Sperm competition games when males invest in paternal care.

Science.gov (United States)

Requena, Gustavo S; Alonzo, Suzanne H

2017-08-16

Sperm competition games investigate how males partition limited resources between pre- and post-copulatory competition. Although extensive research has explored how various aspects of mating systems affect this allocation, male allocation between mating, fertilization and parental effort has not previously been considered. Yet, paternal care can be energetically expensive and males are generally predicted to adjust their parental effort in response to expected paternity. Here, we incorporate parental effort into sperm competition games, particularly exploring how the relationship between paternal care and offspring survival affects sperm competition and the relationship between paternity and paternal care. Our results support existing expectations that (i) fertilization effort should increase with female promiscuity and (ii) paternal care should increase with expected paternity. However, our analyses also reveal that the cost of male care can drive the strength of these patterns. When paternal behaviour is energetically costly, increased allocation to parental effort constrains allocation to fertilization effort. As paternal care becomes less costly, the association between paternity and paternal care weakens and may even be absent. By explicitly considering variation in sperm competition and the cost of male care, our model provides an integrative framework for predicting the interaction between paternal care and patterns of paternity. © 2017 The Author(s).

The agricultural contaminant 17β-trenbolone disrupts male-male competition in the guppy (Poecilia reticulata).

Science.gov (United States)

Tomkins, Patrick; Saaristo, Minna; Bertram, Michael G; Tomkins, Raymond B; Allinson, Mayumi; Wong, Bob B M

2017-11-01

Despite a growing literature highlighting the potential impact of human-induced environmental change on mechanisms of sexual selection, relatively little is known about the effects of chemical pollutants on male-male competition. One class of environmental pollutant likely to impact male competitive interactions is the endocrine-disrupting chemicals (EDCs), a large and heterogeneous group of chemical contaminants with the potential to influence morphology, physiology and behaviour at minute concentrations. One EDC of increasing concern is the synthetic, androgenic steroid 17β-trenbolone, which is used globally to promote growth in beef cattle. Although 17β-trenbolone has been found to cause severe morphological and behavioural abnormalities in fish, its potential impact on male-male competition has yet to be investigated. To address this, we exposed wild male guppies (Poecilia reticulata) to an environmentally realistic concentration of 17β-trenbolone (average measured concentration: 8 ng/L) for 21 days using a flow-through system. We found that, in the presence of a competitor, 17β-trenbolone-exposed males carried out more frequent aggressive behaviours towards rival males than did unexposed males, as well as performing less courting behaviour and more sneak (i.e., coercive) mating attempts towards females. Considering that, by influencing mating outcomes, male-male competition has important consequences for population dynamics and broader evolutionary processes, this study highlights the need for greater understanding of the potential impact of EDCs on the mechanisms of sexual selection. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Sneaker "jack" males outcompete dominant "hooknose" males under sperm competition in Chinook salmon (Oncorhynchus tshawytscha).

Science.gov (United States)

Young, Brent; Conti, David V; Dean, Matthew D

2013-12-01

In a variety of taxa, males deploy alternative reproductive tactics to secure fertilizations. In many species, small "sneaker" males attempt to steal fertilizations while avoiding encounters with larger, more aggressive, dominant males. Sneaker males usually face a number of disadvantages, including reduced access to females and the higher likelihood that upon ejaculation, their sperm face competition from other males. Nevertheless, sneaker males represent an evolutionarily stable strategy under a wide range of conditions. Game theory suggests that sneaker males compensate for these disadvantages by investing disproportionately in spermatogenesis, by producing more sperm per unit body mass (the "fair raffle") and/or by producing higher quality sperm (the "loaded raffle"). Here, we test these models by competing sperm from sneaker "jack" males against sperm from dominant "hooknose" males in Chinook salmon. Using two complementary approaches, we reject the fair raffle in favor of the loaded raffle and estimate that jack males were ∼1.35 times as likely as hooknose males to fertilize eggs under controlled competitive conditions. Interestingly, the direction and magnitude of this skew in paternity shifted according to individual female egg donors, suggesting cryptic female choice could moderate the outcomes of sperm competition in this externally fertilizing species.

Vulnerable discipline: experiences of male competitive bodybuilders.

Science.gov (United States)

Bjørnestad, Jone; Kandal, Øyvind; Anderssen, Norman

2014-09-01

The aim was to understand experiences of male competitive bodybuilders from a non-pathologizing perspective. Six male Norwegian competitive bodybuilders were interviewed. The interviews were analysed using a meaning condensation procedure resulting in five themes: being proud of capacity for discipline, seeing a perfectionist attitude as a necessary evil, experiencing recognition within the bodybuilding community, being stigmatized outside the bodybuilding community and going on stage to display a capacity for willpower and discipline. We suggest that bodybuilders may be stigmatized for breaking social norms: by their distinctive appearance, by the way they handle suspected drug use and by challenging gender norms. © The Author(s) 2013.

Seminal fluid enhances competitiveness of territorial males' sperm in a fish with alternative male reproductive tactics.

Science.gov (United States)

Poli, Federica; Locatello, Lisa; Rasotto, Maria B

2018-05-29

The most common adaptation to sperm competition in males is represented by an increase in the sperm number and/or quality released at mating, to raise their probability of egg fertilization. However, rapidly mounting evidence highlights that seminal fluid may directly influence the competitive fertilization success of a male by affecting either own and/or rival sperm performances. In the black goby, Gobius niger , an external fertilizer with guard-sneaker mating tactics and high sperm competition level, sneaker males' ejaculates contain less seminal fluid and more sperm, that are also of better quality, than those of territorial males. However, territorial males, gain a higher paternity success inside natural nests. Here, we ask whether the seminal fluid can contribute to territorial males' reproductive success by enhancing their sperm performances and/or by decreasing those of sneaker males. Using sperm and seminal fluid manipulation and in vitro fertilization tests, we found that own seminal fluid influences the velocity and fertilization ability of sperm only in territorial males, making them as faster as those of sneakers and with similar fertilization rate. Moreover, both sneaker and territorial males' sperm remain unaffected by the seminal fluid of rival males. Thus, black goby males respond to the different level of sperm competition faced by differently allocating in sperm and non-sperm components of the ejaculate, with sneakers primarily investing in sperm of intrinsic high quality and territorial males relying on the effect of seminal fluid to increase the lower intrinsic quality of their sperm. © 2018. Published by The Company of Biologists Ltd.

Male crickets adjust ejaculate quality with both risk and intensity of sperm competition.

Science.gov (United States)

Simmons, Leigh W; Denholm, Amy; Jackson, Chantelle; Levy, Esther; Madon, Ewa

2007-10-22

Sperm competition theory predicts that males should increase their expenditure on the ejaculate with increasing risk of sperm competition, but decrease their expenditure with increasing intensity. There is accumulating evidence for sperm competition theory, based on examinations of testes size and/or the numbers of sperm ejaculated. However, recent studies suggest that ejaculate quality can also be subject to selection by sperm competition. We used experimental manipulations of the risk and intensity of sperm competition in the cricket, Teleogryllus oceanicus. We found that males produced ejaculates with a greater percentage of live sperm when they had encountered a rival male prior to mating. However, when mating with a female that presented a high intensity of sperm competition, males did not respond to risk, but produced ejaculates with a reduced percentage of live sperm. Our data suggest that males exhibit a fine-tuned hierarchy of responses to these cues of sperm competition.

Sexual size dimorphism, canine dimorphism, and male-male competition in primates: where do humans fit in?

Science.gov (United States)

Plavcan, J Michael

2012-03-01

Sexual size dimorphism is generally associated with sexual selection via agonistic male competition in nonhuman primates. These primate models play an important role in understanding the origins and evolution of human behavior. Human size dimorphism is often hypothesized to be associated with high rates of male violence and polygyny. This raises the question of whether human dimorphism and patterns of male violence are inherited from a common ancestor with chimpanzees or are uniquely derived. Here I review patterns of, and causal models for, dimorphism in humans and other primates. While dimorphism in primates is associated with agonistic male mate competition, a variety of factors can affect male and female size, and thereby dimorphism. The causes of human sexual size dimorphism are uncertain, and could involve several non-mutually-exclusive mechanisms, such as mate competition, resource competition, intergroup violence, and female choice. A phylogenetic reconstruction of the evolution of dimorphism, including fossil hominins, indicates that the modern human condition is derived. This suggests that at least some behavioral similarities with Pan associated with dimorphism may have arisen independently, and not directly from a common ancestor.

Balance Devices Train Golfers for a Consistent Swing

Science.gov (United States)

2015-01-01

As part of the effort to understand the effects of spaceflight on astronauts, NASA funded research that resulted in a commercial product to treat balance disorders. West Palm Beach, Florida-based Sports Therapy Inc. worked with the inventor to modify the technology, creating the Dynamic Balance System (DBS) for sports applications. DBS is now used by Professional Golfers' Association-owned facilities and golf academies to help players achieve an effective, balanced swing.

How does male–male competition generate negative frequency-dependent selection and disruptive selection during speciation?

Science.gov (United States)

Border, Shana E

2018-01-01

Abstract Natural selection has been shown to drive population differentiation and speciation. The role of sexual selection in this process is controversial; however, most of the work has centered on mate choice while the role of male–male competition in speciation is relatively understudied. Here, we outline how male–male competition can be a source of diversifying selection on male competitive phenotypes, and how this can contribute to the evolution of reproductive isolation. We highlight how negative frequency-dependent selection (advantage of rare phenotype arising from stronger male–male competition between similar male phenotypes compared with dissimilar male phenotypes) and disruptive selection (advantage of extreme phenotypes) drives the evolution of diversity in competitive traits such as weapon size, nuptial coloration, or aggressiveness. We underscore that male–male competition interacts with other life-history functions and that variable male competitive phenotypes may represent alternative adaptive options. In addition to competition for mates, aggressive interference competition for ecological resources can exert selection on competitor signals. We call for a better integration of male–male competition with ecological interference competition since both can influence the process of speciation via comparable but distinct mechanisms. Altogether, we present a more comprehensive framework for studying the role of male–male competition in speciation, and emphasize the need for better integration of insights gained from other fields studying the evolutionary, behavioral, and physiological consequences of agonistic interactions. PMID:29492042

Sneaker “jack” males outcompete dominant “hooknose” males under sperm competition in Chinook salmon (Oncorhynchus tshawytscha)

Science.gov (United States)

Young, Brent; Conti, David V; Dean, Matthew D

2013-01-01

In a variety of taxa, males deploy alternative reproductive tactics to secure fertilizations. In many species, small “sneaker” males attempt to steal fertilizations while avoiding encounters with larger, more aggressive, dominant males. Sneaker males usually face a number of disadvantages, including reduced access to females and the higher likelihood that upon ejaculation, their sperm face competition from other males. Nevertheless, sneaker males represent an evolutionarily stable strategy under a wide range of conditions. Game theory suggests that sneaker males compensate for these disadvantages by investing disproportionately in spermatogenesis, by producing more sperm per unit body mass (the “fair raffle”) and/or by producing higher quality sperm (the “loaded raffle”). Here, we test these models by competing sperm from sneaker “jack” males against sperm from dominant “hooknose” males in Chinook salmon. Using two complementary approaches, we reject the fair raffle in favor of the loaded raffle and estimate that jack males were ∼1.35 times as likely as hooknose males to fertilize eggs under controlled competitive conditions. Interestingly, the direction and magnitude of this skew in paternity shifted according to individual female egg donors, suggesting cryptic female choice could moderate the outcomes of sperm competition in this externally fertilizing species. PMID:24455130

Competitive state anxiety and self-confidence: intensity and direction as relative predictors of performance on a golf putting task.

Science.gov (United States)

Chamberlain, Sean T; Hale, Bruce D

2007-06-01

This study considered relationships between the intensity and directional aspects of competitive state anxiety as measured by the modified Competitive Sport Anxiety Inventory-2(D) (Jones & Swain, 1992) in a sample of 12 experienced male golfers. Anxiety and performance scores from identical putting tasks performed under three different anxiety-manipulated competitive conditions were used to assess both the predictions of Multidimensional Anxiety Theory (MAT; Martens et al., 1990) and the relative value of intensity and direction in explaining performance variance. A within-subjects regression analysis of the intra-individual data showed partial support for the three MAT hypotheses. Cognitive anxiety intensity demonstrated a negative linear relationship with performance, somatic anxiety intensity showed a curvilinear relationship with performance, and self-confidence intensity revealed a positive linear relation. Cognitive directional anxiety illustrated a positive linear relationship with putting performance. Multiple regression analyses indicated that direction (42% of variance) was a better predictor of performance than intensity (22%).

Does Competition Really Bring Out the Worst? Testosterone, Social Distance and Inter-Male Competition Shape Parochial Altruism in Human Males

Science.gov (United States)

Diekhof, Esther Kristina; Wittmer, Susanne; Reimers, Luise

2014-01-01

Parochial altruism, defined as increased ingroup favoritism and heightened outgroup hostility, is a widespread feature of human societies that affects altruistic cooperation and punishment behavior, particularly in intergroup conflicts. Humans tend to protect fellow group members and fight against outsiders, even at substantial costs for themselves. Testosterone modulates responses to competition and social threat, but its exact role in the context of parochial altruism remains controversial. Here, we investigated how testosterone influences altruistic punishment tendencies in the presence of an intergroup competition. Fifty male soccer fans played an ultimatum game (UG), in which they faced anonymous proposers that could either be a fan of the same soccer team (ingroup) or were fans of other teams (outgroups) that differed in the degree of social distance and enmity to the ingroup. The UG was played in two contexts with varying degrees of intergroup rivalry. Our data show that unfair offers were rejected more frequently than fair proposals and the frequency of altruistic punishment increased with increasing social distance to the outgroups. Adding an intergroup competition led to a further escalation of outgroup hostility and reduced punishment of unfair ingroup members. High testosterone levels were associated with a relatively increased ingroup favoritism and also a change towards enhanced outgroup hostility in the intergroup competition. High testosterone concentrations further predicted increased proposer generosity in interactions with the ingroup. Altogether, a significant relation between testosterone and parochial altruism could be demonstrated, but only in the presence of an intergroup competition. In human males, testosterone may promote group coherence in the face of external threat, even against the urge to selfishly maximize personal reward. In that way, our observation refutes the view that testosterone generally promotes antisocial behaviors and

Performance and Kinematic Differences in Putting Between Healthy and Disabled Elite Golfers

Directory of Open Access Journals (Sweden)

Gryc Tomáš

2017-12-01

Full Text Available Golfers with disability are limited in the execution of the full golf swing, but their performance in putting may be comparable because this stroke does not demand significant strength, balance and range of motion. Therefore, the aim of this study was to compare putting performance, kinetic and kinematic consistency between golfers with different disabilities and healthy athletes. The participants consisted of three disabled athletes (perinatal cerebral palsy, multiple sclerosis, below knee lower limb amputee and three healthy golfers (age 34 ± 4.5 years, body height 178 ± 3.3 cm, body mass 83 ± 6.2 kg. The golfers’ movements were recorded by active 3D markers for kinematic analyses; the subjects performed 10 trials of a 6 m putting task while standing on separate force platforms placed under each lower limb. Putting performance was measured by the distance of the final ball position to the centre of the hole. ANOVA analyses did not show any differences in clubhead speed and total ball distance from the hole. The consistency of those two parameters expressed by the coefficient of variation (CV was CV = 0.5% or better in both groups for clubhead speed and ranged from CV = 0.40 to 0.61% in healthy and CV = 0.21 to 0.55% in disabled athletes for total error distance. The main effect ANOVA showed differences in weight shift, hip and shoulder kinematics (p < 0.05 between healthy players and all players with disability. All disabled athletes shifted their weight toward the healthy side (towards the healthy lower limb and alternated the end of the swing. The player with below knee amputation had the lowest range of motion in the shoulder joint during the putting stroke. The players with perinatal cerebral palsy and multiple sclerosis had the largest range of motion in the hips. Putting performance of disabled golfers was similar to healthy athletes. During training of disabled players, coaches should pay attention to the specificity of a

KINEMATIC ANALYSES OF THE GOLF SWING HUB PATH AND ITS ROLE IN GOLFER/CLUB KINETIC TRANSFERS

Directory of Open Access Journals (Sweden)

Steven M. Nesbit

2009-06-01

Full Text Available This study analyzed the fundamental geometric and kinematic characteristics of the swing hub path of the golf shot for four diverse subjects. In addition, the role of the hub path geometry in transferring the kinetic quantities from the golfer to the club were investigated. The hub path was found to have a complex geometry with significantly changing radii, and a constantly moving center-of-curvature during the downswing for all subjects. While the size and shape of the hub path differed considerably among the subjects, a three phase radius-based pattern was revealed that aligned with distinct stages of the downswing. Artificially controlling and optimizing the hub path of the better golfer in the group indicated that a non-circular hub path was superior to a constant radius path in minimizing the kinetic loading while generating the highest possible club head velocity. The shape and purpose of the hub path geometry appears to result from a complex combination of achieving equilibrium between the golfer and the club, and a purposeful configuring of the path to control the outward movement of the club while minimizing the kinetic loading on the golfer yet transferring the maximum kinetic quantities to the club. Describing the downswing relative to the hub path phasing is presented and was found to be informative since the phases align with significant swing, kinetic and kinematic markers. These findings challenge golf swing modeling methodologies which fix the center-of-curvature of the hub path thus constraining it to constant radius motion

Inbreeding depresses sperm competitiveness, but not fertilization or mating success in male Tribolium castaneum

Science.gov (United States)

Michalczyk, Łukasz; Martin, Oliver Y.; Millard, Anna L.; Emerson, Brent C.; Gage, Matthew J. G.

2010-01-01

As populations decline to levels where reproduction among close genetic relatives becomes more probable, subsequent increases in homozygous recessive deleterious expression and/or loss of heterozygote advantage can lead to inbreeding depression. Here, we measure how inbreeding across replicate lines of the flour beetle Tribolium castaneum impacts on male reproductive fitness in the absence or presence of male–male competition. Effects on male evolution from mating pattern were removed by enforcing monogamous mating throughout. After inbreeding across eight generations, we found that male fertility in the absence of competition was unaffected. However, we found significant inbreeding depression of sperm competitiveness: non-inbred males won 57 per cent of fertilizations in competition, while inbred equivalents only sired 42 per cent. We also found that the P2 ‘offence’ role in sperm competition was significantly more depressed under inbreeding than sperm ‘defence’ (P1). Mating behaviour did not explain these differences, and there was no difference in the viability of offspring sired by inbred or non-inbred males. Sperm length variation was significantly greater in the ejaculates of inbred males. Our results show that male ability to achieve normal fertilization success was not depressed under strong inbreeding, but that inbreeding depression in these traits occurred when conditions of sperm competition were generated. PMID:20554548

A change in competitive context reverses sexual selection on male size.

Science.gov (United States)

Kasumovic, M M; Andrade, M C B

2009-02-01

In studies of sexual selection, larger size is often argued to increase male fitness, and relatively smaller males are explained by genetic and/or environmental variation. We demonstrate that a size-development life-history trade-off could underlie the maintenance of a broad, unimodal distribution of size in male redback spiders (Latrodectus hasselti). Larger males are superior in direct competition, but redback males mature rapidly at small size in the presence of females. In field enclosures, we simulated two competitive contexts favouring development of divergent male sizes. Relatively smaller males lost when competing directly, but had 10 times higher fitness than relatively larger males when given the temporal advantage of rapid development. Linear selection gradients confirmed the reversal of selection on size, showing that it is critical to consider life-history decisions underlying the development of traits related to fitness.

Is Self-Sacrificial Competitive Altruism Primarily a Male Activity?

Directory of Open Access Journals (Sweden)

Francis T. McAndrew

2012-01-01

Full Text Available This study explored the basis of self-sacrificial prosocial behavior in small groups. Seventy-eight undergraduates (39M, 39F filled out a thirty-item personality scale and then participated in a “group problem-solving study” in which the monetary success of a three-person group depended upon one of its members volunteering to endure pain (a cold stressor test and inconvenience (being soaked in a dunk tank. There were 13 groups consisting of two females and one male, and 13 groups consisting of two males and one female. Across groups, the behavior of the altruist was judged to be more costly, challenging, and important and he/she was liked better, rewarded with more money, and preferred as a future experimental partner. Groups containing two males showed more evidence of competition to become altruists than groups containing two females, and personality traits were more effective predictors of altruistic behavior in males than in females. We conclude that competition between males and “showing off” are key factors in triggering self-sacrificial altruistic behavior.

Mating competitiveness of irradiated males and females of the indian meal moth (Lepidoptera: Pyralidae)

International Nuclear Information System (INIS)

Brower, J.H.

1978-01-01

One-day-old adults of the Indian meal moth, Plodia interpunctella (Huebner), were irradiated (I) with either 35 krad (a partially sterilizing dose) or 50 krad (a sterilizing dose) and combined with untreated (U) adults at numbers of 1, 5, 10, 15, or 25 treated males or females per pair of untreated adults. At 25 males per pair, egg hatch was reduced to 4.8 and 22.2% at 35 and 50 krad, respectively. The calculated degree of competitiveness showed that both males and females were more competitive after treatment with 35 krad than after treatment with 50 krad and that treated females were more competitive (based on percentage egg hatch) at both doses than corresponding males. Irradiated females were fully competitive at most release ratios, but I males were not fully competitive even at the higher release ratios, although the decreases were not large enough to seriously affect their use for field control. (author)

Kinematic relationship between rotation of lumbar spine and hip joints during golf swing in professional golfers.

Science.gov (United States)

Mun, Frederick; Suh, Seung Woo; Park, Hyun-Joon; Choi, Ahnryul

2015-05-14

Understanding the kinematics of the lumbar spine and hip joints during a golf swing is a basic step for identifying swing-specific factors associated with low back pain. The objective of this study was to examine the kinematic relationship between rotational movement of the lumbar spine and hip joints during a golf swing. Fifteen professional golfers participated in this study with employment of six infrared cameras to record their golf swings. Anatomical reference system of the upper torso, pelvis and thigh segments, and the location of each hip and knee joint were defined by the protocols of the kinematic model of previous studies. Lumbar spine and hip joint rotational angle was calculated utilizing the Euler angle method. Cross-correlation and angle-angle plot was used to examine the degree of kinematic relationship between joints. A fairly strong coupling relationship was shown between the lumbar spine and hip rotational movements with an average correlation of 0.81. Leading hip contribution to overall rotation was markedly high in the early stage of the downswing, while the lumbar spine contributed greater towards the end of the downswing; however, the relative contributions of the trailing hip and lumbar spine were nearly equal during the entire downswing. Most of the professional golfers participated in this study used a similar coordination strategy when moving their hips and lumbar spine during golf swings. The rotation of hips was observed to be more efficient in producing the overall rotation during the downswing when compared to the backswing. These results provide quantitative information to better understand the lumbar spine and hip joint kinematic characteristics of professional golfers. This study will have great potential to be used as a normal control data for the comparison with kinematic information among golfers with low back pain and for further investigation of golf swing-specific factors associated with injury.

Rival male relatedness does not affect ejaculate allocation as predicted by sperm competition theory.

Directory of Open Access Journals (Sweden)

Melissa L Thomas

Full Text Available When females are sexually promiscuous, the intensity of sperm competition for males depends on how many partners females mate with. To maximize fitness, males should adjust their copulatory investment in relation to this intensity. However, fitness costs associated with sperm competition may not only depend on how many males a female has mated with, but also how related rival males are. According to theoretical predictions, males should adjust their copulatory investment in response to the relatedness of their male rival, and transfer more sperm to females that have first mated with a non-sibling male than females that have mated to a related male. Here, for the first time, we empirically test this theory using the Australian field cricket Teleogryllus oceanicus. We expose male crickets to sperm competition from either a full sibling or non-sibling male, by using both the presence of a rival male and the rival male's actual competing ejaculate as cues. Contrary to predictions, we find that males do not adjust ejaculates in response to the relatedness of their male rival. Instead, males with both full-sibling and non-sibling rivals allocate sperm of similar quality to females. This lack of kin biased behaviour is independent of any potentially confounding effect of strong competition between close relatives; kin biased behaviour was absent irrespective of whether males were raised in full sibling or mixed relatedness groups.

Sneaker “jack” males outcompete dominant “hooknose” males under sperm competition in Chinook salmon (Oncorhynchus tshawytscha)

OpenAIRE

Young, Brent; Conti, David V; Dean, Matthew D

2013-01-01

In a variety of taxa, males deploy alternative reproductive tactics to secure fertilizations. In many species, small “sneaker” males attempt to steal fertilizations while avoiding encounters with larger, more aggressive, dominant males. Sneaker males usually face a number of disadvantages, including reduced access to females and the higher likelihood that upon ejaculation, their sperm face competition from other males. Nevertheless, sneaker males represent an evolutionarily stable strategy un...

Life-history differences favor evolution of male dimorphism in competitive games.

Science.gov (United States)

Smallegange, Isabel M; Johansson, Jacob

2014-02-01

Many species exhibit two discrete male morphs: fighters and sneakers. Fighters are large and possess weapons but may mature slowly. Sneakers are small and have no weapons but can sneak matings and may mature quickly to start mating earlier in life than fighters. However, how differences in competitive ability and life history interact to determine male morph coexistence has not yet been investigated within a single framework. Here we integrate demography and game theory into a two-sex population model to study the evolution of strategies that result in the coexistence of fighters and sneakers. We incorporate differences in maturation time between the morphs and use a mating-probability matrix analogous to the classic hawk-dove game. Using adaptive dynamics, we show that male dimorphism evolves more easily in our model than in classic game theory approaches. Our results also revealed an interaction between life-history differences and sneaker competitiveness, which shows that demography and competitive games should be treated as interlinked mechanisms to understand the evolution of male dimorphism. Applying our approach to empirical data on bulb mites (Rhizoglyphus robini), coho salmon (Oncorhynchus kisutch), and bullhorned dung beetles (Onthophagus taurus) indicates that observed occurrences of male dimorphism are in general agreement with model predictions.

The form of sexual selection arising from male-male competition depends on the presence of females in the social environment.

Science.gov (United States)

Procter, D S; Moore, A J; Miller, C W

2012-05-01

Sexual selection arises from social interactions, and if social environments vary so too should sexual selection. For example, male-male competition often occurs either in the presence or in the absence of females, and such changes in the social environment could affect the form and strength of sexual selection. Here we examine how the presence of a female influences selection arising from male-male competition in a leaf-footed cactus bug, Narnia femorata, which has a resource defence mating system. Males compete for territories on cacti because females lay eggs on the cactus plants. Females are not always present when this competition first occurs; however, the presence or absence of the female matters. We found that both the form and strength of selection on male traits, those traits that influenced success in intrasexual competition, depended on the social context. When a female was not present, male size and the area of the sexually dimorphic hind legs was only marginally important to winning a contest. However, males with larger overall size and leg area were more likely to win in the presence of a female. There was also positive quadratic selection on these traits when a female was present with both the largest and the smallest males winning. The implication is unexpected alternative strategies when females are present. Our results support the notion that sexual selection should be studied under all relevant social contexts. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Components of competitiveness in sterile male boll weevils (Coleoptera: Curculionidae)

International Nuclear Information System (INIS)

Villavaso, E.J.; McGovern, W.L.; Wagner, T.L.; Willers, J.L.

1998-01-01

This study examines the relative importance of age at the time of irradiation on attractiveness, mating ability, sperm transfer, prior mating, and longevity as factors of competitiveness in sterile male boll weevil, Anthonomus grandis grandis Boheman. The amount of sperm transferred by irradiated males appeared to be the most important factor in competitiveness. More sperm was transferred by virgin males irradiated on day 5 than by virgin males irradiated on day 2, and males irradiated on day 5 had greater impact on egg hatch than those irradiated on day 2. The amount of sperm in spermathecae of females mated to virgin mates irradiated on day 5 was indistinguishable from that in females mated to virgin control males. Mating ability of males of all treatments was similar. Comparable numbers of boll weevils were captured in traps baited with males irradiated at 2 or 5 d during the first 4-5 d after irradiation, but thereafter, generally more weevils were captured in traps baited with males irradiated at 2 d or with control males. Attractiveness of males irradiated at 2 d was generally comparable to that of control males. More than 91% of irradiated males individually caged on cotton, Gossypium hirsutum L., plants lived for 10 d in the field, and 40% lived for 14 d; all individually caged control males lived 14 d. When released into cotton fields, however, the numbers of both irradiated and control males declined sharply over 14 d. Thus, the potential for an effective 2-wk life span in the field suggested by the caged study did not appear to apply to laboratory-reared weevils released into cotton fields

Testis size variation within sneaker males of the dusky frillgoby Bathygobius fuscus (Gobiidae): effects of within-tactic competition

OpenAIRE

Kawase, Shoma; Hayashi, Takahiro; Matsumoto, Yukio; Takegaki, Takeshi

2017-01-01

A ‘sneaking tactic’ is an alternative reproductive strategy that usually results in sperm competition among males with different tactics. Relatively large testes are a sneaker-specific trait that has generally been thought to have evolved due to sperm competition between sneaker males and bourgeois (guarding) males. However, here we show that competition among sneaker males can also affect testis enlargement in the dusky frillgoby (Bathygobius fuscus) sneaker males. The competitive advantage ...

Mating competitiveness of Aedes albopictus radio-sterilized males in large enclosures exposed to natural conditions.

Science.gov (United States)

Bellini, R; Balestrino, F; Medici, A; Gentile, G; Veronesi, R; Carrieri, M

2013-01-01

Mating competitiveness trials have been conducted in large net-screened enclosures (8 by 5 by 2.8 m) built in a natural shaded environment, in the summers of 2006, 2007, 2008, and 2009 in northern Italy. Aedes albopictus (Skuse) males were radio-sterilized by applying gamma radiations at doses in the range 30-60 Gy. Gamma radiation was administered to aged pupae at the rate of 2.3 Gy/min. Reared radiated males (originally collected in Rimini, Forli, Bologna, Matera, Pinerolo) and hybrid radiated males were tested against wild fertile males (originated from eggs collected in Rimini and Cesena) and reared fertile males, in multiple comparisons for mating competitiveness with reared or wild females. The ratio was kept constant at 100-100_100 (fertile males-radiated males_virgin females). Mating competitiveness was estimated through the calculation of the hatching rate of the eggs laid in oviposition traps positioned inside enclosures. No clear effect of the strains tested (reared, wild, or hybrid) was found. Results demonstrated that reducing the radiation dose from 60 to 30 Gy increases males' competitiveness. Laboratory investigations conducted after controversial results in the 2006 preliminary trials, showed that radiation induces precociousness in adult male emergence.

Methyl eugenol aromatherapy enhances the mating competitiveness of male Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae).

Science.gov (United States)

Haq, Ihsan; Vreysen, Marc J B; Cacéres, Carlos; Shelly, Todd E; Hendrichs, Jorge

2014-09-01

Males of Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae) are strongly attracted to methyl eugenol (ME) (1,2-dimethoxy-4-(2-propenyl)benzene), a natural compound occurring in variety of plant species. ME-feeding is known to enhance male B. carambolae mating competitiveness 3 days after feeding. Enhanced male mating competitiveness due to ME-feeding can increase the effectiveness of sterile insect technique (SIT) manifolds. However, the common methods for emergence and holding fruit flies prior to field releases do not allow the inclusion of any ME feeding treatment after fly emergence. Therefore this study was planned to assess the effects of ME-aromatherapy in comparison with ME feeding on male B. carambolae mating competitiveness as aromatherapy is pragmatic for fruit flies emergence and holding facilities. Effects of ME application by feeding or by aromatherapy for enhanced mating competitiveness were evaluated 3d after treatments in field cages. ME feeding and ME aromatherapy enhanced male mating competitiveness as compared to untreated males. Males treated with ME either by feeding or by aromatherapy showed similar mating success but mating success was significantly higher than that of untreated males. The results are discussed in the context of application of ME by aromatherapy as a pragmatic approach in a mass-rearing facility and its implications for effectiveness of SIT. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

A general description of additive and nonadditive elements of sperm competitiveness and their relation to male fertilization success.

Science.gov (United States)

Engqvist, Leif

2013-05-01

A complete understanding of male reproductive success, and thus sexual selection, often requires an insight into male success in sperm competition. Genuine conclusions on male sperm competitiveness can only be made in real competitive situations. However, statistical analyses of sperm competitiveness from fertilization success data have been shown to be problematic. Here, I first outline a comprehensive general description of the different additive and nonadditive elements relevant for the outcome of sperm competition staged between two males. Based on this description, I will highlight two main problems that are frequently encountered in experiments aiming at estimating sperm competitiveness. First, I focus on potential problems when using standardized competitors versus random mating trials, because trials with standardized competitors do not allow generalization if male-male interactions are important. Second, I illustrate the necessity to analyze data on the logit scale rather than on raw proportions, because only the logit scale allows a clean separation of additive and nonadditive effects (i.e., male × male and female × male interactions). © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Effects of competitive pressure on expert performance: underlying psychological, physiological, and kinematic mechanisms.

Science.gov (United States)

Cooke, Andrew; Kavussanu, Maria; McIntyre, David; Boardley, Ian D; Ring, Christopher

2011-08-01

Although it is well established that performance is influenced by competitive pressure, our understanding of the mechanisms which underlie the pressure-performance relationship is limited. The current experiment examined mediators of the relationship between competitive pressure and motor skill performance of experts. Psychological, physiological, and kinematic responses to three levels of competitive pressure were measured in 50 expert golfers, during a golf putting task. Elevated competitive pressure increased putting accuracy, anxiety, effort, and heart rate, but decreased grip force. Quadratic effects of pressure were noted for self-reported conscious processing and impact velocity. Mediation analyses revealed that effort and heart rate partially mediated improved performance. The findings indicate that competitive pressure elicits effects on expert performance through both psychological and physiological pathways. Copyright © 2011 Society for Psychophysiological Research.

Hip joint torques during the golf swing of young and senior healthy males.

Science.gov (United States)

Foxworth, Judy L; Millar, Audrey L; Long, Benjamin L; Way, Michael; Vellucci, Matthew W; Vogler, Joshua D

2013-09-01

Descriptive, laboratory study. To compare the 3-D hip torques during a golf swing between young and senior healthy male amateur golfers. The secondary purpose was to compare the 3-D hip joint torques between the trail leg and lead leg. The generation of hip torques from the hip musculature is an important aspect of the golf swing. Golf is a very popular activity, and estimates of hip torques during the golf swing have not been reported. Twenty healthy male golfers were divided into a young group (mean ± SD age, 25.1 ± 3.1 years) and a senior group (age, 56.9 ± 4.7 years). All subjects completed 10 golf swings using their personal driver. A motion capture system and force plates were used to obtain kinematic and kinetic data. Inverse dynamic analyses were used to calculate 3-D hip joint torques of the trail and lead limbs. Two-way analyses of covariance (group by leg), with club-head velocity as a covariate, were used to compare peak hip torques between groups and limbs. Trail-limb hip external rotator torque was significantly greater in the younger group compared to the senior group, and greater in the trail leg versus the lead leg. When adjusting for club-head velocity, young and senior healthy male amateur golfers generated comparable hip torques during a golf swing, with the exception of the trail-limb hip external rotator torque. The largest hip torque found was the trail-limb hip extensor torque.

A Comparison of Training and Competition Demands in Semiprofessional Male Basketball Players

Science.gov (United States)

Fox, Jordan L.; Stanton, Robert; Scanlan, Aaron T.

2018-01-01

Purpose: The purpose of this study was to quantify and compare training and competition demands in basketball. Methods: Fifteen semiprofessional male basketball players wore microsensors during physical conditioning training (PCT), games-based training (GBT), and competition to measure absolute and relative (·min[superscript -1]) PlayerLoad™ (PL)…

Effect of Caffeine on Golf Performance and Fatigue during a Competitive Tournament.

Science.gov (United States)

Mumford, Petey W; Tribby, Aaron C; Poole, Christopher N; Dalbo, Vincent J; Scanlan, Aaron T; Moon, Jordan R; Roberts, Michael D; Young, Kaelin C

2016-01-01

This study aimed to determine the effect of a caffeine-containing supplement on golf-specific performance and fatigue during a 36-hole competitive golf tournament. Twelve male golfers (34.8 ± 13.9 yr, 175.9 ± 9.3 cm, 81.23 ± 13.14 kg) with a United States Golf Association handicap of 3-10 participated in a double-blind, placebo-controlled, crossover design in which they played an 18-hole round of golf on two consecutive days (36-hole tournament) and were randomly assigned to consume a caffeine-containing supplement (CAF) or placebo (PLA). CAF/PLA was consumed before and after nine holes during each 18-hole round. Total score, drive distance, fairways and greens in regulation, first putt distance, HR, breathing rate, peak trunk acceleration, and trunk posture while putting were recorded. Self-perceived ratings of energy, fatigue, alertness and concentration were also recorded. Total score (76.9 ± 8.1 vs 79.4 ± 9.1, P = 0.039), greens in regulation (8.6 ± 3.3 vs 6.9 ± 4.6, P = 0.035), and drive distance (239.9 ± 33.8 vs 233.2 ± 32.4, P = 0.047) were statistically better during the CAF condition compared with those during PLA. Statistically significant main effects for condition (P golf. There were no substantial differences in HR or breathing rates, peak trunk acceleration, or putting posture between conditions or over the round (P > 0.05). A moderate dose (1.9 ± 0.3 mg · kg(-1)) of caffeine consumed before and during a round of golf improves golf-specific measures of performance and reduces fatigue in skilled golfers.

Muscle dysmorphia in Hungarian non-competitive male bodybuilders.

Science.gov (United States)

Babusa, B; Túry, F

2012-03-01

Muscle dysmorphia (MD) has been described as a male body image disorder, characterized by a pathological preoccupation with muscle size. The aim of the study was to examine the MD features, eating disorder characteristics and body attitudes in non-competitive male bodybuilders in a Hungarian sample. Sixty male bodybuilders and 60 undergraduate university students completed the self-report questionnaires of the Muscle Appearance Satisfaction Scale, the Body Attitude Test and the Eating Disorders Inventory. MD was associated with current bodybuilding activity, higher ideal body weight and eating disorder characteristics. Moreover, current selfreported steroid users displayed higher tendency for MD symptoms than self-reported steroid non-users. Results emphasize the relationship between MD symptoms, eating disorder characteristics and steroid use. MD and body image related concerns among men could be a wide-spread phenomena also in the Central-Eastern European region.

