Male Competition Research Articles

Semen collection from small breed birds and some parameters related to passerine bird semen

It is much more difficult to collect semen from small breed birds than large breed birds. The biggest reason for this situation is that small breed birds are very active and their cloaca is smaller. To receive semen from passerine birds, the birds must be in the breeding season. Having active females around during this period will increase libido due to male competition. Trimming the hair around the cloaca to collect semen both prevents the risk of contamination and provides adequate viewing angles. The most commonly used method of obtaining semen is cloacal massage. Massage should be done cranially from the abdomen towards the cloaca. When the bird ejaculates, it is seen that the semen comes out of the cloaca from the seminal glomera with the pressure applied laterally on the cloaca. It collects the exiting semen with the help of a sterile hematocrit capillary tube. Sperm contaminated with feces should not be taken as it will be contaminated. In bird semen, motility examination is important in the direction of movement, speed of movement, and rate of movement of the spermatozoa. Due to this situation, it is seen that there is a relationship between motility and the morphological structure of spermatozoa in passerine birds. This study aims to give information about semen collection by a cloacal method in small breed canaries and some motility and morphological examination methods in passerine bird semen.

Divergent natural selection alters male sperm competition success in Drosophila melanogaster.

Sexually selected traits may also be subject to non‐sexual selection. If optimal trait values depend on environmental conditions, then “narrow sense” (i.e., non‐sexual) natural selection can lead to local adaptation, with fitness in a certain environment being highest among individuals selected under that environment. Such adaptation can, in turn, drive ecological speciation via sexual selection. To date, most research on the effect of narrow‐sense natural selection on sexually selected traits has focused on precopulatory measures like mating success. However, postcopulatory traits, such as sperm function, can also be under non‐sexual selection, and have the potential to contribute to population divergence between different environments. Here, we investigate the effects of narrow‐sense natural selection on male postcopulatory success in Drosophila melanogaster. We chose two extreme environments, low oxygen (10%, hypoxic) or high CO2 (5%, hypercapnic) to detect small effects. We measured the sperm defensive (P1) and offensive (P2) capabilities of selected and control males in the corresponding selection environment and under control conditions. Overall, selection under hypoxia decreased both P1 and P2, while selection under hypercapnia had no effect. Surprisingly, P1 for both selected and control males was higher under both ambient hypoxia and ambient hypercapnia, compared to control conditions, while P2 was lower under hypoxia. We found limited evidence for local adaptation: the positive environmental effect of hypoxia on P1 was greater in hypoxia‐selected males than in controls. We discuss the implications of our findings for the evolution of postcopulatory traits in response to non‐sexual and sexual selection.

Relationship between body size and sexual size dimorphism in syringophilid quill mites

A positive relationship of body size and sexual size dimorphism (males’ size relative to females), called Rensch’s rule, is often observed in comparisons within non-parasitic taxa. However, this allometric relationship has rarely been tested in comparisons across closely related parasite species. Since male sexual rivalry is often regarded as the main cause of this phenomenon, the present study tests this rule in a taxon where sexual selection is almost totally absent in males. Body size data of (non-physogastric) female and male quill mites (Acari: Syringophilidae) were gathered from the literature to investigate this relationship. The data set consisted of 113 species representing 8 genera. For the data set as a whole, increasing body size came together with decreasing relative body size of males (relative to females), a phenomenon known as converse Rensch’s rule. Repeating the same analysis for the 8 genera separately, similar patterns were found in 4 significant and 3 non-significant cases. There was a significant tendency to comply with Rensch’s rule only in one genus, the Neoaulonastus. Thus, converse Rensch’s rule is the primary trend in syringophilid quill mites that appears repeatedly and independently in several genera. This phenomenon is probably caused by their extreme inbreeding, which strongly reduces sexual competition among males in this taxon.

