Male Fighting Research Articles

Vibrating aggression: spider males perform an unusual assessment strategy during contest displays

Abstract A recurrent question in animal contests is whether individuals adopt a self or mutual assessment rule to decide to withdraw from a contest. However, many empirical studies fail to find conclusive support for one of these two possibilities. A possible explanation is that assessment strategies vary between individuals. In the contests of the orb-web spider Trichonephila clavipes, males perform a vibrational display on webs that may escalate to physical contact. Since all individuals perform the vibrational phase and only some of them escalate, we proposed 2 hypotheses: (1) all individuals perform mutual assessment during the vibrational phase, or (2) some individuals that do not escalate adopt self-assessment, while individuals that escalated adopt mutual assessment. To evaluate these hypotheses, we investigated the relationship between the duration of the vibrational phase and frontal leg length (a proxy of male fight capacity) of loser and winner males in contests that escalated and did not escalate to the physical contact phase. We found a non-significant relationship between duration and losers leg length for both contests that escalate and did not escalate. While we found a positive relationship between duration and winners leg length, particularly in contests that did not escalate. These results do not provide support for mutual assessment or for a mix of different assessment rules among individuals. We suggest that in T. clavipes, the dynamics of the vibrational phase may be explained by two different contest strategies (opponent-only assessment or size-based aggressiveness) that are dependent on intruder motivation to escalate.

Experimental quantification of genetic and ontogenetic effects on fighting behavior in the broad-horned flour beetle

Most animal behaviors show large within- and among-individual variation, and this includes competitive male behaviors. With male fighting for example, aggressiveness often correlates with dominance, and contest duration varies with age. However, few studies have directly quantified how mean aggressiveness and contest duration, the variation among individuals in both traits, and the relationship among them, vary with age. Here we address these gaps and examine the effect of male age and genotype on two key aspects of male fighting behavior - aggressiveness (here measured as latency to fight) and contest duration - and the relationship between them. We do this using isogenic lines of the broad-horned flour beetle Gnatocerus cornutus. We observed fighting behavior of paired males of similar body size and age. Using uni- and multivariate mixed models, we show that although there was a significant difference between younger and older males in contest duration, mean aggressiveness was not affected by male age. However, the variation in aggression and fight duration varied with age, being greater in younger and older males respectively. Additionally, although there was a positive correlation between aggressiveness and contest duration in younger males, this relationship was not found in older males. Finally, the only significant genetic effect was for aggression in younger males. Our study shows that age differentially shapes key components of male fighting behavior as well as the relationship among them, highlighting the dynamic nature and context-dependence of fighting.

A toxicology study of Csf2ra complementation and pulmonary macrophage transplantation therapy of hereditary PAP in mice

Pulmonary macrophage transplantation (PMT) is a gene and cell transplantation approach in development as therapy for hereditary pulmonary alveolar proteinosis (hPAP), a surfactant accumulation disorder caused by mutations in CSF2RA/B (and murine homologs). We conducted a toxicology study of PMT of Csf2ra gene-corrected macrophages (mGM-Rα+Mϕs) or saline-control intervention in Csf2raKO or wild-type (WT) mice including single ascending dose andrepeat ascending dose studies evaluating safety, tolerability, pharmacokinetics, and pharmacodynamics. Lentiviral-mediated Csf2ra cDNA transfer restored GM-CSF signaling in mGM-Rα+Mϕs. Following PMT, mGM-Rα+Mϕs engrafted, remained within the lungs, and did not undergo uncontrolled proliferation or result in bronchospasm, pulmonary function abnormalities, pulmonary or systemic inflammation, anti-transgene product antibodies, or pulmonary fibrosis. Aggressive male fighting caused a similarly low rate of serious adverse events in saline- and PMT-treated mice. Transient, minor pulmonary neutrophilia and exacerbation of pre-existing hPAP-related lymphocytosis were observed 14days after PMT of the safety margin dose but not the target dose (5,000,000 or 500,000 mGM-Rα+Mϕs, respectively) and only in Csf2raKO mice but not in WT mice. PMT reduced lung disease severity in Csf2raKO mice. Results indicate PMT of mGM-Rα+Mϕs was safe, well tolerated, and therapeutically efficacious in Csf2raKO mice, andestablished a no adverse effect level and 10-fold safety margin.

