the current sperm competition models at the intraspecific level, which is still debated for internal fertilizers. This study contributes to better understanding the trade-offs and adaptations resulting from alternative reproductive tactics in mammals.

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

In most teleost fish species, sperm competition is a key factor in determining male reproductive success, leading to selection on males to increase their reproductive investment in gonads and ejaculate competitiveness. In this study, reproductive investment patterns were assayed by examining the relative investment in gonads and sperm quality metrics (in river water and in the presence of ovarian fluid) of masu salmon, Oncorhynchus masou, representing two fixed male alternative reproductive tactics (ARTs; small sneaking parr males and large dominant anadromous males). Although anadromous males were significantly larger in body size compared to parr males, the latter invested significantly more in relative gonad mass than the former. Sperm velocity and motility were significantly higher, and longevity was significantly lower in parr males than in anadromous males in river water. However, no difference in any of these sperm quality metrics was detected between the ARTs in the presence of ovarian fluid. Sperm velocity and motility were not affected by the presence of ovarian fluid compared to river water for parr males, but both traits increased significantly for anadromous males in ovarian fluid relative to river water, whereas longevity significantly increased in the presence of ovarian fluid compared to river water for both ARTs. We interpret these findings in light of potential cryptic female choice mechanisms and the sneak-guard model of sperm competition that is based on differences in sperm competition risk and alternative investment possibilities among ARTs.

Modification of sperm quality after sexual abstinence in Seba's short-tailed bat, Carollia perspicillata.

In polygynous mating systems, few males have stable access to sexual mates. With an expected higher copulation rate, harem males may deplete seminal fluids or increase epididymal sperm maturation, generating poor sperm quality. In a first study, we reported a higher sperm quality in sneaker males of Carollia perspicillata To test whether the lower sperm quality observed in harem males was generated by an elevated copulation rate, we temporarily removed males of both social statuses from the colony. We thus assessed status-related changes of sperm quality resulting from sexual abstinence. Moreover, released from territory and female guarding, harem males were expected to show a reduction in somatic costs. On the basis of sperm competition models, we predicted a higher resource investment in the ejaculate with the reduction of pre-copulatory efforts. In line with our predictions, sperm quality of harem males improved significantly in contrast to sneaker males, whose sperm quality did not change. Without an increase in ejaculate lipid peroxidation, our results also provide evidence that the duration of sexual abstinence was not sufficient to generate sperm oxidative damage through senescence. Harem males did not show a reduction in blood lipid peroxidation or in the ratio of oxidized to reduced glutathione. In line with the maintenance of these somatic costs, harem males did not invest more superoxide dismutase to the ejaculate to maintain sperm quality. Our results suggest that a difference in copulation rate rather than an adaptation to sperm competition provides sneaker males with higher sperm quality in C. perspicillata.

Sperm competition and the coevolution of pre- and postcopulatory traits: Weapons evolve faster than testes among onthophagine dung beetles.

Reproductive competition generates episodes of both pre- and postcopulatory sexual selection. Theoretical models of sperm competition predict that as the fitness gains from expenditure on the weapons of male combat increase, males should increase their expenditure on weapons and decrease their expenditure on traits that contribute to competitive fertilization success. Although traits subject to sexual selection are known to have accelerated evolutionary rates of phenotypic divergence, it is not known whether the competing demands of investment into pre- and postcopulatory traits affect their relative rates of evolutionary divergence. We use a comparative approach to estimate the rates of divergence in pre- and postcopulatory traits among onthophagine dung beetles. Weapons evolved faster than body size while testes mass and sperm length evolved more slowly than body size, suggesting that precopulatory competition is the stronger episode of sexual selection acting on these beetles. Although horns evolved faster than testes, evolutionary increases in horn length were not associated with evolutionary reductions in testes mass. Our data for onthophagines support the notion that in taxa where males are unable to monopolize paternity, expenditure on both weapons and testes should both be favored.