Influence of operational sex ratio and male age on mating competition intensity in reindeer (Rangifer tarandus)

The operational sex ratio (OSR), the ratio of sexually active males to sexually receptive females, is one of the main measures used to predict the intensity and direction of mating competition, influencing the opportunity for sexual selection. Here, we conducted the first experimental study to investigate how OSR and male age impacts the intensity of mating competition in reindeer (Rangifer tarandus), under semi-natural conditions during the rut. We manipulated OSR on two levels in two enclosures, a female biased treatment (3♂:6♀ = OSR 0.5) and a sex balanced treatment (3♂:3♀ = OSR 1), over 2 years with males from two age groups, and with females of various ages. We found some support for prevailing OSR theory, notably with female intrasexual competition occurring at lower frequencies in OSR 1 than OSR 0.5, and male intrasexual competition occurring at higher frequencies in the older male age group. Courtship behaviour was found to occur at higher frequencies in OSR 1 than OSR 0.5; however, there was no effect of male age. To successfully pass on genes to the next generation, one needs access to mates and winning a competitive bout is not always indicative of successfully accomplishing gene flow. Studies on OSR have the potential to help us understand the drivers behind sexual competition and how best to predict breeding outcomes during a rut.

Ecological Constraints on Sexual Selection in a Human-Modified Landscape

Anthropogenic activities are changing the sensory landscape, interfering with transmission and reception of sexual signals. These changes are leading to alterations in mating behaviour with consequences to fitness. In systems where mate-finding involves long-distance signalling by one sex and approach by the other sex, the spatial distribution of signallers can have implications for male and female fitness. Spatial distribution of signallers is typically determined by an interplay of multiple factors, both ecological and evolutionary, including male competition, female choice and resources, such as calling and oviposition sites. We investigated the possible influence of resource distribution (signalling sites) on the strength and direction of sexual selection acting on false-leaf katydid Onomarchus uninotatus males, signalling in a human-modified landscape in the Western Ghats, India, a biodiversity hotspot. The landscape has changed from evergreen forests to plantations owing to human settlements. We first determined the spatial distribution of calling males and of available calling sites, which are trees of the genus Artocarpus, in the landscape. Using the information on male spacing, call transmission and hearing thresholds, the perceptual spaces of male signals were computed to understand the acoustic environment of calling males and females. It was found that both calling males and females could hear calls of males from neighbouring trees with a probability of 0.76 and 0.59, respectively. Although calling males were found to be spaced apart more than predicted by chance, significant overlap was seen in their acoustic ranges. Clustering of males enables females to easily sample multiple males, facilitating mate choice, but is detrimental to males as it increases competition for females. Using simulations, we determined the optimal spatial distributions of O. uninotatus males for female choice, and for reduction of male competition, given the signalling site distribution. The observed distribution of signallers was then compared with the hypothetical optimal distributions to examine the drivers of signaller spacing. Spacing of calling males in the field was found to be not optimal for either males or females. Resource distribution was found to limit the effectiveness of sexual selection drivers in pushing male spacing toward fitness optima of males or females.

Sexual audience affects male's reproduction investment without consequences on reproductive outputs.

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.

Local adaptation and colonization are potential factors affecting sexual competitiveness and mating choice in Anopheles coluzzii populations

The mating behaviour of the malaria vector Anopheles gambiae complex is an important aspect of its reproduction biology. The success of mosquito release programmes based on genetic control of malaria crucially depends on competitive mating between both laboratory-reared and wild individuals, and populations from different localities. It is known that intrinsic and extrinsic factors can influence the mating success. This study addressed some of the knowledge gaps about factors influcencing mosquito mating success. In semi-field conditions, the study compared the mating success of three laboratory-reared and wild allopatric An. coluzzii populations originating from ecologically different locations in Burkina Faso. Overall, it was found that colonization reduced the mating competitiveness of both males and females compared to that of wild type individuals. More importly, females were more likely to mate with males of their own population of origin, be it wild or colonised, suggesting that local adaptation affected mate choice. The observations of mating behaviour of colonized and local wild populations revealed that subtle differences in behaviour lead to significant levels of population-specific mating. This is the first study to highlight the importance of local adaptation in the mating success, thereby highlighting the importance of using local strains for mass-rearing and release of An. coluzzii in vector control programmes.