Trade-offs between immunity and competitive ability in fighting ant males

BackgroundFighting disease while fighting rivals exposes males to constraints and trade-offs during male-male competition. We here tested how both the stage and intensity of infection with the fungal pathogen Metarhizium robertsii interfere with fighting success in Cardiocondyla obscurior ant males. Males of this species have evolved long lifespans during which they can gain many matings with the young queens of the colony, if successful in male-male competition. Since male fights occur inside the colony, the outcome of male-male competition can further be biased by interference of the colony’s worker force.ResultsWe found that severe, but not yet mild, infection strongly impaired male fighting success. In late-stage infection, this could be attributed to worker aggression directed towards the infected rather than the healthy male and an already very high male morbidity even in the absence of fighting. Shortly after pathogen exposure, however, male mortality was particularly increased during combat. Since these males mounted a strong immune response, their reduced fighting success suggests a trade-off between immune investment and competitive ability already early in the infection. Even if the males themselves showed no difference in the number of attacks they raised against their healthy rivals across infection stages and levels, severely infected males were thus losing in male-male competition from an early stage of infection on.ConclusionsMales of the ant C. obscurior have a well-developed immune system that raises a strong immune response very fast after fungal exposure. This allows them to cope with mild pathogen exposures without compromising their success in male-male competition, and hence to gain multiple mating opportunities with the emerging virgin queens of the colony. Under severe infection, however, they are weak fighters and rarely survive a combat already at early infection when raising an immune response, as well as at progressed infection, when they are morbid and preferentially targeted by worker aggression. Workers thereby remove males that pose a future disease threat by biasing male-male competition. Our study thus reveals a novel social immunity mechanism how social insect workers protect the colony against disease risk.

Effect of water temperature of culture medium on the sex ratio and survival rate of fighting fish Betta dennisyongi larvae

Fighting fish Betta dennisyongi is a popular ornamental freshwater fish in Indonesia. Male fighting fish are preferred because the colour pattern and shape of the fins are more attractive so they are more expensive. This study aims to determine the optimum temperature of rearing media water on the male sex ratio and survival rate of fighting fish larvae. A completely randomized design method with three replications was used in this study. The tested rearing temperature water was: 26°C, 28°C, 30°C, and 32°C. Fish were kept for 40 days. The results of the ANOVA test showed that larval rearing temperature affected significantly the ratio of male and female fish larvae survival (P<0.05). The highest percentage of the male sex was found at a temperature of 32 °C (93.33%), this value was significantly different from other temperature treatments. Meanwhile, the highest larval survival was obtained at a rearing temperature of 28 °C (80.00%), where this value was significantly different from other treatments. Therefore, with economic considerations, it is concluded that the optimal larval rearing media temperature is 28 °C.

Evolution of stridulatory mechanisms: vibroacoustic communication may be common in leaf-footed bugs and allies (Heteroptera: Coreoidea).

Intra- and interspecific communication is crucial to fitness via its role in facilitating mating, territoriality and defence. Yet, the evolution of animal communication systems is puzzling-how do they originate and change over time? Studying stridulatory morphology provides a tractable opportunity to deduce the origin and diversification of a communication mechanism. Stridulation occurs when two sclerotized structures rub together to produce vibratory and acoustic (vibroacoustic) signals, such as a cricket 'chirp'. We investigated the evolution of stridulatory mechanisms in the superfamily Coreoidea (Hemiptera: Heteroptera), a group of insects known for elaborate male fighting behaviours and enlarged hindlegs. We surveyed a large sampling of taxa and used a phylogenomic dataset to investigate the evolution of stridulatory mechanisms. We identified four mechanisms, with at least five evolutionary gains. One mechanism, occurring only in male Harmostini (Rhopalidae), is described for the first time. Some stridulatory mechanisms appear to be non-homoplastic apomorphies within Rhopalidae, while others are homoplastic or potentially homoplastic within Coreidae and Alydidae, respectively. We detected no losses of these mechanisms once evolved, suggesting they are adaptive. Our work sets the stage for further behavioural, evolutionary and ecological studies to better understand the context in which these traits evolve and change.