Functional variation of sperm morphology in sticklebacks

Some theoretical models of sperm competition make the assumption that in fish species with external fertilisation, sperm length relates positively to swimming speed at the expense of sperm longevity. Few studies have tested this assumption. We used the three-spined stickleback, Gasterosteus aculeatus L., to study functional sperm morphology. In this study, the relationship between males’ mean sperm length and fertilisation rate was investigated in vitro in a non-competitive situation. Fertilisation at different time points after sperm release was taken into account, and sperm morphology was quantified from scanning electron microscopy images. The time series of artificial fertilisations demonstrated that males which produced sperm with a longer tail fertilised faster, but their sperm had a shorter lifespan (or activity period). It was further suggested that males that produced sperm with a larger midpiece had greater fertilisation chances later on in the fertilisation process. Thus, in sticklebacks, there exists functional variation in sperm morphology, and sperm tail length is traded off against sperm longevity (or activity).

Reproductive investment patterns, sperm characteristics, and seminal plasma physiology in alternative reproductive tactics of Chinook salmon (Oncorhynchus tshawytscha)

Although alternative reproductive tactics (ARTs) are common across a range of taxa, little is known about whether the different tactics have adapted to sperm competition risk. Chinook salmon, Oncorhynchus tshawytscha, have two ARTs: large males that participate in dominance-based hierarchies for access to spawning females, known as hooknoses, and small males that attempt to sneak fertilizations during spawning events from peripheral positions, known as jacks. Jacks continually face sperm competition risk because they always spawn in the presence of another male, whereas hooknoses face relatively low sperm competition risk because other males are not always present during spawning events. Based on the sneak-guard model of sperm competition this asymmetry in sperm competition risk predicts that jacks ought to invest significantly more into sperm-related traits important for sperm competition success relative to hooknoses. In the present study we report on reproductive investment patterns, sperm characteristics, and seminal plasma physiology of males that exhibit ARTs in Chinook salmon. We found that jacks invest significantly more of their somatic tissue into gonads compared with hooknoses. Sperm velocity also varied significantly between the ARTs, with jacks having significantly faster sperm than hooknoses. No significant differences in seminal plasma physiology metrics related to sperm quality were detected between the ARTs. We interpret these sperm investment patterns in light of the sneak-guard model of sperm competition that is based on differences in sperm competition risk and alternative investment possibilities among ARTs.

MALE CONTEST COMPETITION AND THE COEVOLUTION OF WEAPONRY AND TESTES IN PINNIPEDS

Male reproductive success is influenced by competitive interactions during precopulatory and postcopulatory selective episodes. Consequently, males can gain reproductive advantages during precopulatory contest competition by investing in weaponry and during postcopulatory sperm competition by investing in ejaculates. However, recent theory predicts male expenditure on weaponry and ejaculates should be subject to a trade-off, and should vary under increasing risk and intensity of sperm competition. Here, we provide the first comparative analysis of the prediction that expenditure on weaponry should be negatively associated with expenditure on testes mass. Specifically, we assess how sexual selection influences the evolution of primary and secondary sexual traits among pinnipeds (seals, sea lions, and walruses). Using recently developed comparative methods, we demonstrate that sexual selection promotes rapid divergence in body mass, sexual size dimorphism (SSD), and genital morphology. We then show that genital length appears to be positively associated with the strength of postcopulatory sexual selection. However, subsequent analyses reveal that both genital length and testes mass are negatively associated with investment in precopulatory weaponry. Thus, our results are congruent with recent theoretical predictions of contest-based sperm competition models. We discuss the possible role of trade-offs and allometry in influencing patterns of reproductive trait evolution in pinnipeds.