Mating competitiveness of male Anopheles arabiensis mosquitoes irradiated with a partially or fully sterilizing dose in small and large laboratory cages.

Science.gov (United States)

Helinski, M E H; Knols, B G J

2008-07-01

Male mating competitiveness is a crucial parameter in many genetic control programs including the sterile insect technique (SIT). We evaluated competitiveness of male Anopheles arabiensis Patton as a function of three experimental variables: (1) small or large cages for mating, (2) the effects of either a partially sterilizing (70 Gy) or fully sterilizing (120 Gy) dose, and (3) pupal or adult irradiation. Irradiated males competed for females with an equal number of unirradiated males. Competitiveness was determined by measuring hatch rates of individually laid egg batches. In small cages, pupal irradiation with the high dose resulted in the lowest competitiveness, whereas adult irradiation with the low dose gave the highest, with the latter males being equal in competitiveness to unirradiated males. In the large cage, reduced competitiveness of males irradiated in the pupal stage was more pronounced compared with the small cage; the males irradiated as adults at both doses performed similarly to unirradiated males. Unexpectedly, males irradiated with the high dose performed better in a large cage than in a small one. A high proportion of intermediate hatch rates was observed for eggs collected in the large cage experiments with males irradiated at the pupal stage. It is concluded that irradiation of adult An. arabiensis with the partially sterilizing dose results in the highest competitiveness for both cage designs. Cage size affected competitiveness for some treatments; therefore, competitiveness determined in laboratory experiments must be confirmed by releases into simulated field conditions. The protocols described are readily transferable to evaluate male competitiveness for other genetic control techniques.

Male antenna morphology and its effect on scramble competition in false garden mantids

Science.gov (United States)

Jayaweera, Anuradhi; Barry, Katherine L.

2017-10-01

Well-developed antennae are crucial for many insects, but especially for scramble competitors, who race to find their mates using female sex cues. In these systems, the ability of males to locate females quickly is thought to be under strong selection. A rarely tested assumption is that males with more sensory structures are able to locate females faster. In the present study, we used the false garden mantid Pseudomantis albofimbriata to investigate male antennal morphology and its effect on male efficiency in finding a mate. We used scanning electron microscopy to describe the major sensilla types and their arrangement along the length of male antennae. We also conducted field enclosure trials relating male antennal morphology to scramble competition in this system. We identified six different types of antennal sensilla (cheatic, trichoid, basiconic, grooved peg, ceolocapitular and campaniform) on male P. albofimbriata antennae. As expected, males who had more trichoid sensilla located females quicker than did males with fewer sensilla. Results of the current study suggest that antenna morphology plays a significant role in mate location and hence scramble competition in the P. albofimbriata mating system.

The effect of virus-blocking Wolbachia on male competitiveness of the dengue vector mosquito, Aedes aegypti.

Science.gov (United States)

Segoli, Michal; Hoffmann, Ary A; Lloyd, Jane; Omodei, Gavin J; Ritchie, Scott A

2014-12-01

The bacterial endosymbiont Wolbachia blocks the transmission of dengue virus by its vector mosquito Aedes aegypti, and is currently being evaluated for control of dengue outbreaks. Wolbachia induces cytoplasmic incompatibility (CI) that results in the developmental failure of offspring in the cross between Wolbachia-infected males and uninfected females. This increases the relative success of infected females in the population, thereby enhancing the spread of the beneficial bacterium. However, Wolbachia spread via CI will only be feasible if infected males are sufficiently competitive in obtaining a mate under field conditions. We tested the effect of Wolbachia on the competitiveness of A. aegypti males under semi-field conditions. In a series of experiments we exposed uninfected females to Wolbachia-infected and uninfected males simultaneously. We scored the competitiveness of infected males according to the proportion of females producing non-viable eggs due to incompatibility. We found that infected males were equally successful to uninfected males in securing a mate within experimental tents and semi-field cages. This was true for males infected by the benign wMel Wolbachia strain, but also for males infected by the virulent wMelPop (popcorn) strain. By manipulating male size we found that larger males had a higher success than smaller underfed males in the semi-field cages, regardless of their infection status. The results indicate that Wolbachia infection does not reduce the competitiveness of A. aegypti males. Moreover, the body size effect suggests a potential advantage for lab-reared Wolbachia-males during a field release episode, due to their better nutrition and larger size. This may promote Wolbachia spread via CI in wild mosquito populations and underscores its potential use for disease control.

Sterility and mating competitiveness of irradiated males of the large milkweed bug, Oncopeltus fasciatus

International Nuclear Information System (INIS)

Moursy, L.E.; Eesa, N.M.; Cutkomp, L.K.

1991-01-01

Low level gamma radiation adversely affected the reproductive capacity of the large milkweed bug, oncopeltus fasciatus dallas, as expressed by fecundity and fertility. Treatment was applied to late 5th instar male nymphs. Both fecundity and fertility decreased linearly with the treatment dose and complete sterility occurred when males were exposed to 6 kilorads and mated with normal females. The mating competitiveness of O. fasciatus males irradiated at late 5th instar nymphs decreased linearly with the treatment dose. A strong negative relationship existed between dose and mating competitiveness ( r = -0.93). A 3:2 ratio of irradiated males at 4 kilorads ( as late 5th instar as many progeny as normal in F 1 .2 tab.,1 fig

Optimizing methyl-eugenol aromatherapy to maximize posttreatment effects to enhance mating competitiveness of male Bactrocera carambolae (Diptera: Tephritidae).

Science.gov (United States)

Haq, Ihsan ul; Vreysen, Marc J B; Cacéres, Carlos; Shelly, Todd E; Hendrichs, Jorge

2015-10-01

Methyl-eugenol (ME) (1,2-dimethoxy-4-(2-propenyl)benzene), a natural phytochemical, did enhance male Bactrocera carambolae Drew & Hancock (Diptera: Tephritidae) mating competitiveness 3 d after ingestion. Enhanced male mating competitiveness can significantly increase the effectiveness of the sterile insect technique (SIT). ME application to mass reared sterile flies by feeding is infeasible. ME application by aromatherapy however, would be a very practical way of ME application in fly emergence and release facilities. This approach was shown to enhance mating competitiveness of B. carambolae 3 d posttreatment (DPT). Despite this added benefit, every additional day of delaying release will reduce sterile fly quality and will add cost to SIT application. The present study was planned to assess the effects of ME-aromatherapy on male B. carambolae mating competitiveness 1DPT and 2DPT. ME aromatherapy 1DPT or 2DPT did enhance mating competitiveness of B. carambolae males whereas ME feeding 1DPT and 2DPT did not. Male mating competitiveness was enhanced by the ME aromatherapy irrespective if they received 1DPT, 2DPT or 3DPT. ME aromatherapy, being a viable approach for its application, did enhance mating competitiveness of male B. carambolae 1 d posttreatment as ME feeding did 3 d after ingestion. ©2014 The Authors Journal compliation © Insititute of Zoology, Chinese Academy of Science.

Highly competitive reindeer males control female behavior during the rut.

Directory of Open Access Journals (Sweden)

Guillaume Body

Full Text Available During the rut, female ungulates move among harems or territories, either to sample mates or to avoid harassment. Females may be herded by a male, may stay with a preferred male, or aggregate near a dominant male to avoid harassment from other males. In fission-fusion group dynamics, female movement is best described by the group's fission probability, instead of inter-harem movement. In this study, we tested whether male herding ability, female mate choice or harassment avoidance influence fission probability. We recorded group dynamics in a herd of reindeer Rangifer tarandus equipped with GPS collars with activity sensors. We found no evidence that the harassment level in the group affected fission probability, or that females sought high rank (i.e. highly competitive and hence successful males. However, the behavior of high ranked males decreased fission probability. Male herding activity was synchronous with the decrease of fission probability observed during the rut. We concluded that male herding behavior stabilized groups, thereby increasing average group size and consequently the opportunity for sexual selection.

Male reproductive competition in spawning aggregations of cod ( Gadus morhua , L.)

DEFF Research Database (Denmark)

Bekkevold, Dorte; Hansen, Michael Møller; Loeschcke, V.

2002-01-01

Reproductive competition may lead to a large skew in reproductive success among individuals. Very few studies have analysed the paternity contribution of individual males in spawning aggregations of fish species with huge census population sizes. We quantified the variance in male reproductive...... success in spawning aggregations of cod under experimental conditions over an entire spawning season. Male reproductive success was estimated by microsatellite-based parentage analysis of offspring produced in six separate groups of spawning cod. In total, 1340 offspring and 102 spawnings distributed...... across a spawning season were analysed. Our results show that multiple males contributed sperm to most spawnings but that paternity frequencies were highly skewed among males, with larger males on average siring higher proportions of offspring. It was further indicated that male reproductive success...

Immediate Effects of Sports Taping Applied on the Lead Knee of Low- and High-Handicapped Golfers During Golf Swing.

Science.gov (United States)

Kim, Tae-Gyu; Kim, Eun-Kuk; Park, Jong-Chul

2017-04-01

Kim, T-G, Kim, E-K, and Park, J-C. Immediate effects of sports taping applied on the lead knee of low- and high-handicapped golfers during golf swing. J Strength Cond Res 31(4): 981-989, 2017-Elite golf athletes suffer from various musculoskeletal injuries due to repeated golf swings. Repetitive varus moment during golf swing has been suggested as a possible cause of injuries to the lead knee. The aim of this study was to objectively and quantitatively evaluate the immediate effects of sports taping on the lead knee of elite golfers to restrict varus moment. Thirty-one elite golfers were assigned to the low- (LHG, n = 15) or high-handicapped group (HHG, n = 16). Using 3-dimensional motion analysis, the lead knee position on the frontal plane with and without rigid taping (RT), elastic taping (ET), and placebo taping was identified in 4 separate phases by the 5 events of golf swing as follows: the peak of the backswing (E1), parallel to the ground during downswing (E2), ball impact (E3), parallel to the ground during follow-through (E4), and finish (E5). The LHG when using a driver club had decreased movement toward knee varus with RT and ET than that without it from E1 to E2 (p = 0.001). The LHG when using a 5-iron club decreased movement toward knee varus with RT than that without it from E1 to E2 (p = 0.006) and from E2 to E3 (p = 0.019). The HHG when using a driver club had decreased movement toward knee varus with RT from E1 to E2 (p = 0.014). Sports taping may be helpful for elite golfers in terms of reducing varus moment of the lead knee during the downswing and be useful for the development of preventive strategies for golf-related knee injuries.

Mechanical lower back pain and sacroiliac joint dysfunction in golfers at two golf clubs in Durban, South Africa

Directory of Open Access Journals (Sweden)

Siyabonga H. Kunene

2018-03-01

Clinical Implications: This study will provide valuable knowledge that will assist clinicians, especially physiotherapists, in their clinical management of golfers with MLBP and SIJD. Intervention studies are needed to address lower back and sacroiliac joint problems reported in this study.

LOW HANDICAP GOLFERS GENERATE MORE TORQUE AT THE SHOE-NATURAL GRASS INTERFACE WHEN USING A DRIVER

Directory of Open Access Journals (Sweden)

Paul Worsfold

2008-09-01

Full Text Available The aim was to determine the rotational torque occurring at the shoe-natural grass interface during golf swing performance with different clubs, and to determine the influence of handicap and golf shoe design. Twenty-four golfers (8 low 0-7; 8 medium 8-14; and 8 high 15+ performed 5 shots with a driver, 3-iron and 7-iron when 3 shoes were worn: a modern 8 mm metal 7-spike shoe, an alternative 7-spike shoe and a flat soled shoe. Torque was measured at the front and back foot by grass covered force platforms in an outdoor field. Torque at the shoe- natural turf interface was similar at the front foot when using a driver, 3-iron and 7-iron with maximum mean torque (Tzmax 17-19 Nm and torque generation in the entire backswing and downswing approximately 40 Nm. At the back foot, torque was less than at the front foot when using the driver, 3-iron and 7-iron. At the back foot Tzmax was 6-7 Nm, and torque generation was 10-16 Nm, with a trend for greater torque generation when using the driver rather than the irons. The metal spike shoe allowed significantly more back foot torque generation when using a driver than a flat- soled shoe (p 0.05, although back foot mean torques generated tended to be greater for the metal spike shoe. The golf shot outcomes were similar for low, medium and high handicappers in both metal and alternative spike shoes (metal: 87%; 76%; 54%; alternative: 85%; 74%; 54% respectively. The better, low handicap golfers generated significantly more back foot torque (metal spike: 18.2 Nm; alternative: 15.8 Nm; p < 0.05 when using a driver. Further research should consider back foot shoe-grass interface demands during driver usage by low handicap and lighter body-weight golfers

Mating competitiveness and the effect of X-rays and aging on males of Tetranychus urticae (Acarina, Tetranychidae) in relation to genetic control

International Nuclear Information System (INIS)

Feldmann, A.M.

1977-01-01

Males of Tetranychus urticae Koch were irradiated with X-ray doses of 4, 8, 24 and 32 krad (which were applied to 0-1 day-old adult virgin males) and tested in mating competition with one-day-old non-irradiated males. A non-significant excess of parental females were mated to the unirradiated males. This consistent trend in favour of females, mated with unirradiated males was highly significant, when the results of all the experiments were bulked. This indicated that radiation impaired the mating competitiveness of males of T. urticae. Aging of irradiated males resulted in a significant decrease of male-mating competitiveness at least within 2 days after irradiation. When 24 krad X-rays irradiated males were tested in mating competition at different ages, with unirradiated males of equal age, it was demonstrated that the reduction in mating competitiveness of aging irradiated males is caused by accelerated aging due to the irradiation treatment

Selection by mating competitiveness improves the performance of Anastrepha ludens males of the genetic sexing strain Tapachula-7.

Science.gov (United States)

Quintero-Fong, L; Toledo, J; Ruiz, L; Rendón, P; Orozco-Dávila, D; Cruz, L; Liedo, P

2016-10-01

The sexual performance of Anastrepha ludens males of the Tapachula-7 genetic sexing strain, produced via selection based on mating success, was compared with that of males produced without selection in competition with wild males. Mating competition, development time, survival, mass-rearing quality parameters and pheromone production were compared. The results showed that selection based on mating competitiveness significantly improved the sexual performance of offspring. Development time, survival of larvae, pupae and adults, and weights of larvae and pupae increased with each selection cycle. Differences in the relative quantity of the pheromone compounds (Z)-3-nonenol and anastrephin were observed when comparing the parental males with the F4 and wild males. The implications of this colony management method on the sterile insect technique are discussed.

Fitness of Mass-Reared Males of Anastrepha obliqua (Diptera: Tephritidae) Resulting From Mating Competition Tests in Field Cages.

Science.gov (United States)

Hernández, Emilio; Liedo, Pablo; Toledo, Jorge; Montoya, Pablo; Perales, Hugo; Ruiz-Montoya, Lorena

2017-12-05

The sterile insect technique uses males that have been mass-reared in a controlled environment. The insects, once released in the field, must compete to mate. However, the mass-rearing condition supposes a loss of fitness that will be noticeable by wild females. To compare the fitness of wild males and mass-reared males, three competition settings were established. In setting 1, wild males, mass-reared males and wild females were released in field cages. In setting 2, wild females and wild males were released without competition, and in setting 3, mass-reared males and mass-reared females were also released without competition. Male fitness was based on their mating success, fecundity, weight and longevity. The fitness of the females was measured based on weight and several demographic parameters. The highest percentage of mating was between wild males and wild females between 0800 and 0900 h in the competition condition, while the mass-reared males started one hour later. The successful wild males weighed more and showed longer mating times, greater longevity and a higher number of matings than the mass-reared males. Although the mass-reared males showed the lowest percentage of matings, their fecundity when mating with wild females indicated a high fitness. Since the survival and fecundity of wild females that mated with mass-reared males decreased to become similar to those of mass-reared females that mated with mass-reared males, females seem to be influenced by the type of male (wild or mass-reared). © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Aedes albopictus (Skuse) males in laboratory and semi-field cages: release ratios and mating competitiveness.

Science.gov (United States)

Madakacherry, Odessa; Lees, Rosemary Susan; Gilles, Jeremie Roger Lionel

2014-04-01

To control the container-breeding mosquito and major vector of dengue and chikungunya Aedes albopictus, the sterile insect technique (SIT) is proposed as a component of integrated vector management programs in endemic areas. For the technique to be successful, released males, sterilized with 35 Gy of ionizing radiation during the pupal stage, must be able to compete for mating opportunities with wild counterparts and successfully copulate with wild females to induce sterility in the population. Any reduction in competitiveness can be compensated for by increasing the ratio of released sterile to wild males, a ratio which must be optimized for effectiveness and efficiency. Fruit fly SIT programs use field enclosures to test the competitiveness of sterile males to monitor the quality of the colony and adjust release ratios. This is laborious and time consuming, and for mosquito programs it would be advantageous if similarly useful results could be obtained by smaller scale laboratory tests, conducted on a more regular basis. In the present study we compared the competitiveness, as measured by hatching rate of resulting egg batches, of irradiated males measured in small and large laboratory cages and semi-field enclosures in a greenhouse setting, when competing in a 1:1, 3:1, and 5:1 ratio with fertile males. The sterile males were found to be equally competitive when compared to unirradiated counterparts, and a 5:1 ratio was sufficient to reduce, but not eliminate, the fertility of the female populations, irrespective of cage size. Variability in hatch rate in eggs laid by individual females and so-called indeterminate matings, when we could not be certain whether a female had mated a fertile or a sterile male, could be investigated by closer investigation of mating status and the frequency of multiple matings in Ae. albopictus. The laboratory results are encouraging for the effectiveness of the SIT using irradiated males of this species, and we support further

The effects of genetic manipulation, dieldrin treatment and irradiation on the mating competitiveness of male Anopheles arabiensis in field cages.

Science.gov (United States)

Yamada, Hanano; Vreysen, Marc J B; Gilles, Jeremie R L; Munhenga, Givemore; Damiens, David D

2014-08-13

To enable the release of only sterile male Anopheles arabiensis mosquitoes for the sterile insect technique, the genetic background of a wild-type strain was modified to create a genetic sexing strain ANO IPCL1 that was based on a dieldrin resistance mutation. Secondly, the eggs of ANO IPCL1 require treatment with dieldrin to allow complete elimination of female L1 larvae from the production line. Finally, male mosquito pupae need to be treated with an irradiation dose of 75 Gy for sterilization. The effects of these treatments on the competitiveness of male An. arabiensis were studied. The competitiveness of ANO IPCL1 males that were treated either with irradiation or both dieldrin and irradiation, was compared with that of the wild-type strain (An. arabiensis Dongola) at a 1:1 ratio in 5.36 m3 semi-field cages located in a climate-controlled greenhouse. In addition, three irradiated: untreated male ratios were tested in semi-field cages (1:1, 5:1 and 10:1) and their competition for virgin wild-type females was assessed. The ANO IPCL1 males were equally competitive as the wild-type males in this semi-field setting. The ANO IPCL1 males irradiated at 75 Gy were approximately half as competitive as the unirradiated wild-type males. ANO IPCL1 males that had been treated with dieldrin as eggs, and irradiated with 75 Gy as pupae were slightly more competitive than males that were only irradiated. Ratios of 1:1, 5:1 and 10:1 irradiated ANO IPCL1 males: untreated wild-type males resulted in 31, 66 and 81% induced sterility in the female cage population, respectively. An irradiation dose of 75 Gy reduced the competitiveness of male ANO IPCL1 significantly and will need to be compensated by releasing higher numbers of sterile males in the field. However, the dieldrin treatment used to eliminate females appears to have an unexpected radioprotectant effect, however the mechanism is not understood. A sterile to wild-type ratio of 10:1 effectively reduced the population

Age, psychological skills, and golf performance: a prospective investigation.

Science.gov (United States)

Hayslip, Bert; Petrie, Trent A

2014-03-01

This study explored the influence of age in understanding mental skills utilization in the context of performance at a major national golf competition. Participants, who ranged in age and in skill level, included 1150 male and 170 female amateur golfers competing in the Dupont World Amateur Golf Championship in Myrtle Beach, South Carolina. Measures targeted general mental skills used in competitions, golf-specific skills, and competitive trait anxiety. Hierarchical linear regression was utilized to explore the potential moderating role that chronological age may play in influencing the impact of psychological skills and anxiety on competitive tournament performance across the adult life span. Findings suggested no significant age-moderating effects and instead pointed to the importance of developing golf-specific psychological skills to enhance or maintain performance, irrespective of age. Although automaticity (performance feels "automatic") predicted performance for all golfers, commitment to the game and confidence in one's putting did so only for the men. These findings reinforce the age-irrelevant role of such skills in fostering the experience of peak performance in a competitive sport context and underscore the importance of interventions targeting older players to help maintain or facilitate the use of psychological skills in helping them manage their games.

Sexual Competitiveness of Anastrepha ludens (Diptera: Tephritidae) Males Exposed to Citrus aurantium and Citrus paradisi Essential Oils.

Science.gov (United States)

Morató, Santiago; Shelly, Todd; Rull, Juan; Aluja, Martin

2015-04-01

Males of the Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) display increased mating competitiveness following exposure to the odor of certain host and nonhost plants, and this phenomenon has been used in the sterile insect technique to boost the mating success of released, sterile males. Here, we aimed to establish whether males of the Mexican fruit fly (Anastrepha ludens (Loew)) gain a mating advantage when exposed to the aroma of two preferred hosts, grapefruit (Citrus paradisi Macfadyen) and bitter orange (Citrus aurantium L.). Under seminatural conditions, we observed that, in trials using wildish males (from a young laboratory colony started with wild flies) exclusively, exposure to the aroma of bitter orange had no effect on male mating success but exposure to the odor grapefruit oil increased male mating success significantly. In a separate test involving both exposed and nonexposed wildish and mass-reared, sterile males, although wildish males were clearly more competitive than sterile males, exposure to grapefruit oil had no detectable effect on either male type. Exposure to oils had no effect on copulation duration in any of the experiments. We discuss the possibility that the positive effect of grapefruit essential oils on wildish male competitiveness may have been linked to exposure of females to grapefruit as a larval food, which may have imprinted them with grapefruit odors during pupal eclosion and biased their response as adults to odors of their maternal host. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of a golf-specific load monitoring tool: Content validity and feasibility.

Science.gov (United States)

Williams, Scott B; Gastin, Paul B; Saw, Anna E; Robertson, Sam

2018-05-01

Athletes often record details of their training and competitions, supported by information such as environmental conditions, travel, as well as how they felt. However, it is not known how prevalent these practices are in golfers, or how valuable this process is perceived. The purpose of this study was to develop a golf-specific load monitoring tool (GLMT), and establish the content validity and feasibility of this tool amongst high-level golfers. In the first phase of development, 21 experts were surveyed to determine the suitability of items for inclusion in the GLMT. Of the 36 items, 21 received >78% agreement, a requirement to establish content validity and for inclusion in the GLMT. Total duration was the preferred metric for golf-specific activities, whilst rating of perceived exertion (RPE) was preferred for measuring physical training. In the second phase, feasibility of the tool was assessed by surveying 13 high-level male golfers following 28-days of daily GLMT use. All items included in the GLMT were deemed feasible to record, with all players participating in the feasibility study providing high to very high ratings. Golfers responded that they would consider using a load monitoring tool of this nature long term, provided it can be completed in less than five minutes per day.

Sterility and Sexual Competitiveness of Tapachula-7 Anastrepha ludens Males Irradiated at Different Doses.

Science.gov (United States)

Orozco-Dávila, Dina; Adriano-Anaya, Maria de Lourdes; Quintero-Fong, Luis; Salvador-Figueroa, Miguel

2015-01-01

A genetic sexing strain of Anastrepha ludens (Loew), Tapachula-7, was developed by the Mexican Program Against Fruit Flies to produce and release only males in programs where the sterile insect technique (SIT) is applied. Currently, breeding are found at a massive scale, and it is necessary to determine the optimum irradiation dose that releases sterile males with minimum damage to their sexual competitiveness. Under laboratory and field conditions, we evaluated the effects of gamma irradiation at doses of 0, 20, 40, 60 and 80 Gy on the sexual competitiveness of males, the induction of sterility in wild females and offspring survivorship. The results of the study indicate that irradiation doses have a significant effect on the sexual behavior of males. A reduction of mating capacity was inversely proportional to the irradiation dose of males. It is estimated that a dose of 60 Gy can induce more than 99% sterility in wild females. In all treatments, the degree of offspring fertility was correlated with the irradiation dose of the parents. In conclusion, the results of the study indicate that a dose of 60 Gy can be applied in sterile insect technique release programs. The application of this dose in the new genetic sexing strain of A. ludens is discussed.

The Relationship between Cortisol and Bone Mineral Density in Competitive Male Cyclists

Directory of Open Access Journals (Sweden)

Shannon L. Mathis

2013-01-01

Full Text Available Objective. The purpose of this study was to determine whether race day cortisol was related to bone mineral density (BMD in competitive male cyclists. A secondary purpose was to determine additional factors associated with BMD in competitive male cyclists. Methods. Measurements of lumbar spine and hip BMD were performed in 35 male competitors in a state championship cycling time trial event. Salivary cortisol was measured 10 minutes prior to the start of the race and 5 minutes after race finished. Participants reported daily calcium intake, age, years of bike training, races per season, and average weekly minutes spent riding a bike, weight training, and running on a survey. Results. Cortisol level increased significantly from pre- to postcompetition but was not significantly associated with BMD. Increased weekly minutes of weight training was associated with higher BMD of the lumbar spine and the hip. The increased number of years of cycling experience was associated with lower BMD of the femoral neck. Increased daily calcium intake was associated with higher BMD of the lumbar spine and femoral neck. Conclusions. Findings indicate that cyclists should participate in weight training and increase calcium intake in order to increase or maintain BMD of the lumbar spine and hip.

Performance processes within affect-related performance zones: a multi-modal investigation of golf performance.

Science.gov (United States)

van der Lei, Harry; Tenenbaum, Gershon

2012-12-01

Individual affect-related performance zones (IAPZs) method utilizing Kamata et al. (J Sport Exerc Psychol 24:189-208, 2002) probabilistic model of determining the individual zone of optimal functioning was utilized as idiosyncratic affective patterns during golf performance. To do so, three male golfers of a varsity golf team were observed during three rounds of golf competition. The investigation implemented a multi-modal assessment approach in which the probabilistic relationship between affective states and both, performance process and performance outcome, measures were determined. More specifically, introspective (i.e., verbal reports) and objective (heart rate and respiration rate) measures of arousal were incorporated to examine the relationships between arousal states and both, process components (i.e., routine consistency, timing), and outcome scores related to golf performance. Results revealed distinguishable and idiosyncratic IAPZs associated with physiological and introspective measures for each golfer. The associations between the IAPZs and decision-making or swing/stroke execution were strong and unique for each golfer. Results are elaborated using cognitive and affect-related concepts, and applications for practitioners are provided.

Physiological Changes Following Competition in Male and Female Physique Athletes: A Pilot Study.

Science.gov (United States)

Trexler, Eric T; Hirsch, Katie R; Campbell, Bill I; Smith-Ryan, Abbie E

2017-10-01

The purpose of the current study was to evaluate changes in body composition, metabolic rate, and hormones during postcompetition recovery. Data were collected from natural physique athletes (7 male/8 female) within one week before (T1) competition, within one week after (T2), and 4-6 weeks after (T3) competition. Measures included body composition (fat mass [FM] and lean mass [LM] from ultrasongraphy), resting metabolic rate (RMR; indirect calorimetry), and salivary leptin, testosterone, cortisol, ghrelin, and insulin. Total body water (TBW; bioelectrical impedance spectroscopy) was measured at T1 and T2 in a subsample (n = 8) of athletes. Significant (p T2 > T1), LM (T1 = 57.6 ± 13.9 kg, T2 = 59.4 ± 14.2, T3 = 59.3 ± 14.2; T2 and T3 > T1), and FM (T1 = 7.7 ± 4.4 kg, T2 = 8.0 ± 4.4, T3 = 10.0 ± 6.2; T3 > T1 and T2). TBW increased from T1 to T2 (Δ=1.9 ± 1.3 L, p < .01). RMR increased from baseline (1612 ± 266 kcal/day; 92.0% of predicted) to T2 (1881 ± 329, 105.3%; p < .01) and T3 (1778 ± 257, 99.6%; p < .001). Cortisol was higher (p < .05) at T2 (0.41 ± 0.31 μg/dL) than T1 (0.34 ± 0.31) and T3 (0.35 ± 0.27). Male testosterone at T3 (186.6 ± 41.3 pg/mL) was greater than T2 (148.0 ± 44.6, p = .04). RMR changes were associated (p ≤ .05) with change in body fat percent (ΔBF%; r = .59) and T3 protein intake (r= .60); male testosterone changes were inversely associated (p≤ .05) with ΔBF%, ΔFM, and Δweight (r=-0.81--0.88). TBW increased within days of competition. Precompetition RMR suppression appeared to be variable and markedly reversed by overfeeding, and reverted toward normal levels following competition. RMR and male testosterone increased while FM was preferentially gained 4-6 weeks postcompetition.

The influence of late-stage pupal irradiation and increased irradiated: un-irradiated male ratio on mating competitiveness of the malaria mosquito Anopheles arabiensis Patton.

Science.gov (United States)

Helinski, M E H; Knols, B G J

2009-06-01

Competitiveness of released males in genetic control programmes is of critical importance. In this paper, we explored two scenarios to compensate for the loss of mating competitiveness after pupal stage irradiation in males of the malaria mosquito Anopheles arabiensis. First, competition experiments with a higher ratio of irradiated versus un-irradiated males were performed. Second, pupae were irradiated just prior to emergence and male mating competitiveness was determined. Males were irradiated in the pupal stage with a partially or fully-sterilizing dose of 70 or 120 Gy, respectively. Pupae were irradiated aged 20-26 h (young) as routinely performed, or the pupal stage was artificially prolonged by cooling and pupae were irradiated aged 42-48 h (old). Irradiated males competed at a ratio of 3:1:1 to un-irradiated males for mates in a large cage design. At the 3:1 ratio, the number of females inseminated by males irradiated with 70 Gy as young pupae was similar to the number inseminated by un-irradiated males for the majority of the replicates. At 120 Gy, significantly fewer females were inseminated by irradiated than by un-irradiated males. The irradiation of older pupae did not result in a significantly improved male mating competitiveness compared to the irradiation of young pupae. Our findings indicate that the loss of competitiveness after pupal stage irradiation can be compensated for by a threefold increase of irradiated males, but only for the partially-sterilizing dose. In addition, cooling might be a useful tool to facilitate handling processes of large numbers of mosquitoes in genetic control programmes.

Ephestia Kuehniella Z.: Gamma irradiation effects on the adult stage and mating competitiveness of sterile males

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.; El-Banby, M.A.; Salem, Y.S.; Abdel-Baky, S.M.

1985-01-01

Effects of gamma radiation dosages from 5 to 50 Krad on the adult stage of Ephestia Kuehielia Z. were studied. Irradiated adults paired with untreated adults produced fewer eggs than pairs of unirradiated adults, and these eggs had reduced hatch. This effect was more pronounced with irradiated females or when both parents were irradiated. Radiation greatly reduced life span of treated adults. Adult females were more sensitive to the sterilizing effect of gamma radiation than were males. Males were sterilized when irradiated at 50 Krad, but females at 25 Krad. Previous studies showed that males irradiated as fully grown pupae at 45 Krad were completely sterile. When irradiated (I) males were confined with unirradiated (U) males and females (1:1:1 ratio), infertility of eggs was 48%. Increasing the ratio to 5:1:1, 10:1:1 and 15:1:1 caused 77.9, 84.6 and 94.4 percent infertility of the resulting eggs, respectively. The calculated competitiveness values for the 4 ratios were 0.55, 0.52, 0.42 and 0.88, respectively. Thus I males were only competitive at the highest flooding ration (15:1:1)

Opportunities to improve competitiveness in male sexual strain has genetic sex determination Ceratitis capitata Wiedemann (Diptera: Tephritidae)

International Nuclear Information System (INIS)

Tlemcani, Meriem

2010-01-01

The success of TIS program depends essentially on the capacity of the sterile males to compete with fertile males to couple with wild females. This program becomes more and more efficient if one good mastery its various factors, mainly the performances of males of the origin of ceratite in genetic sexing within the production unit of sterile flies of the National Center of the Sciences and Nuclear Technologies. Researches turned to the improvement of the competitiveness of the sterile males by the addition of bacteria in the nourishing circles of breeding. By basing itself on the symbiotic relations between the present bacteria in the bowel of the ceratite, we adopted, in this present work, a method of breeding which could improve the quality of the males of genetic sexing GSS. This method consists in introducing certain beneficial bacteria in the ceratite (Enterobacteriaceae and Pseudomonas aerogenes) into the middle of breeding according to various combinations. The effect of these bacteria was analyzed by making various tests of quality control (weight, emergence, capacity in the flight, the longevity) and of reproduction (competitiveness, lasted mating, latent period). It turns out that the addition of Enterobacteriaceae in the middle of breeding outstandingly improved the percentage of emergence of the males of the GSS. Besides, these bacteria contributed to the improvement of the competitiveness of these males with regard to those of the other circles. Besides, the addition of Pseudomonas aerogenes in the middle of breeding gave the best latent period to the males GSS. We also noticed that the association of Enterobacteriaceae with Pseudomonas aerogenes has a positive effect on the capacity in the flight of the males of the GSS and their duration of mating.

Self-ratings of physical attractiveness in a competitive context: when males are more sensitive to self-perceptions than females.

Science.gov (United States)

Saad, Gad; Gill, Tripat

2009-10-01

The authors investigated sex differences in the ratings of physical attractiveness in a competitive context. Participants in an Ultimatum Game experiment offered to split a sum of money with their opponents who could either accept or reject the offers; subsequently, physical attractiveness ratings (both self-ratings and of the other) were obtained. The authors found that male participants rated themselves higher on physical attractiveness when facing male opponents than when facing female ones; there was no such difference for the female participants. Furthermore, male participants' self-ratings of physical attractiveness were higher than the ratings provided by their corresponding male opponents. The authors discuss these findings using the tenets of evolutionary psychology pertaining to as male intra-sexual rivalry in competitive contexts.

Sterility and mating competitiveness of male ceratitis capitata as affected by gamma radiation and di methane insecticide. Vol. 4

Energy Technology Data Exchange (ETDEWEB)

Wakid, A M; Fadel, A M; El-Akhdar, E A [Radiobiology Department, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt); Helmy, N M [Entomology Department, Faculty of Science, Zagazig University, Benha, (Egypt)

1996-03-01

In the present work, the effects of pupal gamma-irradiation (50, 70, 90 Gy), or adult treatment with dimethoate insecticide (0.93 ppm) on the male sterility and mating competitiveness of the medfly, ceratitis capitata (Wied.) were studied. Results indicated that treatment of the adult medfly with dimethoate had no clear effect on male fertility whether this male mated with treated or normal females. However, gamma irradiation drastically decreased hatch ability of eggs laid by normal or treated (dimethoate) females, when mated with irradiated males all gamma doses. This reduction in egg hatch ability increased increased with increasing gamma dose. Irradiated females did not lay eggs at any of the gamma doses used. At all mating combinations, the male mating competitiveness was decreased especially when irradiated males were confined with treated males for mating with normal or treated females. Results are indicated and discussed in the text. 4 figs.

Functional and morphological studies of photodamaged skin on the hands of middle-aged Japanese golfers.

Science.gov (United States)

Kikuchi-Numagami, K; Suetake, T; Yanai, M; Takahashi, M; Tanaka, M; Tagami, H

2000-06-01

The skin of golfers' hands provides a suitable model to study the effect of chronic sun exposure, because one of their hands is exposed to the outer environment, especially sunlight, while the other one is always protected by a glove during play. Our purpose was to find out the influence of photodamage on the properties of the skin surface of middle-aged Japanese by using non-invasive methods. We measured hydration state, and water barrier function of the stratum corneum (SC) and the color of the skin of the dorsum of the hands. In a separate study, we evaluated the skin surface contour by using replicas taken from the skin in a slightly stretched or relaxed position. We found a significant decrease in hydration of the skin surface of the exposed skin as compared to that of the protected skin, whereas no such difference was found with transepidermal water loss, a parameter for water barrier function of the SC. Luminance of skin color was also reduced in the sun-exposed skin. Replica analysis revealed that large wrinkles developing in a relaxed position were more prominent on the exposed than on the protected skin, while fine furrows noted in a slightly stretched position were shallower on the former than the latter. The data obtained indicate that the chronically exposed skin of golfers' hands shows morphological and functional changes resulting from long time exposure to the outer environment especially sunlight. Furthermore, bioengineering non-invasive methods are found to be useful to detect early photodamage of the skin in a more quantitative fashion which is rather difficult to demonstrate clinically.

Performance Aspects and Physiological Responses in Male Amateur Boxing Competitions: A Brief Review.

Science.gov (United States)

Slimani, Maamer; Chaabène, Helmi; Davis, Philip; Franchini, Emerson; Cheour, Foued; Chamari, Karim

2017-04-01

Slimani, M, Chaabène, H, Davis, P, Franchini, E, Cheour, F, and Chamari, K. Performance aspects and physiological responses in male amateur boxing competitions: a brief review. J Strength Cond Res 31(4): 1132-1141, 2017-Boxing is one of the most popular striking combat sports in the world. The aim of this review was to present data concerning performance analysis (time-motion and technical-tactical analysis) and physiological responses (i.e., blood lactate concentration [BLC], heart rate, and oxygen consumption) during novice and elite male simulated and official amateur boxing competitions in any age category. The present review shows that boxing competition is a high-intensity intermittent striking combat sport. Typically, the activity-to-rest ratio was higher in elite (18:1) than in novice (9:1) boxers and significant differences were observed between rounds (first round = 16:1, second round = 8:1, and third round = 6:1) in novice boxers. Thus, total stop-time and total stop-frequency increased over subsequent rounds in novice boxers. The technical-tactical aspects in elite and novice boxing bouts were different between rounds and dependent on the match outcome (i.e., winners vs. losers). Particularly, the current review highlights that triple-punch combinations, total combinations, block- and counter-punch combinations, total punches to the head, technical performance effectiveness, and defensive- and offensive-skills effectiveness may have contributed to win in novice and elite boxing competitions. Higher frequencies of technical movements were also observed in elite compared with novice boxers. From a physiological point of view, BLC increased significantly from postround 1 compared with postround 3 in novice boxing match. BLC was also higher in official than in simulated elite boxing matches in senior compared with junior boxers and in medium heavy-weight category compared with light- and medium-weight categories in junior boxing competition. A higher

Alfalfa weevil male: effect of γ-radiation and weevil age on mating competitiveness and sperm transfer

International Nuclear Information System (INIS)

Wollam, J.D.; Hower, A.A. Jr.