Quantitative genetics of breeding coloration in sand lizards; genic capture unlikely to maintain additive genetic variance

Sexual selection on fitness-determining traits should theoretically erode genetic variance and lead to low heritability. However, many sexually selected traits maintain significant phenotypic and additive genetic variance, with explanations for this “lek paradox” including genic capture due to condition-dependence, and breaks on directional selection due to environmental sources of variance including maternal effects. Here we investigate genetic and environmental sources of variance in the intrasexually selected green badge of the sand lizard (Lacerta agilis). The badge functions as a cue to male fighting ability in this species, and male–male interactions determine mate acquisition. Using animal models on a pedigree including three generations of males measured over an extensive 9-year field study, we partition phenotypic variance in both badge size and body condition into additive genetic, maternal, and permanent environmental effects experienced by an individual over its lifespan. Heritability of badge size was 0.33 with a significant estimate of underlying additive genetic variance. Body condition was strongly environmentally determined in this species and did not show either significant additive genetic variance or heritability. Neither badge size nor body condition was responsive to maternal effects. We propose that the lack of additive genetic variance and heritability of body condition makes it unlikely that genic capture mechanisms maintain additive genetic variance for badge size. That said, genic capture was originally proposed for male traits under female choice, not agonistic selection. If developmental pathways generating variance in body condition, and/or the covarying secondary sex trait, differ between inter- and intrasexual selection, or the rate at which their additive genetic variance or covariance is depleted, future work may show whether genic capture is largely restricted to intersexual selection processes.

Effect of male–female relatedness on aggression and inbreeding in an egg parasitoid wasp

Aggressive behavior is important for acquiring crucial resources in many animals. As such behavior is costly, selection favors contestants that can accurately gather information regarding the likely costs and benefits of conflict to enable appropriate tactical decisions. Mate choice based on relatedness is widespread among animals and has severe consequences. Theoretically, due to the potential costs of inbreeding, contestants may benefit from discriminating between relative and nonrelative mates and adjusting their behavior accordingly. If inbreeding results in fitness costs, related mates might be perceived as less valuable and individuals might be expected to invest less in costly aggression, and vice versa. However, the role of male–female relatedness in aggression has been less addressed. The egg parasitoid wasp Anastatus disparis, which exhibits extreme male–male aggressive behavior for mating opportunities, was used as an experimental model to explore the role of male–female relatedness in aggression. Inconsistent with our prediction, male–female relatedness had no significant effect on male–male fighting frequency or intensity in A. disparis. The ability of males to discriminate relative from nonrelative females is a prerequisite for male–female relatedness to affect males’ aggression. However, A. disparis males did not exhibit any mating preferences for relative or nonrelative females. Besides, inbreeding did not result in depression in terms of longevity, fecundity or sex ratio in A. disparis. Our finding of no effect of male–female relatedness on male–male fights in A. disparis may be caused by a lack of kin discrimination ability or/and a lack of benefits from discriminating relatives from nonrelatives.

Iridescent scales signal male fighting ability to access females in the jewelled splitfin Xenotoca variata.

Jewelled splitfin males (Xenotoca variata) possess multi-colour iridescent scales (speckles) on the flanks. This study tested the hypothesis that the number of speckles could be a good proxy for predicting fighting ability in contests for access to females. The experiments consisted in observing and recording males' agonistic behaviour, courtship displays and mating attempts in mixed-sex groups. The data were analysed and presented based on a Bayesian approach, which revealed that the density (cm-2 ) of speckles was positively correlated with the increase observed in the proportional frequency of attacks. Similarly, the density of speckles was positively associated with the increase observed in the frequency of courtship behaviour and with the frequency of mating attempts. Male-male aggressions drastically diminished (by eightfold) when females were removed from the observation tanks. These results indicate that the number of speckles is a consistent predictor of successful access to females and therefore, speckled males are likely to be able to gain more mating opportunities. This finding highlights the ubiquitous role iridescent colours play in visual signalling.

Humpback spiders from Ecuador: relationships, prosoma ‘inflation’ and genital asymmetry (Araneae: Pholcidae: Mecolaesthus)