Sperm competition roles and ejaculate investment in a promiscuous mammal

Theoretical models of sperm competition predict how males should allocate sperm and seminal fluid components to ejaculates according to their mating role (dominant vs. subordinate). Here, we present a detailed analysis of ejaculate expenditure according to male roles in the bank vole (Myodes glareolus). Sperm competition occurs regularly in this species, and dominant males typically achieve higher fertilization success than subordinates. Contrary to theoretical predictions, we found that dominant male bank voles invest more sperm per ejaculate than subordinates, both absolutely and relative to body and testes mass. The testes of dominant males were also absolutely (although not relatively) larger than those of subordinates. However, we found no evidence that subordinate males compensate for lower sperm numbers per ejaculate by increasing ejaculation frequency or sperm velocity. Similarly, we found no evidence for differential investment in copulatory plug size according to male roles in sperm competition, although dominant males had significantly larger seminal vesicles (both absolutely and relative to body mass) compared with subordinates. We conclude that sperm competition roles can have significant but unexpected influences on ejaculate investment in mammals with clearly defined differences in male social status.

Discriminating Males and Unpredictable Females: Males Bias Sperm Allocation in Favor of Virgin Females

When both sexes mate with multiple partners, theory predicts that males should adjust their investment in ejaculates in response to the risk and/or intensity of sperm competition. Here, we demonstrate that, in the harlequin beetle riding pseudoscorpion, Cordylochernes scorpioides, males use cues deposited on females by previous males to distinguish between virgin, once-mated, and multiply-mated females and adjust sperm allocation accordingly. Sperm number declined in direct proportion to the number of previous males, with virgin females receiving nearly three times more sperm than females exposed to three previous males. Given the lack of first-male sperm precedence in C. scorpioides, this pattern is not consistent with current sperm competition models and appears best explained by a significant risk of wasting ejaculates on deceitful, mated females. In C. scorpioides, males transfer sperm indirectly to females via a stalked spermatophore deposited on the substrate. Mated females often feign sexual receptivity and cooperate throughout mating, only to reject the sperm packet produced by the male. While indirect sperm transfer facilitates a high level of female deceit and control, females of many species are able to influence the number and fate of sperm transferred during copulation and are likely to conceal their sexual unreceptivity to minimize male retaliation. If males cannot accurately assess female receptivity, increased risk of sperm rejection by mated females could outweigh the risk of sperm competition and favor greater sperm allocation to virgin females.

Song and Sperm in Crickets: A Trade-off between Pre- and Post-copulatory Traits or Phenotype-Linked Fertility?

When females mate multiply (polyandry) both pre- and post-copulatory sexual selection can occur. Sperm competition theory predicts there should be a trade-off between investment in attracting mates and investment in ejaculate quality. In contrast, the phenotype-linked fertility hypothesis predicts a positive relationship should exist between investment in attracting mates and investment in ejaculate quality. Given the need to understand how pre- and post-copulatory sexual selection interacts, we investigated the relationship between secondary sexual traits and ejaculate quality using the European house cricket, Acheta domesticus. Although we found no direct relationship between cricket secondary sexual signals and ejaculate quality, variation in ejaculate quality was dependent on male body weight and mating latency: the lightest males produced twice as many sperm as the heaviest males but took longer to mate with females. Our findings are consistent with current theoretical models of sperm competition. Given light males may have lower mating success than heavy males because females take longer to mate with them in no-choice tests, light males may be exhibiting an alternative reproductive tactic by providing females with more living sperm. Together, our findings suggest that the fitness of heavy males may depend on pre-copulatory sexual selection, while the fitness of light males may depend on post-copulatory fertilization success.

No evidence for sperm priming responses under varying sperm competition risk or intensity in guppies

Sperm competition theory predicts that males should tailor their investment in ejaculates according to the number of rival males competing to fertilize a female's eggs. Research spanning several taxa supports this prediction by showing that males are often sensitive to the level of sperm competition and adjust their investment in sperm numbers accordingly. More recent work has revealed that males may also tailor the quality of sperm according to the number of males competing for fertilization. Here I test for both effects in guppies (Poecilia reticulata) in an experiment that simultaneously evaluates the risk and intensity models of sperm competition. The experiment determined whether male guppies adjust the number (stripped ejaculate size) and quality (sperm velocity and viability) of sperm that are primed over a 3-day period according to experimental changes in the perceived level of sperm competition. A total of 136 focal males were initially stripped of all retrievable sperm and assayed for these sperm traits before being allocated at random to one of four treatments simulating different levels of sperm competition risk and intensity. During the 3-day treatment phase, focal males had visual and olfactory access to a sexually receptive (initially virgin) female maintained with different numbers of stimulus males to simulate variation in the risk and intensity of sperm competition. Following this, males were assayed again for the sperm traits. Contrary to predictions, there was no significant change in any of the measured variables among treatments, although qualitatively the patterns for sperm velocity and viability did conform to expectation. The lack of any trend for the number of sperm primed was unequivocal and future work examining the effects of sperm competition on sperm production should focus on whether males differentially allocate sperm numbers among matings that differ in the level of sperm competition.