1977-01-01

Virgin male Hypera postica (Gyllenhal) were irradiated at 1, 2, 3, 4, and 5 weeks of age. Alfalfa weevils from each age group were subjected to γ-radiation doses of 0, 2, 3, 4, 5, and 6 krads. Mating competitiveness was reduced by the 5 to 6 krad doses in all age groups except those 4 weeks old. Weevils irradiated at 1 week of age showed a reduction in competitiveness at doses above 2 krad. Radiation dose and age at irradiation had little noticeable effect on sperm transfer

Song competition affects monoamine levels in sensory and motor forebrain regions of male Lincoln's sparrows (Melospiza lincolnii.

Directory of Open Access Journals (Sweden)

Kendra B Sewall

Full Text Available Male animals often change their behavior in response to the level of competition for mates. Male Lincoln's sparrows (Melospiza lincolnii modulate their competitive singing over the period of a week as a function of the level of challenge associated with competitors' songs. Differences in song challenge and associated shifts in competitive state should be accompanied by neural changes, potentially in regions that regulate perception and song production. The monoamines mediate neural plasticity in response to environmental cues to achieve shifts in behavioral state. Therefore, using high pressure liquid chromatography with electrochemical detection, we compared levels of monoamines and their metabolites from male Lincoln's sparrows exposed to songs categorized as more or less challenging. We compared levels of norepinephrine and its principal metabolite in two perceptual regions of the auditory telencephalon, the caudomedial nidopallium and the caudomedial mesopallium (CMM, because this chemical is implicated in modulating auditory sensitivity to song. We also measured the levels of dopamine and its principal metabolite in two song control nuclei, area X and the robust nucleus of the arcopallium (RA, because dopamine is implicated in regulating song output. We measured the levels of serotonin and its principal metabolite in all four brain regions because this monoamine is implicated in perception and behavioral output and is found throughout the avian forebrain. After controlling for recent singing, we found that males exposed to more challenging song had higher levels of norepinephrine metabolite in the CMM and lower levels of serotonin in the RA. Collectively, these findings are consistent with norepinephrine in perceptual brain regions and serotonin in song control regions contributing to neuroplasticity that underlies socially-induced changes in behavioral state.

The Effects of Resistance Training on Golf Performance and Physiological Stress Response During Competition in Intercollegiate Golfers

National Research Council Canada - National Science Library

Doan, Brandon

2002-01-01

...) on clubhead speed, consistency, and putting distance control. 2) To investigate the effects of 36 continuous holes of competitive golf on testosterone and cortisol response and their relation to performance. Study #1...

Combining the Sterile Insect Technique with the Incompatible Insect Technique: III-Robust Mating Competitiveness of Irradiated Triple Wolbachia-Infected Aedes albopictus Males under Semi-Field Conditions.

Science.gov (United States)

Zhang, Dongjing; Lees, Rosemary Susan; Xi, Zhiyong; Bourtzis, Kostas; Gilles, Jeremie R L

2016-01-01

Combination of the sterile insect technique with the incompatible insect technique is considered to be a safe approach to control Aedes albopictus populations in the absence of an accurate and scalable sex separation system or genetic sexing strain. Our previous study has shown that the triple Wolbachia-infected Ae. albopictus strain (wAlbA, wAlbB and wPip) was suitable for mass rearing and females could be completely sterilized as pupae with a radiation dose of at least 28 Gy. However, whether this radiation dose can influence the mating competitiveness of the triple infected males was still unknown. In this study we aimed to evaluate the effects of irradiation on the male mating competitiveness of the triple infected strain under laboratory and semi-field conditions. The results herein indicate that irradiation with a lower, female-sterilizing dose has no negative impact on the longevity of triple infected males while a reduced lifespan was observed in the wild type males (wAlbA and wAlbB) irradiated with a higher male-sterilizing dose, in small cages. At different sterile: fertile release ratios in small cages, triple-infected males induced 39.8, 81.6 and 87.8% sterility in a wild type female population at 1:1, 5:1 and 10:1 release ratios, respectively, relative to a fertile control population. Similarly, irradiated triple infected males induced 31.3, 70.5 and 89.3% sterility at 1:1, 5:1 and 10:1 release ratios, respectively, again relative to the fertile control. Under semi-field conditions at a 5:1 release ratio, relative to wild type males, the mean male mating competitiveness index of 28 Gy irradiated triple-infected males was significantly higher than 35 Gy irradiated wild type males, while triple infected males showed no difference in mean mating competitiveness to either irradiated triple-infected or irradiated wild type males. An unexpected difference was also observed in the relative male mating competitiveness of the triple infected strain after

Exhibitionist Eating: Who Wins Eating Competitions?

Science.gov (United States)

Wansink, Brian; Kniffin, Kevin M

2016-01-01

How and why does competition and spectator involvement influence eating behaviors? The primary objective of this article is to explore the nature of competitive eating with the goal of identifying implications for other social situations. Study 1 investigated how many chicken wings were eaten by men and women in a 30-min eating competition when cheering spectators either were or were not present (compared to a control condition). The second study sought to explain Study 1's findings through a survey of 93 students who rated male or female competitive eaters (in randomized order) based on intelligence, attractiveness, health, strength, and how romantic they expected the eaters to be. Exploratory findings show competitive eaters ate approximately four times as many chicken wings as a similar control group, and the presence of a cheering audience further increased wing consumption for males (but decreased consumption for females). Study 2 suggests part of the over-performance of males may be related to a shared positive perception that competitive male eaters are strong and virile. Even in relatively low-stakes environments, competitive visibility may dramatically increase how much males eat. These preliminary results help illuminate recent discoveries that males overeat in various social situations where there are opportunities for men to "show off." This may have relevance for dining behavior - especially among younger males - at parties, banquets, group dinners, and similar social situations.

Experimental evolution of sperm competitiveness in a mammal

Directory of Open Access Journals (Sweden)

Simmons Leigh W

2011-01-01

Full Text Available Abstract Background When females mate with multiple partners, sperm from rival males compete to fertilise the ova. Studies of experimental evolution have proven the selective action of sperm competition on male reproductive traits. However, while reproductive traits may evolve in response to sperm competition, this does not necessarily provide evidence that sperm competitive ability responds to selection. Indeed, a study of Drosophila failed to observe divergence in sperm competitive ability of males in lines selected for enhanced sperm offence and defence. Results Adopting the naturally polygamous house mouse (Mus domesticus as our vertebrate model, we performed an experimental evolution study and observed genetic divergence in sperm quality; males from the polygamous selection lines produced ejaculates with increased sperm numbers and greater sperm motility compared to males from the monogamous lines. Here, after 12 generations of experimental evolution, we conducted competitive matings between males from lineages evolving under sperm competition and males from lineages subject to relaxed selection. We reduced variation in paternity arising from embryo mortality by genotyping embryos in utero at 14 days gestation. Our microsatellite data revealed a significant paternity bias toward males that evolved under the selective regime of sperm competition. Conclusion We provide evidence that the sperm competitiveness phenotype can respond to selection, and show that improved sperm quality translates to greater competitive fertilisation success in house mice.

When the ball is in the female's court: How the scramble-competition mating system of the North American red squirrel has shaped male physiology and testosterone dynamics.

Science.gov (United States)

Boonstra, Rudy; Dušek, Adam; Lane, Jeffrey E; Boutin, Stan

2017-10-01

Male reproductive success in most mammals is determined by their success in direct inter-male competition through aggression and conflict, resulting in female-defense mating systems being predominant. This is linked to male testosterone levels and its dynamics. However, in certain environments, a scramble-competition mating system has evolved, where female reproductive behavior takes precedence and male testosterone dynamics are unlikely to be related to inter-male competition. We studied the North American red squirrel (Tamiasciurus hudsonicus), a species with a well-established scramble-competition system. Using an ACTH hormonal challenge protocol as a proxy for competitive interactions, we compared the testosterone dynamics in breeding males in late winter with that in nonbreeding males in late spring in the Yukon. To gain an integrated picture of their physiological state, we also assessed changes in their stress response, body mass, energy mobilization, and indices of immune function. Testosterone levels at the base bleed were high in breeding males (2.72ng/mL) and virtually absent in non-breeding males (0.04ng/mL). Breeding males were in better condition (heavier body mass, higher hematocrit, and higher erythrocytes), had higher indices of immune function (neutrophil:lymphocyte ratio), but a similar ability to mobilize energy (glucose) compared with non-breeding males. Though total cortisol was higher in non-breeding males, free cortisol was twice as high in breeding males as their corticosteroid binding globulin levels were half as high. In response to the ACTH challenge, testosterone levels in breeding males declined 49% over the first hour and increased 36% over the next hour; in non-breeding males levels showed no change. Free cortisol increased only modestly (26% in breeding males; 23% in non-breeding males). Glucose levels changed similarly in breeding and nonbreeding males, declining for the first 30min and then increasing for the next 60min. Thus

Exhibitionist eating: Who wins eating competitions?

Directory of Open Access Journals (Sweden)

Brian Wansink

2016-11-01

Full Text Available Objective: How and why does competition and spectator involvement influence eating behaviors? The primary objective of this article is to explore the nature of eating competitions with the goal of identifying implications for other social situations.Design: Study 1 investigated how many chicken wings were eaten by men and women in a 30-minute eating competition when cheering spectators either were or were not present (compared to a control condition. A second study sought to explain Study 1’s findings through a survey of 93 students who rated male or female competitive eaters (in randomized order based on intelligence, attractiveness, health, strength, and how romantic they expected the eaters to be.Results: Exploratory findings show competitive eaters ate approximately four times as many chicken wings as a similar control group, and the presence of a cheering audience further increased wing consumption for males (but decreased consumption for females. Study 2 suggests part of the over-performance of males may be related to a shared positive perception that competitive male eaters are strong and virile. Conclusions: Even in relatively low-stakes environments, competitive visibility may dramatically increase how much males eat. These preliminary results help illuminate recent discoveries that males overeat in various social situations where there are opportunities for men to show off. This may have relevance for dining behavior – especially among younger males – at parties, banquets, group dinners, and similar social situations.

The relevance of age and nutritional status on the mating competitiveness of medfly males (Diptera: Teprhitidae

Directory of Open Access Journals (Sweden)

Alzira Kelly Passos Roriz

2013-10-01

Full Text Available Results of previous investigations trying to ascertain which physiological factors are more important to the mating success of medfly males are controversial. In part, this controversy owes to the fact that each factor was evaluated by an independent study using different experimental designs and populations. In the present study we compare the roles of age and nutritional status (immature and adult phases on the mating competitiveness of Ceratitis capitata (Wiedemann, 1824 males. Three parameters were used to evaluate the male mating success: calling behavior (pheromone emission, lek participation and copulation (ability to be chosen by a female. Females gave preference to the males that were given a high protein diet in the larval phase. By contrast, females did not give preference to males that had been well-nourished in the adult phase only. The other parameters evaluated followed the same pattern: young males and males that had been fed a high protein diet during their immature phase had a greater participation in leks and called more often than older males and males that had been fed a diet poor in protein during their larval phase. Therefore, we conclude that the mating success of C. capitata males is determined both by age and nourishment during the immature stage.

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners.

Science.gov (United States)

Kuhman, Daniel; Melcher, Daniel; Paquette, Max R

2016-01-01

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile(-1)) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game

DEFF Research Database (Denmark)

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G

2018-01-01

We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated...

Study of the compatibility and competitiveness of sterile males in the framework of the struggle by the sterile insect technique against the Ceratitis

International Nuclear Information System (INIS)

Azzabi, Jihene

2007-01-01

We evaluated under semi-natural field-cage conditions sexual compatibility and competitivity of laboratory strain (Genetic Sexing Strain GSS) ''Vienna 8''. The GSS strain is produced under mass (rearing conditions at the facility of production of sterile males at Sidi Thabat. Wild flies were obtained from infested Sommer oranges. Twenty-five wild males, 25 wild females and 25 GSS were released into cage and mating pairs collected. The determination of indices such as the Isolation Index (ISI), the Male Relative Index (MRPI), the Stalker Index (I) and the Relative Sterile Index (RSI) shows that there is no compatibility and competitiveness between the two strains with a tendency to behaviour of sexual isolation. Sterile male tests dissection irradiated at the dose of (0 Gy, 110 Gy, 120 Gy, 130 Gy and 145 Gy) and correspondent female spermatic show the important damage of the irradiation on the cells but decrease the quality of the sterile male (mating duration, sperm transfer.). (Author)

Overthinking skilled motor performance: or why those who teach can't do.

Science.gov (United States)

Flegal, Kristin E; Anderson, Michael C

2008-10-01

Skilled athletes often maintain that overthinking disrupts performance of their motor skills. Here, we examined whether these experiences have a basis in verbal overshadowing, a phenomenon in which describing memories for ineffable perceptual experiences disrupts later retention. After learning a unique golf-putting task, golfers of low and intermediate skill either described their actions in detail or performed an irrelevant verbal task. They then performed the putting task again. Strikingly, describing their putting experience significantly impaired higher skill golfers' ability to reachieve the putting criterion, compared with higher skill golfers who performed the irrelevant verbal activity. Verbalization had no such effect, however, for lower skill golfers. These findings establish that the effects of overthinking extend beyond dual-task interference and may sometimes reflect impacts on long-term memory. We propose that these effects are mediated by competition between procedural and declarative memory, as suggested by recent work in cognitive neuroscience.

Maize ROP2 GTPase provides a competitive advantage to the male gametophyte.

Science.gov (United States)

Arthur, K M; Vejlupkova, Z; Meeley, R B; Fowler, J E

2003-12-01

Rop GTPases have been implicated in the regulation of plant signal transduction and cell morphogenesis. To explore ROP2 function in maize, we isolated five Mutator transposon insertions (rop2::Mu alleles). Transmission frequency through the male gametophyte, but not the female, was lower than expected in three of the rop2::Mu mutants. These three alleles formed an allelic series on the basis of the relative transmission rate of each when crossed as trans-heterozygotes. A dramatic reduction in the level of ROP2-mRNA in pollen was associated with the three alleles causing a transmission defect, whereas a rop2::Mu allele that did not result in a defect had wild-type transcript levels, thus confirming that mutation of rop2 causes the mutant phenotype. These data strongly support a role for rop2 in male gametophyte function, perhaps surprisingly, given the expression in pollen of the nearly identical duplicate gene rop9. However, the transmission defect was apparent only when a rop2::Mu heterozygote was used as the pollen donor or when a mixture of wild-type and homozygous mutant pollen was used. Thus, mutant pollen is at a competitive disadvantage compared to wild-type pollen, although mutant pollen grains lacked an obvious cellular defect. Our data demonstrate the importance in vivo of a specific Rop, rop2, in the male gametophyte.

Competitive societies are happy if the women are less competitive than the men

NARCIS (Netherlands)

Van de Vliert, E.; Janssen, O.

2002-01-01

Societies are less happy to the extent that their members are more competitive. A 42-nation regression study, based on aggregated indicators of female competitiveness, male competitiveness, four components of happiness, and national development restricts this negative cultural link between overall

A Nation at Risk: Increasing College Participation and Persistence Among African American Males to Stimulate U.S. Global Competitiveness

Directory of Open Access Journals (Sweden)

Adriel A. Hilton

2010-05-01

Full Text Available Today’s knowledge-based, global commerce requires continuous investment in human capital through postsecondary education for countries to be fiercely competitive. Countries, such as China and India, are experiencing growth in the number of people participating in postsecondary education; the United States has fallen behind. While America needs to focus on increasing college access and degree completion among underrepresented ethnic minorities, particularly in Science, Technology, Engineering, and Mathematics (STEM, educators and policymakers assert that this is particularly important for African American males. Increasing matriculation and graduation rates for African Americans is not only a matter of equity, but in the context of STEM, it has major implications for the competitiveness of the United States in the global economy. This article identifies strategies that educators and policymakers can employ to promote the participation of African American males in college in general, particularly in STEM.

Somatotype, Level of Competition, and Performance in Attack in Elite Male Volleyball

Science.gov (United States)

Giannopoulos, Nikiforos; Vagenas, George; Noutsos, Konstantinos; Barzouka, Karolina; Bergeles, Nikolaos

2017-01-01

Abstract This study investigated the relationship between somatotype, level of competition, and performance in attack in elite level male volleyball players. The objective was to test for the potential covariation of competition level (Division A1 vs. A2) and playing position (hitters vs. centers vs. opposites) considering performance in attack. Anthropometric, body composition and somatotype variables were measured according to the Heath-Carter method. The attack actions of 144 players from 48 volleyball matches were analyzed and their performance was rated using a 5-point numerical scale. Results showed that players of Division A1 were taller, heavier, more muscular, and less endomorphic compared to those of Division A2. MANOVA and follow-up discriminant function analysis revealed somatotype differences among playing positions with centers and opposites being endomorph-ectomorph and hitters being central. Centers performed constantly better than hitters and opposites regardless of the division and somatotype. Multiple linear regression analysis showed that variables defining ectomorph and endomorph players, centers, and players of Division A1 significantly determined the relative performance superiority and were able to explain the variation in performance by almost 25%. These results could be taken into account by coaches when assigning players to particular playing positions or when designing individualized position-specific training programs. PMID:28828084

Somatotype, Level of Competition, and Performance in Attack in Elite Male Volleyball

Directory of Open Access Journals (Sweden)

Giannopoulos Nikiforos

2017-08-01

Full Text Available This study investigated the relationship between somatotype, level of competition, and performance in attack in elite level male volleyball players. The objective was to test for the potential covariation of competition level (Division A1 vs. A2 and playing position (hitters vs. centers vs. opposites considering performance in attack. Anthropometric, body composition and somatotype variables were measured according to the Heath-Carter method. The attack actions of 144 players from 48 volleyball matches were analyzed and their performance was rated using a 5-point numerical scale. Results showed that players of Division A1 were taller, heavier, more muscular, and less endomorphic compared to those of Division A2. MANOVA and follow-up discriminant function analysis revealed somatotype differences among playing positions with centers and opposites being endomorph-ectomorph and hitters being central. Centers performed constantly better than hitters and opposites regardless of the division and somatotype. Multiple linear regression analysis showed that variables defining ectomorph and endomorph players, centers, and players of Division A1 significantly determined the relative performance superiority and were able to explain the variation in performance by almost 25%. These results could be taken into account by coaches when assigning players to particular playing positions or when designing individualized position-specific training programs.

Parental social status and intrasexual competitiveness among adolescents.

Science.gov (United States)

Buunk, Abraham P; Stulp, Gert; Ormel, Johan

2014-11-17

A study among 1,881 adolescents (52.3% girls) with a mean age of 19.1 years examined the effects of parental social status upon intrasexual competitiveness. Whereas females were consistently more intrasexually competitive the higher the socio-economic status of their parents, males with parents of the lowest socio-economic status tended to be more intrasexually competitive than those with parents of medium socio-economic status, and nearly as intrasexually competitive as those with parents of high socio-economic status. Only among adolescents with parents of low socio-economic status were males more intrasexually competitive than females. Among males and females, higher levels of intrasexual competitiveness were related to a higher family income, to a higher occupational status of the father as well as of the mother, and to a higher educational level of the mother. Only among females were higher levels of intrasexual competitiveness associated with a higher educational level of the father. Males whose fathers had only elementary education had a relatively high level of intrasexual competitiveness. The results are discussed in the context of the multifaceted nature of human status, and the potential relevance of intrasexual competitiveness for individuals of high versus low social status.

Functional Movement Screen for Predicting Running Injuries in 18- to 24-Year-Old Competitive Male Runners.

Science.gov (United States)

Hotta, Takayuki; Nishiguchi, Shu; Fukutani, Naoto; Tashiro, Yuto; Adachi, Daiki; Morino, Saori; Shirooka, Hidehiko; Nozaki, Yuma; Hirata, Hinako; Yamaguchi, Moe; Aoyama, Tomoki

2015-10-01

The purpose of this study was to investigate whether the functional movement screen (FMS) could predict running injuries in competitive runners. Eighty-four competitive male runners (average age = 20.0 ± 1.1 years) participated. Each subject performed the FMS, which consisted of 7 movement tests (each score range: 0-3, total score range: 0-21), during the preseason. The incidence of running injuries (time lost because of injury ≤ 4 weeks) was investigated through a follow-up survey during the 6-month season. Mann-Whitney U-tests were used to investigate which movement tests were significantly associated with running injuries. The receiver-operator characteristic (ROC) analysis was used to determine the cutoff. The mean FMS composite score was 14.1 ± 2.3. The ROC analysis determined the cutoff at 14/15 (sensitivity = 0.73, specificity = 0.54), suggesting that the composite score had a low predictability for running injuries. However, the total scores (0-6) from the deep squat (DS) and active straight leg raise (ASLR) tests (DS and ASLR), which were significant with the U-test, had relatively high predictability at the cutoff of 3/4 (sensitivity = 0.73, specificity = 0.74). Furthermore, the multivariate logistic regression analysis revealed that the DS and ASLR scores of ≤3 significantly influenced the incidence of running injuries after adjusting for subjects' characteristics (odds ratio = 9.7, 95% confidence interval = 2.1-44.4). Thus, the current study identified the DS and ASLR score as a more effective method than the composite score to screen the risk of running injuries in competitive male runners.

Responses to Forces Influencing Cohesion as a Function of Player Status and Level of Male Varsity Basketball Competition.

Science.gov (United States)

Gruber, Joseph J.; Gray, Gary R.

1982-01-01

A study analyzed team cohesion perceptions of 515 male varsity basketball players (10 to 22 years of age) to determine if factors influencing team cohesion were a function of competitive intensity or of the importance of individual players to their team. Players with the most game playing time were more satisfied than those with less playing time.…

Male mating competitiveness of a Wolbachia-introgressed Aedes polynesiensis strain under semi-field conditions.

Directory of Open Access Journals (Sweden)

Eric W Chambers

2011-08-01

Full Text Available Lymphatic filariasis (LF, a global public health problem affecting approximately 120 million people worldwide, is a leading cause of disability in the developing world including the South Pacific. Despite decades of ongoing mass drug administration (MDA in the region, some island nations have not yet achieved the threshold levels of microfilaremia established by the World Health Organization for eliminating transmission. Previously, the generation of a novel Aedes polynesiensis strain (CP infected with an exogenous type of Wolbachia has been described. The CP mosquito is cytoplasmically incompatible (i.e., effectively sterile when mated with wildtype mosquitoes, and a strategy was proposed for the control of A. polynesiensis populations by repeated, inundative releases of CP males to disrupt fertility of wild females. Such a strategy could lead to suppression of the vector population and subsequently lead to a reduction in the transmission of filarial worms.CP males and F1 male offspring from wild-caught A. polynesiensis females exhibit near equal mating competitiveness with F1 females under semi-field conditions.While laboratory experiments are important, prior projects have demonstrated the need for additional testing under semi-field conditions in order to recognize problems before field implementation. The results reported here from semi-field experiments encourage forward progression toward small-scale field releases.

Life table and male mating competitiveness of wild type and of a chromosome mutation strain of Tetranychus urticae in relation to genetic pest control

International Nuclear Information System (INIS)

Feldmann, A.M.

1981-01-01

Males of Tetranychus urticae Koch (Acarina: Tetranychidae) from a strain, homozygous for a structural chromosome mutation (T) were competed against males from a standard (wild-type) strain for mating of wild-type fermales. The T-males exhibited only a slight reduction in male mating competitiveness. The debilitating influence of ageing on male mating competitiveness was equal for males of both strains. Life-table studies on both strains showed that the net reproductive rate (R 0 ) of the T-strain was 53.3, which was higher than the R 0 -value of the standard strain (43.3). This difference was caused by the higher rate of age-dependent mortality of adult females of the standard strain. Also differences between both strains in the total sex-ratio were observed; the T-strain produced significantly fewer males and more females than the standard strain. The mean generation time of both strains was almost equal (14 days). The values of the intrinsic rate of increase (rsub(m)) for the T-strain and the standard strain were 0.286 and 0.273, respectively. The life-table data correspond well with those published elsewhere on Tetranychus urticae. The feasibility of T-strains for application in genetic pest control considering the use of structural chromosome mutations as a 'transport mechanism' for conditional lethals is discussed. (orig.)

Sexual competitiveness of gamma irradiated red flour beetle, tribolium castaneum (herbst)

International Nuclear Information System (INIS)

Satar, A.; Khan, A.; Khattak, S.U.; Salihan, Z.

1989-01-01

Studies on the sexual competitiveness of radiated male and female adults of tribolium castaneum were conducted under controlled laboratory conditions. The results evaluated on the basis of tendency infertility and competitiveness showed that a ratio of 5:1:1 (Irradiated male/female: Unirradiated male/female: Unirradiated female/male) was the best followed by 4:1:1, 3;1:1, 2:1:1 and 1:1:1 in both the sexes. However, females were found more competitive than male. (author)

Competition between the sperm of a single male can increase the evolutionary rate of haploid expressed genes.

Science.gov (United States)

Ezawa, Kiyoshi; Innan, Hideki

2013-07-01

The population genetic behavior of mutations in sperm genes is theoretically investigated. We modeled the processes at two levels. One is the standard population genetic process, in which the population allele frequencies change generation by generation, depending on the difference in selective advantages. The other is the sperm competition during each genetic transmission from one generation to the next generation. For the sperm competition process, we formulate the situation where a huge number of sperm with alleles A and B, produced by a single heterozygous male, compete to fertilize a single egg. This "minimal model" demonstrates that a very slight difference in sperm performance amounts to quite a large difference between the alleles' winning probabilities. By incorporating this effect of paternity-sharing sperm competition into the standard population genetic process, we show that fierce sperm competition can enhance the fixation probability of a mutation with a very small phenotypic effect at the single-sperm level, suggesting a contribution of sperm competition to rapid amino acid substitutions in haploid-expressed sperm genes. Considering recent genome-wide demonstrations that a substantial fraction of the mammalian sperm genes are haploid expressed, our model could provide a potential explanation of rapid evolution of sperm genes with a wide variety of functions (as long as they are expressed in the haploid phase). Another advantage of our model is that it is applicable to a wide range of species, irrespective of whether the species is externally fertilizing, polygamous, or monogamous. The theoretical result was applied to mammalian data to estimate the selection intensity on nonsynonymous mutations in sperm genes.

Mating competitiveness of sterile genetic sexing strain males (GAMA) under laboratory and semi-field conditions: Steps towards the use of the Sterile Insect Technique to control the major malaria vector Anopheles arabiensis in South Africa.

Science.gov (United States)

Munhenga, Givemore; Brooke, Basil D; Gilles, Jeremie R L; Slabbert, Kobus; Kemp, Alan; Dandalo, Leonard C; Wood, Oliver R; Lobb, Leanne N; Govender, Danny; Renke, Marius; Koekemoer, Lizette L

2016-03-02

Anopheles arabiensis Patton is primarily responsible for malaria transmission in South Africa after successful suppression of other major vector species using indoor spraying of residual insecticides. Control of An. arabiensis using current insecticide based approaches is proving difficult owing to the development of insecticide resistance, and variable feeding and resting behaviours. The use of the sterile insect technique as an area-wide integrated pest management system to supplement the control of An. arabiensis was proposed for South Africa and is currently under investigation. The success of this technique is dependent on the ability of laboratory-reared sterile males to compete with wild males for mates. As part of the research and development of the SIT technique for use against An. arabiensis in South Africa, radio-sensitivity and mating competitiveness of a local An. arabiensis sexing strain were assessed. The optimal irradiation dose inducing male sterility without compromising mating vigour was tested using Cobalt 60 irradiation doses ranging from 70-100 Gy. Relative mating competitiveness of sterile laboratory-reared males (GAMA strain) compared to fertile wild-type males (AMAL strain) for virgin wild-type females (AMAL) was investigated under laboratory and semi-field conditions using large outdoor cages. Three different sterile male to fertile male to wild-type female ratios were evaluated [1:1:1, 5:1:1 and 10:1:1 (sterile males: fertile, wild-type males: fertile, wild-type females)]. Irradiation at the doses tested did not affect adult emergence but had a moderate effect on adult survivorship and mating vigour. A dose of 75 Gy was selected for the competitiveness assays. Mating competitiveness experiments showed that irradiated GAMA male mosquitoes are a third as competitive as their fertile AMAL counterparts under semi-field conditions. However, they were not as competitive under laboratory conditions. An inundative ratio of 10:1 induced the

Male Mating Competitiveness of a Wolbachia-Introgressed Aedes polynesiensis Strain under Semi-Field Conditions

Science.gov (United States)

Bossin, Hervé; Dobson, Stephen L.

2011-01-01

Background Lymphatic filariasis (LF), a global public health problem affecting approximately 120 million people worldwide, is a leading cause of disability in the developing world including the South Pacific. Despite decades of ongoing mass drug administration (MDA) in the region, some island nations have not yet achieved the threshold levels of microfilaremia established by the World Health Organization for eliminating transmission. Previously, the generation of a novel Aedes polynesiensis strain (CP) infected with an exogenous type of Wolbachia has been described. The CP mosquito is cytoplasmically incompatible (i.e., effectively sterile) when mated with wildtype mosquitoes, and a strategy was proposed for the control of A. polynesiensis populations by repeated, inundative releases of CP males to disrupt fertility of wild females. Such a strategy could lead to suppression of the vector population and subsequently lead to a reduction in the transmission of filarial worms. Methodology/Principal Findings CP males and F1 male offspring from wild-caught A. polynesiensis females exhibit near equal mating competitiveness with F1 females under semi-field conditions. Conclusions/Significance While laboratory experiments are important, prior projects have demonstrated the need for additional testing under semi-field conditions in order to recognize problems before field implementation. The results reported here from semi-field experiments encourage forward progression toward small-scale field releases. PMID:21829750

Studies on the ecology of insects sterilized artificially (gamma radiation), 6. Mating competitiveness between the /sup 137/Cs gamma-substerile males reared artificially and natural ones of the tobacco cutworms

Energy Technology Data Exchange (ETDEWEB)

Kiyoku, M; Tsukuda, R [Okayama Univ. (Japan). Faculty of Agriculture

1973-10-01

Two different inbred lines of tobacco cutworms were used for the present experiments. One was a line reared on an artificial medium during the larval period, and the other was reared on leaves of the taro plants. Male pupae from the former medium were irradiated with 12 kR of gamma rays from /sup 137/Cs to substerilize. Other males and females from the latter were not irradiated. From one to four substerilized adults with one normal male were exposed to one normal female in a fixed mating-oviposition jar or cage for investigating the male mating competitiveness and mating behavior between substerilized and normal. In the experiments using substerilized adults less than two with one normal male were exposed to one female in the jar, the hatch percentages of eggs were more than 41.7%. It might not be fully competitive. When four substerile and one normal males were combined with one normal female, however, the percentage in the egg hatch was 5.6%. The value obtained was significantly lower than the theoretical estimation of hatch percentage, and this indicates that substerilized males had been mated more than normal. The result was considered to be fully competitive based on the percentage of egg hatch. Besides that, number of eggs laid in this combination showed a considerable reduction as compared with the control.

Free-ranging male koalas use size-related variation in formant frequencies to assess rival males.

Directory of Open Access Journals (Sweden)

Benjamin D Charlton

Full Text Available Although the use of formant frequencies in nonhuman animal vocal communication systems has received considerable recent interest, only a few studies have examined the importance of these acoustic cues to body size during intra-sexual competition between males. Here we used playback experiments to present free-ranging male koalas with re-synthesised bellow vocalisations in which the formants were shifted to simulate either a large or a small adult male. We found that male looking responses did not differ according to the size variant condition played back. In contrast, male koalas produced longer bellows and spent more time bellowing when they were presented with playbacks simulating larger rivals. In addition, males were significantly slower to respond to this class of playback stimuli than they were to bellows simulating small males. Our results indicate that male koalas invest more effort into their vocal responses when they are presented with bellows that have lower formants indicative of larger rivals, but also show that males are slower to engage in vocal exchanges with larger males that represent more dangerous rivals. By demonstrating that male koalas use formants to assess rivals during the breeding season we have provided evidence that male-male competition constitutes an important selection pressure for broadcasting and attending to size-related formant information in this species. Further empirical studies should investigate the extent to which the use of formants during intra-sexual competition is widespread throughout mammals.

Examining the relationship between relative age, competition level, and dropout rates in male youth ice-hockey players.

Science.gov (United States)

Lemez, S; Baker, J; Horton, S; Wattie, N; Weir, P

2014-12-01

The relative age effect suggests that athletes born in the first two quartiles of a given selection year experience a selection advantage and therefore a greater opportunity for success. We describe two studies examining the relationship between relative age, competition level, and dropout rates of Ontario Minor Hockey Association male ice-hockey players from ages 10 to 15 years (n = 14 325). In Study 1, dropout was highest among players born in quartiles three and four [χ(2) (3) = 16.32, P < 0.05; w = 0.06], while Study 2 found dropped out players to have less movement between competition levels compared to retained players. This study confirms a relationship between relative age and dropout from ice-hockey and adds further depth to our understanding of this persistent phenomenon. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Male density affects large-male advantage in the golden silk spider, Nephila clavipes

OpenAIRE

Clare C. Rittschof

2010-01-01

Across a variety of animal taxa, the outcome of male--male contests depends on male body size; winners are usually the larger males or the males with bigger weapons. However, high male density can either increase or reverse large-male advantage because density changes the frequency and intensity of male--male interactions. In the golden orb-web spider Nephila clavipes, large males have a competitive advantage in male--male contests. However, this species shows more than 2-fold variation in ma...

Diversifying evolution of competitiveness.

Science.gov (United States)

Baldauf, Sebastian A; Engqvist, Leif; Weissing, Franz J

2014-10-29

In many species, individuals express phenotypic characteristics that enhance their competitiveness, that is, the ability to acquire resources in competition with others. Moreover, the degree of competitiveness varies considerably across individuals and in time. By means of an evolutionary model, we provide an explanation for this finding. We make the assumption that investment into competitiveness enhances the probability to acquire a high-quality resource, but at the same time reduces the ability of exploiting acquired resources with maximal efficiency. The model reveals that under a broad range of conditions competitiveness either converges to a polymorphic state, where individuals differing in competitive ability stably coexist, or is subject to perpetual transitions between periods of high and low competitiveness. The dynamics becomes even more complex if females can evolve preferences for (or against) competitive males. In extreme cases, such preferences can even drive the population to extinction.

Color and behavior differently predict competitive outcomes for divergent stickleback color morphs

Science.gov (United States)

Lehto, Whitley R; Lierheimer, V Faith

2018-01-01

Abstract Our knowledge of how male competition contributes to speciation is dominated by investigations of competition between within-species morphs or closely related species that differ in conspicuous traits expressed during the breeding season (e.g. color, song). In such studies, it is important to consider the manner in which putatively sexually selected traits influence the outcome of competitive interactions within and between types because these traits can communicate information about competitor quality and may not be utilized by homotypic and heterotypic receivers in the same way. We studied the roles of breeding color and aggressive behaviors in competition within and between two divergent threespine stickleback Gasterosteus aculeatus color types. Our previous work in this system showed that the switch from red to black breeding coloration is associated with changes in male competition biases. Here, we find that red and black males also use different currencies in competition. Winners of both color types performed more aggressive behaviors than losers, regardless of whether the competitor was of the same or opposite color type. But breeding color differently predicted competitive outcomes for red and black males. Males who were redder at the start of competition were more likely to win when paired with homotypic competitors and less likely to win when paired with heterotypic competitors. In contrast, black color, though expressed in the breeding season and condition dependent, was unrelated to competitive outcomes. Placing questions about the role of male competition in speciation in a sexual signal evolution framework may provide insight into the “why and how” of aggression biases and asymmetries in competitive ability between closely related morphs and species. PMID:29492044

Sperm competition in humans: mate guarding behavior negatively correlates with ejaculate quality.

Science.gov (United States)

Leivers, Samantha; Rhodes, Gillian; Simmons, Leigh W

2014-01-01

In species where females mate with multiple males, the sperm from these males must compete to fertilise available ova. Sexual selection from sperm competition is expected to favor opposing adaptations in males that function either in the avoidance of sperm competition (by guarding females from rival males) or in the engagement in sperm competition (by increased expenditure on the ejaculate). The extent to which males may adjust the relative use of these opposing tactics has been relatively neglected. Where males can successfully avoid sperm competition from rivals, one might expect a decrease in their expenditure on tactics for the engagement in sperm competition and vice versa. In this study, we examine the relationship between mate guarding and ejaculate quality using humans as an empirical model. We found that men who performed fewer mate guarding behaviors produced higher quality ejaculates, having a greater concentration of sperm, a higher percentage of motile sperm and sperm that swam faster and less erratically. These effects were found independent of lifestyle factors or factors related to male quality. Our findings suggest that male expenditure on mate guarding and on the ejaculate may represent alternative routes to paternity assurance in humans.

Studies on the ecology of insects sterilized artificially (gamma radiation), 8. Experimental analysis of the sexual competitiveness between normal males of the oriental fruit fly and males sterilized by the /sup 137/Cs gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Kiyoku, M; Tsukuda, R [Okayama Univ. (Japan). Faculty of Agriculture

1974-09-01

Gamma-ray irradiation of 7 KR from /sup 137/Cs on the oriental fruit fly pupae two days before emerging did not significantly reduce the percentage of emergence and longevity of adult flies. However, highly sterile adults (more than 98.9%) were found in those combinations, S..gamma.. x N/sup -/, N..gamma.. x S/sup -/ and S..gamma.. x S/sup -/. The result of observation of sperm activity in spermathecae of females mated with sterilized males showed that the sterility is caused by dominant lethalities. The sexual competitiveness between S..gamma.. and N..gamma.. has been examined in experiments of S..gamma.. x N..gamma.. x N/sup -/. (1) The data suggest that the sterility percentage concerning with egg hatchability is proportional to the rate of sterilized males replaced for normal males when that is expressed with a multiple of the ratio of normal males to normal females. Seven such straight lines thus obtained made us possible to find the theoretical expectation of sterility percentage. (2) Relationship between the percent egg hatch observed (y), or that estimated theoretically (Y), and logarithm of ratio, S..gamma../N..gamma.. (x) was showed to be two straight regression equations, y=18.413-11.952 (x - 1.295) and Y=11.890-15.462 (x - 1.295). Ratio of regression coefficients of the equations was 0.772. (3) Correlations between the sterility percentage and ratio, S..gamma../N..gamma.., showed in three convex curves under three degrees of competitiveness (0.265, 0.576 and 1.001). When both the values of S..gamma../N..gamma.. in the mating experiments and the sterility percentages are given, it is possible to obtain degrees of competitiveness using the curves.