Males of the South American spider genus Mecolaesthus Simon, 1893 are characterised by a dorsally ‘inflated’ prosoma or hump. Here we describe the first representatives of the genus from Ecuador. A phylogenetic analysis of molecular sequence data suggests that the new species are part of an Amazonian-West Indian clade. Whether this clade is sister to ‘true’ (northern Venezuelan) Mecolaesthus or not remains unclear. The two clades occupy different major Neotropical biogeographic regions. Our phylogenetic reanalysis of Mecolaesthus and related genera greatly expands the taxon sampling compared to previous analyses (from 9 to 46 species representing the ‘Venezuelan clade’ of genera) but remains ambiguous regarding the monophyly of Mecolaesthus. In addition, we present first micro-computed tomography (µ-CT) data of the unique prosoma ‘inflation’, showing that these ‘inflations’ are tightly packed with muscles inserted at the leg coxae, mainly of legs 2 and 3. Male (but not female) leg length is negatively correlated with body size and this is highly unusual in Pholcidae. We predict that male–male fights in Mecolaesthus rely on powerful leg movements of legs 2 and 3 rather than on using legs 1 to assess the opponent’s body size. Finally, we document structural genital asymmetry in females of three of the four new species and in M. putumayo Huber, 2000 (of which the female is newly described). This constitutes the fourth known case of structural genital asymmetry in Pholcidae. ZooBank: urn:lsid:zoobank.org:pub:3110BCD6-BA65-45E2-A758-71F2767BD6E4

Adult sex ratios and partial dominance of females over males in the rock hyrax

Competition in group-living animals often results in a dominance hierarchy. The sex that is larger (usually the males) generally dominates the one that is smaller (the females). In certain species, however, despite being smaller, the females dominate several males. Female dominance over males may here arise from the self-reinforcing effects of winning and losing fights, the so-called winner-loser effect, as demonstrated in the model DomWorld. In the model, females may become dominant over more males when the percentage of males in the group is higher due to the higher intensity of aggression of males than females combined with the higher frequency of male–male fights. This association between female dominance and the percentage of adult males in the group has been confirmed in several primate species. Since in the model DomWorld this association requires few assumptions, it should be tested beyond primates. In the present study, we investigated it in the group-living rock hyrax (Procavia capensis), because it fulfilled most requirements. We used data on adults from six groups, collected over 20 years in natural colonies in Israel. We confirmed that body weight and intensity of aggression was greater in males than females. Three measurements indicated that females dominated ca. 70% of the males. Unexpectedly, only in the data where groups comprised several males, female dominance over males was shown to increase with male percentage, but not when including (the many) years in which groups comprised a single male. We attribute this non significance to the limited male–male interactions. One of the requirements of DomWorld is that individuals live in permanent groups, but in rock hyrax there were also bachelor males, that were not permanently associated with a group. Thus, we expected and confirmed that there was no association between the percentage of males and female dominance over males when including them. In conclusion, our results support the hypothesis that the winner-loser effect contributes to the dominance of females over males, and the association between the percentage of males in a group and female dominance over males requires an extra criterion: that most groups contain multiple males.

Do reproductive characteristics of the species explain differences in the investment in weapon size present in males?

AbstractSexually selected traits, such as male weapons, are highly variable in shape and size across species. However, little is known about the mechanisms that may govern this variation. Because males with greater investment in weapon size tend to win more fights, but also pay higher costs related to weapon development and maintenance, larger weapons should be expected only in species in which victory in male–male fights generate reproductive benefits that outweigh investment costs. Here, we hypothesized that the reproductive characteristics that increase the chances of winners to access females or to fertilize eggs will favor the evolution of larger weapons. To evaluate this hypothesis, we conducted a meta‐analysis using arthropods as model organisms. To measure investment in weapon size, we gathered both Pearson correlation coefficient and the standardized (but non centralized) slope values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing female eggs with a victory does not modulate the investment in male weapon size. Perhaps the cost–benefit ratio between weapon size investment and reproductive success is not the main factor driving the variation in weapon size.

The breeding biology of erect-crested penguins, Eudyptes sclateri: Hormones, behavior, obligate brood reduction and conservation.

Erect-crested penguins are the least studied of all penguins. They breed on two isolated subantarctic island groups, the Antipodes and Bounty Islands. Sporadic nest counts indicate a dramatic decline in numbers of erect-crested penguins over the last 50 years. Here we present data from a study undertaken in 1998 on the breeding biology, behavior and hormones of erect-crested penguins. It represents, even today, by far the most detailed data available on this species. The penguins exhibited extreme reversed egg-size dimorphism, whereby the first-laid A-egg was much smaller than the second-laid B-egg. A-eggs were lost before (42.3%) or on (37.8%) the day the B-egg was laid, and none survived more than 7 days after that. The penguins were in a low state of reproductive readiness, as evidenced by low levels of copulation, fighting, and testosterone in males during the courtship/laying period when, curiously, plasma levels of testosterone were at least as high in females. The laying interval (5.4 days) is the longest recorded for any penguin species, and incubation was highly variable until clutch completion. Most nests (91.2%) contained no nesting material and eggs were laid directly onto the ground. A-eggs were lost mainly by rolling out of the nest. However, even when prevented from doing so by an experimental manipulation, A-eggs survived no longer than those in control nests. Testosterone levels in males increased after clutch completion, when they remained in attendance at the nest for up to 13 days, despite females assuming most of the incubation duties. The bills of males were significantly larger than those of females and probably help with guarding the nest. We discuss explanations for obligate brood reduction in crested penguins and the options for conservation in light of our census results, which indicate that this enigmatic penguin species could be in trouble.