Raising the Bar: Causal Evidence on Gender Differences in Risk-Taking From a Natural Experiment

We investigate the risk-taking behavior of women and men in high-stakes jumping competitions. Results indicated that female and male athletes differ in the timing and extent of their reactions to an increase in the risk of failure. Male competitors increased risk-taking in the more risky environment immediately after the changes. Female athletes, however, increased risk-taking two years after the rule change. Over time, female athletes revert to pre-reform risk-taking levels, and male athletes’ continued to make more risky decisions in the new environment. We attribute our findings to gender differences in competitiveness and risk preferences.

Roosters Algorithm: A Novel Nature-Inspired Optimization Algorithm

Some species of females, e.g., chicken, bird, fish etc., might mate with more than one males. In the mating of these polygamous creatures, there is competition between males as well as among their offspring. Thus, male reproductive success depends on both male competition and sperm rivalry. Inspired by this type of sexual life of roosters with chickens, a novel nature-inspired optimization algorithm called Roosters Algorithm (RA) is proposed. The algorithm was modelled and implemented based on the sexual behavior of roosters. 13 well-known benchmark optimization functions and 10 IEEE CEC 2018 test functions are utilized to compare the performance of RA with the performance of well-known algorithms; Standard Genetic Algorithm (SGA), Differential Evolution (DE), Particle Swarm Optimization (PSO), Cuckoo Search (CS) and Grey Wolf Optimizer (GWO). Also, non-parametric statistical tests, Friedman and Wilcoxon Signed Rank Tests, were performed to demonstrate the significance of the results. In 20 of the 23 functions that were tested, RA either offered the best results or offered similar results to other compared algorithms. Thus, in this paper, we not only present a novel nature-inspired algorithm, but also offer an alternative method to the well-known algorithms commonly used in the literature, at least as effective as them.

Privlačenje sterilnih mužjaka mediteranske voćne muhe prema plodovima masline u laboratorijskim uvjetima

Sterile insect technique (SIT) control method is integrated in many ongoing area-wide programs for Ceratitis capitata W. control management who largely depends on the sterile male competitiveness. The use of semiochemical supplements originated from host and non-host plant materials to better manage the physical conditions and handling of sterile C. capitata males in fly emergence and release facilities improve the cost-effectiveness of the SIT worldwide. Since C. capitata adults are regularly captured in groves of nonhost olive, Olea europaea L. in the Mediterranean region, the aims of this research were to asses: (1) attraction of sterile males by olive fruit of different maturity stages; (2) attraction to olive fruits surface (egzocarp) and mesocarp and (3) attraction to three different olive cultivars. The results provide clear evidence that sterile males show strong attraction to volatile compounds from the surface and mesocarp of immature and semi matured olive fruits with no significant difference between fruits treated and nontreated with artificial cuts in mesocarp. The response of sterile C. capitata males to fully matured fruits were significantly the weakest. Sexually mature sterile males were attracted to green immature olive fruits stronger than sexually immature sterile males, while both categories showed strong attraction to semi matured olive fruits without significant difference between both categories.

CHRONOLOGICAL AGE OF ALPINE SKI MEDAL WINNERS IN THE 2015-2018 OLYMPIC CYCLE

Personal motivation, as well as engagement in alpine skiing, brought the authors to inspect the differences in average chronological age of alpine skiers, and to present the results to the professional public, in order to improve planning and programming of the training process. The paper analyzed the average chronological age of medal winning professional alpine skiers in the World Cups in the 2015-2018 Olympic cycle. The following alpine disciplines were analyzed: Slalom (SL), Giant Slalom (GS), Super-G (SG), Downhill (DH) and Alpine Combination (AC). The obtained results indicate that there was a significant difference in the average chronological age between male and female competitors. The results of the present study show that there were differences in GS, SG, DH, and AC, where male skiers are on average older than female skiers. Conversely, there was no significant difference between male and female skiers in SL. The results of this study could aid coaches and experts in future years of individual management of sports careers of male and female skiers.