There is more: Intrasexual competitiveness, physical dominance, and intrasexual collaboration.

Science.gov (United States)

Buunk, Abraham P

2017-01-01

It is emphasized that in organizational settings, the responses to same-sex attractive others are enhanced among individuals high in intrasexual competitiveness; that especially attractive rivals who are perceived as unfriendly will induce competition; that among males, physical dominance may induce more competition than physical attractiveness; and that especially males may prefer to associate with attractive same-sex others for intrasexual collaboration.

Experimental studies on the sterile male technique of spodoptera litura (F. ) by the gamma radiation from /sup 137/Cs, 3. Experiments of the mating competitiveness between moths irradiated as pupae and unirradiated ones in the field cage

Energy Technology Data Exchange (ETDEWEB)

Tsukuda, R; Kiyoku, M [Okayama Univ. (Japan). Faculty of Agriculture

1973-10-01

Experiments of the mating competitiveness between the substerilized tobacco cutworms and the normal ones were carried out in a field cage (200 x 120 x 180 cm/plot). Pupae of seven days old reared on an artificial medium during the larval stage irradiated with 12 kR of the gamma rays to substerilize. The normal adults were cultured using leaves of cabbages. Cabbages and soybeans were planted in the purpose of egg laying for adult females mated with males in the cage. Substerilized males only or both substerilized males and females were combined with normal males and females. The mating behavior, longevity, egg deposition, percentage of egg hatch and spermatophore in a receptaculum seminis were investigated. When more than ten substerilized and one normal males were exposed to one female, or more than fourteen substerilized and two normal males were combined two normal females, the substerilized males showed high competitiveness with normal males for virgin females. When both five substerilized males and females placed together with one pair of normal male and female in the cage, or each ten substerilized males and females with each two normals, these substerilized males showed full competitiveness. In addition, it was found that offspring obtained from the combination between substerilized males and normal females were sterile.

Kinematic evaluation of movement smoothness in golf: relationship between the normalized jerk cost of body joints and the clubhead.

Science.gov (United States)

Choi, Ahnryul; Joo, Su-Bin; Oh, Euichaul; Mun, Joung Hwan

2014-02-26

When the human body is introduced to a new motion or movement, it learns the placement of different body parts, sequential muscle control, and coordination between muscles to achieve necessary positions, and it hones this new skill over time and repetition. Previous studies have demonstrated definite differences in the smoothness of body movements with different levels of training, i.e., amateurs compared with professionals. Therefore, we tested the hypothesis that skilled golfers swing a driver with a smoother motion than do unskilled golfers. In addition, the relationship between the smoothness of body joints and that of the clubhead was evaluated to provide further insight into the mechanism of smooth golf swing. Two subject groups (skilled and unskilled) participated in the experiment. The skilled group comprised 20 male professional golfers registered with the Korea Professional Golf Association, and the unskilled group comprised 19 amateur golfers who enjoy golf as a hobby. Six infrared cameras (VICON460 system) were used to record the 3D trajectories of markers attached to the clubhead and body segments, and the resulting data was evaluated with kinematic analysis. A physical quantity called jerk was calculated to investigate differences in smoothness during downswing between the two study groups. The hypothesis that skilled golfers swing a driver with a smoother motion than do unskilled golfers was supported. The normalized jerk of the clubhead of skilled golfers was lower than that of unskilled golfers in the anterior/posterior, medial/lateral, and proximal/distal directions. Most human joints, especially in the lower body, had statistically significant lower normalized jerk values in the skilled group. In addition, the normalized jerk of the skilled group's lower body joints had a distinct positive correlation with the normalized jerk of the clubhead with r = 0.657 (p golf swings and, eventually, to improve golf performance.

Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid.

Science.gov (United States)

Bartlett, Michael J; Steeves, Tammy E; Gemmell, Neil J; Rosengrave, Patrice C

2017-10-31

In many species, males can make rapid adjustments to ejaculate performance in response to sperm competition risk; however, the mechanisms behind these changes are not understood. Here, we manipulate male social status in an externally fertilising fish, chinook salmon ( Oncorhynchus tshawytscha ), and find that in less than 48 hr, males can upregulate sperm velocity when faced with an increased risk of sperm competition. Using a series of in vitro sperm manipulation and competition experiments, we show that rapid changes in sperm velocity are mediated by seminal fluid and the effect of seminal fluid on sperm velocity directly impacts paternity share and therefore reproductive success. These combined findings, completely consistent with sperm competition theory, provide unequivocal evidence that sperm competition risk drives plastic adjustment of ejaculate quality, that seminal fluid harbours the mechanism for the rapid adjustment of sperm velocity and that fitness benefits accrue to males from such adjustment.

Male-male aggression peaks at intermediate relatedness in a social spider mite

NARCIS (Netherlands)

Sato, Y.; Egas, M.; Sabelis, M.W.; Mochizuki, A.

2013-01-01

Theory predicts that when individuals live in groups or colonies, male-male aggression peaks at intermediate levels of local average relatedness. Assuming that aggression is costly and directed toward nonrelatives and that competition for reproduction acts within the colony, benefits of aggressive

The evolution of strategic male mating effort in an information transfer framework.

Science.gov (United States)

Engqvist, L; Taborsky, M

2017-06-01

Sperm competition theory predicts that males should use cues indicating the risk and intensity of sperm competition to tailor their sperm investment accordingly. Rival males are an important source of social information regarding sperm competition risk. However, revealing such information may not be in the rival males' interest. Here, we use a theoretical approach based on informed and uninformed games to investigate when information transfer about sperm competition risk to competitors is beneficial for a male, and when it is not. The results show that signalling to potential future mates that a female has already mated is beneficial when the signalling male has a sperm competition disadvantage, whereas it is unfavourable when the signaller has an advantage. The reason for this counterintuitive result is that the rival males' optimal response is to reduce sperm investment when the signaller has a disadvantage and, conversely, to increase investment when the signaller has an advantage. Furthermore, we analysed scenarios where males use alternative reproductive tactics. In this situation, signalling the awareness of sperm competition risk rarely pays; instead, it is beneficial to maintain an information advantage. Thus, it may be beneficial for bourgeois males to accept cuckoldry instead of revealing their sperm competition awareness to reproductive parasites. These results provide new insight into the evolution of communication between rivals in the context of sperm competition. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition.

Science.gov (United States)

Marlowe, Frank W; Berbesque, J Colette

2012-12-01

Among mammals, male-male competition for sexual access to females frequently involves fighting. Larger body size gives males an advantage in fighting, which explains why males tend to be larger than females in many species, including anthropoid primates. Mitani et al. derived a formula to measure the operational sex ratio (OSR) to reflect the degree of male-male competition using the number of reproductively available males to females who are cycling and capable of conceiving. The OSR should predict the degree of sexual dimorphism in body mass-at least if male-male competition involves much fighting or threatening. Here, we use hunter-gatherer demographic data and the Mitani et al. formula to calculate the human OSR. We show that humans have a much lower degree of body mass sexual dimorphism than is predicted by our OSR. We suggest this is because human competition rarely involves fighting. In human hunter-gatherer societies, differences in the ages of marriage have an impact on competition in that the age of males at first marriage is younger when there is a lower percentage of married men with two or more wives, and older when there is a higher percentage of married men with two or more wives. We discuss the implications of this for females, along with the effects of two key life history traits that influence the OSR, concealed ovulation and menopause. While menopause decreases the number of reproductively available females to males and thus increases male-male competition, concealed ovulation decreases male-male competition. Finally, we discuss the importance of mostly monogamous mate bonds in human evolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

Muscle damage produced during a simulated badminton match in competitive male players.

Science.gov (United States)

Abián, Pablo; Del Coso, Juan; Salinero, Juan José; Gallo-Salazar, César; Areces, Francisco; Ruiz-Vicente, Diana; Lara, Beatriz; Soriano, Lidón; Muñoz, Victor; Lorenzo-Capella, Irma; Abián-Vicén, Javier

2016-01-01

The purpose of the study was to assess the occurrence of muscle damage after a simulated badminton match and its influence on physical and haematological parameters. Sixteen competitive male badminton players participated in the study. Before and just after a 45-min simulated badminton match, maximal isometric force and badminton-specific running/movement velocity were measured to assess muscle fatigue. Blood samples were also obtained before and after the match. The badminton match did not affect maximal isometric force or badminton-specific velocity. Blood volume and plasma volume were significantly reduced during the match and consequently haematite, leucocyte, and platelet counts significantly increased. Blood myoglobin and creatine kinase concentrations increased from 26.5 ± 11.6 to 197.3 ± 70.2 µg·L(-1) and from 258.6 ± 192.2 to 466.0 ± 296.5 U·L(-1), respectively. In conclusion, a simulated badminton match modified haematological parameters of whole blood and serum blood that indicate the occurrence of muscle fibre damage. However, the level of muscle damage did not produce decreased muscle performance.

Individual adjustment of sperm expenditure accords with sperm competition theory.

Science.gov (United States)

Pilastro, Andrea; Scaggiante, Marta; Rasotto, Maria B

2002-07-23

Sperm competition theory predicts that males should strategically allocate their sperm reserves according to the level of sperm competition, defined as the probability that the sperm of two males compete for fertilizing a given set of ova. Substantial evidence from numerous animal taxa suggests that, at the individual level, sperm expenditure increases when the risk of sperm competition is greater. In contrast, according to the "intensity model" of sperm competition [Parker, G. A., Ball, M. A., Stockley, P. & Gage, M. J. G. (1996) Proc. R. Soc. London Ser. B 263, 1291-1297], when more than two ejaculates compete during a given mating event, sperm expenditure should decrease as the number of competing males increases. Empirical evidence supporting this prediction, however, is still lacking. Here we measured sperm expenditure in two gobiid fishes, the grass (Zosterisessor ophiocephalus) and black goby (Gobius niger), in which up to six sneakers can congregate around the nest of territorial males and release their sperm when females spawn. We show that, in accordance with theory, sneaker males of both species release fewer sperm as the number of competitors increases.

Effect of gamma irradiation on fertility of potato tuber moth males and study of inherited sterility phenomena in partially sterile males

International Nuclear Information System (INIS)

Saour, G.; Makee, H.

1996-01-01

Newly emerged adult males (0-18 h) potato tuber moth (PTM) phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) were irradiated with various doses of gamma irradiation ranging from 5 to 45 krad. Sterility in order of 91% was induced when males were irradiated with a dose of 45 Krad. Longevity of male PTM was not affected by the application of irradiation, while mating ability and frequency of mating of the males irradiated with 25, 35 and 45 Krad were decreased. The mean number of eggs laid by females mated with males irradiated at 35 and 45 Krad was lower than the control. When males PTM were irradiated with high doses their competitiveness values were reduced, while the competitiveness was increased when the sex ratio of irradiated males to normal males was increased, specially with ration 1 : 10 : 1 (Normal male: Irradiated males: Normal female). Application of 15 Krad dose permitted, the ability to obtain a desired level of male sterility with acceptable reduction in its competitiveness. The inherited sterility phenomena in partially sterile males irradiated with 10-15 and 20 Krad was studied. Sterility in F1 progeny was higher than that in their irradiated male parents. The sex ratio of F1 progeny was distorted in favour of the males. (author). 24 refs., 5 figs

Effect of gamma irradiation on fertility of potato tuber moth males and study of inherited sterility phenomena in partially sterile males

Energy Technology Data Exchange (ETDEWEB)

Saour, G; Makee, H [Atomic Energy Commission, Damascus (Syrian Arab Republic). Dept. of Radiation Agriculture

1996-01-01

Newly emerged adult males (0-18 h) potato tuber moth (PTM) phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) were irradiated with various doses of gamma irradiation ranging from 5 to 45 krad. Sterility in order of 91% was induced when males were irradiated with a dose of 45 Krad. Longevity of male PTM was not affected by the application of irradiation, while mating ability and frequency of mating of the males irradiated with 25, 35 and 45 Krad were decreased. The mean number of eggs laid by females mated with males irradiated at 35 and 45 Krad was lower than the control. When males PTM were irradiated with high doses their competitiveness values were reduced, while the competitiveness was increased when the sex ratio of irradiated males to normal males was increased, specially with ration 1 : 10 : 1 (Normal male: Irradiated males: Normal female). Application of 15 Krad dose permitted, the ability to obtain a desired level of male sterility with acceptable reduction in its competitiveness. The inherited sterility phenomena in partially sterile males irradiated with 10-15 and 20 Krad was studied. Sterility in F1 progeny was higher than that in their irradiated male parents. The sex ratio of F1 progeny was distorted in favour of the males. (author). 24 refs., 5 figs.

Sex-dependent components of the analgesia produced by athletic competition.

Science.gov (United States)

Sternberg, W F; Bokat, C; Kass, L; Alboyadjian, A; Gracely, R H

2001-02-01

Competing in various athletic events (track meet, basketball game, or fencing match) can produce analgesia to cold pressor stimuli in male and female college athletes compared with baseline assessments. This competition-induced analgesia has been attributed to the stress associated with competition, which has components related to both physical exercise and the cognitive aspects of competing. This study evaluated the analgesic effect of exercise-related stress, and that caused by the cognitively stressful components of competing independent of exercise. Cold pressor pain ratings were assessed after competition in a track meet and after treadmill exercise or sedentary video game competition in both athletes and nonathletes. As expected, competing in athletics resulted in a decrease in cold pressor ratings in both male and female athletes. Independent of athletic status, treadmill running induced analgesia in women, but not in males, whereas sedentary video game competition produced analgesia in men, but not in women. These findings suggest that different components of the competitive athletic experience might be responsible for the analgesic effects in a sex-dependent manner.

Physical and Physiological Demands of Experienced Male Basketball Players During a Competitive Game.

Science.gov (United States)

Puente, Carlos; Abián-Vicén, Javier; Areces, Francisco; López, Roberto; Del Coso, Juan

2017-04-01

Puente, C, Abián-Vicén, J, Areces, F, López, R, and Del Coso, J. Physical and physiological demands of experienced male basketball players during a competitive game. J Strength Cond Res 31(4): 956-962, 2017-The aim of this investigation was to analyze the physical and physiological demands of experienced basketball players during a real and competitive game. Twenty-five well-trained basketball players (8 guards, 8 forwards, and 9 centers) played a competitive game on an outdoor court. Instantaneous running speeds, the number of body impacts above 5 g, and the number of accelerations and decelerations were assessed by means of a 15-Hz global Positioning System accelerometer unit. Individual heart rate was also recorded using heart rate monitors. As a group mean, the basketball players covered 82.6 ± 7.8 m·min during the game with a mean heart rate of 89.8 ± 4.4% of maximal heart rate. Players covered 3 ± 3% of the total distance running at above 18 km·h and performed 0.17 ± 0.13 sprints per minute. The number of body impacts was 8.2 ± 1.8 per minute of play. The running pace of forwards was higher than that of centers (86.8 ± 6.2 vs. 76.6 ± 6.0 m·min; p ≤ 0.05). The maximal speed obtained during the game was significantly higher for guards than that for centers (24.0 ± 1.6 km·h vs. 21.3 ± 1.6 km·h; p ≤ 0.05). Centers performed a lower number of accelerations/decelerations than guards and forwards (p ≤ 0.05). In conclusion, the extraordinary rates of specific movements performed by these experienced basketball players indicate the high physiological demands necessary to be able to compete in this sport. The centers were the basketball players who showed lower physiological demands during a game, whereas there were no differences between guards and forwards. These results can be used by coaches to adapt basketball training programs to the specific demands of each playing position.

Initiating technical refinements in high-level golfers: Evidence for contradictory procedures.

Science.gov (United States)

Carson, Howie J; Collins, Dave; Richards, Jim

2016-01-01

When developing motor skills there are several outcomes available to an athlete depending on their skill status and needs. Whereas the skill acquisition and performance literature is abundant, an under-researched outcome relates to the refinement of already acquired and well-established skills. Contrary to current recommendations for athletes to employ an external focus of attention and a representative practice design,  Carson and  Collins' (2011) [Refining and regaining skills in fixation/diversification stage performers: The Five-A Model. International Review of Sport and Exercise Psychology, 4, 146-167. doi: 10.1080/1750984x.2011.613682 ] Five-A Model requires an initial narrowed internal focus on the technical aspect needing refinement: the implication being that environments which limit external sources of information would be beneficial to achieving this task. Therefore, the purpose of this paper was to (1) provide a literature-based explanation for why techniques counter to current recommendations may be (temporarily) appropriate within the skill refinement process and (2) provide empirical evidence for such efficacy. Kinematic data and self-perception reports are provided from high-level golfers attempting to consciously initiate technical refinements while executing shots onto a driving range and into a close proximity net (i.e. with limited knowledge of results). It was hypothesised that greater control over intended refinements would occur when environmental stimuli were reduced in the most unrepresentative practice condition (i.e. hitting into a net). Results confirmed this, as evidenced by reduced intra-individual movement variability for all participants' individual refinements, despite little or no difference in mental effort reported. This research offers coaches guidance when working with performers who may find conscious recall difficult during the skill refinement process.

The physical profile of adult male basketball players: Differences between competitive levels and playing positions.

Science.gov (United States)

Ferioli, Davide; Rampinini, Ermanno; Bosio, Andrea; La Torre, Antonio; Azzolini, Matteo; Coutts, Aaron J

2018-04-26

This study examined the physical differences in adult male basketball players of different competitive level and playing position using a large cohort. In the middle of the regular season, 129 players from four different Divisions completed a Yo-YoIR1 and, after 3-to-8 days, they performed a 6-min continuous running test (Mognoni's test), a counter-movement jump (CMJ) test and a 5-min High-intensity Intermittent running test (HIT). Magnitude-based inferences revealed that differences in HIT were very likely moderate between Division I and II and likely small between Division II and III. The differences in absolute peak power and force produced during CMJs between Division I and II and between Division II and III were possibly small. Differences in Yo-YoIR1 and Mognoni's test were very likely-to-almost certain moderate/large between Division III and VI. We observed possibly-to-likely small differences in HIT and Mognoni's test between guards and forwards and almost certainly moderate differences in absolute peak power and force during CMJs between guards and centres. The ability to sustain high-intensity intermittent efforts (i.e. HIT) and strength/power characteristics can differentiate between competitive level, while strength/power characteristics discriminate guards from forwards/centres. These findings inform practitioners on the development of identification programs and training activities in basketball.

Should attractive males sneak: the trade-off between current and future offspring.

Directory of Open Access Journals (Sweden)

Ulrika Candolin

Full Text Available Alternative reproductive tactics are predicted to be adopted by less competitive males when competition for fertilization is intense. Yet, in some species, competitively superior males use an alternative tactic alongside the conventional tactic. This can jeopardize their success through the conventional tactic, but surprisingly little attention has been paid to this cost. We investigated 1 the degree to which competitive males sneak fertilize eggs in the polygamous threespine stickleback, Gasterosteus aculeatus, and 2 if males balance the cost of sneaking against its benefit. We found competitive males that succeeded in establishing a territory and in attracting spawning females to perform most sneak fertilizations. However, when we reduced the benefit of sneak attempts, by reducing visibility and the success rate of sneak attempts, males sneaked less. When we increased the cost of sneak attempts, by increasing the perceived value of current offspring (by mating males to preferred females rather than unpreferred females or no females, the interest of males in sneak opportunities decreased. Intriguingly, larger males, who presumably had a higher probability of future reproduction, were more willing to risk their current offspring for sneak opportunities. These findings suggest that competitive males that are attractive to females carefully balance costs against benefits in their sneaking decisions. More broadly, our results imply that changes in the environment can influence the cost-benefit ratio of sneaking and alter the distribution of fertilizations in a population. We end with discussing the implications that alterations in sneaking behavior could have for the operation of sexual selection in changing environments.

Sperm competition in bats.

OpenAIRE

Hosken, D J

1997-01-01

Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and ...

IMPROVED MOTOR-TIMING: EFFECTS OF SYNCHRONIZED METRO-NOME TRAINING ON GOLF SHOT ACCURACY

Directory of Open Access Journals (Sweden)

Louise Rönnqvist

2009-12-01

Full Text Available This study investigates the effect of synchronized metronome training (SMT on motor timing and how this training might affect golf shot accuracy. Twenty-six experienced male golfers participated (mean age 27 years; mean golf handicap 12.6 in this study. Pre- and post-test investigations of golf shots made by three different clubs were conducted by use of a golf simulator. The golfers were randomized into two groups: a SMT group and a Control group. After the pre-test, the golfers in the SMT group completed a 4-week SMT program designed to improve their motor timing, the golfers in the Control group were merely training their golf-swings during the same time period. No differences between the two groups were found from the pre-test outcomes, either for motor timing scores or for golf shot accuracy. However, the post-test results after the 4-weeks SMT showed evident motor timing improvements. Additionally, significant improvements for golf shot accuracy were found for the SMT group and with less variability in their performance. No such improvements were found for the golfers in the Control group. As with previous studies that used a SMT program, this study's results provide further evidence that motor timing can be improved by SMT and that such timing improvement also improves golf accuracy

Studies on mating competitiveness of sterile oriental fruit fly, Bactrocera dorsalis (Hendel)

International Nuclear Information System (INIS)

Limohpasmanee, W.; Segsarnviriya, S.

1998-01-01

An essential prerequisite for insect control by the sterile insect technique releasing method is mass rearing and sterilizing that do not have adverse effects on longevity and mating behavior of the released males. But many laboratory studies have shown that males irradiated at the completely sterility dose often could not compete with untreated males in mating. This paper studies the effects of gamma radiation at the sterile dose on mating, sexual and sperm competitiveness of the oriental fruit fly, Bactrocera dorsalis (Hendel) under the laboratory condition. It is found that irradiation at the completely sterility dose (90 Gy) had reduced the mating and sperm competition ability of the males. Though the sexual competition was not

Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level.

Science.gov (United States)

Sattler, Tine; Hadžić, Vedran; Dervišević, Edvin; Markovic, Goran

2015-06-01

Vertical jump (VJ) performance is an important element for successful volleyball practice. The aims of the study were (a) to explore the overall VJ performance of elite volleyball players of both sexes, (b) to explore the differences in VJ performance among different competition levels and different playing positions, and (c) to evaluate the sex-related differences in the role of the arm swing and 3-step approach with arm swing on the jump height. We assessed the VJ capacity in 253 volleyball players (113 males and 140 females) from Slovenian first and second Volleyball Division. The height of squat jump (SJ), countermovement jump, block jump, and attack jump was tested using an Optojump system. We observed significant differences (p ≤ 0.05) in VJ height between different levels of play that were most pronounced in the SJ. Position-related differences in VJ performance were observed in male players between receivers and setters (p ≤ 0.05), whereas in females, VJ performance across different playing positions seems equal. Finally, we found that male players significantly better use the arm swing during VJ than females (p ≤ 0.05), whereas the use of eccentric part of the jump and approach before the spike to improve VJ performance seem to be equally mastered activity in both sexes. These results could assist coaches in the development of jumping performance in volleyball players. Furthermore, presented normative data for jump heights of elite male and female volleyball players could be useful in selection and profiling of young volleyball players.

Testosterone and reproductive effort in male primates.

Science.gov (United States)

Muller, Martin N

2017-05-01

Considerable evidence suggests that the steroid hormone testosterone mediates major life-history trade-offs in vertebrates, promoting mating effort at the expense of parenting effort or survival. Observations from a range of wild primates support the "Challenge Hypothesis," which posits that variation in male testosterone is more closely associated with aggressive mating competition than with reproductive physiology. In both seasonally and non-seasonally breeding species, males increase testosterone production primarily when competing for fecund females. In species where males compete to maintain long-term access to females, testosterone increases when males are threatened with losing access to females, rather than during mating periods. And when male status is linked to mating success, and dependent on aggression, high-ranking males normally maintain higher testosterone levels than subordinates, particularly when dominance hierarchies are unstable. Trade-offs between parenting effort and mating effort appear to be weak in most primates, because direct investment in the form of infant transport and provisioning is rare. Instead, infant protection is the primary form of paternal investment in the order. Testosterone does not inhibit this form of investment, which relies on male aggression. Testosterone has a wide range of effects in primates that plausibly function to support male competitive behavior. These include psychological effects related to dominance striving, analgesic effects, and effects on the development and maintenance of the armaments and adornments that males employ in mating competition. Copyright © 2016 Elsevier Inc. All rights reserved.

Structure of Coordination Motor Abilities in Male Basketball Players at Different Levels of Competition

Directory of Open Access Journals (Sweden)

Jerzy Sadowski

2015-03-01

Full Text Available Introduction. The purpose of this investigation was to examine the structure of coordination motor abilities (CMA in male basketball players at different levels of competition. Material and methods. The study included 183 male basketball players from 10 Polish sports clubs. The examined groups consisted of seniors (n=42 aged 24.5 (± 3.3, juniors (n=37 aged 16.8 (± 0.6, cadets (n=54 aged 14.5 (± 0.1 and children (n=50 aged 13.4 (± 0.2. A battery of motor tests was administered to assess the following CMA: kinesthetic differentiation of movements, spatio-temporal orientation, reaction time, movement coupling, sense of balance, sense of rhythm and adjustment of movements. The structure of CMA under investigation was determined based on the results of Hotelling's principal component analysis in Tucker's modification, completed with Kaiser's Varimax rotation [1, 2]. Results. The CMA structure of basketball players was composed of three or four factors. Most often these included rhythm, movement differentiation, movement coupling and adjustment of movements. Less frequently the structure consisted of spatio-temporal orientation, balance and reaction time. An in-depth analysis of the CMA structure revealed that factors ranged from heterogeneous (children and cadets to homogeneous ones (juniors and seniors. The distribution of identified factors in the common variance was the smallest in children and cadets (58.9% and 62.9%, respectively and the biggest in juniors and seniors (69.3% and 68.48%, respectively.

Laboratory and field evaluation of sterile male boll weevil competitiveness

International Nuclear Information System (INIS)

McGovern, W.L.

1976-01-01

The production of pheromone by boll weevils, Anthonomus grandis Boheman, treated with 10,000 rad of CO-60 gamma irradiation compared favorably with that of control weevils for 5 days; however, feeding (determined by frass collection) was reduced from the first day post-treatment. No direct correlation was found between production of pheromone and elimination of frass. Overwintered male boll weevils were found to produce small quantities of pheromone and the ratio of components was less attractive at the same concentration as the standard laboratory formulation of grandlure. Most healthy sterilized male weevils should be more attractive than overwintered males. Laboratory-reared sterilized male boll weevils can be as attractive to female weevils as overwintered field males. Weevils treated with busulfan (1,4-butanediol dimethanesulfonate) alone were more attractive than those treated with combinations of busulfan and hempa. In general, sterilization reduced the attractiveness of laboratory males by about 50 percent. Evidence is presented for the existence of ''super-males.''

Sexual competitiveness of adult Indian meal moths irradiated as mature pupae

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.; Brower, J.H.; Tilton, E.W.

1976-01-01

When 7-day-old pupae of Plodia interpunctella (Huebner) were treated with 50 krad γ irradiation, 94.5 percent of the resulting females mated with untreated males, but the few eggs laid were infertile. Also, resulting males were sterile when they were paired with untreated females. A ratio of 1:1:1 irradiated males, untreated males, and untreated females resulted in 28.5 percent infertile eggs. Ratios of irradiated to untreated males of 5:1, 15:1 or 25:1 produced 54.7, 61.6, and 91.8 percent infertile eggs, respectively. Thus, irradiated males were fully competitive only at a ratio of 25:1. When both irradiated males and females were placed with untreated males and females to give ratios of 1:1:1:1, 5:5:1:1, 10:10:1:1 or 15:15:1:1, the percentages of infertile eggs were 54.1, 95.7, 81.0, and 100 percent, respectively, and competitiveness was good at all but the lowest ratio. Irradiation of 7-day-old pupae of the Indian meal moth produced sexually competitive sterile adults when released at high flooding ratios, and results were better when both sexes were released together

Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts

DEFF Research Database (Denmark)

Jensen, Peter; Scott, Suzanne; Krustrup, Peter

2013-01-01

Abstract Physiological responses and performance were examined during and after a simulated trampoline competition (STC). Fifteen elite trampoline gymnasts participated, of which whereas eight completed two routines (EX1 and EX2) and a competition final (EX3). Trampoline-specific activities were...... gymnastic competition includes a high number of repeated explosive and energy demanding jumps, which impairs jump performance during and 24 h post-competition....

Wake up and smell the conflict: odour signals in female competition

Science.gov (United States)

Stockley, Paula; Bottell, Lisa; Hurst, Jane L.

2013-01-01

Odour signals used in competitive and aggressive interactions between males are well studied in the context of sexual selection. By contrast, relatively little is known about comparable signals used by females, despite current interest in the evolution of female ornaments and weaponry. Available evidence suggests that odour signals are important in competitive interactions between female mammals, with reductions or reversals of male-biased sexual dimorphism in signalling where female competition is intense. Scent marking is often associated with conflict between females over access to resources or reproductive opportunities. Female scent marks may therefore provide reliable signals of competitive ability that could be used both by competitors and potential mates. Consistent with this hypothesis, we report that aggressive behaviour of female house mice is correlated with the amount of major urinary protein (MUP) excreted in their urine, a polymorphic set of proteins that are used in scent mark signalling. Under semi-natural conditions, females with high MUP output are more likely to produce offspring sired by males that have high reproductive success, and less likely to produce offspring by multiple different sires, suggesting that females with strong MUP signals are monopolized by males of particularly high quality. We conclude that odour signals are worthy of more detailed investigation as mediators of female competition. PMID:24167312

Comparison of physical capacities between nonselected and selected elite male competitive surfers for the National Junior Team.

Science.gov (United States)

Tran, Tai T; Lundgren, Lina; Secomb, Josh; Farley, Oliver R L; Haff, G Gregory; Seitz, Laurent B; Newton, Robert U; Nimphius, Sophia; Sheppard, Jeremy M

2015-03-01

To determine whether a previously validated performance-testing protocol for competitive surfers is able to differentiate between Australian elite junior surfers selected (S) to the national team and those not selected (NS). Thirty-two elite male competitive junior surfers were divided into 2 groups (S=16, NS=16). Their age, height, body mass, sum of 7 skinfolds, and lean-body-mass ratio (mean±SD) were 16.17±1.26 y, 173.40±5.30 cm, 62.35±7.40 kg, 41.74±10.82 mm, 1.54±0.35 for the S athletes and 16.13±1.02 y, 170.56±6.6 cm, 61.46±10.10 kg, 49.25±13.04 mm, 1.31±0.30 for the NS athletes. Power (countermovement jump [CMJ]), strength (isometric midthigh pull), 15-m sprint paddling, and 400-m endurance paddling were measured. There were significant (P≤.05) differences between the S and NS athletes for relative vertical-jump peak force (P=.01, d=0.9); CMJ height (P=.01, d=0.9); time to 5-, 10-, and 15-m sprint paddle; sprint paddle peak velocity (P=.03, d=0.8; PV); time to 400 m (P=.04, d=0.7); and endurance paddling velocity (P=.05, d=0.7). All performance variables, particularly CMJ height; time to 5-, 10-, and 15-m sprint paddle; sprint paddle PV; time to 400 m; and endurance paddling velocity, can effectively discriminate between S and NS competitive surfers, and this may be important for athlete profiling and training-program design.

Structure and Dynamics of Humpback Whales Competitive Groups in Ecuador

Directory of Open Access Journals (Sweden)

Fernando Félix

2015-02-01

Full Text Available We assessed the social structure and behavior of humpback whale (Megaptera novaeangliae competitive groups off Ecuador between July and August 2010. During this time we followed 185 whales in 22 competitive groups for 41.45 hr. The average group size was 8.4 animals (SD = 2.85. The average sighting time was 113.05 min/group (SD = 47.1. We used photographs of dorsal fins and video to record interactions and estimate an association index (AI between each pair of whales within the groups. Sightings were divided into periods, which were defined by changes in group membership. On average, group composition changed every 30.2 min, which confirms that the structure of competitive groups is highly dynamic. Interactions between escorts characterized by low level of aggression. At least 60% of escorts joined or left together the group in small subunits between two and five animals, suggesting some type of cooperative association. Although singletons, as well as pairs or trios were able to join competitive groups at any moment, escorts that joined together were able to stay longer with the group and displace dominant escorts. Genetic analysis showed that in three occasions more than one female was present within a competitive group, suggesting either males are herding females or large competitive groups are formed by subunits. Males and females performed similar surface displays. We propose that competition and cooperation are interrelated in humpback whales’ competitive groups and that male cooperation would be an adaptive strategy either to displace dominant escorts or to fend off challengers.

Sperm competition, immunity, selfish genes and cancer.

Science.gov (United States)

Lewis, Z; Price, T A R; Wedell, N

2008-10-01

Sperm competition is widespread and has played an important role in shaping male reproductive characters such as testis size and numbers of sperm produced, and this is reflected in the rapid evolution of many reproductive genes. Additionally, sperm competition has been implicated in the rapid evolution of seminal fluids. However, our understanding of the molecular basis of many traits thought to be important in sperm competition is rudimentary. Furthermore, links between sperm competition and a range of issues not directly related to reproduction are only just beginning to be explored. These include associations between sperm competition and selfish genes, immunity and diseases such as cancer.We briefly review these topics and suggest areas we consider worthy of additional research.

Chronic Co-species Housing Mice and Rats Increased the Competitiveness of Male Mice.

Science.gov (United States)

Liu, Ying-Juan; Li, Lai-Fu; Zhang, Yao-Hua; Guo, Hui-Fen; Xia, Min; Zhang, Meng-Wei; Jing, Xiao-Yuan; Zhang, Jing-Hua; Zhang, Jian-Xu

2017-03-01

Rats are predators of mice in nature. Nevertheless, it is a common practice to house mice and rats in a same room in some laboratories. In this study, we investigated the behavioral and physiological responsively of mice in long-term co-species housing conditions. Twenty-four male mice were randomly assigned to their original raising room (control) or a rat room (co-species-housed) for more than 6 weeks. In the open-field and light-dark box tests, the behaviors of the co-species-housed mice and controls were not different. In a 2-choice test of paired urine odors [rabbit urine (as a novel odor) vs. rat urine, cat urine (as a natural predator-scent) vs. rabbit urine, and cat urine vs. rat urine], the co-species-housed mice were more ready to investigate the rat urine odor compared with the controls and may have adapted to it. In an encounter test, the rat-room-exposed mice exhibited increased aggression levels, and their urines were more attractive to females. Correspondingly, the levels of major urinary proteins were increased in the co-species-housed mouse urine, along with some volatile pheromones. The serum testosterone levels were also enhanced in the co-species-housed mice, whereas the corticosterone levels were not different. The norepinephrine, dopamine, and 5-HT levels in the right hippocampus and striatum were not different between the 2. Our findings indicate that chronic co-species housing results in adaptation in male mice; furthermore, it appears that long-term rat-odor stimuli enhance the competitiveness of mice, which suggests that appropriate predator-odor stimuli may be important to the fitness of prey animals. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sexual competion of irradiated males of the cowpea weevil, callosobruchus maculatus (F.)

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.; Younes, M.W.F.

1981-01-01

When unmated males of Callosobruchus maculatus were irradiated with 7.5 or 10 Krad and confined with normal females, 97.90 and 89.32%, respectively, of the eggs did not hatch, compared with 15.49% infertility of the control eggs. Increasing the dose to 12.5 or 15 Krad induced 99.44 and 100%, respectively, sterility in the irradiated (I) males. When males treated with 7.5, 10 or 12.5 Krad were confined with unirradiated (U) males and females (1:1:1 ratio), infertility of the resulting eggs were 60.06, 67.96 and 69.04%, respectively. The competitiveness values of irradiated males with the above doses and ratio were 1.2, 1.6 and 1.8. Thus, males treated with substerilizing doses (7.5, 10 or 12.5 Krad) competed favourably with (U) males, and males treated with the sterilizing dose (15 Krad) were also fully competitive with (U) males. These results indicated that irradiation with 15 Krad, a sterilizing dose, did not decrease sexual competitiveness of irradiated males. (author)

Social structure affects mating competition in a damselfish

Science.gov (United States)

Wacker, Sebastian; Ness, Miriam Horstad; Östlund-Nilsson, Sara; Amundsen, Trond

2017-12-01

The strength of mating competition and sexual selection varies over space and time in many animals. Such variation is typically driven by ecological and demographic factors, including adult sex ratio and consequent availability of mates. The spatial scale at which demographic factors affect mating competition and sexual selection may vary but is not often investigated. Here, we analyse variation in size and sex ratio of social groups, and how group structure affects mating competition, in the site-attached damselfish Chrysiptera cyanea. Site-attached reef fishes are known to show extensive intraspecific variation in social structure. Previous work has focused on species for which the size and dynamics of social groups are constrained by habitat, whereas species with group structure unconstrained by habitat have received little attention. Chrysiptera cyanea is such a species, with individuals occurring in spatial clusters that varied widely in size and sex ratio. Typically, only one male defended a nest in multi-male groups. Nest-holding males were frequently visited by mate-searching females, with more visits in groups with more females, suggesting that courtship and mating mostly occur within groups and that male mating success depends on the number of females in the group. Male-male aggression was frequent in multi-male groups but absent in single-male groups. These findings demonstrate that groups are distinct social units. In consequence, the dynamics of mating and reproduction are mainly a result of group structure, largely unaffected short term by overall population demography which would be important in open social systems. Future studies of the C. cyanea model system should analyse longer-term dynamics, including how groups are formed, how they vary in relation to density and time of season and how social structure affects sexual selection.

African Journal for Physical Activity and Health Sciences - Vol 18 ...

African Journals Online (AJOL)

African Journal for Physical, Health Education, Recreation and Dance. ... severity and mechanism of acute injuries in elite male African youth soccer players ... on golfers' physical and functional fitness as well as golf performance: A pilot study ...

Changes in Subjective Sleep Quality Before a Competition and Their Relation to Competitive Anxiety.