Presence of rivals reduces mating probability but does not affect ejaculate size in the freshwater crayfish Austropotamobius italicus

Sperm competition models predict that males should adjust their sperm expenditure according to the risk and intensity of sperm competition, increasing it when competing with at least one other ejaculate and decreasing it when the number of competing ejaculates rises above two. However, when the raffle to fertilize eggs is strongly loaded due to sperm removal by subsequent rivals, it could be hypothesized that first-mating males progressively decrease their sperm expenditure and/or defer copulation with an increasing number of nearby competitors. Here, by varying experimentally the number of competitors around a mating pair, we analysed mating behaviour of both sexes and sperm expenditure in relation to variation in the immediate risk of sperm competition in the freshwater crayfish Austropotamobius italicus , a species where males remove all or part and feed on sperm laid by previous mating males. We found that male mating behaviour varied significantly with increasing number of rivals, because interactions between focal males and competitors, as well as male refusals to copulate, increased with number of the latter. As a consequence, the probability to reach an effective copulation decreased with increasing number of competitors. However, males released similar amounts of sperm independently of the number of surrounding competitors. Thus, the observed lack of variation in sperm expenditure in relation to the number of surrounding rivals suggests that freshwater crayfish males are unable to adjust the size of their ejaculates to short-term variation in the immediate risk of sperm competition.

Male monarch butterflies, Danaus plexippus, adjust ejaculates in response to intensity of sperm competition

During mating, male Lepidoptera transfer spermatophores that consist of accessory gland material, eupyrene (nucleated) sperm and apyrene sperm that is incapable of fertilizing eggs. Sexual selection theory predicts that males should allocate these materials strategically based on the risk and intensity of sperm competition. We studied the relationship between behavioural and physiological cues and material allocation by male monarch butterflies, Danaus plexippus. Males that had waited longer between matings transferred larger spermatophores and more apyrene and eupyrene sperm. Eupyrene sperm number was also correlated with female mating history, with males transferring more sperm to females that had larger amounts of spermatophore material stored from previous mates, regardless of whether this came from one or three mates. This result suggests that males use stored ejaculates to assess female mating history and increase eupyrene sperm investment under increased sperm competition intensity. Male monarchs appear to be capable of independently manipulating the different components of their ejaculates. Ejaculate allocation patterns suggest that males benefit by maximizing spermatophore size and apyrene sperm number, possibly to delay future female remating. However, males allocate more eupyrene sperm to females when sperm competition is more intense, which is consistent with predictions from recent sperm competition models.

A preliminary analysis of mate choice in a bush cricket (Poecilimon laevissimus: Tettigoniidae) suggests virginity is more important than body size

Insects are predicted to prefer larger partners for a number of reasons relating to fitness. In species where males provide an expensive nuptial gift, male and female preferences for a larger partner are likely to be more pronounced. In nuptial-feeding insects however, models of sperm competition and female choice predict that males and females should also prefer virgin partners. Here we test the relative importance of size vs virginity in a Greek bushcricket, Poecilimon laevissimus, in which males offer typically large nuptial gifts during mating. While only a small number of replicates could be implemented, and there is a clear need for further analysis, we found that all males and females preferred to mate with virgins, despite the fact that nearly 90% of the virgins were smaller in size than the nonvirgins offered. In terms of mate choice, virginity therefore appears more important than body size in P. laevissimus.