Influence of operational sex ratio and male age on mating competition intensity in reindeer (Rangifer tarandus)

The operational sex ratio (OSR), the ratio of sexually active males to sexually receptive females, is one of the main measures used to predict the intensity and direction of mating competition, influencing the opportunity for sexual selection. Here, we conducted the first experimental study to investigate how OSR and male age impacts the intensity of mating competition in reindeer (Rangifer tarandus), under semi-natural conditions during the rut. We manipulated OSR on two levels in two enclosures, a female biased treatment (3♂:6♀ = OSR 0.5) and a sex balanced treatment (3♂:3♀ = OSR 1), over 2 years with males from two age groups, and with females of various ages. We found some support for prevailing OSR theory, notably with female intrasexual competition occurring at lower frequencies in OSR 1 than OSR 0.5, and male intrasexual competition occurring at higher frequencies in the older male age group. Courtship behaviour was found to occur at higher frequencies in OSR 1 than OSR 0.5; however, there was no effect of male age. To successfully pass on genes to the next generation, one needs access to mates and winning a competitive bout is not always indicative of successfully accomplishing gene flow. Studies on OSR have the potential to help us understand the drivers behind sexual competition and how best to predict breeding outcomes during a rut.

The Development of Womens Status in the Olympic Games

The These days, with the progress of womens status, female athletes have played a more positive role in modern women sports, especially in women's participation in the Olympic Games. It is generally argued that the degree of womens participation in Olympics Games denotes a sign of gender equality progress. Women do not only take their participation number and events in the Olympic Games as a measure of the gender progress in the field of sports but also tend to have a louder voice in decision-making. This article examines how the rising of womens status gradually result in broader participation in Olympic Games by measuring the number of events and the distribution of medals among different countries for male and female competitions and the higher degree of womens participation in IOC (International Olympic Committee). In fact, with the awakening awareness of gender equality, this research method can also employ in a wide range of fields in the future.

Sex differences in behavioural and anatomical estimates of visual acuity in the green swordtail, Xiphophorus helleri.

ABSTRACTAmong fishes in the family Poeciliidae, signals such as colour patterns, ornaments and courtship displays play important roles in mate choice and male–male competition. Despite this, visual capabilities in poeciliids are understudied, in particular, visual acuity, the ability to resolve detail. We used three methods to quantify visual acuity in male and female green swordtails (Xiphophorus helleri), a species in which body size and the length of the male's extended caudal fin (‘sword’) serve as assessment signals during mate choice and agonistic encounters. Topographic distribution of retinal ganglion cells (RGCs) was similar in all individuals and was characterized by areas of high cell densities located centro-temporally and nasally, as well as a weak horizontal streak. Based on the peak density of RGCs in the centro-temporal area, anatomical acuity was estimated to be approximately 3 cycles per degree (cpd) in both sexes. However, a behavioural optomotor assay found significantly lower mean acuity in males (0.8 cpd) than females (3.0 cpd), which was not explained by differences in eye size between males and females. An additional behavioural assay, in which we trained individuals to discriminate striped gratings from grey stimuli of the same mean luminance, also showed lower acuity in males (1–2 cpd) than females (2–3 cpd). Thus, although retinal anatomy predicts identical acuity in males and females, two behavioural assays found higher acuity in females than males, a sexual dimorphism that is rare outside of invertebrates. Overall, our results have implications for understanding how poeciliids perceive visual signals during mate choice and agonistic encounters.

When Taekwondo Referees See Red, but It Is an Electronic System That Gives the Points.