Science.gov (United States)

Ehrlenspiel, Felix; Erlacher, Daniel; Ziegler, Matthias

2016-12-09

The aim of this study was to examine the effects of competitions on subjective sleep quality. Previous studies have been inconclusive and lack differentiated and standardized measurements of subjective sleep quality. Furthermore the temporal relation between precompetitive anxiety and sleep quality was investigated. Anxiety and nervousness associated with competitions are considered to cause sleep impairments. A convenience sample of N = 79 elite male athletes from various sports participated. In a time-to-event paradigm, sleep quality and competitive anxiety were assessed via standardized self-report measurements 4 days before a competition and on the day of the competition. Univariate analyses were used to examine differences between time points. To examine cross-lagged effects between anxiety and sleep quality a latent change score model (LCSM) was specified that tested an effect of anxiety on changes in sleep quality. Evaluations of nocturnal sleep deteriorated significantly from 4 days before competition to the day of competition, but there were no differences regarding perceptions of the restorative value of sleep. LCSM revealed that athletes who reported more intense worry symptoms 4 days before competition also reported greater deterioration in evaluations of nocturnal sleep. The findings support earlier reports of impaired subjective sleep quality before competitions. Precompetitive sleep impairments appear also to be preceded by cognitive anxiety. Whereas interventions should thus address worry-cognitions associated with competition and sleep, research should address the practical importance of these perceptions of sleep impairments.

Sexual Experience Enhances Drosophila melanogaster Male Mating Behavior and Success

Science.gov (United States)

Saleem, Sehresh; Ruggles, Patrick H.; Abbott, Wiley K.; Carney, Ginger E.

2014-01-01

Competition for mates is a wide-spread phenomenon affecting individual reproductive success. The ability of animals to adjust their behaviors in response to changing social environment is important and well documented. Drosophila melanogaster males compete with one another for matings with females and modify their reproductive behaviors based on prior social interactions. However, it remains to be determined how male social experience that culminates in mating with a female impacts subsequent male reproductive behaviors and mating success. Here we show that sexual experience enhances future mating success. Previously mated D. melanogaster males adjust their courtship behaviors and out-compete sexually inexperienced males for copulations. Interestingly, courtship experience alone is not sufficient in providing this competitive advantage, indicating that copulation plays a role in reinforcing this social learning. We also show that females use their sense of hearing to preferentially mate with experienced males when given a choice. Our results demonstrate the ability of previously mated males to learn from their positive sexual experiences and adjust their behaviors to gain a mating advantage. These experienced-based changes in behavior reveal strategies that animals likely use to increase their fecundity in natural competitive environments. PMID:24805129

Sexual experience enhances Drosophila melanogaster male mating behavior and success.

Directory of Open Access Journals (Sweden)

Sehresh Saleem

Full Text Available Competition for mates is a wide-spread phenomenon affecting individual reproductive success. The ability of animals to adjust their behaviors in response to changing social environment is important and well documented. Drosophila melanogaster males compete with one another for matings with females and modify their reproductive behaviors based on prior social interactions. However, it remains to be determined how male social experience that culminates in mating with a female impacts subsequent male reproductive behaviors and mating success. Here we show that sexual experience enhances future mating success. Previously mated D. melanogaster males adjust their courtship behaviors and out-compete sexually inexperienced males for copulations. Interestingly, courtship experience alone is not sufficient in providing this competitive advantage, indicating that copulation plays a role in reinforcing this social learning. We also show that females use their sense of hearing to preferentially mate with experienced males when given a choice. Our results demonstrate the ability of previously mated males to learn from their positive sexual experiences and adjust their behaviors to gain a mating advantage. These experienced-based changes in behavior reveal strategies that animals likely use to increase their fecundity in natural competitive environments.

An electromyographic study of the effect of hand grip sizes on forearm muscle activity and golf performance.

Science.gov (United States)

Sorbie, Graeme G; Hunter, Henry H; Grace, Fergal M; Gu, Yaodong; Baker, Julien S; Ugbolue, Ukadike Chris

2016-01-01

The study describes the differences in surface electromyography (EMG) activity of two forearm muscles in the lead and trail arm at specific phases of the golf swing using a 7-iron with three different grip sizes among amateur and professional golfers. Fifteen right-handed male golfers performed five golf swings using golf clubs with three different grip sizes. Surface EMG was used to measure muscle activity of the extensor carpi radialis brevis (ECRB) and flexor digitorum superficialis (FDS) on both forearms. There were no significant differences in forearm muscle activity when using the three golf grips within the group of 15 golfers (p > 0.05). When using the undersize grip, club head speed significantly increased (p = 0.044). During the backswing and downswing phases, amateurs produced significantly greater forearm muscle activity with all three grip sizes (p < 0.05). In conclusion, forearm muscle activity is not affected by grip sizes. However, club head speed increases when using undersize grips.

Correlation of Titleist Performance Institute (TPI) level 1 movement screens and golf swing faults.

Science.gov (United States)

Gulgin, Heather R; Schulte, Brian C; Crawley, Amy A

2014-02-01

Although some research in the past has examined how physical limitations in strength or flexibility affect a golfer's performance, the performance outcome most measured was driving distance. Currently, there are no data that have examined the relationship between selected strength and flexibility variables and golf swing faults. The purpose of this study was to examine the relationship between Titleist Performance Institute (TPI) level 1 movement screen variables and 14 common golf swing faults. Thirty-six male and female golfers (mean age, 25.4 ± 9.9 years; height, 175.9 ± 16.2 cm; mass, 76.2 ± 14.6 kg; handicap, 14.2 ± 10.4) participated. Twelve physical tests of strength, flexibility, and balance were assessed using the TPI level 1 golf fitness screening tool. Golfers then hit 4 golf shots (with a 5-iron) while being videoed, and those were then analyzed for 14 different golf swing faults (using V1Pro software). Three significant associations between a physical limitation and a particular golf swing fault were found: toe touch and early hip extension (p = 0.015), bridge on right side with both early hip extension (p = 0.050), and loss of posture (p = 0.028). In addition, an odds ratio showed that when a golfer could not overhead deep squat or single leg balance on left side, they were 2-3 times more likely to exhibit a early hip extension, loss of posture, or slide during the golf swing, as compared with those who could perform a correct overhead deep squat. Based on our findings, it is important for the golf fitness professional to particularly address a golfer's core strength, balance, and hamstring flexibility to help avoid common golf swing faults, which affect a golfer's ball striking ability and ultimately their performance.

Competitiveness values of irradiated adults of callosobruchus maculatus (F.) irradiated as mature pupae

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.

1981-01-01

When mature pupae of Callosobruchus maculatus were treated with 3 Krad, the resulting adults were sterile when they were paired with untreated opposite sex. Males and females both treated with a sterilizing dose (3 Krad) and confined with untreated (U) males and females at a I male: I female: U male: U female (irradiated males: irradiated females: unirradiated males: unirradiated females) ratio caused 69.1% infertility in the resulting eggs. When the ratio of sterile males and females was increased to 5.5:1:1; 10:10:1:1 or 15:1:1 (I male: female: U male: U female) the percentage infertility reached 82.5, 95.0 and 100.0, respectively. The percentage of observed infertility was less than the expected infertility for the ratios 1:1:1:1:5:5:1:1 and 10:10:1:1, but it was exceeded with the highest ratio used (15:15:1:1). Competitiveness values for irradiated adults increased with an increasing ratio of irradiated to unirradiated adults. Since the ratio of 15:15:1:1 gave rise to 100% egg infertility (the expected infertility was 99.6%), no F 1 adults was produced; and the competitiveness value slightly exceeded 1.0 (i.e. the sterile adults were fully competitive with the normal ones). These results indicated that irradiation with 3 Krad, a sterilizing dose, did not decrease sexual competitiveness of irradiated adults. Also, the release of (I) females together with (I) males could give good results in controlling a population of C. maculatus in a autocidal control program; and, therefore, separation of the sexes prior to release is probably unnecessary. (author)

Sexual and social competition: broadening perspectives by defining female roles.

Science.gov (United States)

Rubenstein, Dustin R

2012-08-19

Males figured more prominently than females in Darwin's view of sexual selection. He considered female choice of secondary importance to male-male competition as a mechanism to explain the evolution of male ornaments and armaments. Fisher later demonstrated the importance of female choice in driving male trait evolution, but his ideas were largely ignored for decades. As sexual selection came to embrace the notions of parent-offspring and sexual conflict, and experimental tests of female choice showed promise, females began to feature more prominently in the framework of sexual selection theory. Recent debate over this theory has centred around the role of females, not only over the question of choice, but also over female-female competition. Whereas some have called for expanding the sexual selection framework to encompass all forms of female-female competition, others have called for subsuming sexual selection within a broader framework of social selection, or replacing it altogether. Still others have argued for linking sexual selection more clearly to other evolutionary theories such as kin selection. Rather than simply debating terminology, we must take a broader view of the general processes that lead to trait evolution in both sexes by clearly defining the roles that females play in the process, and by focusing on intra- and inter-sexual interactions in males and females.

Physiological responses and performance in a simulated trampoline gymnastics competition in elite male gymnasts.

Science.gov (United States)

Jensen, Peter; Scott, Suzanne; Krustrup, Peter; Mohr, Magni

2013-01-01

Physiological responses and performance were examined during and after a simulated trampoline competition (STC). Fifteen elite trampoline gymnasts participated, of which eight completed two routines (EX1 and EX2) and a competition final (EX3). Trampoline-specific activities were quantified by video-analysis. Countermovement jump (CMJ) and 20 maximal trampoline jump (20-MTJ) performances were assessed. Heart rate (HR) and quadriceps muscle temperature (Tm) were recorded and venous blood was drawn. A total of 252 ± 16 jumps were performed during the STC. CMJ performance declined (P trampoline gymnastic competition includes a high number of repeated explosive and energy demanding jumps, which impairs jump performance during and 24 h post-competition.

Visual feedback attenuates mean concentric barbell velocity loss, and improves motivation, competitiveness, and perceived workload in male adolescent athletes.

Science.gov (United States)

Weakley, Jonathon Js; Wilson, Kyle M; Till, Kevin; Read, Dale B; Darrall-Jones, Joshua; Roe, Gregory; Phibbs, Padraic J; Jones, Ben

2017-07-12

It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat, and to identify changes in motivation, competitiveness, and perceived workload. In a randomised-crossover design (Feedback vs. Control) feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ±0.04 m·s) and Control (0.65 ±0.05 m·s) observed. Additionally, individual repetition mean concentric velocity ranged from possibly (repetition number two: 0.79 ±0.04 vs. 0.78 ±0.04 m·s) to almost certainly (repetition number 10: 0.58 ±0.05 vs. 0.49 ±0.05 m·s) greater when provided feedback, while almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance training.

Age-dependent male mating tactics in a spider mite-A life-history perspective.

Science.gov (United States)

Sato, Yukie; Rühr, Peter T; Schmitz, Helmut; Egas, Martijn; Blanke, Alexander

2016-10-01

Males often fight with rival males for access to females. However, some males display nonfighting tactics such as sneaking, satellite behavior, or female mimicking. When these mating tactics comprise a conditional strategy, they are often thought to be explained by resource holding potential (RHP), that is, nonfighting tactics are displayed by less competitive males who are more likely to lose a fight. The alternative mating tactics, however, can also be explained by life-history theory, which predicts that young males avoid fighting, regardless of their RHP, if it pays off to wait for future reproduction. Here, we test whether the sneaking tactic displayed by young males of the two-spotted spider mite can be explained by life-history theory. We tested whether young sneaker males survive longer than young fighter males after a bout of mild or strong competition with old fighter males. We also investigated whether old males have a more protective outer skin-a possible proxy for RHP-by measuring cuticle hardness and elasticity using nanoindentation. We found that young sneaker males survived longer than young fighter males after mild male competition. This difference was not found after strong male competition, which suggests that induction of sneaking tactic is affected by male density. Hardness and elasticity of the skin did not vary with male age. Given that earlier work could also not detect morphometric differences between fighter and sneaker males, we conclude that there is no apparent increase in RHP with age in the mite and age-dependent male mating tactics in the mite can be explained only by life-history theory. Because it is likely that fighting incurs a survival cost, age-dependent alternative mating tactics may be explained by life-history theory in many species when reproduction of old males is a significant factor in fitness.

Males do not see only red: UV wavelengths and male territorial aggression in the three-spined stickleback ( Gasterosteus aculeatus)

Science.gov (United States)

Rick, Ingolf P.; Bakker, Theo C. M.

2008-07-01

Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks ( Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback.

Sperm competition, but not major histocompatibility divergence, drives differential fertilization success between alternative reproductive tactics in Chinook salmon.

Science.gov (United States)

Lehnert, S J; Helou, L; Pitcher, T E; Heath, J W; Heath, D D

2018-01-01

Post-copulatory sexual selection processes, including sperm competition and cryptic female choice (CFC), can operate based on major histocompatibility (MH) genes. We investigated sperm competition between male alternative reproductive tactics [jack (sneaker) and hooknose (guard)] of Chinook salmon (Oncorhynchus tshawytscha). Using a full factorial design, we examined in vitro competitive fertilization success of paired jack and hooknose males at three time points after sperm activation (0, 15 and 60 s) to test for male competition, CFC and time effects on male fertilization success. We also examined egg-mediated CFC at two MH genes by examining both the relationship between competitive fertilization success and MH divergence as well as inheritance patterns of MH alleles in resulting offspring. We found that jacks sired more offspring than hooknose males at 0 s post-activation; however, jack fertilization success declined over time post-activation, suggesting a trade-off between sperm speed and longevity. Enhanced fertilization success of jacks (presumably via higher sperm quality) may serve to increase sneaker tactic competitiveness relative to dominant hooknose males. We also found evidence of egg-mediated CFC (i.e. female × male interaction) influencing competitive fertilization success; however, CFC was not acting on the MH genes as we found no relationship between fertilization success and MH II β 1 or MH I α 1 divergence and we found no deviations from Mendelian inheritance of MH alleles in the offspring. Our study provides insight into evolutionary mechanisms influencing variation in male mating success within alternative reproductive tactics, thus underscoring different strategies that males can adopt to attain success. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Don't get the blues: conspicuous nuptial colouration of male moor frogs (Rana arvalis) supports visual mate recognition during scramble competition in large breeding aggregations.

Science.gov (United States)

Sztatecsny, Marc; Preininger, Doris; Freudmann, Anita; Loretto, Matthias-Claudio; Maier, Franziska; Hödl, Walter

2012-12-01

Conspicuous male colouration is expected to have evolved primarily through selection by female choice. In what way conspicuous colours could be advantageous to males scrambling for mates remains largely unknown. The moor frog (Rana arvalis) belongs to the so-called explosive breeders in which spawning period is short; intrasexual competition is strong, and males actively search and scramble for females. During breeding, male body colouration changes from a dull brown (similar to females) to a conspicuous blue, and we wanted to test if male blueness influences mating success or facilitates male mate recognition. To do so, we first measured the colour of mated and non-mated males using a spectrophotometer. In an experiment, we then analysed interactions of actual male moor frogs in natural spawning aggregations with a brown (resembling a female or a non-breeding male) and a blue model frog. Mated and non-mated males did not differ in colouration, suggesting that female choice based on colour traits was unlikely. In our behavioural experiment, male moor frogs spent significantly more time in contact and in amplexus with the brown model than with the blue model. Our results suggest that the nuptial colouration in moor frogs can act as a new type of visual signal in anurans evolved to promote instantaneous mate recognition allowing males to quickly move between rivals while scrambling for females. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00265-012-1412-6) contains supplementary material, which is available to authorized users.

Sneaker Males Affect Fighter Male Body Size and Sexual Size Dimorphism in Salmon.

Science.gov (United States)

Weir, Laura K; Kindsvater, Holly K; Young, Kyle A; Reynolds, John D

2016-08-01

Large male body size is typically favored by directional sexual selection through competition for mates. However, alternative male life-history phenotypes, such as "sneakers," should decrease the strength of sexual selection acting on body size of large "fighter" males. We tested this prediction with salmon species; in southern populations, where sneakers are common, fighter males should be smaller than in northern populations, where sneakers are rare, leading to geographical clines in sexual size dimorphism (SSD). Consistent with our prediction, fighter male body size and SSD (fighter male∶female size) increase with latitude in species with sneaker males (Atlantic salmon Salmo salar and masu salmon Oncorhynchus masou) but not in species without sneakers (chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha). This is the first evidence that sneaker males affect SSD across populations and species, and it suggests that alternative male mating strategies may shape the evolution of body size.

Use of rhodamine B to mark the body and seminal fluid of male Aedes aegypti for mark-release-recapture experiments and estimating efficacy of sterile male releases.

Science.gov (United States)

Johnson, Brian J; Mitchell, Sara N; Paton, Christopher J; Stevenson, Jessica; Staunton, Kyran M; Snoad, Nigel; Beebe, Nigel; White, Bradley J; Ritchie, Scott A

2017-09-01

Recent interest in male-based sterile insect technique (SIT) and incompatible insect technique (IIT) to control Aedes aegypti and Aedes albopictus populations has revealed the need for an economical, rapid diagnostic tool for determining dispersion and mating success of sterilized males in the wild. Previous reports from other insects indicated rhodamine B, a thiol-reactive fluorescent dye, administered via sugar-feeding can be used to stain the body tissue and seminal fluid of insects. Here, we report on the adaptation of this technique for male Ae. aegypti to allow for rapid assessment of competitiveness (mating success) during field releases. Marking was achieved by feeding males on 0.1, 0.2, 0.4 or 0.8% rhodamine B (w/v) in 50% honey solutions during free flight. All concentrations produced >95% transfer to females and successful body marking after 4 days of feeding, with 0.4 and 0.8% solutions producing the longest-lasting body marking. Importantly, rhodamine B marking had no effect on male mating competitiveness and proof-of-principle field releases demonstrated successful transfer of marked seminal fluid to females under field conditions and recapture of marked males. These results reveal rhodamine B to be a potentially useful evaluation method for male-based SIT/IIT control strategies as well as a viable body marking technique for male-based mark-release-recapture experiments without the negative side-effects of traditional marking methods. As a standalone method for use in mating competitiveness assays, rhodamine B marking is less expensive than PCR (e.g. paternity analysis) and stable isotope semen labelling methods and less time-consuming than female fertility assays used to assess competitiveness of sterilised males.

Use of rhodamine B to mark the body and seminal fluid of male Aedes aegypti for mark-release-recapture experiments and estimating efficacy of sterile male releases.

Directory of Open Access Journals (Sweden)

Brian J Johnson

2017-09-01

Full Text Available Recent interest in male-based sterile insect technique (SIT and incompatible insect technique (IIT to control Aedes aegypti and Aedes albopictus populations has revealed the need for an economical, rapid diagnostic tool for determining dispersion and mating success of sterilized males in the wild. Previous reports from other insects indicated rhodamine B, a thiol-reactive fluorescent dye, administered via sugar-feeding can be used to stain the body tissue and seminal fluid of insects. Here, we report on the adaptation of this technique for male Ae. aegypti to allow for rapid assessment of competitiveness (mating success during field releases.Marking was achieved by feeding males on 0.1, 0.2, 0.4 or 0.8% rhodamine B (w/v in 50% honey solutions during free flight. All concentrations produced >95% transfer to females and successful body marking after 4 days of feeding, with 0.4 and 0.8% solutions producing the longest-lasting body marking. Importantly, rhodamine B marking had no effect on male mating competitiveness and proof-of-principle field releases demonstrated successful transfer of marked seminal fluid to females under field conditions and recapture of marked males.These results reveal rhodamine B to be a potentially useful evaluation method for male-based SIT/IIT control strategies as well as a viable body marking technique for male-based mark-release-recapture experiments without the negative side-effects of traditional marking methods. As a standalone method for use in mating competitiveness assays, rhodamine B marking is less expensive than PCR (e.g. paternity analysis and stable isotope semen labelling methods and less time-consuming than female fertility assays used to assess competitiveness of sterilised males.

Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes [v2; ref status: indexed, http://f1000r.es/1ko

Directory of Open Access Journals (Sweden)

David Bierbach

2013-08-01

Full Text Available Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect, thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR. Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation, but did not detect a correlation between aggressiveness and

Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes [v3; ref status: indexed, http://f1000r.es/1zi

Directory of Open Access Journals (Sweden)

David Bierbach

2013-10-01

Full Text Available Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect, thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR. Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation, but did not detect a correlation between aggressiveness and

THE COMPETITIVE DEMANDS OF ELITE MALE RINK HOCKEY

Directory of Open Access Journals (Sweden)

Aladino Fernández

2013-06-01

Full Text Available The aim of this study was to simulate the activity pattern of rink hockey by designing a specific skate test (ST to study the energy expenditure and metabolic responses to this intermittent high-intensity exercise and extrapolate the results from the test to competition. Six rink hockey players performed, in three phases, the 20-metre multi-stage shuttle roller skate test, a tournament match and the ST. Heart rate was monitored in all three phases. Blood lactate, oxygen consumption, ventilation and respiratory exchange ratio were also recorded during the ST. Peak HR was 190.7±7.2 beats · min-1. There were no differences in peak HR between the three tests. Mean HR was similar between the ST and the match (86% and 87% of HRmax, respectively. Peak and mean ventilation averaged 111.0±8.8 L · min-1 and 70.3±14.0 L · min-1 (60% of VEmax, respectively. VO2max was 56.3±8.4 mL · kg-1 · min-1, and mean oxygen consumption was 40.9±7.9 mL · kg-1 · min-1 (70% of VO2max. Maximum blood lactate concentration was 7.2±1.3 mmol · L-1. ST yielded an energy expenditure of 899.1±232.9 kJ, and energy power was 59.9±15.5 kJ · min-1. These findings suggest that the ST is suitable for estimating the physiological demands of competitive rink hockey, which places a heavy demand on the aerobic and anaerobic systems, and requires high energy consumption.

Color polymorphism and intrasexual competition in assemblages of cichlid fish

NARCIS (Netherlands)

Dijkstra, Peter; Hemelrijk, Charlotte; Seehausen, Ole; Groothuis, Ton G.G.

2009-01-01

The origin and maintenance of phenotypic polymorphisms is a classical problem in evolutionary ecology. Aggressive male-male competition can be a source of negative frequency-dependent selection stabilizing phenotypic polymorphisms when aggression is biased toward the own morph. We studied

Sterilization of full grown pupae of the long headed flour beetle with gamma radiation and its effect on mating competitiveness

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.; Aboul-Nasr, A.E.; Abdel-Rahmal, A.M.; Ahmed, Z.A.

1985-01-01

When fully grown pupae of Lathyticus oryzae were irradiated at 8Krad, the resulting adults were completely sterile. When sterile males were added to the unirradiated males and females ratios of 1:1:1, 5:1:1, 10:1:1 and 15:1:1, the percentage of egg hatch decreased from 79.2 for the controls to 48.1 at the ratio of 1:1:1. Male competitiveness value for this ratio was 0.64. Increasing the ratio to 15:1:1 decreased percentage of egg hatch to 4.0. The competitiveness value at this ratio was 1.3 (i.e. the sterile males were fully competitive). The effects of releasing both sterile males and females were also investigated. The present results indicated that release of sterile females together with sterile males give good results, especially with flooding ratio 15:15:1:1, which gave 98.3% infertility in the resulting eggs. The competitiveness value showed that the sterile adults were fully competitive with normal adults at this flooding ratio

Physiological implications of preparing for a natural male bodybuilding competition.

Science.gov (United States)

Mitchell, Lachlan; Slater, Gary; Hackett, Daniel; Johnson, Nathan; O'Connor, Helen

2018-03-01

This study aimed to describe the body composition and physiological changes which take place during the in-season and recovery periods of a group of natural bodybuilders. Natural male bodybuilders (n = 9) were assessed 16 (PRE16), 8 (PRE8), and 1 (PRE1) week(s) before, and 4 (POST4) weeks after a bodybuilding competition. Assessments included body composition, resting metabolic rate (RMR), serum hormones, and 7-day weighed food and training diaries. Change in parameters was assessed using repeated-measures analysis of variance. Dietary protein intake remained high throughout the study period (2.8-3.1 g kg -1  d -1 ). Fat mass (FM) was significantly reduced from PRE16 to PRE1 (8.8 ± 3.1 vs. 5.3 ± 2.4 kg, P  .05). Large reductions in total and free testosterone (16.4 ± 4.4 vs. 10.1 ± 3.6 nmol L -1 , P < .05; 229.3 ± 72.4 vs. 116.8 ± 76.9 pmol L -1 , P < .05), and insulin-like growth factor-1 (IGF-1) (27.0 ± 7.7 vs. 19.9 ± 7.6 nmol L -1 , P < .05) occurred between PRE16 and PRE1. LM and IGF-1 increased from PRE1 to POST4 (70.9 ± 9.1 vs. 72.5 ± 8.5 kg, P < .05; 19.9 ± 7.6 vs. 25.4 ± 9.3 nmol L -1 , P < .05). Despite substantial reductions in FM, participants maintained almost all of their LM. The reduction in anabolic hormone concentration is likely attributable to the prolonged negative energy balance, despite a high dietary protein intake.

The relationship between ventilatory threshold and repeated-sprint ability in competitive male ice hockey players

Directory of Open Access Journals (Sweden)

Matthew R. Lowery

2018-04-01

Full Text Available Background/objective: The relationship between ventilatory threshold (VT1, VT2 and repeated-sprint ability (RSA in competitive male ice hockey players was investigated. Methods: Forty-three male ice hockey players aged 18–23 years competing in NCAA Division I, NCAA Division III, and Junior A level participated. Participants performed an incremental graded exercise test on a skate treadmill to determine V˙O2peak, VT1, and VT2 using MedGraphics Breezesuit™ software (v-slope. Participants performed an on-ice repeated shift (RSA test consisting of 8-maximal skating bouts, lasting approximately 25 s and interspersed with 90 s of passive recovery, to determine first gate, second gate, and total sprint decrement (%dec. Pearson product-moment correlations and multiple regressions were used to assess relationships between ventilatory threshold variables (VT1, VT2, Stage at VT1, and Stage at VT2 and RSA (first gate, second gate, and total course decrement. Results: Stage at VT2 was the only variable substantially correlated with first gate (r = −0.35; P < 0.05, second gate (r = −0.58; P < 0.001 and total course decrement (r = −0.42; P < 0.05. Conclusion: The results of this study demonstrated that VT is substantially associated with RSA, and VT2 is more strongly correlated with RSA than V˙O2peak. This study suggests that longer duration high-intensity interval training at intensities that increase workrate at VT2 may lead to possible improvements in RSA. Keywords: Athletes, Aerobic capacity, Fatigue, Sprint decrement

Sperm competitive ability and genetic relatedness in Drosophila melanogaster: similarity breeds contempt.

Science.gov (United States)

Mack, Paul D; Hammock, Brian A; Promislow, Daniel E L

2002-09-01

Offspring of close relatives often suffer severe fitness consequences. Previous studies have demonstrated that females, when given a choice, will choose to avoid mating with closely related males. But where opportunities for mate choice are limited or kin recognition is absent, precopulatory mechanisms may not work. In this case, either sex could reduce the risks of inbreeding through mechanisms that occur during or after copulation. During mating, males or females could commit fewer gametes when mating with a close relative. After mating, females could offset the effects of mating with a closely related male through cryptic choice. Few prior studies of sperm competition have examined the effect of genetic similarity, however, and what studies do exist have yielded equivocal results. In an effort to resolve this issue, we measured the outcome of sperm competition when female Drosophila melanogaster were mated to males of four different degrees of genetic relatedness and then to a standardized competitor. We provide the strongest evidence to date that sperm competitive ability is negatively correlated with relatedness, even after controlling for inbreeding depression.

Sterility and meeting competitiveness of medfly, Ceratitis Capitata (Wiedemann)

International Nuclear Information System (INIS)

Taein-Tun; Molly-Maung-Maung

2001-01-01

The basic methodology in the determination of sterilising dosage in male med flies and mating competitiveness with the normal males was carried out in the laboratory. Application of the Sterile Insect Technique (S.I.T.) by three irradiation dosages on Seib-6096 pupae results in sterility when dosage increased. A lower mating competitiveness was observed with the increase in sterility value. This value was determined from the corrected egg hatch percent. The resulting data showed that irradiation dosage of γ 10.0 Krad gave a good advantage to suppress the population in the next generation. The method suggested a good application in the control and eradication of fruit flies. (author)

The effect of liquid losses in trainings during competition period on some biochemical values of u18 male judokas ( age 15-17

Directory of Open Access Journals (Sweden)

Nuri Muhammet Çelik

2017-10-01

Full Text Available Background/Objective: The purpose of this study is to investigate the effect of liquid losses occurring in training sessions during the competition period on some biochemical values of the male Judokas competing in the U18 category. Methods:  The values of the 17 male athletes, who were included in the national team at least once, were checked in our study which compares the values of athletes before the competition and immediately after the competition. Urine Density, Urine pH, BUN, Creatine and Potassium values from the biochemistry values were measured besides the age, height and weight of the athletes participating in the study. Results: As a result of the measurements made; it was found that the kg pre-test averages of the participant athletes were 67,82 ±17,87, post-test averages were 64,88±16,89, Urine Density pre-test averages were 1.017,94 ±7,08, post-test averages were 1.025±8,48, Urine pH pre-test averages were 6,15±0,70, post-test averages were 5,82±0,50, BUN pre-test averages were 15,65±3,14, post-test averages were 24,35±3,60, Creatine pre-test averages were 0,48±0,20, post-test averages were 0,93±0,41,  K Potassium pre-test averages were 4,16±0,35,  post-test averages were 4,95 ±0,64. As a result of the statistical analysis, although there was no significant difference in urine pH pre-test and post-test values, statistically significant difference was found between pre-test and post-test values in other selected parameters (p <0,05. Conclusions: As a result; it is thought that in our country in which the adjustment of the weight class is made unconsciously and unplanned, this will lead to the health problems of the athletes in many ways, especially in the later ages. Particularly in the professional sense, the health problems, which athletes who enter weight competitions and who enter at least 10 international competitions in the Olympic sense for the Judo branch a year can experience in the later ages as a result

Socially cued seminal fluid gene expression mediates responses in ejaculate quality to sperm competition risk.

Science.gov (United States)

Simmons, Leigh W; Lovegrove, Maxine

2017-08-30

There is considerable evidence that males will increase the number of sperm ejaculated in response to sperm competition risk. However, whether they have the capacity to adjust seminal fluid components of the ejaculate has received less attention. Male crickets ( Teleogryllus oceanicus ) have been shown to adjust the viability of sperm in their ejaculate in response to sperm competition risk. Here we show that socially mediated plasticity in sperm viability is probably due, at least in part, to male adjustments in the protein composition of the seminal fluid. Seven seminal fluid protein genes were found to have an increased expression in males exposed to rival calls. Increased expression of these genes was correlated with increased sperm viability in whole ejaculates, and gene knockdown confirmed that at least one of these proteins promotes sperm viability. Our results lend support for recent theoretical models that predict complex responses in male allocation to seminal fluid composition in response to sperm competition risk. © 2017 The Author(s).

Physical demands in competitive ultimate frisbee

DEFF Research Database (Denmark)

Krustrup, Peter; Mohr, Magni

2015-01-01

The objective was to study game demands in competitive ultimate Frisbee by performing match analysis during a game. Thirteen moderately trained (Yo-Yo intermittent recovery test levels 1 and 2 [Yo-Yo IR1 and IR2] performance: 1790 ± 382 m and 657 ± 225 m, respectively) competitive male ultimate...... = 0.74, p ≤ 0.05). Ultimate Frisbee is an intense intermittent team sport with high cardiovascular loading and clear indications of fatigue toward the end of each half. Yo-Yo IR test performances correlate with physical match performance....

The link between competitive sports and gambling behaviors among youths.

Science.gov (United States)

Gavriel-Fried, Belle; Bronstein, Israel; Sherpsky, Idit

2015-04-01

This study examines the association between physical activities and gambling, making a distinction between two characteristics of the former: intensity level and type (competitive/non-competitive). 316 adolescents from four high schools in Israel completed questionnaires. For males, participation in competitive athletic sports was associated with gambling frequency and problem gambling. For females, participation in competitive athletic sports was associated only with gambling frequency. Both types of physical activity and gender are important when analyzing the association between gambling and sporting activities. Youths involved in competitive sports are at greater risk for gambling involvement. (Am J Addict 2015;24:200-202). © American Academy of Addiction Psychiatry.

Japan's progressive sex: male homosexuality, national competition, and the cinema.

Science.gov (United States)

Hall, J M

2000-01-01

This essay serves as a broad investigation of the origins of what came to be called the "gay boom" in 1990's Japanese cinema: a culmination of print media, television, and especially films which made the gay male not merely a visible (political) subject but also the site of displaced contestations of gendered (female) desire. The most visible transnational signifier of the "gay boom" was the 1992 film Okoge, a film which, in keeping with a Japanese trend which relocates the gay male as a safe displacement of female desire, posits the heterosexual female as the audience's point of identification in a film about the lives of gay Japanese men. Using this as a starting point, this essay seeks to explore how male homosexuality and gender construction operate within both Japanese nationalism and the transnational discourse of Japanese cinema's dissemination.

Competitiveness value of the indian meal, plodia interpunctella (Hub). irradiated as full grown pupae

International Nuclear Information System (INIS)

Ahmed, M.Y.Y.; Elhawary, I.S.; Boshra, S.A.

1992-01-01

When 6-day-old pupae of the indian meal moth, plodia interpunctella (Hubner) were treated with 60 K.rad, the resulting adults were sterile when they paired with the untreated opposite sex. A ratio of 1:1:1 irradiated males, in irradiated males, and unirradiated females resulted in 41.0% infertile eggs. Ratios of irradiated to unirradiated males of 5:1, 10:1, 15:1, 20:1, or 25:1 produced 75.7, 91.7, 95.0 and 96.3% infertile eggs, respectively. Thus, irradiated males were competitive only at a ratio of 25:1. When both irradiated males and females were placed with unirradiated males and females to give ratios of 1:1:1:1, 5:5:1:1, 10:10:1:1: or 15:15:1:1:, the percentage of infertile eggs were 55.7, 81.0, 95.3, and 100.0% respectively, and competitiveness was good at all but the lowest ratio. Irradiation of 6-day-old pupae of the indian meal moth produced sexually competitive sterile adults when released at high flooding ratios, and results were better when both sexes released together.2 tab

Pleiotropic Effects of DDT Resistance on Male Size and Behaviour.

Science.gov (United States)

Rostant, Wayne G; Bowyer, Jemima; Coupland, Jack; Facey, James; Hosken, David J; Wedell, Nina

2017-07-01

Understanding the evolution and spread of insecticide resistance requires knowing the relative fitness of resistant organisms. In the absence of insecticides, resistance is predicted to be costly. The Drosophila melanogaster DDT resistance allele (DDT-R) is associated with a male mating cost. This could be because resistant males are generally smaller, but DDT-R may also alter courtship behaviours. Here we tested for body size and courtship effects of DDT-R on mating success in competitive and non-competitive mating trials respectively. We also assessed relative aggression in resistant and susceptible males because aggression can also influence mating success. While the effect of DDT-R on male size partly contributed to reduced mating success, resistant males also had lower rates of courtship and were less aggressive than susceptible males. These differences contribute to the observed DDT-R mating costs. Additionally, these pleiotropic effects of DDT-R are consistent with the history and spread of resistance alleles in nature.

Postmating-prezygotic isolation between two allopatric populations of Drosophila montana: fertilisation success differs under sperm competition.

Science.gov (United States)

Ala-Honkola, Outi; Ritchie, Michael G; Veltsos, Paris

2016-03-01

Postmating but prezygotic (PMPZ) interactions are increasingly recognized as a potentially important early-stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population (Vancouver) to penetrate the eggs of the other population (Colorado). As the natural mating system of D. montana is polyandrous (females remate rapidly), we set up double matings of all possible crosses between the same populations to test whether competitive effects between ejaculates influence this PMPZ isolation. We measured premating isolation in no-choice tests, female fecundity, fertility and egg-to-adult viability after single and double matings as well as second-male paternity success (P2). Surprisingly, we found no PMPZ reproductive isolation between the two populations under a competitive setting, indicating no difficulty of sperm from Vancouver males to fertilize Colorado eggs after double matings. While there were subtle differences in how P2 changed over time, suggesting that Vancouver males' sperm are somewhat less competitive in a first-male role within Colorado females, these effects did not translate into differences in overall P2. Fertilisation success can thus differ dramatically between competitive and noncompetitive conditions, perhaps because the males that mate second produce higher quality ejaculates in response to sperm competition. We suggest that unlike in more divergent species comparisons, where sperm competition typically increases reproductive isolation, ejaculate tailoring can reduce the potential for PMPZ isolation when recently diverged populations interbreed.

Sexual courtship of steriles males of Ceratitis Capitata (WIED) in SIT program

International Nuclear Information System (INIS)

Fadhel, Salma

2008-01-01

In the SIT programme, the success of sterile males to compete with the fertile males is an important parameter for assuring efficiency. In this study, two methods are tested to improve the sterile male quality: the first is the exposure of sterile males to different concentrations of Ginger Root Oil (GRO) (0, 20, 50 and 80 μl), the second is the exposure of males to different irradiation doses (80, 90, 100, 110, 120 and 145 Gy). The comparison of these methods depends to study of quality parameters (emergence, flight ability, survival) and courtship behaviour of sterile males (sperm production, mating competitiveness, sperm transfer). The 80μl concentration of GRO improves the mating competitiveness of males to compare with the Control (respectively: 68% and 46%). The 80 Gy irradiation dose assure the same result then the Control. (Author)

Mating Competitiveness of Agrotis ipsilon (Hufn.) Irradiated as Parental Pupae

International Nuclear Information System (INIS)

El-Naggar, S.E.M.; Ibrahim, S.M.; El-Shall, S.S.A.