Head Trauma Exposure in Mixed Martial Arts.

Combat sports training involves a high risk of head injury. Previously published research on head trauma exposure in MMA evaluated only the knockouts (KO), without calculating all head strikes. The aim of the research was to evaluate the total head trauma exposure during MMA competitions among male and female fighters. Two thousand four hundred and eighty-eight MMA fights from all numbered UFC events between 2000 and 2021 were analyzed. A database containing the results from officially published scorecards with information such as the outcome of a fight, its duration, number of strikes (significant and total amount of hits) depending on location and knockdowns was created. Additional video verification of the knockout technique was carried out. The athletes received an average of 2.41 significant head strikes out of a total of 6.30 head strikes per minute. Head strikes were more common in female fights than in male. Women executed more total and significant head strikes per minute than men. Head trauma caused the ending of 31.6% of all fights—more often in male fights (32.2%) than female (23.1%). It was the most common cause of knockouts—88.1%. Professional fights in mixed martial arts involve high exposure to head trauma. A careful evaluation of the risk involved in training in such a discipline is necessary to provide adequate prevention methods.

Développement Testiculaire chez Poisson Combattant (Betta splendens), variété de Demi-lune, Subis 35 jours de Différents Régimes de Photopériodes

Fighting fish (Betta splendens) is one of the fresh water ornamental fish with highly commercial value. This fish has a distinctive morphological shape which is aesthetic and is easy to maintain. Demand for this fish increased leading to opportunities for cultivation. Quality and quantity of fries were constantly needed, and this could be achieved by manipulating reproduction. Photoperiod regimes could play a role to do this. The purpose of this study was to determine the effect of photoperiods on the testis development of halfmoon strains of fighting fish.&#x0D; A completely randomized design was run to test 3 treatments in quintuplicates. The fish were reared under treatment P1 (10 hours light L and 14 hours dark D), treatment P2 (14 hours L and 10 hours D) and treatment P0 (12 hours L and 12 hours D). The fish were maintained for 35-d, in Aquatic Resources Laboratory of FPIK Unsoed. The results showed that treatment P2 was significantly different (P&lt;0.05), which the highest spermatogenesis stage (54.78 ± 16.64%) was obtained. The study concluded that male fighting fish under P2 photoperiod could accelerate testicular maturation.

The shell measurements that best describe sexual dimorphism in the spur-thighed tortoise &lt;em&gt;Testudo graeca&lt;/em&gt; from Algeria

Due to phenotypic plasticity and sex-biased selective pressures, intraspecific variation in tortoise morphology is usually assessed by studying sexual dimorphism. However, inferences may differ based on the choice of shell size measurements for analyses. In this work, we identified linear measurements that best describe sexual dimorphism for the spur-thighed tortoise Testudo graeca whitei. We assessed 34 carapace and plastron measurements in 67 individuals (24 males, 43 females) in a population at the natural Mergueb site located on the central limit of the Algerian steppe. Twenty-two out of 34 measurements significantly showed sexual size dimorphism in ANOVA tests. When analyzing sexual shape dimorphism with ANCOVAs, nine measurements showed no shared allometry with the measurements used as covariates to correct by size. Meanwhile, 17 out of the remaining 23 measurements showed significant differences in shape. PCA analyses similarly described T. graeca’s sexual dimorphism. In general, females tend to be bigger than males, especially in central scutes what is probably linked with clutch sizes commitments. On the other hand, males are larger-sized in anterior and posterior scutes, probably as a result of courtship, male fighting and copulation. Some of the analyzed measurements are revealed as being especially adequate for further studying the geographical variation of sexual dimorphism in Testudo graeca