Previous studies in taekwondo have considered the use of the manual scoring system or the electronic system with only the use of the electronic body protector. The objective of this study was to analyze the relationship between the color protectors and success in 1,327 taekwondo matches from six World Grand Prix Series of two 4-year Olympic periods when electronic body and head protectors are used. In the total sample, the results did not show a relationship between the match outcome and the color of the protectors (p = 0.97, C = 0.001). For the individual six editions, the results showed a positive and strong relationship between wearing blue protectors and winning matches and one between wearing red protectors and winning matches (p = 0.001, C = 0.19; p = 0.001; C = 0.19). Regarding the weight categories, 8 and 5 of 48 showed higher percentages of blue and red winners, respectively. Regarding sex, male competitors showed a positive relationship between blue color and winning the match in 6 of 24 weight categories, and wearing red and winning the match was shown in 2 of 24 weight categories. Female competitors showed a positive relationship between blue color and winning the match in 2 of 24 weight categories, and wearing red and winning the match was shown in 3 of 24 weight categories. When it comes to the influence of being a seeded athlete, the results did show a significant confounding effect on the color of the protectors worn by the winner of the match in 2 of 13 weight categories in which a color effect was observed (p = 0.02, C = 0.28; p = 0.02, C = 0.28). In conclusion, wearing red does not provide a higher chance of winning the match. It seems that seeing red has a stronger effect than wearing red, especially in male contenders. Moreover, being a seeded athlete does not explain the result of the match. It seems that the introduction of the electronic helmet protector, in addition to the electronic body protector, made the scoring system more objective, decreasing the advantage of wearing red in winning matches.

Is There an Optimal Interval for Medal Winning Performance in World Para Powerlifting Competition?

The aim of the study was to determine the optimal interval between competitions for success in World Para Powerlifting events. A total of 1034 female (age = 34.4 ± 9.1 yrs) and 1,697 male (age = 33.7 ± 8.3 yrs) competition results from international Paralympic powerlifting events conducted between 2014 and 2020 were analyzed. Odds ratios for preparations intervals between competitive events were evaluated considering the dependent variable, earning a medal, and the independent variable, level of competition. There was an increased probability of winning a medal when the preparation interval was in the range of 22-30 wks ( P = 0.004), as compared with less than 11 wks, while competing at World Cup events, whereas for World Championships and Paralympic Games, there was an increased probability of winning a medal when the interval range was 23-31 wks ( P = 0.002) and 40 wks or more ( P = 0.011) compared with less than 23 wks. However, there were no significant differences between preparation intervals for Regional Games/Championships. The Para Powerlifting athletes participating in the World Cup events, World Championships, and Paralympic Games share an optimal interval for success of approximately 21-31 wks and results from the World Championships and Paralympic Games, which can also be optimized with an interval of 40 wks or more.

Socially Complex Breeding Interactions in Humpback Whales Are Mediated Using a Complex Acoustic Repertoire

Intraspecific conflict can be costly; therefore, many species engage in ritualized contests composed of several stages. Each stage is typically characterized by different levels of aggression, arousal, and physical conflict. During these different levels of “intensity,” animals benefit from communicating potential information related to features such as resource holding potential, relative fighting ability, level of aggression, intent (i.e., fight or flight), and whether or not the competitor currently holds the resource (e.g., a receptive female). This information may be conveyed using both visual displays and a complex acoustic repertoire containing fixed (e.g., age, sex, and body size) and flexible information (e.g., motivation or arousal). Calls that contain fixed information are generally considered “discrete” or stereotyped, while calls that convey flexible information are more “graded,” existing along an acoustic continuum. The use of displays and calls, and the potential information they convey, is likely dependent on factors like intensity level. The breeding system of humpback whales (Megaptera novaeangliae) involves intense male competition for access to a relatively limited number of breeding females (the resource). Here, we investigated the behavior and acoustic repertoire of competitive groups of humpback whales to determine if an increase in intensity level of the group was correlated with an increase in the complexity of the vocal repertoire. We categorized the behavior of humpback whales in competitive groups into three mutually exclusive stages from low to high intensity. While discrete calls were infrequent compared to graded calls overall, their use was highest in “low” and “moderate” intensity groups, which may indicate that this stage of contest is important for assessing the relative resource holding potential of competitors. In contrast, visual displays, call rates, and the use of graded call types, were highest during “high intensity” competitive groups. This suggests that flexible information may be more important in “high intensity” levels as males continue to assess the motivation and intent of competitors while actively engaged in costly conflict. We have shown that the relatively complex social call repertoire and visual displays of humpback whales in competitive groups likely functions to mediate frequently changing within-group relationships.