1999-01-01

Laboratory studied were carried out to evaluate the mating competitiveness of P 1 and F 1 generations of Agrotis ipsilon when irradiated as full grown pupae with 75 and 150 Gy of gamma irradiation. The mating competitiveness values showed that either males or females of P 1 or F 1 generation were full competitive after treatment with 75 or 150 Gy at all released ratios. Mating competitiveness of both irradiated males and females was also studied to avoid problems concerning mass sexing. The results revealed that confining both sexes together gave an excellent results for population suppression in both P 1 and F 1 in both tested doses and ratios. The addition of irradiated females to the release ratio make these females encountered in mating with untreated females, and possessed 78% of all matings occurred in parent generation in the two tested doses at 5:5:1 ratio and increased to reach 88% by F 1 females 75 Gy while it was reduced to only 31% at 150 Gy, but still act in mating

On the relative effect of spawning asynchrony, sperm quantity and sperm quality on paternity under sperm competition in an external fertilizer

Directory of Open Access Journals (Sweden)

Torvald Blikra Egeland

2015-07-01

Full Text Available How much of a fitness benefit is obtained by dominant males of external fertilizers from releasing ejaculates in synchrony with female egg-release when engaging in sperm competition, and what is the most important sperm trait for paternity in these situations? The Arctic charr (Salvelinus alpinus is an external fertilizer experiencing intense male-male competition over reproductive opportunities including sperm competition. To compensate for their disadvantage the sneaker males, which often spawn out of synchrony with the female, produce more and faster sperm than the guarding males. We used controlled in vitro fertilization trials with experimentally produced dominant and subordinate, sneaker males to test what effect relative synchrony in gamete release, sperm quality (i.e., motility and velocity and sperm quantity have on a male’s fertilization success in pair-wise sperm competitions. When the sneaker males released ejaculates after the guarding male there was no overall difference in fertilization success. The quality (i.e., motility and velocity of a male’s sperm relative to that of the competing male was the best predictor of male fertilization success regardless of their mating tactic and spawning synchrony. The relative number of sperm cells also had an effect on fertilization success, but mainly when the dominant and sneaker male ejaculated synchronously. Our close imitation of natural sperm competition in charr shows that the sneaker males of external fertilizing species may fully compensate for their disadvantaged mating role by producing ejaculates of higher quality - an adjustment strangely not met by dominants.

The capture of heritable variation for genetic quality through social competition.

Science.gov (United States)

Wolf, Jason B; Harris, W Edwin; Royle, Nick J

2008-09-01

In theory, females of many species choose mates based on traits that are indicators of male genetic quality. A fundamental question in evolutionary biology is why genetic variation for such indicator traits persists despite strong persistent selection imposed by female preference, which is known as the lek paradox. One potential solution to the lek paradox suggests that the traits that are targets of mate choice should evolve condition-dependent expression and that condition should have a large genetic variance. Condition is expected to exhibit high genetic variance because it is affected by a large number of physiological processes and hence, condition-dependent traits should 'capture' variation contributed by a large number of loci. We suggest that a potentially important cause of variation in condition is competition for limited resources. Here, we discuss a pair of models to analyze the evolutionary genetics of traits affected by success in social competition for resources. We show that competition can contribute to genetic variation of 'competition-dependent' traits that have fundamentally different evolutionary properties than other sources of variation. Competition dependence can make traits honest indicators of genetic quality by revealing the relative competitive ability of males, can provide a component of heritable variation that does not contribute to trait evolution, and can help maintain heritable variation under directional selection. Here we provide a general introduction to the concept of competition dependence and briefly introduce two models to demonstrate the potential evolutionary consequences of competition-dependent trait expression.

Sexually selected nest-building--Pomatoschistus minutus males build smaller nest-openings in the presence of sneaker males.

Science.gov (United States)

Svensson, O; Kvarnemo, C

2003-09-01

Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.

A disparity between locomotor economy and territory-holding ability in male house mice.

Science.gov (United States)

Morris, Jeremy S; Ruff, James S; Potts, Wayne K; Carrier, David R

2017-07-15

Both economical locomotion and physical fighting are important performance traits to many species because of their direct influence on components of Darwinian fitness. Locomotion represents a substantial portion of the total daily energy budget of many animals. Fighting performance often determines individual reproductive fitness through the means of resource control, social dominance and access to mates. However, phenotypic traits that improve either locomotor economy or fighting ability may diminish performance in the other. Here, we tested for a predicted disparity between locomotor economy and competitive ability in wild-derived house mice ( Mus musculus ). We used 8 week social competition trials in semi-natural enclosures to directly measure male competitive ability through territorial control and female occupancy within territories. We also measured oxygen consumption during locomotion for each mouse using running trials in an enclosed treadmill and open-flow respirometry. Our results show that territory-holding males have higher absolute and mass-specific oxygen consumption when running (i.e. reduced locomotor economy) compared with males that do not control territories. This relationship was present both before and after 8 week competition trials in semi-natural enclosures. This disparity between physical competitive ability and economical locomotion may impose viability costs on males in species for which competition over mates is common and may constrain the evolution of behavioral and phenotypic diversity, particularly in natural settings with environmental and resource variability. © 2017. Published by The Company of Biologists Ltd.

Sperm competition and reproductive mode influence sperm dimensions and structure among snakes.

Science.gov (United States)

Tourmente, Maximiliano; Gomendio, Montserrat; Roldan, Eduardo R S; Giojalas, Laura C; Chiaraviglio, Margarita

2009-10-01

The role of sperm competition in increasing sperm length is a controversial issue, because findings from different taxa seem contradictory. We present a comparative study of 25 species of snakes with different levels of sperm competition to test whether it influences the size and structure of different sperm components. We show that, as levels of sperm competition increase, so does sperm length, and that this elongation is largely explained by increases in midpiece length. In snakes, the midpiece is comparatively large and it contains structures, which in other taxa are present in the rest of the flagellum, suggesting that it may integrate some of its functions. Thus, increases in sperm midpiece size would result in more energy as well as greater propulsion force. Sperm competition also increases the area occupied by the fibrous sheath and outer dense fibers within the sperm midpiece, revealing for the first time an effect upon structural elements within the sperm. Finally, differences in male-male encounter rates between oviparous and viviparous species seem to lead to differences in levels of sperm competition. We conclude that the influence of sperm competition upon different sperm components varies between taxa, because their structure and function is different.

The Incidence of Anabolic Steroid Use among Competitive Bodybuilders.

Science.gov (United States)

Tricker, Ray; And Others

1989-01-01

Investigated incidence of anabolic steroid use among 380 competitive male and female bodybuilders in Kansas and Missouri. Results indicated more than half (54 percent) of the male bodybuilders were using steroids on a regular basis compared to 10 percent of the female competitors. Found main reason for use of steroids was desire to win. (Author/TE)

Pollinator Competition as a Driver of Floral Divergence: An Experimental Test.

Directory of Open Access Journals (Sweden)

Ethan J Temeles

Full Text Available Optimal foraging models of floral divergence predict that competition between two different types of pollinators will result in partitioning, increased assortative mating, and divergence of two floral phenotypes. We tested these predictions in a tropical plant-pollinator system using sexes of purple-throated carib hummingbirds (Anthracothorax jugularis as the pollinators, red and yellow inflorescence morphs of Heliconia caribaea as the plants, and fluorescent dyes as pollen analogs in an enclosed outdoor garden. When foraging alone, males exhibited a significant preference for the yellow morph of H. caribaea, whereas females exhibited no preference. In competition, males maintained their preference for the yellow morph and through aggression caused females to over-visit the red morph, resulting in resource partitioning. Competition significantly increased within-morph dye transfer (assortative mating relative to non-competitive environments. Competition and partitioning of color morphs by sexes of purple-throated caribs also resulted in selection for floral divergence as measured by dye deposition on stigmas. Red and yellow morphs did not differ significantly in dye deposition in the competition trials, but differences in dye deposition and preferences for morphs when sexes of purple-throated caribs foraged alone implied fixation of one or the other color morph in the absence of competition. Competition also resulted in selection for divergence in corolla length, with the red morph experiencing directional selection for longer corollas and the yellow morph experiencing stabilizing selection on corolla length. Our results thus support predictions of foraging models of floral divergence and indicate that pollinator competition is a viable mechanism for divergence in floral traits of plants.

Evolutionary Modeling Predicts a Decrease in Postcopulatory Sperm Viability as a Response to Increasing Levels of Sperm Competition

NARCIS (Netherlands)

Engqvist, Leif

Sperm competition has been found to have a strong influence on the evolution of many male and female reproductive traits. Theoretical models have shown that, with increasing levels of sperm competition, males are predicted to increase ejaculate investment, and there is ample empirical evidence

Parker's sneak-guard model revisited: why do reproductively parasitic males heavily invest in testes?

Science.gov (United States)

Ota, Kazutaka; Kohda, Masanori; Hori, Michio; Sato, Tetsu

2011-10-01

Alternative reproductive tactics are widespread in males and may cause intraspecific differences in testes investment. Parker's sneak-guard model predicts that sneaker males, who mate under sperm competition risk, invest in testes relatively more than bourgeois conspecifics that have lower risk. Given that sneakers are much smaller than bourgeois males, sneakers may increase testes investment to overcome their limited sperm productivity because of their small body sizes. In this study, we examined the mechanism that mediates differential testes investment across tactics in the Lake Tanganyika cichlid fish Lamprologus callipterus. In the Rumonge population of Burundi, bourgeois males are small compared with those in other populations and have a body size close to sneaky dwarf males. Therefore, if differences in relative testis investment depend on sperm competition, the rank order of relative testis investment should be dwarf males > bourgeois males in Rumonge = bourgeois males in the other populations. If differences in relative testis investment depend on body size, the rank order of relative testes investment should be dwarf males > bourgeois males in Rumonge > bourgeois males in the other populations. Comparisons of relative testis investment among the three male groups supported the role of sperm competition, as predicted by the sneak-guard model. Nevertheless, the effects of absolute body size on testes investment should be considered to understand the mechanisms underlying intraspecific variation in testes investment caused by alternative reproductive tactics.

Challenging the other: exploring the role of opponent gender in digital game competition for female players.

Science.gov (United States)

Vermeulen, Lotte; Núñez Castellar, Elena; Van Looy, Jan

2014-05-01

Abstract The present study investigated the effect of opponent gender on the game experience of female players. Concretely, it looked into skill perception and player emotions of women in same gender and cross-gender game competition. We set up a 2×2×2 (male vs. female opponent×low vs. high competitive women×lost vs. won game) experimental design in which women were instructed to play against a proclaimed male and female competitor. Unknowingly, however, participants played against an AI, which was configured to produce a winning and a losing condition for each opponent by manipulating difficulty. Results indicated that opponent gender only had an effect on perceived stress, which was higher with male opponents. Moreover, players evaluated their own gaming skills as lower and the skills of presumed male opponents as higher when they thought they were playing against men. Importantly, our results also showed that the above described pattern for self-perceived skills and perceived opponent skills was modulated by trait competitiveness with a larger effect size for low competitive women. Overall, this study illustrates that gender dynamics affect the play experience of women in cross-gender gaming competition. Implications and suggestions for future research are discussed.

Pre-Release Consumption of Methyl Eugenol Increases the Mating Competitiveness of Sterile Males of the Oriental Fruit Fly, Bactrocera dorsalis, in Large Field Enclosures

Science.gov (United States)

Shelly, Todd E.; Edu, James; McInnis, Donald

2010-01-01

The sterile insect technique may be implemented to control populations of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), when environmental concerns preclude widespread use of chemical attractants or toxicants. The goal of the present study was to evaluate whether the mating competitiveness of sterile B. dorsalis males could be increased via pre-release feeding on methyl eugenol. Males of the oriental fruit fly are strongly attracted to this plant-borne compound, which they ingest and use in the synthesis of the sex pheromone. Previous studies conducted in the laboratory and small field-cages have shown that males given methyl eugenol produce a more attractive pheromone for females and have a higher mating success rate than males denied methyl eugenol. Here, levels of egg sterility were compared following the release of wild-like flies and either methyl eugenol-fed (treated) or methyl eugenol-deprived (control) sterile males in large field enclosures at four over flooding ratios ranging from 5:1 to 60:1 (sterile: wild-like males). Treated sterile males were fed methyl eugenol for 1–4 h (depending on the over flooding ratio tested) 3 d prior to release. Eggs were dissected from introduced fruits (apples), incubated in the laboratory, and scored for hatch rate. The effect of methyl eugenol was most pronounced at lower over flooding ratios. At the 5:1 and 10:1 over flooding ratios, the level of egg sterility observed for treated, sterile males was significantly greater than that observed for control, sterile males. In addition, the incidence of egg sterility reported for treated sterile males at these lower over flooding ratios was similar to that noted for treated or control sterile males at the 30:1 or 60:1 over flooding ratios. This latter result, in particular, suggests that pre-release feeding on methyl eugenol allows for a reduction in the number of sterile flies that are produced and released, thus increasing the cost

Studies on mating competition of irradiated melon flies

International Nuclear Information System (INIS)

Limohpasmanee, W.

1994-01-01

Mating competition is the key factor for fruit flies control by using sterile insect technique project. Mass rearing and irradiation can reduce the mating competition of fruit flies. This experiment has purpose to evaluate the mating competition of the irradiated melon fly. The results show that mating competition values of irradiated melon flies were 0.36 and 0.24 when they mated with normal and irradiated females. Both normal male and female can mate more frequency than irradiated flies. (Z=1.322, P<0.05; Z=1.851, P<0.05). The results show that quality of mass rearing and irradiated melon fly was lower than the normal flies. So that quality of irradiated fly must be improved and the number of released flies as less must be higher than natural flies 6 time

Mating success of males with and without wing patch in Drosophila biarmipes.

Science.gov (United States)

Hegde, S N; Chethan, B K; Krishna, M S

2005-10-01

Some males of D. biarmipes--synonym of D. rajasekari and D. raychaudhuri have a black patch on the wing. The patch extends from the apical margin of wing to the third longitudinal vein. Field and laboratory studies have been carried out in D. biarmipes to study role of male's wing patch in mating success. The field study shows that nature favors D. biarmipes males with patch. Although males without patch mated, males with patch have higher mating success suggesting the role of wing patch during courtship. Further, among mating males, males with patch had longer wings than males without patch. During courtship, males with patch oriented and mated faster; performed courtship acts such as tapping, scissoring, vibration, licking and twist dance more times than males without patch in both competitive and non-competitive situations. The results indicate that there is a casual relationship between the presence of wing patch, mating speed and success. Also there is a correlation between presence of wing patch, size of the flies and mating success.

Prevalence of injuries in Wushu competition during the 1st Asian Martial Arts Games 2009.

Science.gov (United States)

Yiemsiri, Pichet; Wanawan, Amarin

2014-02-01

To determine the prevalence and characteristic of injuries in Wushu Competition during the IP' Asian MartialArts Games 2009. Sixty international athletes (38 males) participating in Wushu Competition during the 1st Asian Martial Arts Games 2009. Injuries were recorded on injury report forms to document any injuries seen and treatment provided by tournament physician during competitions. The injury forms described the athlete s causes, type, site, and severity of the injuries. There were 60 international athletes the average age were 22.49 +/- 3.75 years. The prevalence ofinjuries was 228.07/ 1000 athlete exposure (AE). The prevalence in males andfemales was 161.76/1000 AE and 326.09/1000 AE, respectively. The most common injured body parts in males were lower extremities 102.94/1000 AE, followed by head and face injuries 58.82/1000 AE. The most common injured body parts in females were lower extremities 282.61/1000 AE. The most common types of injuries in males were contusions 58.82/1000 AE, concussion 29.41/1000 AE and strain-sprain 29.41/1000 AE. In females the most common type of injury were contusion 195.65/1000 AEfollowed by strain-sprain 130.43/1000 AE. The most common mechanism of injury in males werereceiving a punch 58.82/1000 AE, receiving a kick 44.12/1000 AE and delivering a kick 44.12/1000 AE. Meanwhile, in females common mechanisms were receiving a kick 152.17/1000 AE followed by delivering a kick 130.43/1000 AE. High prevalence of injuries in Wushu competition during the 1" Asian MartialArts Games 2009 revealedfemale injuries were higher than male and had a higher prevalence compared with Muay Thai or Taekwondo competitions.

Sexual Competitiveness, Field Survival, and Dispersal of Anastrepha obliqua (Diptera: Tephritidae) Fruit Flies Irradiated at Different Doses.

Science.gov (United States)

Gallardo-Ortiz, Uriel; Pérez-Staples, Diana; Liedo, Pablo; Toledo, Jorge

2018-04-02

The sterile insect technique (SIT) is used in area-wide pest management programs for establishing low pest prevalence and/or areas free of fruit flies (Diptera: Tephritidae). The aim of this technique is to induce high levels of sterility in the wild population, for this the released insects must have a high sexual competitiveness and field dispersal. However, radiation decreases these biological attributes that do not allow it to compete successfully with wild insects. In this study the sexual competitiveness, field survival and dispersal of Anastrepha obliqua (Macquart; Diptera: Tephritidae) irradiated at 0, 40, 50, 60, 70, and 80 Gy were evaluated in laboratory. A dose of 60 Gy produced 98% sterility, whereas doses of 70 and 80 Gy produced 99% sterility. Sexual competitiveness was assessed in field cages, comparing males irradiated at 0, 50, 60, 70, and 80 Gy against wild males for mating with wild fertile females. Males irradiated at 50 and 60 Gy achieved more matings than those irradiated at 70 and 80 Gy. Wild males were more competitive than mass-reared males, even when these were not irradiated (0 Gy). There was no effect of irradiation on mating latency, yet wild males showed significantly shorter mating latency than mass-reared males. Female remating did not differ among those that mated with wild males and those that mated with males irradiated with different doses. The relative sterility index (RSI) increased from 0.25 at 80 Gy to 0.37 at 60 Gy. The Fried competitiveness index was 0.69 for males irradiated at 70 Gy and 0.57 for those irradiated at 80 Gy, which indicates that a 10 Gy reduction in the irradiation dose produces greater induction of sterility in the wild population. There were no significant differences in field survival and dispersal between flies irradiated at 70 or 80 Gy. Reducing the irradiation dose to 60 or 70 Gy could improve the performance of sterile males and the effectiveness of the SIT. Our results also distinguish between the

Male Music Frogs Compete Vocally on the Basis of Temporal Sequence Rather Than Spatial Cues of Rival Calls

Institute of Scientific and Technical Information of China (English)

Fan JIANG; Guangzhan FANG; Fei XUE; Jianguo CUI; Steven E BRAUTH; Yezhong TANG

2015-01-01

Male-male vocal competition in anuran species may be influenced by cues related to the temporal sequence of male calls as well by internal temporal, spectral and spatial ones. Nevertheless, the conditions under which each type of cue is important remain unclear. Since the salience of different cues could be reflected by dynamic properties of male-male competition under certain experimental manipulation, we investigated the effects of repeating playbacks of conspecific calls on male call production in the Emei music frog (Babina daunchina). In Babina, most males produce calls from nest burrows which modify the spectral features of the cues. Females prefer calls produced from inside burrows which are defined as highly sexually attractive (HSA) while those produced outside burrows as low sexual attractiveness (LSA). In this study HSA and LSA calls were broadcasted either antiphonally or stereophonically through spatially separated speakers in which the temporal sequence and/or spatial position of the playbacks was either predictable or random. Results showed that most males consistently avoided producing advertisement calls overlapping the playback stimuli and generally produced calls competitively in advance of the playbacks. Furthermore males preferentially competed with the HSA calls when the sequence was predictable but competed equally with HSA and LSA calls if the sequence was random regardless of the availability of spatial cues, implying that males relied more on available sequence cues than spatial ones to remain competitive.

Low risk of concussions in top-level karate competition.

Science.gov (United States)

Arriaza, Rafael; Cierna, Dusana; Regueiro, Patricia; Inman, David; Roman, Franco; Abarca, Benjamin; Barrientos, Mercé; Saavedra, Miguel A

2017-02-01

Although it is well known that injuries occur in combat sports, the true incidence of concussions is not clearly defined in the literature for karate competition. To determine the incidence of concussions in top-level (World Karate Federation World Championships) karate competition. Injuries that took place in 4 consecutive World Karate Championships (from 2008 to 2014) were prospectively registered. A total of 4625 fights (2916 in the male category and 1709 in the female category) were scrutinised, and concussions were identified and analysed separately for frequency (rate per fight) and injury risk. A total of 4 concussions were diagnosed by the attending physicians after carrying out athlete examinations. Globally, there was 1 concussion in every 1156 fights, or 0.43/1000 athlete-exposures (AE). In male athletes, the rate of concussion was 1/5832 min of fighting, and in female athletes, it was 1/6836 min. OR for concussion in women is 0.57 (95% CI 0.06 to 5.47; z=0.489; p=0.6249) and risk ratio for concussions in men is RR 1.478 (95% CI 0.271 to 8.072), p=0.528, representing a higher risk of definite concussions in men than in women, but not statistically significant. There is not a significantly higher risk of concussions in team competition (no weight limit) when compared with individual competition (held with strict weight limits for each category). The risk of concussions in top-level karate competition is low, with a tendency for an increased risk for men and for competition without weight limits, but not statistically significant with respect to women or individual competition. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Effect of irradiation sterilizing dose on the mating competitiveness of Trogoderma Granarium Everts treated as adults at different ages

International Nuclear Information System (INIS)

Gharieb, O.H.

2002-01-01

Males of Trogoderma Granarium at ages of 1, 3, 5 and 7 days were irradiated with 200 GY (sterilizing dose) and combined with the same ages of the normal males mated with 1-d-old females. (I male : u male : U ) in the fohowing ratios of (1:1:1), (5:1:1), (10:1:1) and (15:1:1). At 15 irradiated males per pair, egg hatch was reduced to 4.5 and 2.2% at male ages of 1 and 3 d-old, respectively, but, it was 4.9 and 7.5 at male ages of 5 and 7 d-old, respectively. The calculated degree of mating competitiveness at this ratio was 1.10, 1.03, 0.97 and 0.94 for the corresponding ages. Females at the aformentioned ages irradiated with 60 GY (sterilizing dose) and competed with normal females for normal males. At 15 irradiated females per pair, the egg hatch was reduced to 5.4, 2.1, 1.8 and 1.4 % for the corresponding ages tested. Therefore, (I) females showed good competitiveness at most release ratios, but (I) females were fully competitive (1.00) at the higher release ratio I:U females (15:1). In general, (I) females were more competitive (based on number of eggs per female and percent infertility) than the corresponding (I) males especially at later ages (5 and 7 d-old adults) even, at the higher release ratios. =

Differences in anthropometric characteristics in relation to throwing velocity and competitive level in professional male team handball: a tool for talent profiling.

Science.gov (United States)

Fieseler, Georg; Hermassi, Souhail; Hoffmeyer, Birgit; Schulze, Stephan; Irlenbusch, Lars; Bartels, Thomas; Delank, Karl-Stefan; Laudner, Kevin G; Schwesig, René

2017-01-01

The primary aim of the study was to examine the anthropometric characteristics as well as throwing and sprinting performance of professional handball players classified by playing position and competition level. 21 male players (age: 25.2±5.1 years) from the first German handball league (FGL) and 34 male players (age: 26.1±4.1 years) from the third German handball league (TGL) were categorized as backs, pivots, wings and goalkeepers. Measurements included anthropometric data (height, mass and body mass index (BMI)), throwing and sprinting performance selected out of a complex handball test (HBCT), which was conducted twice (2 rounds). During the HBCT, the subjects performed two sprints (10, 20 m), two standing throws with run-up (ST) and four vertical jump throws (VJT) over a hurdle (20 cm) with and without precision for goal shot. The anthropometric data revealed a significantly (P=0.038 and η2=0.079) shorter body height for TGL than for FGL players. In the cohort of first league athletes the pivots were the tallest (1.98±0.04 m), backs in the third league showed the maximum body height (1.90±0.05 m). Regarding body mass, pivots were the heaviest players independent from the league membership. The FGL players showed a significantly (P0.10) higher throwing velocity in all type of throws. Body height was significantly related to ST (r=0.53) and VJT (r=0.52) in the first round of HBCT but only for the FGL athletes. Throwing velocity was also correlated with BMI (r=-0.50) among the TGL players. Substantial differences of body characteristics, throwing and sprinting performance between playing positions and competitive levels underline the importance of a careful scouting and position-specific training for professional handball players.

Alternative phenotypes of male mating behaviour in the two-spotted spider mite

NARCIS (Netherlands)

Sato, Y.; Sabelis, M.W.; Egas, M.; Faraji, F.

2013-01-01

Severe intraspecific competition for mates selects for aggressive individuals but may also lead to the evolution of alternative phenotypes that do not act aggressively, yet manage to acquire matings. The two-spotted spider mite, Tetranychus urticae, shows male mate-guarding behaviour and male-male

Myocardial Fibrosis in Competitive Triathletes Detected by Contrast-Enhanced CMR Correlates With Exercise-Induced Hypertension and Competition History.

Science.gov (United States)

Tahir, Enver; Starekova, Jitka; Muellerleile, Kai; von Stritzky, Alexandra; Münch, Julia; Avanesov, Maxim; Weinrich, Julius M; Stehning, Christian; Bohnen, Sebastian; Radunski, Ulf K; Freiwald, Eric; Blankenberg, Stefan; Adam, Gerhard; Pressler, Axel; Patten, Monica; Lund, Gunnar K

2017-12-08

This study analyzed the presence of myocardial fibrosis detected by late gadolinium-enhancement (LGE) cardiac magnetic resonance (CMR) in correlation with the performance of competitive triathletes objectified by an exercise test and individual competition history. Myocardial fibrosis detected by LGE CMR has been reported to occur in 0% to 50% of asymptomatic athletes. However, the cause and mechanisms of myocardial fibrosis are unclear. Eighty-three asymptomatic triathletes undergoing >10 training h per week (43 ± 10 years of age; 65% male) and 36 sedentary controls were studied by using LGE and extracellular volume (ECV) CMR. Parameters of physical fitness were measured by spiroergometry. Triathletes reported their lifetime competition results. LGE CMR revealed focal nonischemic myocardial fibrosis in 9 of 54 (17%) male triathletes (LGE + ) but in none of the female triathletes (p pressure (213 ± 24 mm Hg) than LGE - triathletes (194 ± 26 mm Hg; p 1,880 km completed during competition had the highest accuracy to predict LGE, with an area under the curve value of 0.876 (p pressure (p < 0.05) and the swimming race distance (p < 0.01) as independent predictors of LGE presence. Myocardial fibrosis in asymptomatic triathletes seems to be associated with exercise-induced hypertension and the race distances. There appears to be a safe upper limit, beyond which exercise may result in myocardial fibrosis. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

The power of competition: Effects of social motivation on attention, sustained physical effort, and learning

Directory of Open Access Journals (Sweden)

Brynne Catherine DiMenichi

2015-09-01

Full Text Available Competition has often been implicated as a means to improve effort-based learning and attention. Two experiments examined the effects of competition on effort and memory. In Experiment 1, participants completed a physical effort task in which they were rewarded for winning an overall percentage, or for winning a competition they believed was against another player. In Experiment 2, participants completed a memory task in which they were rewarded for remembering an overall percentage of shapes, or more shapes than a competitor. We found that, in the physical effort task, participants demonstrated faster reaction times—a previous indicator of increased attention— in the competitive environment. Moreover, individual differences predicted the salience of competition’s effect. Furthermore, male participants showed faster reaction times and greater sustained effort as a result of a competitive environment, suggesting that males may be more affected by competition in physical effort tasks. However, in Experiment 2, participants remembered fewer shapes when competing, and later recalled less of these shapes during a post-test, suggesting that competition was harmful in our memory task. The different results from these two experiments suggest that competition can improve attention in a physical effort task, yet caution the use of competition in memory tasks.

Competition and opportunity shape the reproductive tactics of males in the ant Cardiocondyla obscurior.

Directory of Open Access Journals (Sweden)

Sylvia Cremer

Full Text Available Context-dependent adjustment of mating tactics can drastically increase the mating success of behaviourally flexible animals. We used the ant Cardiocondyla obscurior as a model system to study adaptive adjustment of male mating tactics. This species shows a male diphenism of wingless fighter males and peaceful winged males. Whereas the wingless males stay and exclusively mate in the maternal colony, the mating behaviour of winged males is plastic. They copulate with female sexuals in their natal nests early in life but later disperse in search for sexuals outside. In this study, we observed the nest-leaving behaviour of winged males under different conditions and found that they adaptively adjust the timing of their dispersal to the availability of mating partners, as well as the presence, and even the type of competitors in their natal nests. In colonies with virgin female queens winged males stayed longest when they were the only male in the nest. They left earlier when mating partners were not available or when other males were present. In the presence of wingless, locally mating fighter males, winged males dispersed earlier than in the presence of docile, winged competitors. This suggests that C. obscurior males are capable of estimating their local breeding chances and adaptively adjust their dispersal behaviour in both an opportunistic and a risk-sensitive way, thus showing hitherto unknown behavioural plasticity in social insect males.

Melon flies: dosage-response and sexual competitiveness after treatment with gamma irradiation in a nitrogen atmosphere

International Nuclear Information System (INIS)

Ashraf, M.; Chatha, N.; Ohinata, K.; Harris, E.J.

1975-01-01

Doses of 18-19 krad of gamma irradiation were needed to produce a level of sterility of 99.5% or higher in males Dacus cucurbitae Coquillett treated in nitrogen as pupae 2 days before eclosion or as 2- or 5-day-old adults. The same level of sterility was obtained with 6-8 krad when pupae or 2-day-old adults were irradiated in air. Males irradiated in nitrogen either as pupae or as 2-day-old adults were fully competitive with normal males, but males treated in nitrogen as 5-day-old adults and males irradiated in air as 2-day-old adults or as pupae were only 40-60% as competitive as normal males. Recovery of fertility with time occurred in males treated in nitrogen as 2-day-old adults, although not in males treated in nitrogen in the late pupal stage. However, mortality in males treated in nitrogen in the pupal stage at 6 wk was about twice that of the former groups

Effects of gamma irradiation on some major elements and mating competitiveness of the red Palm Weevil, Rhynchophorus Ferrugineus (OLIVIER), Coleoptera : Curculionidae

International Nuclear Information System (INIS)

Mohamed, H.F.; EL-Naggar, S.M.; EL-Kkoly, E.M.S.

2006-01-01

In the present study, effects of three gamma doses (5, 10 and 15 Gray) applied to adult male and female weevils of the red palm weevil, Rhynchophorus ferrugineus (Olivier), were investigated. The concentration levels of sodium, potassium, calcium and phosphorous were determined in the haemolymph treated and untreated F1 progeny (males or females) at the 4th instar larvae descendants from irradiated parents male and female weevils. Results indicated that gamma irradiation might have an effect on most investigated elements. No clear relationship could be detected among the applied doses and effect on the level of any of the studied elements. Male mating competitiveness was determined from the egg infertility resulting from F1 males originating from irradiated parental male weevils confined in various ratios with unirradiated adults. Studies comparing mating performance of irradiated males with that of normal males revealed that the mating competitiveness of the irradiated males was increased as the ratio of irradiated to unirradiated males increased from 1 : 1 to 3 : 1 , except at the lesser dose 5 Gy .The results also showed that the infertility was increased as the ratios increased except at the dose rate 10 Gy . The irradiated males were not fully competitive with normal males at the dose 5 Gy among the two ratios 1 : 1 and 3 : 1 and also among the ratio 1:1 at the doses 10 and 15 Gy. The irradiated males were fully competitive with normal males at the doses 10 and 15 Gy among the ratio 3 : 1

CONCEPTUAL APPROACH OF COMPETITIVENESS AND INTERDEPENDENCE BETWEEN COMPETITION AND COMPETITIVENESS

Directory of Open Access Journals (Sweden)

Tatiana GUTIUM

2017-11-01

Full Text Available This article is devoted to analysis of interdependence and correlation between competition and competitiveness, and competition’s consequences. The author analysed some authors’ visions on competitiveness, and common features between theories of competition and competitiveness. Using the synthetic indicator elaborated by author has been evaluated the competitiveness of domestic goods on the internal and external market. At the end of this article, the author has developed proposals to increase competitiveness.

Epidemiology of golf related musculo-skeletal injuries

Directory of Open Access Journals (Sweden)

Dhillon Mandeep

2006-01-01

Full Text Available Background : Golfing has become an increasingly popular sport enjoyed by both men and women. Although the game is not viewed as hazardous, golfers do sustain injuries connected with the game. However, golf injuries have received little attention in the literature and there is no study from Asia. Methods : A prospective study was undertaken to analyze the incidence, cause and type of injury among amateur golfers. Open ended questionnaires were sent to 1000 golfers; 240 responded (Av age 51 years, 200 males and 40 females. The respondents played an average of 2 rounds per week. Results : One hundered and ten (46% responders had sustained one or more orthopaedic injuries. Both among men and women, the lower back was the most common site of injury followed by shoulder and dorsal spine. There was a difference in the injury pattern in skilled and relatively unskilled players. Lack of warm up, excessive practice and improper swing mechanics were the most common causes. Conclusion : Golf injuries perhaps could be prevented or reduced by proper technique, controlled practice routines, physical conditioning and pre-play stretching exercises. The most important factor in this playing population seems to be prevention.

A test of genetic association among male nuptial coloration, female mating preference, and male aggression bias within a polymorphic population of cichlid fish

Directory of Open Access Journals (Sweden)

Inke van der SLUIJS, Peter D. DIJKSTRA, Charlotte M. LINDEYER et al.

2013-04-01

Full Text Available Both inter- and intrasexual selection have been implicated in the origin and maintenance of species-rich taxa with diverse sexual traits. Simultaneous disruptive selection by female mate choice and male-male competition can, in theory, lead to speciation without geographical isolation if both act on the same male trait. Female mate choice can generate discontinuities in gene flow, while male-male competition can generate negative frequency-dependent selection stabilizing the male trait polymorphism. Speciation may be facilitated when mating preference and/or aggression bias are physically linked to the trait they operate on. We tested for genetic associations among female mating preference, male aggression bias and male coloration in the Lake Victoria cichlid Pundamilia. We crossed females from a phenotypically variable population with males from both extreme ends of the phenotype distribution in the same population (blue or red. Male offspring of a red sire were significantly redder than males of a blue sire, indicating that intra-population variation in male coloration is heritable. We tested mating preferences of female offspring and aggression biases of male offspring using binary choice tests. There was no evidence for associations at the family level between female mating preferences and coloration of sires, but dam identity had a significant effect on female mate preference. Sons of the red sire directed significantly more aggression to red than blue males, whereas sons of the blue sire did not show any bias. There was a positive correlation among individuals between male aggression bias and body coloration, possibly due to pleiotropy or physical linkage, which could facilitate the maintenance of color polymorphism [Current Zoology 59 (2: 221-229, 2013].

A new approach to the study of Gold Putting | Dias | South African ...

African Journals Online (AJOL)

The aim of this study was to apply non-linear techniques in the analysis of golf putting performance. How players adapt to the variability that emerges from the putting execution and how they self-organize their performance toward the task constraints was investigated. The sample consisted of 10 adult male golfers ...

Competitive interactions are mediated in a sex-specific manner by arbuscular mycorrhiza in Antennaria dioica.

Science.gov (United States)

Varga, S; Vega-Frutis, R; Kytöviita, M-M

2017-03-01

Plants usually interact with other plants, and the outcome of such interaction ranges from facilitation to competition depending on the identity of the plants, including their sexual expression. Arbuscular mycorrhizal (AM) fungi have been shown to modify competitive interactions in plants. However, few studies have evaluated how AM fungi influence plant intraspecific and interspecific interactions in dioecious species. The competitive abilities of female and male plants of Antennaria dioica were examined in a greenhouse experiment. Females and males were grown in the following competitive settings: (i) without competition, (ii) with intrasexual competition, (iii) with intersexual competition, and (iv) with interspecific competition by Hieracium pilosella - a plant with similar characteristics to A. dioica. Half of the pots were grown with Claroideoglomus claroideum, an AM fungus isolated from the same habitat as the plant material. We evaluated plant survival, growth, flowering phenology, and production of AM fungal structures. Plant survival was unaffected by competition or AM fungi. Competition and the presence of AM fungi reduced plant biomass. However, the sexes responded differently to the interaction between fungal and competition treatments. Both intra- and interspecific competition results were sex-specific, and in general, female performance was reduced by AM colonization. Plant competition or sex did not affect the intraradical structures, extraradical hyphae, or spore production of the AM fungus. These findings suggest that plant sexual differences affect fundamental processes such as competitive ability and symbiotic relationships with AM fungi. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Interdependent effects of male and female body size plasticity on mating behaviour of predatory mites.

Science.gov (United States)

Walzer, Andreas; Schausberger, Peter

2015-02-01

The adaptive canalization hypothesis predicts that traits with low phenotypic plasticity are more fitness relevant, because they have been canalized via strong past selection, than traits with high phenotypic plasticity. Based on differing male body size plasticities of the predatory mites Phytoseiulus persimilis (low plasticity) and Neoseiulus californicus (high plasticity), we accordingly hypothesized that small male body size entails higher costs in female choice and male-male competition in P. persimilis than N. californicus . Males of both species are highly polygynous but females differ in the level of polyandry (low level in P. persimilis ; medium level in N. californicus ). We videotaped the mating interactions in triplets of either P. persimilis or N. californicus , consisting of a virgin female (small or standard-sized) and a small and a standard-sized male. Mating by both small and standard-sized P. persimilis females was biased towards standard-sized males, resulting from the interplay between female preference for standard-sized males and the inferiority of small males in male-male competition. In contrast, mating by N. californicus females was equally balanced between small and standard-sized males. Small N. californicus males were more aggressive ('Napoleon complex') in male-male competition, reducing the likelihood of encounter between the standard-sized male and the female, and thus counterbalancing female preference for standard-sized males. Our results support the hypothesis that male body size is more important to fitness in the low-level polyandrous P. persimilis than in the medium-level polyandrous N. californicus and provide a key example of the implications of sexually selected body size plasticity on mating behaviour.