A preliminary assessment of the physiological and morphological correlates of beetle aggression in an emerging sugarcane pest, Cacosceles newmannii (Thomson, 1877) (Coleoptera: Cerambycidae)

Understanding the morphological and physiological correlates of competitive behaviours can provide important insights into the ecology of competition, home range size and resource consumption. Here we first estimated and defined sexual dimorphism in a poorly studied African cerambycid species, Cacosceles newmannii (Thomson, 1877). We then assessed morphological and physiological attributes of male beetles in relation to their fighting behaviour. Suites of morphological and energetic measurements were carried out on adult males, the latter before and after male-male interactions. Aggressive behaviour and the outcomes of male fighting trials were assessed under controlled conditions. The species is highly sexually dimorphic in relation to mandible size. During male-male interactions, a continuum of behaviours with an increasing risk of injury and metabolic cost was observed. Grasping was prolonged in males with larger fighting apparatus, who also tended to use more energy during the encounter than males displaying other behaviours. Our results indicate that the mandible size in C. newmannii serves as an honest signal of fighting ability in this species. Additionally, energetic assessments in preparation for fighting, costs during a fight, and persistence of metabolic costs post-fighting may be useful for understanding the relative fitness costs of competition.

Selection for winners impacts the endocrine system in the Siamese fighting fish

In southeast Asia, males of the Siamese fighting fish, Betta splendens, have been selected across centuries for winning paired staged fights and previous work has shown that males from fighter strains are more aggressive than wild-types. This strong directional selection for winners is likely to have targeted aggression-related endocrine systems, and a comparison between fighter and wild-type strains can bring into evidence the key hormones implicated in aggression. Here, we compared the plasma levels of the androgen 11-ketotestosterone (KT) and of the corticosteroid cortisol (F) in F2 males of a fighter and a wild-type strain raised under similar laboratory conditions. We show that F was generally lower in fighter as compared with wild-type males, while no overall differences in KT levels were detected between strains. When presented with a mirror-induced aggressive challenge, post-fight levels of F increased but more significantly so in wild-type males, while KT increased in males of both strains. After the challenge, fighter males had higher levels of KT as compared with wild-type males, while the pattern for F was opposite. As compared with animals in social groups, wild-type males placed under social isolation had lower F levels, while KT decreased for fighters.Taken together, this data suggests that while wild-type males responded to aggression with an increase in circulating levels of both androgens and corticosteroids, males selected for winning fights maintained a blunt F response, increasing only KT levels. These data agree with the hypothesis that a combination of high levels of androgens and low levels of corticosteroids is associated with high aggression. Overall, these results seem to indicate that selection for winning had a stronger impact in the hypothalamus-pituitary-interrenal axis than in the hypothalamus-pituitary–gonadal axis in B. splendens.

Static allometry of a threat device that is not a weapon: wing spots in male Heterandrium fallax (Hymenoptera Agaonidae)

Males of the agaonid wasp Heterandrium fallax have wing spots that they display during aggressive encounters near the ostioles of syconia of the fig Ficus pertusa, apparently in competition for the opportunity to copulate with emerging females. In accord with predictions of the “functional allometry hypothesis” for the allometry of structures that are under sexual selection as threat devices and that do not function as weapons, larger males tended to have proportionally larger wing spots. Some smaller males lacked spots, and smaller males were less likely to be collected near female emergence sites or to show antennal damage that probably results from male fights.

Encounter with heavier females changes courtship and fighting efforts of male field crickets Gryllus bimaculatus (Orthoptera: Gryllidae)

The effects of mating experience on male mating behavior are mediated by four factors: mating cost, such as resource depletion, perception of mating opportunities, self-perception of attractiveness, and female quality. For example, encountering females might increase male expectations of prospective mating opportunities, while copulation increases self-perception of attractiveness in males. To determine the relative importance of these factors, the effect of mating on the two components of reproductive effort (courtship and fighting effort) in Gryllus bimaculatus was examined. Calling activity before and after encountering females was measured, and copulation success was recorded. Subsequently, the intensity and outcome of male–male fighting behavior was recorded. Female encounter increased calling activity irrespective of copulation, thereby indicating that the perception of mating opportunities is important factor for the males. Changes in courtship effort of males were larger and fighting success was lower when they were previously paired with relatively heavier females. These results indicate that male reproductive effort is also affected by quality of previous mating partners.