Sex role similarity and sexual selection predict male and female song elaboration and dimorphism in fairy-wrens.

Historically, bird song complexity was thought to evolve primarily through sexual selection on males; yet, in many species, both sexes sing and selection pressure on both sexes may be broader. Previous research suggests competition for mates and resources during short, synchronous breeding seasons leads to more elaborate male songs at high, temperate latitudes. Furthermore, we expect male–female song structure and elaboration to be more similar at lower, tropical latitudes, where longer breeding seasons and year‐round territoriality yield similar social selection pressures in both sexes. However, studies seldom take both types of selective pressures and sexes into account. We examined song in both sexes in 15 populations of nine‐fairy‐wren species (Maluridae), a Southern Hemisphere clade with female song. We compared song elaboration (in both sexes) and sexual song dimorphism to latitude and life‐history variables tied to sexual and social selection pressures and sex roles. Our results suggest that song elaboration evolved in part due to sexual competition in males: male songs were longer than female songs in populations with low male survival and less male provisioning. Also, female songs evolved independently of male songs: female songs were slower paced than male songs, although only in less synchronously breeding populations. We also found male and female songs were more similar when parental care was more equal and when male survival was high, which provides strong evidence that sex role similarity correlates with male–female song similarity. Contrary to Northern Hemisphere latitudinal patterns, male and female songs were more similar at higher, temperate latitudes. These results suggest that selection on song can be sex specific, with male song elaboration favored in contexts with stronger sexual selection. At the same time, selection pressures associated with sex role similarity appear to favor sex role similarity in song structure.

Harmonic convergence coordinates swarm mating by enhancing mate detection in the malaria mosquito Anopheles gambiae

The mosquito Anopheles gambiae is a major African malaria vector, transmitting parasites responsible for significant mortality and disease burden. Although flight acoustics are essential to mosquito mating and present promising alternatives to insecticide-based vector control strategies, there is limited data on mosquito flight tones during swarming. Here, for the first time, we present detailed analyses of free-flying male and female An. gambiae flight tones and their harmonization (harmonic convergence) over a complete swarm sequence. Audio analysis of single-sex swarms showed synchronized elevation of male and female flight tones during swarming. Analysis of mixed-sex swarms revealed additional 50 Hz increases in male and female flight tones due to mating activity. Furthermore, harmonic differences between male and female swarm tones in mixed-sex swarms and in single-sex male swarms with artificial female swarm audio playback indicate that frequency differences of approximately 50 Hz or less at the male second and female third harmonics (M2:F3) are maintained both before and during mating interactions. This harmonization likely coordinates male scramble competition by maintaining ideal acoustic recognition within mating pairs while acoustically masking phonotactic responses of nearby swarming males to mating females. These findings advance our knowledge of mosquito swarm acoustics and provide vital information for reproductive control strategies.

Opportunity and inequality in the emerging esports labor market

Esports is often described as a growing industry ripe with financial opportunities for young professional, competitive gamers. However, these claims rarely consider how income is distributed amongst players. This study uses prize earnings data from 2005 to 2019 to examine labor market inequality and related social inequalities and social stratifications. Lorenz curves and Gini coefficients show that inequality has increased in the labor market overall and the labor markets for the five top games based on total prizes awarded ( Dota 2, Counter-Strike: Global Offensive, Fortnite, League of Legends, StarCraft II). Competitors can expect to earn more today than in 2005, but median incomes have shown sporadic and inconsistent growth compared with top incomes. Moreover, most competitors earn less than the US poverty threshold. Comparing the earnings of the top female players to the whole labor market shows that gender inequalities exist in median incomes and the likelihood of earning more than the poverty threshold. The esports labor market is an engine of inequality that provides opportunities for a few (primarily male) competitors while building a growing class of lowly paid players who support the interests of game designers and event organizers.