Assessment of Energy Intake and Energy Expenditure of Male Adolescent Academy-Level Soccer Players during a Competitive Week

Science.gov (United States)

Briggs, Marc A.; Cockburn, Emma; Rumbold, Penny L. S.; Rae, Glen; Stevenson, Emma J.; Russell, Mark

2015-01-01

This study investigated the energy intake and expenditure of professional adolescent academy-level soccer players during a competitive week. Over a seven day period that included four training days, two rest days and a match day, energy intake (self-reported weighed food diary and 24-h recall) and expenditure (tri-axial accelerometry) were recorded in 10 male players from a professional English Premier League club. The mean macronutrient composition of the dietary intake was 318 ± 24 g·day−1 (5.6 ± 0.4 g·kg−1 BM) carbohydrate, 86 ± 10 g·day−1 (1.5 ± 0.2 g·kg−1 BM) protein and 70 ± 7 g·day−1 (1.2 ± 0.1 g·kg−1 BM) fats, representing 55% ± 3%, 16% ± 1%, and 29% ± 2% of mean daily energy intake respectively. A mean daily energy deficit of −1302 ± 1662 kJ (p = 0.035) was observed between energy intake (9395 ± 1344 kJ) and energy expenditure (10679 ± 1026 kJ). Match days (−2278 ± 2307 kJ, p = 0.012) and heavy training days (−2114 ± 2257 kJ, p = 0.016) elicited the greatest deficits between intake and expenditure. In conclusion, the mean daily energy intake of professional adolescent academy-level soccer players was lower than the energy expended during a competitive week. The magnitudes of these deficits were greatest on match and heavy training days. These findings may have both short and long term implications on the performance and physical development of adolescent soccer players. PMID:26445059

Assessment of Energy Intake and Energy Expenditure of Male Adolescent Academy-Level Soccer Players during a Competitive Week

Directory of Open Access Journals (Sweden)

Marc A. Briggs

2015-10-01

Full Text Available This study investigated the energy intake and expenditure of professional adolescent academy-level soccer players during a competitive week. Over a seven day period that included four training days, two rest days and a match day, energy intake (self-reported weighed food diary and 24-h recall and expenditure (tri-axial accelerometry were recorded in 10 male players from a professional English Premier League club. The mean macronutrient composition of the dietary intake was 318 ± 24 g·day−1 (5.6 ± 0.4 g·kg−1 BM carbohydrate, 86 ± 10 g·day−1 (1.5 ± 0.2 g·kg−1 BM protein and 70 ± 7 g·day−1 (1.2 ± 0.1 g·kg−1 BM fats, representing 55% ± 3%, 16% ± 1%, and 29% ± 2% of mean daily energy intake respectively. A mean daily energy deficit of −1302 ± 1662 kJ (p = 0.035 was observed between energy intake (9395 ± 1344 kJ and energy expenditure (10679 ± 1026 kJ. Match days (−2278 ± 2307 kJ, p = 0.012 and heavy training days (−2114 ± 2257 kJ, p = 0.016 elicited the greatest deficits between intake and expenditure. In conclusion, the mean daily energy intake of professional adolescent academy-level soccer players was lower than the energy expended during a competitive week. The magnitudes of these deficits were greatest on match and heavy training days. These findings may have both short and long term implications on the performance and physical development of adolescent soccer players.

Responses of female rock lizards to multiple scent marks of males: effects of male age, male density and scent over-marking.

Science.gov (United States)

Martín, José; López, Pilar

2013-03-01

Scent-marked substrates may inform conspecifics on the characteristics of territorial males. Scent-marks of male Carpetan rock lizards (Iberolacerta cyreni) affect space use of females, which by selecting an area may increase the probability of mating with the male that has scent-marked that area. However, males do not hold exclusive territories, and scent-marks of different individual males are often together. This may provide complex information from multiple sources on the social structure. Here, we examined female preference in response to scent marks of various males and combinations in a laboratory experiment. Females preferred areas scent-marked by territorial old males against those scent-marked by young satellite-sneaker males. This reflected the known preference of females for mating with old males. In a second experiment, females preferred areas scent-marked by two males to areas of similar size marked by a single male. This may increase the probability of obtaining multiple copulations with different males, which may favour sperm competition and cryptic female choice, or may be a way to avoid infertile males. Finally, when we experimentally over-marked the scent-marks of an old male with scent-marks of a young male, females did not avoid, nor prefer, the over-marked area, suggesting that the quality of the old male may override the presence of a satellite male. We suggest that, irrespective of the causes underlying why a female selects a scent-marked area, this strategy may affect her reproductive success, which may have the same evolutionary consequences that "direct" mate choice decisions of other animals. Copyright © 2013 Elsevier B.V. All rights reserved.

Biological Studies On The Radioprotective Role Of Melatonin On The Medfly Ceratitis Capitata (WIED.), Sterile Males

International Nuclear Information System (INIS)

SHOMAN, A.A.; MAHMOUD, E.A.

2010-01-01

The sterile insect technique (SIT) has been used successfully against the medfly. The use of gamma irradiation for sterilizing insects has some adverse effects on their competitiveness which in turn reduces the efficiency of the technique. This study was carried out to evaluate the radioprotective effects of melatonin (N-acetyl-5-methoxytyrptamine) on egg hatchability, larval duration, pupal recovery, pupal weight, adult recovery, sex ratio, adult survival, flight ability and mating competitiveness of the medfly, Ceratitis capitata (Wied.), sterile males against the oxidative stress induced by gamma radiation. The results showed that the use of melatonin before the application of radiation doses did not affect the percentages of egg hatchability, larval duration and pupal weight while the addition of melatonin to the larval diet led to a significant increase in the percent of the pupal recovery as compared with the control group. The results also showed significant increases in adult recovery, adult survival and flight ability of males reared on larval diet containing melatonin before irradiation as compared to those treated with radiation alone. The competitiveness values were drastically decreased (0.30, 0.17 and 0.19) with the increase of gamma irradiation (90, 100 and 110 Gy, respectively). However, the results showed that the competitiveness values were increased in males previously reared on a larval diet containing 1 g melatonin/kg larval media (0.1%) and the produced full grown pupae were irradiated with 90, 100 and 110 Gy. The highest male mating competitiveness was recorded when melatonin was added to the larval diet then irradiated the produced pupae with the sterilizing dose (90 Gy). The results showed that the competitiveness values were 0.67, 0.47 and 0.46 for the doses 90, 100 and 110 Gy, respectively. The results refer to availability of using melatonin as a simple and effective means to improve the quality and the male mating competitiveness of the

Maternal effects, but no good or compatible genes for sperm competitiveness in Australian crickets.

Science.gov (United States)

Dowling, Damian K; Nystrand, Magdalena; Simmons, Leigh W

2010-05-01

Explanations for the evolution of polyandry often center on the idea that females garner genetic benefits for their offspring by mating multiply. Furthermore, postcopulatory processes are thought to be fundamental to enabling polyandrous females to screen for genetic quality. Much attention has focused on the potential for polyandrous females to accrue such benefits via a sexy- or good-sperm mechanism, whereby additive variation exists among males in sperm competitiveness. Likewise, attention has focused on an alternative model, in which offspring quality (in this context, the sperm competitiveness of sons) hinges on an interaction between parental haplotypes (genetic compatibility). Sperm competitiveness that is contingent on parental compatibility will exhibit nonadditive genetic variation. We tested these models in the Australian cricket, Teleogryllus oceanicus, using a design that allowed us to partition additive, nonadditive genetic, and parental variance for sperm competitiveness. We found an absence of additive and nonadditive genetic variance in this species, challenging the direct relevance of either model to the evolution of sperm competitiveness in particular, and polyandry in general. Instead, we found maternal effects that were possibly sex-linked or cytoplasmically linked. We also found effects of focal male age on sperm competitiveness, with small increments in age conferring more competitive sperm.

Paternity in horseshoe crabs when spawning in multiple-male groups.

Science.gov (United States)

Brockmann; Nguyen; Potts

2000-12-01

Unpaired or satellite male horseshoe crabs, Limulus polyphemus, are attracted to and often form a group around a pair (a female with an attached male) that is nesting in the high intertidal zone. These males are engaged in sperm competition. We observed nesting pairs and their associated satellites in the wild, collected and reared their eggs and used genetic markers to examine paternity. We found that the unpaired, satellite males are highly successful at fertilizing eggs; two satellites can leave the attached male with few fertilizations. Two satellites together are each as successful as one spawning with a pair. A satellite's location around the female greatly affects his success, and males compete for access to a position over the dorsal canal between the prosoma and opisthosoma of the female and under the front margin of the paired male where they are most likely to fertilize eggs. Although eggs and sperm retain their viability for some time after spawning, nearly all eggs are fertilized by the satellites that are around the nesting pair at the time of egg laying and by the attached male. A number of factors including beach current, female size and male behaviour affect the outcome of sperm competition in this externally fertilizing species. Copyright 2000 The Association for the Study of Animal Behaviour.

Sperm swimming velocity predicts competitive fertilization success in the green swordtail Xiphophorus helleri.

Directory of Open Access Journals (Sweden)

Clelia Gasparini

Full Text Available Sperm competition is expected to favour the evolution of traits that influence the performance of sperm when they compete to fertilize a female's eggs. While there is considerable evidence that selection favours increases in sperm numbers, much less is known about how sperm quality contributes towards competitive fertilization success. Here, we determine whether variation in sperm quality influences competitive fertilization success in the green swordtail Xiphophorus helleri, a highly promiscuous livebearing fish. We use artificial insemination as a method of controlled sperm delivery and show that sperm swimming velocity is the primary determinant of fertilization success when ejaculates from two males compete to fertilize a female's eggs. By contrast, we found no evidence that sperm length had any effect on siring success. We also found no evidence that pre- and postcopulatory sexual traits were phenotypically integrated in this species, suggesting that the previous observation that reproductive skew favours males with high mating rates is unlikely to be due to any direct association between sperm quality and male sexual ornamentation.

Physical and physiological characteristics of male handball players: influence of playing position and competitive level.

Science.gov (United States)

Haugen, Thomas A; Tønnessen, Espen; Seiler, Stephen

2016-01-01

The purpose of this study was to quantify differences in anthropometrical and physical characteristics according to playing position and competitive level in male elite handball. One hundred and seventy-six national team and 1st division players (age 23±4 years, body mass 89±11 kg, body height 188±5 cm) participated in the study. All participants were tested on throwing velocity, 20-meter sprint, countermovement jump, 3000-meter run, 1RM squat and bench press. Back players achieved higher throwing velocities compared to other positions. National team back players achieved higher velocities in set shots (9.4%, Pteam back players ran faster than 1st division back players over 3000 meters (4.9%, P=0.011, d=0.7). Back players showed better relative strength in squat than pivots (12.1%, P=0.016, d=0.7). Wings had better relative strength in squat that pivots (17.4%, P=0.001, d=1.0) and goalkeepers (13.1%, P=0.016, d=0.8). Pivots were 8.9% stronger than wing players (P=0.044, d=0.7) in 1RM bench press. Varying on-court demands in handball are reflected by different physical and physiological characteristics across playing standard and positions. Physical conditioning of players should therefore be individualized and targeted to solve the position-dependent tasks during play.

Experience of mating rivals causes males to modulate sperm transfer in the fly Drosophila pseudoobscura.

Science.gov (United States)

Price, Tom A R; Lizé, Anne; Marcello, Marco; Bretman, Amanda

2012-12-01

Male responses to risk of sperm competition play an important role in sexual selection, sexual conflict, and the evolution of mating systems. Such responses can combine behavioural and physiological processes, and can be mediated through different components of the ejaculate such as sperm numbers and seminal proteins. An additional level of ejaculate complexity is sperm heteromorphism, with the inclusion of non-fertilising parasperm in the ejaculate. We now test the response to rivals in a sperm heteromorphic species, Drosophila pseudoobscura, measuring the behavioural response and sperm transfer and, crucially, relating these to short-term fitness. Males respond to exposure to conspecific rivals by increasing mating duration, but do not respond to heterospecific rivals. In addition, after exposure to a conspecific rival, males increased the transfer of fertilising eusperm, but not non-fertilising parasperm. Males exposed to a conspecific rival also achieve higher offspring production. This suggests that the evolution of parasperm in flies was not driven by sperm competition and adds to the increasing evidence that males can make extremely sophisticated responses to mating competition. Copyright © 2012. Published by Elsevier Ltd.

Polyandrous females provide sons with more competitive sperm: Support for the sexy-sperm hypothesis in the rattlebox moth (Utetheisa ornatrix).

Science.gov (United States)

Egan, Andrea L; Hook, Kristin A; Reeve, H Kern; Iyengar, Vikram K

2016-01-01

Given the costs of multiple mating, why has female polyandry evolved? Utetheisa ornatrix moths are well suited for studying multiple mating in females because females are highly polyandrous over their life span, with each male mate transferring a substantial spermatophore with both genetic and nongenetic material. The accumulation of resources might explain the prevalence of polyandry in this species, but another, not mutually exclusive, possibility is that females mate multiply to increase the probability that their sons will inherit more-competitive sperm. This latter "sexy-sperm" hypothesis posits that female multiple mating and male sperm competitiveness coevolve via a Fisherian runaway process. We tested the sexy-sperm hypothesis by using competitive double matings to compare the sperm competition success of sons of polyandrous versus monandrous females. In accordance with sexy-sperm theory, we found that in 511 offspring across 17 families, the male whose polyandrous mother mated once with each of three different males sired significantly more of all total offspring (81%) than did the male whose monandrous mother was mated thrice to a single male. Interestingly, sons of polyandrous mothers had a significantly biased sex ratio of their brood toward sons, also in support of the hypothesis. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

A curvilinear effect of height on reproductive success in human males

NARCIS (Netherlands)

Stulp, G.; Pollet, T.V.; Verhulst, S.; Buunk, A.P.

2012-01-01

Human male height is associated with mate choice and intra-sexual competition, and therefore potentially with reproductive success. A literature review (n = 18) on the relationship between male height and reproductive success revealed a variety of relationships ranging from negative to curvilinear

A curvilinear effect of height on reproductive success in human males

NARCIS (Netherlands)

Stulp, Gert; Pollet, Thomas V.; Verhulst, Simon; Buunk, Abraham P.

Human male height is associated with mate choice and intra-sexual competition, and therefore potentially with reproductive success. A literature review (n = 18) on the relationship between male height and reproductive success revealed a variety of relationships ranging from negative to curvilinear

Why small males have big sperm: dimorphic squid sperm linked to alternative mating behaviours.

Science.gov (United States)

Iwata, Yoko; Shaw, Paul; Fujiwara, Eiji; Shiba, Kogiku; Kakiuchi, Yasutaka; Hirohashi, Noritaka

2011-08-10

Sperm cells are the target of strong sexual selection that may drive changes in sperm structure and function to maximize fertilisation success. Sperm evolution is regarded to be one of the major consequences of sperm competition in polyandrous species, however it can also be driven by adaptation to the environmental conditions at the site of fertilization. Strong stabilizing selection limits intra-specific variation, and therefore polymorphism, among fertile sperm (eusperm). Here we analyzed reproductive morphology differences among males employing characteristic alternative mating behaviours, and so potentially different conditions of sperm competition and fertilization environment, in the squid Loligo bleekeri. Large consort males transfer smaller (average total length = 73 μm) sperm to a female's internal sperm storage location, inside the oviduct; whereas small sneaker males transfer larger (99 μm) sperm to an external location around the seminal receptacle near the mouth. No significant difference in swimming speed was observed between consort and sneaker sperm. Furthermore, sperm precedence in the seminal receptacle was not biased toward longer sperm, suggesting no evidence for large sperm being favoured in competition for space in the sperm storage organ among sneaker males. Here we report the first case, in the squid Loligo bleekeri, where distinctly dimorphic eusperm are produced by different sized males that employ alternative mating behaviours. Our results found no evidence that the distinct sperm dimorphism was driven by between- and within-tactic sperm competition. We propose that presence of alternative fertilization environments with distinct characteristics (i.e. internal or external), whether or not in combination with the effects of sperm competition, can drive the disruptive evolution of sperm size.

Why small males have big sperm: dimorphic squid sperm linked to alternative mating behaviours

Directory of Open Access Journals (Sweden)

Shiba Kogiku

2011-08-01

Full Text Available Abstract Background Sperm cells are the target of strong sexual selection that may drive changes in sperm structure and function to maximize fertilisation success. Sperm evolution is regarded to be one of the major consequences of sperm competition in polyandrous species, however it can also be driven by adaptation to the environmental conditions at the site of fertilization. Strong stabilizing selection limits intra-specific variation, and therefore polymorphism, among fertile sperm (eusperm. Here we analyzed reproductive morphology differences among males employing characteristic alternative mating behaviours, and so potentially different conditions of sperm competition and fertilization environment, in the squid Loligo bleekeri. Results Large consort males transfer smaller (average total length = 73 μm sperm to a female's internal sperm storage location, inside the oviduct; whereas small sneaker males transfer larger (99 μm sperm to an external location around the seminal receptacle near the mouth. No significant difference in swimming speed was observed between consort and sneaker sperm. Furthermore, sperm precedence in the seminal receptacle was not biased toward longer sperm, suggesting no evidence for large sperm being favoured in competition for space in the sperm storage organ among sneaker males. Conclusions Here we report the first case, in the squid Loligo bleekeri, where distinctly dimorphic eusperm are produced by different sized males that employ alternative mating behaviours. Our results found no evidence that the distinct sperm dimorphism was driven by between- and within-tactic sperm competition. We propose that presence of alternative fertilization environments with distinct characteristics (i.e. internal or external, whether or not in combination with the effects of sperm competition, can drive the disruptive evolution of sperm size.

Alternative male mating behaviour in the two-spotted spider mite: dependence on age and density

NARCIS (Netherlands)

Sato, Y.; Sabelis, M.W.; Egas, M.

2014-01-01

Highlights • We investigated alternative male mating behaviour in the two-spotted spider mite. • We found no differences between genetic lines of fighting and sneaking behaviour. • The proportion of sneaker males changed with male density and with male age. • In competition with old males, young

Body image, binge eating, and bulimia nervosa in male bodybuilders.

Science.gov (United States)

Goldfield, Gary S; Blouin, Arthur G; Woodside, D Blake

2006-03-01

Male bodybuilders (MBB) exhibit more severe body dissatisfaction, bulimic eating behaviour, and negative psychological characteristics, compared with male athletic and nonathletic control subjects, but few studies have directly compared MBB and men with eating disorders. This study compared men with bulimia nervosa (MBN), competitive male bodybuilders (CMBB), and recreational male bodybuilders (RMBB) on a broad range of eating attitudes and behaviours and psychological characteristics to more accurately determine similarities and differences among these groups. Anonymous questionnaires, designed to assess eating attitudes, body image, weight and shape preoccupation, prevalence of binge eating, weight loss practices, lifetime rates of eating disorders, anabolic androgenic steroid (AAS) use, and general psychological factors, were completed by 22 MBN, 27 CMBB, and 25 RMBB. High rates of weight and shape preoccupation, extreme body modification practices, binge eating, and bulimia nervosa (BN) were reported among MBB, especially among those who competed. CMBB reported higher rates of binge eating, BN, and AAS use compared with RMBB, but exhibited less eating-related and general psychopathology compared with MBN. Few psychological differences were found between CMBB and RMBB. MBB, especially competitors, and MBN appear to share many eating-related features but few general psychological ones. Longitudinal research is needed to determine whether men with a history of disordered eating or BN disproportionately gravitate to competitive bodybuildin and (or) whether competitive bodybuilding fosters disordered eating, BN, and AAS use.

Effect of gamma irradiation on sperm activity, sperm viability and adult competitiveness of the pulse beetle Collosobruchus Chinensis L

International Nuclear Information System (INIS)

Roushdy, H.M.; Ahmed, M.Y.Y.; Abdel-Nasr, A.E.; Abdel-Rahman, A.M.; Haiba, I.M.H.

1984-01-01

When mature pupae of callosobruchus chinensis L. were treated with 7 krad, the resulting adults were sterile. Replacing normal males by irradiate ones in the normal population, decreases the egg hatchability. Hatchability decreased from 88.23% in the 1st 3 days to 32.44% after replacing normal males by sterile ones (in the 2nd 3 days). Insemination by normal males could approximately nullify insemination by irradiated males, as the egg hatchability increased from zero to 37.79% even after replacing the irradiated males by normal ones. Percent egg infertility of the eggs produced from newly emerged virgin females mated with sterile males was 100%. When males irradiated (1) with 7 krad as fully grown pupae were confined with unirradiated (U) males and females (1:1:1 ratio), infertility of the resulting eggs were 44.98%. The competitiveness value of irradiated males was 0.54. Males and females both treated as fully grown pupae with a sterilizing dose (7 krad) and confined with U males and U females at a 1 male :1 female :U male : female ratio caused 55.77% infertility in the resulting eggs. When the ratio of sterile males and females was increased to 5:5:1:1 or 10:10:1:1, the infertility reached 91.27% and 100.0% respectively. The percentage of actual infertility was less than expected for the ratios 1:1:1:1 and 5:5:1:1, but it was exceeded with the highest ratio used (10:10:1:1). The competitiveness value for this flooding ratio was 1.00 i.e., the sterile adults were fully competitive with the normal ones. These results indicated that irradiation with 7 krad, a sterilizing dose, did not decrease sexual competitiveness of adults. Also, the release of 1 males together with 1 female could give good results in controlling a population of the pulse beetle in an autocidal control program; and therefore, separation of the sexes prior to release is probably unnecessary

Correlates of androgens in wild male Barbary macaques: Testing the challenge hypothesis.

Science.gov (United States)

Rincon, Alan V; Maréchal, Laëtitia; Semple, Stuart; Majolo, Bonaventura; MacLarnon, Ann

2017-10-01

Investigating causes and consequences of variation in hormonal expression is a key focus in behavioral ecology. Many studies have explored patterns of secretion of the androgen testosterone in male vertebrates, using the challenge hypothesis (Wingfield, Hegner, Dufty, & Ball, 1990; The American Naturalist, 136(6), 829-846) as a theoretical framework. Rather than the classic association of testosterone with male sexual behavior, this hypothesis predicts that high levels of testosterone are associated with male-male reproductive competition but also inhibit paternal care. The hypothesis was originally developed for birds, and subsequently tested in other vertebrate taxa, including primates. Such studies have explored the link between testosterone and reproductive aggression as well as other measures of mating competition, or between testosterone and aspects of male behavior related to the presence of infants. Very few studies have simultaneously investigated the links between testosterone and male aggression, other aspects of mating competition and infant-related behavior. We tested predictions derived from the challenge hypothesis in wild male Barbary macaques (Macaca sylvanus), a species with marked breeding seasonality and high levels of male-infant affiliation, providing a powerful test of this theoretical framework. Over 11 months, 251 hr of behavioral observations and 296 fecal samples were collected from seven adult males in the Middle Atlas Mountains, Morocco. Fecal androgen levels rose before the onset of the mating season, during a period of rank instability, and were positively related to group mating activity across the mating season. Androgen levels were unrelated to rates of male-male aggression in any period, but higher ranked males had higher levels in both the mating season and in the period of rank instability. Lower androgen levels were associated with increased rates of male-infant grooming during the mating and unstable periods. Our results

Stress-related hormonal and psychological changes to official youth Taekwondo competitions.

Science.gov (United States)

Chiodo, S; Tessitore, A; Cortis, C; Cibelli, G; Lupo, C; Ammendolia, A; De Rosas, M; Capranica, L

2011-02-01

The aim of this study was to evaluate the effects of an official Taekwondo competition on the heart rate (HR), salivary α-amylase (sA-A), salivary free cortisol (sC), and Profile of Mood States (POMS) in 10 young male (14±0 years) and six female (13±1 years) athletes. POMS and hormones were measured 15 min before and directly after the competition. During the recovery phase (30 and 90 min), sA-A and sC were also measured. HR measured during the competition was expressed as a percentage of individual's maximal heart rate (%HR(max) ) to evaluate the intensity of exercise. During the competition, athletes spent 65% of the time working at HR>90% of individuals HR(max). A significant increase (Ppre-competition level. The peak sC values were observed at 30 min of recovery (Ppre-competition level at 90 min of recovery. A gender difference (P=0.01) emerged only for sC, although a similar trend was observed for female and male athletes. Significantly higher post-match scores emerged for Anger-hostility (pre: 6.1±1.1, post: 11.2±1.9; P=0.03) and Depression-dejection (pre: 4.5±0.5, post: 10.2±1.9; P=0.006), whereas the reverse picture was observed for Vigour-activity (pre: 23.2±1.2, post: 16.3±1.7; P=0.0006). Taekwondo competition results in temporary changes in the stress-related parameters measured in this study. The present findings suggest that this experimental paradigm can represent a useful model for further research on the effects of various stressors (i.e., training and competition) in Taekwondo athletes of different levels (i.e., novice, international). © 2009 John Wiley & Sons A/S.

Primary sex ratio adjustment by ant queens in response to local mate competition

DEFF Research Database (Denmark)

de Menten, Ludivine; Cremer, Sylvia; Heinze, Jürgen

2005-01-01

In the ant Cardiocondyla obscurior, wingless males compete with nestmate males for access to female mating partners, leading to local mate competition (LMC). Queen number varies between colonies, resulting in variation in the strength of LMC. Cremer & Heinze (2002, Proceedings of the Royal Society...

Comparison between two types of anaerobic speed endurance training in competitive soccer players

DEFF Research Database (Denmark)

Mohr, Magni; Krustrup, Peter

2016-01-01

The purpose of the present study was to examine the effects of additional in-season speed endurance production versus speed endurance maintenance training regimes on performance in competitive male soccer players. In a randomised controlled trial 18 male sub-elite players were exposed to additional...... during training were higher (psoccer players with superior...... speed endurance production (SEP) or speed endurance maintenance (SEM) training (two additional sessions/wk for 4 weeks) during the competitive season. Players performed the Yo-Yo intermittent recovery level 2 test (YYIR2) and a repeated sprint test (RST) pre- and postintervention. Yo-Yo IR2 performance...

Sport and male sexuality.

Science.gov (United States)

Sgrò, P; Di Luigi, L

2017-09-01

The relationships between sport and sexuality in males are of great social and clinical interest, because of sports and motor activities that highly promote social and sexual relationships. Even if few literature exist, two main questions should be taken into account: whether and how physical exercise and sport positively or negatively influence sexual health and behavior and/or whether and how sexual behavior may affect a sub-sequent sport performance. Physical exercise and sport per se can influence, positively or negatively, the hypothalamic-pituitary-testicular axis function and, consequently, the individual's reproductive and/or sexual health. This depends on individual factors such as genetic and epigenetic ones and on different variables involved in the practice of sport activities (type of sport, intensity and duration of training, doping and drug use and abuse, nutrition, supplements, psychological stress, allostatic load, etc.). If well conducted, motor and sport activities could have beneficial effects on sexual health in males. Among different lifestyle changes, influencing sexual health, regular physical activity is fundamental to antagonize the onset of erectile dysfunction (ED). However, competitive sport can lead both reproductive and/or sexual tract damages and dysfunctions, transient (genital pain, hypoesthesia of the genitalia, hypogonadism, DE, altered sexual drive, etc.) or permanent (hypogonadism, DE, etc.), by acting directly (traumas of the external genitalia, saddle-related disorders in cyclists, etc.) or indirectly (exercise-related hypogonadism, drug abuse, doping, stress, etc.). Sexual activities shortly performed before a sport competition could differently influence sport performance. Due to the few existing data, it is advisable to avoid an absolute pre-competition sexual abstinence.

Does the risk of sperm competition help explain cooperation between reproductive competitors? A study in the ocellated wrasse (Symphodus ocellatus).

Science.gov (United States)

Stiver, Kelly A; Alonzo, Suzanne H

2013-03-01

Although cooperating individuals may gain benefits, they risk being cheated by their allies. Therefore, to understand the persistence of cooperation by mutual benefits, it is important to document both the potential benefits of cooperation and the risks of cheating. We experimentally examined evidence of cooperation in the ocellated wrasse (Symphodus ocellatus), a fish species with males that exercise three reproductive strategies: satellite and sneaker males attempt to parasitically spawn in the nests of nesting males. Nesting males have been hypothesized to tolerate satellites as a result of satellite aid in defense against sneaker males and help in courting females. Here, we provide evidence that cooperation between reproductive competitors may arise in response to sperm competition from other males. After we experimentally removed satellites, nesting males had more sneakers at their nest and experienced a higher rate of sneaking when they spawned (increased sperm competition risk). When we experimentally distracted nesting males to prevent their acting aggressively toward satellites, satellites spawned with females and ate eggs in the nest. Our results suggest that nesting males and satellites gain fitness benefits of reduced direct reproductive and sperm competition through cooperation. However, nesting males risk losing paternity, while satellites experience increased aggression and must invest in aggression themselves (i.e., they act aggressively toward sneakers).

The Effect of Biological Movement Variability on the Performance of the Golf Swing in High- and Low-Handicapped Players

Science.gov (United States)

Bradshaw, Elizabeth J.; Keogh, Justin W. L.; Hume, Patria A.; Maulder, Peter S.; Nortje, Jacques; Marnewick, Michel

2009-01-01

The purpose of this study was to examine the role of neuromotor noise on golf swing performance in high- and low-handicap players. Selected two-dimensional kinematic measures of 20 male golfers (n = 10 per high- or low-handicap group) performing 10 golf swings with a 5-iron club was obtained through video analysis. Neuromotor noise was calculated…

Sperm Precedence in Zebra Finches Does Not Require Special Mechanisms of Sperm Competition

NARCIS (Netherlands)

Colegrave, N.; Birkhead, T.R.; Lessells, C.M.

1995-01-01

Competition between the spermatozoa of different males to fertilize the eggs of a single female acts as a selection pressure on the behaviour of males and females. However, quantitative predictions about behaviour fan only be made if the paternity consequences of different patterns of copulation are

Seasonal resource value and male size influence male aggressive interactions in the leaf footed cactus bug, Narnia femorata.

Science.gov (United States)

Nolen, Zachary J; Allen, Pablo E; Miller, Christine W

2017-05-01

In animal contests, resource value (the quality of a given resource) and resource holding potential (a male's absolute fighting ability) are two important factors determining the level of engagement and outcome of contests. Few studies have tested these factors simultaneously. Here, we investigated whether natural, seasonal differences in cactus phenology (fruit quality) influence interactions between males in the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae). We also considered whether males were more likely to interact when they were similar in size, as predicted by theory. Finally, we examined if male size relative to the size of an opponent predicted competitive success. We found that males have more interactions on cactus with high value ripe fruit, as we predicted. Further, we found that males that were closer in size were more likely to interact, and larger males were more likely to become dominant. Copyright © 2017 Elsevier B.V. All rights reserved.

Differential phytosociological interactions involving male and female atriplex bonnevillensis

Science.gov (United States)

Sinclair, J.; Emlen, J.M.; Rinella, M.; Snelgrove, J.; Freeman, D.C.

2009-01-01

Wind-pollinated dioecious plants often exhibit spatial segregation of the sexes. This partial niche separation has most often been explored using abiotic niche axes. However, if the sexes are truly separated in space, then they are apt to encounter different plant species that may heavily affect growth and reproduction. Also, to the extent that their niches differ, the sexes may respond differently to the same co-occurring species. Here we examine interspecific interactions that influence male and female reproductive potential in Atriplex bonnevillensis. Using Emlen's interaction assessment, a technique which assesses species interactions based on cover classes, we show that Salsola species compete significantly with females but not males, while Halogeton glomeratus competes with males but not females. The effect of competition only became apparent when we corrected for site-specific fertility. These results imply that differential competition must be considered when studying dioecious plants that display spatial segregation of the sexes.

Competing for the benefit of offspring eliminates the gender gap in competitiveness.

Science.gov (United States)

Cassar, Alessandra; Wordofa, Feven; Zhang, Y Jane

2016-05-10

Recent advances have highlighted the evolutionary significance of female competition, with the sexes pursuing different competitive strategies and women reserving their most intense competitive behaviors for the benefit of offspring. Influential economic experiments using cash incentives, however, have found evidence suggesting that women have a lower desire to compete than men. We hypothesize that the estimated gender differences critically depend on how we elicit them, especially on the incentives used. We test this hypothesis through an experiment with adults in China (n = 358). Data show that, once the incentives are switched from monetary to child-benefitting, gender differences disappear. This result suggests that female competition can be just as intense as male competition given the right goals, indicating important implications for policies designed to promote gender equality.

Seminal fluid mediates ejaculate competition in social insects

DEFF Research Database (Denmark)

Den Boer, Susanne Petronella A; Baer, Boris; Boomsma, Jacobus Jan

2010-01-01

Queens of ants and bees normally obtain a lifetime supply of sperm on a single day of sexual activity, and sperm competition is expected to occur in lineages where queens receive sperm from multiple males. We compared singly mated (monandrous) and multiply mated (polyandrous) sister groups of ants...

The evolution of male traits in social insects

DEFF Research Database (Denmark)

Boomsma, Jacobus J; Baer, Boris; Heinze, Jürgen

2005-01-01

Pair formation in social insects mostly happens early in adult life and away from the social colony context, which precludes promiscuity in the usual sense. Termite males have continuous sperm production, but males of social Hymenoptera have fixed complements of sperm, except for a few species...... that mate before female dispersal and show male-fighting and lifelong sperm production. We develop an evolutionary framework for testing sexual selection and sperm competition theory across the advanced eusocial insects (ants, wasps, bees, termites) and highlight two areas related to premating sexual...

Exposure to odors of rivals enhances sexual motivation in male giant pandas.

Directory of Open Access Journals (Sweden)

Xiaoxing Bian

Full Text Available Males will alter their mating behavior to cope with the presence of their competitors. Even exposure to odors from potential competitors can greatly increase male ejaculate expenditure in a variety of animals including insects, fishes, birds and rodents. Major efforts have been made to examine males' plastic responses to sperm competition and its fitness benefits. However, the effects of competitor absence on male's sexual motivation and behaviors remain unclear, which has been proposed to be one of the causes for the poor sexual performance of some captive mammals. This study revealed that sexual motivation can be greatly enhanced in captive male giant pandas (Ailuropoda melanoleuca by exposure to chemosensory cues from either one or three conspecifics males. It had been shown that potential rivals' odors increased males' chemosensory investigation behavior, as well as their observing, following and sniffing behaviors towards estrous females. Behaviors changed regardless of the number of rivals (one or three. Our results demonstrate the effects of potential competition on male giant pandas' sexual motivation and behavioral coping strategy. We anticipate that our research will provide a fresh insight into the mechanisms underlying poor sexual performance in male captive mammals, and valuable information for the practical management and ex situ conservation of endangered species.

Relationships between Competitive Anxiety, Social Support and Self-Handicapping in Youth Sport

Science.gov (United States)

Wezyk, Agata

2011-01-01

Study aim: To assess the level of self-handicapping tendency, competitive anxiety (trait) and social support within groups of young male and female athletes, as well as to determine the relationships between those variables. Material and methods: A group of 75 athletes (46 male football players and 29 female volleyball players) from Sport Mastery…

Sex-specific effects of altered competition on nestling growth and survival: an experimental manipulation of brood size and sex ratio.

Science.gov (United States)

Nicolaus, Marion; Michler, Stephanie P M; Ubels, Richard; van der Velde, Marco; Komdeur, Jan; Both, Christiaan; Tinbergen, Joost M

2009-03-01

1. An increase of competition among adults or nestlings usually negatively affects breeding output. Yet little is known about the differential effects that competition has on the offspring sexes. This could be important because it may influence parental reproductive decisions. 2. In sexual size dimorphic species, two main contradictory mechanisms are proposed regarding sex-specific effects of competition on nestling performance assuming that parents do not feed their chicks differentially: (i) the larger sex requires more resources to grow and is more sensitive to a deterioration of the rearing conditions ('costly sex hypothesis'); (ii) the larger sex has a competitive advantage in intra-brood competition and performs better under adverse conditions ('competitive advantage hypothesis'). 3. In the present study, we manipulated the level of sex-specific sibling competition in a great tit population (Parus major) by altering simultaneously the brood size and the brood sex ratio on two levels: the nest (competition for food among nestlings) and the woodlot where the parents breed (competition for food among adults). We investigated whether altered competition during the nestling phase affected nestling growth traits and survival in the nest and whether the effects differed between males, the larger sex, and females. 4. We found a strong negative and sex-specific effect of experimental brood size on all the nestling traits. In enlarged broods, sexual size dimorphism was smaller which may have resulted from biased mortality towards the less competitive individuals i.e. females of low condition. No effect of brood sex ratio on nestling growth traits was found. 5. Negative brood size effects on nestling traits were stronger in natural high-density areas but we could not confirm this experimentally. 6. Our results did not support the 'costly sex hypothesis' because males did not suffer from higher mortality under harsh conditions. The 'competitive advantage hypothesis' was

A big win for the CERN Golf Club at the ASCERI tournament

CERN Multimedia

Katarina Anthony

2010-01-01

The CERN Golf Club returned victorious from the autumn ASCERI (Association of the Sports Communities of the European Research Institutes) tournament which was held from 17 to 20 September.   The CERN Golf Team (left to right: Peter Jones, Alasdair Ross, Claes Frisk and Per Werner) celebrates its victories at ASCERI. Competitions took place on the Dreihof Golf Club at Essingen in southern Germany, starting with the singles Stableford competition on the first day and a 4 ball, better ball Stableford group competition the next day. CERN’s four-man team – Peter Jones, Per Werner, Claes Frisk and Alasdair Ross – came first in the group competition, with Peter Jones, CERN’s star golfer from the IT Department, winning the individual competition. The autumn ASCERI tournament included competitions in football, tennis and cart racing as well as golf. Over 230 representatives of research institutes across Europe took part. “The CERN Golf Club only began p...

Difference in peak weight transfer and timing based on golf handicap.

Science.gov (United States)

Queen, Robin M; Butler, Robert J; Dai, Boyi; Barnes, C Lowry

2013-09-01

Weight shift during the golf swing has been a topic of discussion among golf professionals; however, it is still unclear how weight shift varies in golfers of different performance levels. The main purpose of this study was to examine the following: (a) the changes in the peak ground reaction forces (GRF) and the timing of these events between high (HHCP) and low handicap (LHCP) golfers and (b) the differences between the leading and trailing legs. Twenty-eight male golfers were recruited and divided based on having an LHCP 9. Three-dimensional GRF peaks and the timing of the peaks were recorded bilaterally during a golf swing. The golf swing was divided into different phases: (a) address to the top of the backswing, (b) top of the backswing to ball contact, and (c) ball contact to the end of follow through. Repeated measures analyses of variance (α = 0.05) were completed for each study variable: the magnitude and the timing of peak vertical GRF, peak lateral GRF, and peak medial GRF (α = 0.05). The LHCP group had a greater transfer of vertical force from the trailing foot to the leading foot in phase 2 than the HHCP group. The LHCP group also demonstrated earlier timing of peak vertical force throughout the golf swing than the HHCP group. The LHCP and HHCP groups demonstrated different magnitudes of peak lateral force. The LHCP group had an earlier timing of peak lateral GRF in phase 2 and earlier timing of peak medial GRF in phases 1 and 2 than the HHCP group. In general, LHCP golfers demonstrated greater and earlier force generation than HHCP golfers. It may be relevant to consider both the magnitude of the forces and the timing of these events during golf-specific training to improve performance. These data reveal weight shifting differences that can be addressed by teaching professionals to help their students better understand weight transfer during the golf swing to optimize performance.

Changes in body composition, diet, and strength of bodybuilders during the 12 weeks prior to competition.

Science.gov (United States)

Bamman, M M; Hunter, G R; Newton, L E; Roney, R K; Khaled, M A

1993-12-01

The purpose of this study was to monitor body composition, diet, and strength in male bodybuilders (No. 6) during the 12 weeks prior to competition. Data were collected every third week and analyzed with repeated measures ANOVA (p training volumes were found during pre-competition. Nutritional analyses showed significant reductions (p pre-competition practices were effective in reducing subcutaneous fat stores while maintaining muscle. Finally, the onset of the pre-competition phase resulted in strength loss.

VIRTUAL COMPETITIVENESS: YOUTHS’ VIEWS

Directory of Open Access Journals (Sweden)

M. Yu. Semenov

2018-01-01

Full Text Available Introduction. Nowadays, the use of information and communication technologies (ICT has become an integral part both of every individual’s life and of the society in general. It is no longer possible to deny the impact of virtual environment on socialisation and development of the identity of young people. In this regard, the investigation of young people’s view on virtual social networks, and the possibility of students’ own competitiveness realization through various web services. The aim of the research presented in the article is to study the factors of students’ assessment of virtual social networks as a tool of personal fulfillment. Methodology and research methods. Content analysis and synthesis of scientific publications studies were carried out at a theoretical stage of the research; secondary sampling analysis of sociologic data material sources was conducted. The empirical research stage involved the instrument of questionnaire surveys, statistical data processing and interpretation of the results. Results and scientific novelty. The social survey conducted in 2017 with the participation of 1087 high school students and 1196 college students of the Tyumen Region shown that the more competitive students consider themselves, the more competitive they perceive the people having great popularity on the Internet. At that, compared to girls, young people are more inclined to consider the people having great popularity on the Internet competitive. It is determined that having a popular virtual media account for the young person is less worthwhile than for female respondents. The author explains this fact: male representatives regard it as “social capital” which can contribute to growth of their competitiveness in society as well as to achieve some profit. The author concludes that youth views on competitiveness are not directly related to the activity in virtual social networks. Frequent use by respondents of the Internet and

Competitive interactions are mediated in a sex-specific manner by arbuscular mycorrhiza in Antennaria dioica

OpenAIRE

Varga, S.; Vega-Frutis, R.; Kytöviita, M.-M.; Franken, P.

2017-01-01

Plants usually interact with other plants, and the outcome of such interaction ranges from facilitation to competition depending on the identity of the plants, including their sexual expression. Arbuscular mycorrhizal (AM) fungi have been shown to modify competitive interactions in plants. However, few studies have evaluated how AM fungi influence plant intraspecific and interspecific interactions in dioecious species. The competitive abilities of female and male plants of Antennaria dioic...

Aggressive transition between alternative male social tactics in a long-lived Australian dragon (Physignathus lesueurii living at high density.

Directory of Open Access Journals (Sweden)

Troy A Baird

Full Text Available Theory predicts the evolution of alternative male social tactics when intense competition coupled with the superior competitive ability of some individuals limits access to reproductive opportunities by others. How selection has shaped alternative social tactics may be especially interesting in long-lived species where size among sexually mature males varies markedly. We conducted experimental studies on long-lived eastern Australian water dragons living where competition was intense to test the hypotheses that mature males adopt alternative social tactics that are plastic, and that large size and body condition determine resource-holding potential. Approximately one-half of mature males (N = 14 defended territories using high rates of patrol and advertisement display, whereas 16 smaller mature males having lower body condition indices utilized non-territorial social tactics. Although territorial males were larger in absolute size and head dimensions, their heads were not allometrically larger. Territorial males advertised very frequently using displays involving stereotypical movements of the head and dewlap. More aggressive displays were given infrequently during baseline social conditions, but increased during periods of social instability. Female home ranges overlapped those of several territorial and non-territorial males, but females interacted more frequently with territorial males. The extreme plasticity of social tactics in this species that are dependent on body size was confirmed by two instances when relatively large non-territorial males spontaneously evicted territory owners, and by marked shifts in tactics by non-territorial males in response to temporary experimental removals of territory owners, followed (usually by their expulsion when original owners were reinstated. The high level of social plasticity in this population where same-sex competitors are densely concentrated in preferred habitat suggests that chronic high

Condition-dependent female preference for male genitalia length is based on male reproductive tactics.

Science.gov (United States)

Hernandez-Jimenez, Armando; Rios-Cardenas, Oscar

2017-12-06

There is extensive morphological variation of male genitalia across animals with internal fertilization, even among closely related species. Most studies attempting to explain this extraordinary diversity have focused on processes that occur post-copula (e.g. sperm competition, cryptic female choice). Only a few studies have focused on the pre-copula process of female preference. In addition, the extent to which this variation could be associated with the use of different reproductive tactics has yet to be explored. Here, we show that female preference for male genitalia length in two livebearing fishes depends on the type of reproductive tactic of the males being evaluated as well as the body condition of the female. In a species where all males coax females to acquire matings (courters), females preferred males with short genitalia. In a species with genetically influenced alternative reproductive tactics (courter males that only court and produce courter sons, sneaker males that use the coercive tactic of sneak chase and produce sneaker sons), female preference depended on an interaction between male tactic and female condition: females in good condition preferred courter males with short genitalia, and sneaker males with long genitalia. Our results suggest that female preference for male traits favourable to their sons may be an important factor contributing to the diversification of male genitalia. Despite the contrasting selection for genitalia length that our female preference tests suggest, we found no significant differences in genitalia length between coaxing (courters) and coercive (sneakers) males. Our study represents a starting point to more clearly understand the role of alternative reproductive tactics and variation in female mate preference in the evolution of male genitalia. © 2017 The Author(s).

Evolution of increased competitiveness in cows trades off with reduced milk yield, fertility and more masculine morphology.

Science.gov (United States)

Sartori, Cristina; Mazza, Serena; Guzzo, Nadia; Mantovani, Roberto

2015-08-01

In some species females compete for food, foraging territories, mating, and nesting sites. Competing females can exhibit morphological, physiological, and behavioral adaptations typical of males, which are commonly considered as secondary sexual traits. Competition and the development of traits increasing competitiveness require much energy and may exert adverse effects on fecundity and survival. From an evolutionary perspective, positive selection for increased competitiveness would then result in evolution of reduced values for traits related to fitness such as fecundity and survival. There is recent evidence for such evolutionary trade-offs involving male competition, but no study has considered competing females so far. Using data from competitions for dominance in cows (Bos taurus), we found negative genetic correlations between traits providing success in competition, that is, fighting ability and fitness traits related to milk production and with fertility (the inverse of parity-conception interval). Fighting ability also showed low but positive genetic correlations with "masculine" morphological traits, and negative correlations with "feminine" traits. A genetic change in traits over time has occurred due to selection on competitiveness, corresponding to an evolutionary process of "masculinization" counteracting the official selection for milk yield. Similar evolutionary trade-off between success in competition and fitness components may be present in various species experiencing female competition. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Ultraviolet reflectance affects male-male interactions in the blue tit (Parus caeruleus ultramarinus)

OpenAIRE

Carlos Alonso-Alvarez; Claire Doutrelant; Gabriele Sorci

2004-01-01

Several animal species have been shown to use phenotypic traits to assess the competitive ability of opponents and adjust their aggressiveness depending on the likelihood to win the contest. In birds, these phenotypic traits usually involve patches of colored feathers. The benefit to harbor honest signals of male quality is the avoidance of wasteful aggressive interactions. Recent work has shown that ultraviolet (UV) plumage reflectance is an important signal used by females during mate choic...

Androgen responses to reproductive competition of males pursuing either fixed or plastic alternative reproductive tactics.

Science.gov (United States)

von Kuerthy, Corinna; Ros, Albert F H; Taborsky, Michael

2016-11-15

Alternative reproductive tactics (ARTs), which can be plastic or fixed for life, may be characterized by distinct hormonal profiles. The relative plasticity hypothesis predicts flexible androgen regulation for adult males pursuing plastic tactics, but a less flexible regulation for males using a fixed tactic throughout life. Furthermore, androgen profiles may respond to changes in the social environment, as predicted by the social reciprocity models of hormone/behaviour interactions. The cichlid fish Lamprologus callipterus provides a rare opportunity to study the roles of androgens for male ARTs within a single species, because fixed and plastic ARTs coexist. We experimentally exposed males to competitors pursuing either the same or different tactics to test predictions of the relative plasticity and the social reciprocity models. Androgen profiles of different male types partly comply with predictions derived from the relative plasticity hypothesis: males of the plastic bourgeois/sneaker male trajectory showed different 11-ketotestosterone (11-KT) levels when pursuing either bourgeois or parasitic sneaker male behaviours. Surprisingly, males pursuing the fixed dwarf male tactic showed the highest free and conjugated 11-KT and testosterone (T) levels. Our experimental social challenges significantly affected the free 11-KT levels of bourgeois males, but the androgen responses did not differ between challenges involving different types of competitors. Furthermore, the free T-responses of the bourgeois males correlated with their aggressive behaviour exhibited against competitors. Our results provide new insights into the endocrine responsiveness of fixed and plastic ARTs, confirming and refuting some predictions of both the relative plasticity and the social reciprocity models. © 2016. Published by The Company of Biologists Ltd.

Sterilization of melon flies: mating competitiveness after treatment with tepa or gamma irradiation and ratios of treated to untreated flies producing population suppression

International Nuclear Information System (INIS)

Ashraf, M.; Keiser, I.; Harris, E.J.

1976-01-01

Male melon flies, Dacus cucurbitae Coquillett, treated with a single dose of the chemosterilant tepa (tris(l-aziridinyl) phosphine oxide), or with gamma irradiation, either single or fractionated doses, did not differ significantly in sexual competitiveness as determined by percentage hatch of eggs. Mating competitiveness of males treated by either method ranged from 53 to 66 percent of that of untreated males. In another study, melon flies (males and females) sterilized with 0.0125 percent tepa, the threshold dose for both sexes, completely suppressed a population when the ratio was 16:16:1:1 (sterile males-sterile females-untreated males-untreated females) as determined by no egg hatch

Pre-competition habits and injuries in Taekwondo athletes

Directory of Open Access Journals (Sweden)

Su Choung Young

2005-05-01

Full Text Available Abstract Background Over the past decade, there has been heightened interest in injury rates sustained by martial arts athletes, and more specifically, Taekwondo athletes. Despite this interest, there is a paucity of research on pre-competition habits and training of these athletes. The purpose of this pilot study was to assess training characteristics, competition preparation habits, and injury profiles of Taekwondo athletes. Methods A retrospective survey of Canadian male and female Taekwondo athletes competing in a national tournament was conducted. Competitors at a Canadian national level tournament were given a comprehensive survey prior to competition. Items on training characteristics, diet, and injuries sustained during training and competition were included. Questionnaires were distributed to 60 athletes. Results A response rate of 46.7% was achieved. Of those that responded, 54% dieted prior to competition, and 36% dieted and exercised pre-competition. Sixty-four percent of the athletes practised between 4–6 times per week, with 54% practicing 2 hours per session. Lower limb injuries were the most common (46.5%, followed by upper extremity (18%, back (10%, and head (3.6%. The majority of injuries consisted of sprains/strains (45%, followed by contusions, fractures, and concussions. More injuries occurred during training, including 59% of first injuries. Conclusion More research needs to be conducted to further illustrate the need for appropriate regulations on weight cycling and injury prevention.

Pre-competition habits and injuries in Taekwondo athletes

Science.gov (United States)

Kazemi, Mohsen; Shearer, Heather; Su Choung, Young

2005-01-01

Background Over the past decade, there has been heightened interest in injury rates sustained by martial arts athletes, and more specifically, Taekwondo athletes. Despite this interest, there is a paucity of research on pre-competition habits and training of these athletes. The purpose of this pilot study was to assess training characteristics, competition preparation habits, and injury profiles of Taekwondo athletes. Methods A retrospective survey of Canadian male and female Taekwondo athletes competing in a national tournament was conducted. Competitors at a Canadian national level tournament were given a comprehensive survey prior to competition. Items on training characteristics, diet, and injuries sustained during training and competition were included. Questionnaires were distributed to 60 athletes. Results A response rate of 46.7% was achieved. Of those that responded, 54% dieted prior to competition, and 36% dieted and exercised pre-competition. Sixty-four percent of the athletes practised between 4–6 times per week, with 54% practicing 2 hours per session. Lower limb injuries were the most common (46.5%), followed by upper extremity (18%), back (10%), and head (3.6%). The majority of injuries consisted of sprains/strains (45%), followed by contusions, fractures, and concussions. More injuries occurred during training, including 59% of first injuries. Conclusion More research needs to be conducted to further illustrate the need for appropriate regulations on weight cycling and injury prevention. PMID:15921510

Demolishing the competition: the longitudinal link between competitive video games, competitive gambling, and aggression.

Science.gov (United States)

Adachi, Paul J C; Willoughby, Teena

2013-07-01

The majority of research on the link between video games and aggression has focused on the violent content in games. In contrast, recent experimental research suggests that it is video game competition, not violence, that has the greatest effect on aggression in the short-term. However, no researchers have examined the long-term relationship between video game competition and aggression. In addition, if competition in video games is a significant reason for the link between video game play and aggression, then other competitive activities, such as competitive gambling, also may predict aggression over time. In the current study, we directly assessed the socialization (competitive video game play and competitive gambling predicts aggression over time) versus selection hypotheses (aggression predicts competitive video game play and competitive gambling over time). Adolescents (N = 1,492, 50.8 % female) were surveyed annually from Grade 9 to Grade 12 about their video game play, gambling, and aggressive behaviors. Greater competitive video game play and competitive gambling predicted higher levels of aggression over time, after controlling for previous levels of aggression, supporting the socialization hypothesis. The selection hypothesis also was supported, as aggression predicted greater competitive video game play and competitive gambling over time, after controlling for previous competitive video game play and competitive gambling. Our findings, taken together with the fact that millions of adolescents play competitive video games every day and that competitive gambling may increase as adolescents transition into adulthood, highlight the need for a greater understanding of the relationship between competition and aggression.

BIOCHEMICAL CHANGES AND ENDOCRINE RESPONSES IN PRE-COMPETITION TRAINING IN ELITE SWIMMERS

Directory of Open Access Journals (Sweden)

Yue Li

2012-01-01

Full Text Available The aim of this study was to describe biochemical changes and endocrine responses to low-volume pre-competition swimming training for elite swimmers. Twelve sprint swimmers (6 males and 6 females participated in 3-week pre-competition training. Measures of velocity anaerobic threshold (VAT, creatine kinase (CK, blood urea (BU, haemoglobin (Hb and testosterone/cortisol ratio (TC were obtained before and after the 1st, 2nd and 3rd week of training. The training load decreased from 27.3 to 13.7 km per week within 3 weeks. The VAT tested the load with an increased training protocol of 200 m×4 freestyle swimming and initial loads were 85, 90, 95, and 100 percent of the individual load. There were changes in the values of VAT, CK, BU, Hb and TC ratio during the training, and the changes corresponded to the changes of the training stimuli in time. There were also differences between the male and female swimmers. The most significant finding in this study was that such training stimulated the enginery of the swimmers and helped the swimmers recover enginery and indicated improved velocity in the competition with the following adjusting exercise after pre-competition training.

Options for modulating intra-specific competition in colonial pinnipeds: the case of harbour seals (Phoca vitulina in the Wadden Sea

Directory of Open Access Journals (Sweden)

Rory P. Wilson

2015-06-01

Full Text Available Colonial pinnipeds may be subject to substantial consumptive competition because they are large, slow-moving central place foragers. We examined possible mechanisms for reducing this competition by examining the diving behaviour of harbour seals (Phoca vitulina after equipping 34 seals (11 females, 23 males foraging from three locations; Rømø, Denmark and Lorenzenplate and Helgoland, Germany, in the Wadden Sea area with time-depth recorders. Analysis of 319,021 dives revealed little between-colony variation but appreciable inter-sex differences, with males diving deeper than females, but for shorter periods. Males also had higher vertical descent rates. This result suggests that males may have higher overall swim speeds, which would increase higher oxygen consumption, and may explain the shorter dive durations compared to females. Intersex variation in swim speed alone is predicted to lead to fundamental differences in the time use of three-dimensional space, which may help reduce consumptive competition in harbour seals and other colonial pinnipeds.

Laboratory longevity and competitiveness of Dacus ciliatus Loew (Diptera: Tephritidae) following sub-sterilizing gamma irradiation.

Science.gov (United States)

Nemny-Lavy, E; Nestel, D; Rempoulakis, P

2016-06-01

The effect of a sub-sterilizing gamma radiation dose on Dacus ciliatus adults was investigated to assess the suitability of the sterile insect technique (SIT) as an alternative method to control this pest. Late pupae (48 h prior to adult emergence) from a laboratory strain were irradiated with 120 Gy of gamma rays emitted by a 60Co source. Following adult emergence, the mortality of irradiated and non-irradiated cohorts was recorded. Over a period of 50 days after emergence, no significant negative effects of irradiation upon the longevity of male or female laboratory flies were observed. A laboratory competitiveness study (Fried test), using irradiated laboratory and wild males at a ratio of 3:1 was conducted to assess the ability of irradiated males to reduce the egg hatch rates of a wild population. The overall competitiveness was found to be ca. 0.32, suggesting a reduced, but satisfactory, quality of irradiated laboratory as compared with wild males. Based on the above findings, we calculated and proposed effective male release ratios for field application of SIT against D. ciliatus.

Insights into Sexism: Male Status and Performance Moderates Female-Directed Hostile and Amicable Behaviour.

Directory of Open Access Journals (Sweden)

Michael M Kasumovic

Full Text Available Gender inequality and sexist behaviour is prevalent in almost all workplaces and rampant in online environments. Although there is much research dedicated to understanding sexist behaviour, we have almost no insight into what triggers this behaviour and the individuals that initiate it. Although social constructionist theory argues that sexism is a response towards women entering a male dominated arena, this perspective doesn't explain why only a subset of males behave in this way. We argue that a clearer understanding of sexist behaviour can be gained through an evolutionary perspective that considers evolved differences in intra-sexual competition. We hypothesised that female-initiated disruption of a male hierarchy incites hostile behaviour from poor performing males who stand to lose the most status. To test this hypothesis, we used an online first-person shooter video game that removes signals of dominance but provides information on gender, individual performance, and skill. We show that lower-skilled players were more hostile towards a female-voiced teammate, especially when performing poorly. In contrast, lower-skilled players behaved submissively towards a male-voiced player in the identical scenario. This difference in gender-directed behaviour became more extreme with poorer focal-player performance. We suggest that low-status males increase female-directed hostility to minimize the loss of status as a consequence of hierarchical reconfiguration resulting from the entrance of a woman into the competitive arena. Higher-skilled players, in contrast, were more positive towards a female relative to a male teammate. As higher-skilled players have less to fear from hierarchical reorganization, we argue that these males behave more positively in an attempt to support and garner a female player's attention. Our results provide the clearest picture of inter-sexual competition to date, highlighting the importance of considering an evolutionary

Insights into Sexism: Male Status and Performance Moderates Female-Directed Hostile and Amicable Behaviour.

Science.gov (United States)

Kasumovic, Michael M; Kuznekoff, Jeffrey H

2015-01-01

Gender inequality and sexist behaviour is prevalent in almost all workplaces and rampant in online environments. Although there is much research dedicated to understanding sexist behaviour, we have almost no insight into what triggers this behaviour and the individuals that initiate it. Although social constructionist theory argues that sexism is a response towards women entering a male dominated arena, this perspective doesn't explain why only a subset of males behave in this way. We argue that a clearer understanding of sexist behaviour can be gained through an evolutionary perspective that considers evolved differences in intra-sexual competition. We hypothesised that female-initiated disruption of a male hierarchy incites hostile behaviour from poor performing males who stand to lose the most status. To test this hypothesis, we used an online first-person shooter video game that removes signals of dominance but provides information on gender, individual performance, and skill. We show that lower-skilled players were more hostile towards a female-voiced teammate, especially when performing poorly. In contrast, lower-skilled players behaved submissively towards a male-voiced player in the identical scenario. This difference in gender-directed behaviour became more extreme with poorer focal-player performance. We suggest that low-status males increase female-directed hostility to minimize the loss of status as a consequence of hierarchical reconfiguration resulting from the entrance of a woman into the competitive arena. Higher-skilled players, in contrast, were more positive towards a female relative to a male teammate. As higher-skilled players have less to fear from hierarchical reorganization, we argue that these males behave more positively in an attempt to support and garner a female player's attention. Our results provide the clearest picture of inter-sexual competition to date, highlighting the importance of considering an evolutionary perspective when

Understanding sleep disturbance in athletes prior to important competitions.

Science.gov (United States)

Juliff, Laura E; Halson, Shona L; Peiffer, Jeremiah J

2015-01-01

Anecdotally many athletes report worse sleep in the nights prior to important competitions. Despite sleep being acknowledged as an important factor for optimal athletic performance and overall health, little is understood about athlete sleep around competition. The aims of this study were to identify sleep complaints of athletes prior to competitions and determine whether complaints were confined to competition periods. Cross-sectional study. A sample of 283 elite Australian athletes (129 male, 157 female, age 24±5 y) completed two questionnaires; Competitive Sport and Sleep questionnaire and the Pittsburgh Sleep Quality Index. 64.0% of athletes indicated worse sleep on at least one occasion in the nights prior to an important competition over the past 12 months. The main sleep problem specified by athletes was problems falling asleep (82.1%) with the main reasons responsible for poor sleep indicated as thoughts about the competition (83.5%) and nervousness (43.8%). Overall 59.1% of team sport athletes reported having no strategy to overcome poor sleep compared with individual athletes (32.7%, p=0.002) who utilised relaxation and reading as strategies. Individual sport athletes had increased likelihood of poor sleep as they aged. The poor sleep reported by athletes prior to competition was situational rather than a global sleep problem. Poor sleep is common prior to major competitions in Australian athletes, yet most athletes are unaware of strategies to overcome the poor sleep experienced. It is essential coaches and scientists monitor and educate both individual and team sport athletes to facilitate sleep prior to important competitions. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Body size correlates with fertilization success but not gonad size in grass goby territorial males.

Directory of Open Access Journals (Sweden)

Jose Martin Pujolar

Full Text Available In fish species with alternative male mating tactics, sperm competition typically occurs when small males that are unsuccessful in direct contests steal fertilization opportunities from large dominant males. In the grass goby Zosterisessor ophiocephalus, large territorial males defend and court females from nest sites, while small sneaker males obtain matings by sneaking into nests. Parentage assignment of 688 eggs from 8 different nests sampled in the 2003-2004 breeding season revealed a high level of sperm competition. Fertilization success of territorial males was very high but in all nests sneakers also contributed to the progeny. In territorial males, fertilization success correlated positively with male body size. Gonadal investment was explored in a sample of 126 grass gobies collected during the period 1995-1996 in the same area (61 territorial males and 65 sneakers. Correlation between body weight and testis weight was positive and significant for sneaker males, while correlation was virtually equal to zero in territorial males. That body size in territorial males is correlated with fertilization success but not gonad size suggests that males allocate much more energy into growth and relatively little into sperm production once the needed size to become territorial is attained. The increased paternity of larger territorial males might be due to a more effective defense of the nest in comparison with smaller territorial males.

Body size correlates with fertilization success but not gonad size in grass goby territorial males.

Science.gov (United States)

Pujolar, Jose Martin; Locatello, Lisa; Zane, Lorenzo; Mazzoldi, Carlotta

2012-01-01

In fish species with alternative male mating tactics, sperm competition typically occurs when small males that are unsuccessful in direct contests steal fertilization opportunities from large dominant males. In the grass goby Zosterisessor ophiocephalus, large territorial males defend and court females from nest sites, while small sneaker males obtain matings by sneaking into nests. Parentage assignment of 688 eggs from 8 different nests sampled in the 2003-2004 breeding season revealed a high level of sperm competition. Fertilization success of territorial males was very high but in all nests sneakers also contributed to the progeny. In territorial males, fertilization success correlated positively with male body size. Gonadal investment was explored in a sample of 126 grass gobies collected during the period 1995-1996 in the same area (61 territorial males and 65 sneakers). Correlation between body weight and testis weight was positive and significant for sneaker males, while correlation was virtually equal to zero in territorial males. That body size in territorial males is correlated with fertilization success but not gonad size suggests that males allocate much more energy into growth and relatively little into sperm production once the needed size to become territorial is attained. The increased paternity of larger territorial males might be due to a more effective defense of the nest in comparison with smaller territorial males.

Relationship Between Resilience and Coping Strategies in Competitive Sport.

Science.gov (United States)

Secades, Xabel García; Molinero, Olga; Salguero, Alfonso; Barquín, Roberto Ruíz; de la Vega, Ricardo; Márquez, Sara

2016-02-01

Resilience is important in sport performers to withstand the pressure they experience. This study analyzed the relationship among resilient qualities and coping strategies in 235 Spanish athletes (126 males, 109 females; M age = 20.7 yr) who practiced different sports (79.1% team sports, 20.9% individual sports). They were evaluated at the beginning of the last competitive mesocycle and after an important competition. Coping strategies and level of resilient qualities were measured by the Coping Inventory for Competitive Sport and the Resilience Scale. There was no significant difference in resilience scores between evaluations performed during the last mesocycle or competition. A significant increase occurred in the scores for emotion-oriented and distraction-oriented coping during competition. Resilience scores correlated positively to task-oriented coping and negatively to disengagement- and distraction-oriented coping during both periods. Analysis of variance indicated that athletes with high individual resilient qualities reached higher scores in task-oriented coping, using to a lower extent disengagement- and distraction-oriented coping. Results obtained suggest that resilient characteristics may associate in athletes to the use of more potentially adaptative coping strategies. © The Author(s) 2016.

A prospective study of injuries sustained during competitive Muay Thai kickboxing.

Science.gov (United States)

Gartland, Sam; Malik, Mohammad Hammad; Lovell, Martyn

2005-01-01

To investigate prospectively the type and rate of injuries sustained during amateur Muay Thai competition. Prospective cohort study collection of data following clinical examination. Amateur Muay Thai competitions in the United Kingdom organized by the International Amateur Muay Thai Federation. Amateur Muay Thai boxers. Both sexes. Lightweight to super heavyweight. There were 92 participants, 12 females and 82 males. The average age was 17.3 years, and the average previous number of bouts was 3.9. A total of 588.5 minutes of competition time was assessed during a total of 10 events. Injury rates were 1.3 injuries per 100 minutes of competition in the lightweight category, 2.25 per 100 minutes of competition in the middleweight category, 30 per 100 minutes of competition in the heavyweight category, and 2.54 per 100 minutes of competition in the super heavyweight category. Compared with other reported martial arts, the injury rates are higher in Muay Thai. The head was shown to be the most common site of injury in amateur fighters, but there was an almost complete absence of lower limb injuries, which again is at variance with reported figures for other martial arts.

Body-esteem of pupils who attended single-sex versus mixed-sex schools: a cross-sectional study of intrasexual competition and peer victimization.

Science.gov (United States)

Lereya, Suzet Tanya; Eryigit-Madzwamuse, Suna; Patra, Chanchala; Smith, Joshua H; Wolke, Dieter

2014-10-01

In intrasexual competition (competition for reproductive resources), bullying can be viewed as a tool to devalue competitors, gain a high status and a powerful, dominant position in the peer group which may lead to beneficial gains such as access to potential romantic partners. This study investigated the relationship between intrasexual competition, bullying victimization and body-esteem, in single-sex versus mixed-sex schools. 420 participants completed a body-esteem scale, a retrospective bullying questionnaire, and intrasexual competition scales. Our results showed that relational victimization was associated with low body-esteem for both females and males. Females in single-sex schools experienced higher intrasexual competition which in turn was associated with their body-esteem directly and indirectly via relational victimization. In males, intrasexual competition was indirectly associated with body-esteem via relational victimization. Interventions to improve body esteem may focus on reducing intrasexual competition and peer victimization. Copyright © 2014 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

An investigation into the relationship between pre-competition mood states, age, gender and a national ranking in artistic gymnastics.

Science.gov (United States)

Boldizsár, Dóra; Soós, István; Whyte, Ian; Hamar, Pál

2016-06-01

This study investigated the relationship between pre-competition mood state factors in gymnastics by gender, age and a national ranking. Participant-gymnasts (total n=116, male n=49, female n=67) completed a Brunel Mood Scale (BRUMS) one day prior to their main competition of the year. Information was also gathered from gymnasts of gender, age and a national ranking. Consistent with theoretical predictions, results confirmed that a number of pre-competition mood states differed by age with both juniors and seniors having a higher level of anger than children (p<.05 respectively). Also, seniors demonstrated higher tension than children (p<.001). However, only anger showed significant differences by gender with male gymnasts demonstrating higher levels of anger than female gymnasts (p<.05), and with international gymnasts registering higher levels of anger compared with second class gymnasts (p<.05). Authors suggest that future research should investigate relationships between the pre-competition mood in other gymnastics-related disciplines and sports, as well as competitive performances.

HEAD INJURIES IN FULL CONTACT KARATE COMPETITION! IS THE PREJUDICE IN MANAGEMENT MINIMISING THE REQUIRED INVESTIGATION?

OpenAIRE

Michael R. Graham; Bruce Davies; Julien S. Baker

2007-01-01

A 33 year old male karate practitioner presented himself for a full-contact national karate competition. This individual competed for approximately 2 minutes and received a kick to the head. He collapsed in the competitive arena, and suffered a tonic-clonic seizure, lasting for 3 minutes 25 seconds. Examination in the competitive arena revealed an individual who was unconscious. First aid, and paramedic support was provided immediately. Medical assessment identified the presence of vital sign...

Sterilization of oriental fruit fly by gamma irradiation and its effect on competitiveness

International Nuclear Information System (INIS)

Manoto, E.C.; Bautista, R.C.

1975-01-01

The Oriental fruit fly, Dacus dorsalis Hendel, was irradiated with 5, 7, or 9 krad of Co-60 gamma rays at one or two days before adult eclosion. It was not clear whether or not male fruit flies were more competitive when irradiated at two days than at one day before adult eclosion. A dose of 5 krad was considered better than the higher doses of 7 or 9 krad because the higher the dosages increased percentage sterility of the male only slightly from 99.8% at 5 krad but considerably reduced male competitiveness from 72% at 5 krad to 52% at 9 krad for flies treated 2 days before emergence. The lowest dose of 5 krad was enough to prevent the female fruit flies from laying any egg. Irradiation at any of the dose levels did not affect the number of adults that emerged and the longevity of the fruit flies up to 38 days after adult eclosion

Sperm quality but not relatedness predicts sperm competition success in threespine sticklebacks (Gasterosteus aculeatus).

Science.gov (United States)

Mehlis, Marion; Rahn, Anna K; Bakker, Theo C M

2015-04-26

Mating between close relatives often leads to a reduction of an individual's fitness, due to an increased expression of deleterious alleles. Thus, in many animal taxa pre- as well as postcopulatory inbreeding avoidance mechanisms have evolved. An increased risk of inbreeding and hence a loss of genetic variation may occur during founder events as in most cases only few individuals establish a new population. The threespine stickleback (Gasterosteus aculeatus) is a small externally fertilizing fish species subject to strong sperm competition. Sticklebacks inhabit both marine and freshwater environments and anadromous populations have repeatedly established new genetically less diverse freshwater populations. Previous studies showed that anadromous sticklebacks strongly suffer from inbreeding depression and when given the choice females prefer to mate with unrelated males. The present study aimed to address whether there exists a postcopulatory inbreeding avoidance mechanism solely based on sperm-egg interactions in sperm competition experiments. We used F1 individuals that originated either from a large, genetically heterogeneous anadromous population or from a small, genetically less diverse freshwater population. For each population, eggs of two different females were in vitro fertilized by the same two males' sperm in a paired study design. In the main experiment one male was the female's full-sib brother and in the control experiment all individuals were unrelated. The results revealed that fertilization success was independent of relatedness in both populations suggesting a general lack of a postcopulatory inbreeding avoidance mechanism. Instead, male quality (i.e. sperm morphology) predicted paternity success during competitive fertilization trials. In sticklebacks, there is no evidence for postcopulatory inbreeding avoidance. Sperm morphology predicted paternity instead, thus sperm quality traits are under strong sexual selection, presumably driven by the

Relations of competitive state anxiety and efficacy of young volleyball players.

Science.gov (United States)

Milavić, Boris; Jurko, Damir; Grgantov, Zoran

2013-05-01

With the aim of validating the Competitive State Anxiety Inventory on a population of young Croatian volleyball players, 286 examinees, 106 male and 180 female volleyball players (average age of 16.09+/-1.83), filled out the CSAI-2, constructed by Martens, Vealey, Burton, Bump and Smith (1990)1. Given the fact that all scales of the Competitive State Anxiety Inventory have good homogeneity, reliability and sensitivity, it can be concluded that they represent high-quality measuring instruments for measuring psychological characteristics of young volleyball players. Young male and female volleyball players generally have a moderate level of self-confidence, and their cognitive anxiety is more prominent that somatic anxiety. In order to determine the age and gender differences in somatic and cognitive anxiety and self-confidence, parametric analysis of differences was performed and coefficients of the independent samples t-test were calculated. By analysis of differences according to age, it has been established that female junior players, in relation to female youth players, express a significantly lower level of somatic and cognitive anxiety and a significantly higher level of self-confidence. As opposed to female players, male youth and junior players do not differ in any of the analysed variables. By analysis of differences according to gender, it has been established that male youth players have a significantly higher level of self-confidence in comparison to female youth players. No significant differences were found in the level of competitive anxiety and self-confidence by analysis of variance between different player roles. No significant differences were found by discriminant analysis in somatic and cognitive anxiety, and self-confidence of female volleyball players of different situational efficacy. The group of least efficient male volleyball players is characterized by a very low level of self-confidence, while the most efficient group of volleyball

Effect of mating activity and dominance rank on male masturbation among free-ranging male rhesus macaques.

Science.gov (United States)

Dubuc, Constance; Coyne, Sean P; Maestripieri, Dario

2013-11-01

The adaptive function of male masturbation is still poorly understood, despite its high prevalence in humans and other animals. In non-human primates, male masturbation is most frequent among anthropoid monkeys and apes living in multimale-multifemale groups with a promiscuous mating system. In these species, male masturbation may be a non-functional by-product of high sexual arousal or be adaptive by providing advantages in terms of sperm competition or by decreasing the risk of sexually transmitted infections. We investigated the possible functional significance of male masturbation using behavioral data collected on 21 free-ranging male rhesus macaques ( Macaca mulatta ) at the peak of the mating season. We found some evidence that masturbation is linked to low mating opportunities: regardless of rank, males were most likely to be observed masturbating on days in which they were not observed mating, and lower-ranking males mated less and tended to masturbate more frequently than higher-ranking males. These results echo the findings obtained for two other species of macaques, but contrast those obtained in red colobus monkeys ( Procolobus badius ) and Cape ground squirrels ( Xerus inauris ). Interestingly, however, male masturbation events ended with ejaculation in only 15% of the observed masturbation time, suggesting that new hypotheses are needed to explain masturbation in this species. More studies are needed to establish whether male masturbation is adaptive and whether it serves similar or different functions in different sexually promiscuous species.

Perceptions of five-year competitive categories: model of how relative age influences competitiveness in masters sport.

Science.gov (United States)

Medic, Nikola; Young, Bradley W; Grove, J Robert

2013-01-01

The purpose of this study was to examine the contrasting perceptions of masters swimmers related to the first and fifth constituent years of a 5-year age category. Swimmers aged between 35 and 93 years (154 male, 184 female) were surveyed at the 2008 FINA World Masters Championships. Exploratory factor analysis indicated the existence of the following five factors considered important for preparation, attendance, and success at masters competitions: awareness of advantages, expectancy, motivation, training, and physiological capacity. One sample t-tests showed that masters swimmers are conscious of advantages that 5-year age categories afford to relatively-younger cohorts (i.e., those who are in the first year of any age category). They also perceive that, in the first compared to the fifth year of an age category, they have greater physiological capacity, engage in more training, have higher expectations to perform well, and are more motivated (all ps competitions than relatively older masters athletes. Key PointsThere are at least five psycho-social and physical factors (i.e., awareness of advantages, expectancy, motivation, training, and physiological capacity) that may explain why relatively younger masters athletes are more likely to perform better and to participate more in masters competitions than relatively older masters athletes.Masters athletes are conscious of the advantage that 5-year age categories afford to relatively younger cohorts of athletes.Differential perceptions associated with the 5-year age categories might compromise masters athletes' continuity of sport competitiveness and underlying training.

Testosterone affects song modulation during simulated territorial intrusions in male black redstarts (Phoenicurus ochruros.

Directory of Open Access Journals (Sweden)

Beate Apfelbeck

Full Text Available Although it has been suggested that testosterone plays an important role in resource allocation for competitive behavior, details of the interplay between testosterone, territorial aggression and signal plasticity are largely unknown. Therefore, we investigated if testosterone acts specifically on signals that communicate the motivation or ability of individuals to engage in competitive situations in a natural context. We studied the black redstart, a territorial songbird species, during two different life-cycle stages, the early breeding phase in spring and the non-breeding phase in fall. Male territory holders were implanted with the androgen receptor blocker flutamide (Flut and the aromatase inhibitor letrozole (Let to inhibit the action of testosterone and its estrogenic metabolites. Controls received a placebo treatment. Three days after implantation birds were challenged with a simulated territorial intrusion (STI. Song was recorded before, during and after the challenge. In spring, both treatment groups increased the number of elements sung in parts of their song in response to the STI. However, Flut/Let-implanted males reacted to the STI with a decreased maximum acoustic frequency of one song part, while placebo-implanted males did not. Instead, placebo-implanted males sang the atonal part of their song with a broader frequency range. Furthermore, placebo-, but not Flut/Let-implanted males, sang shorter songs with shorter pauses between parts in the STIs. During simulated intrusions in fall, when testosterone levels are naturally low in this species, males of both treatment groups sang similar to Flut/Let-implanted males during breeding. The results suggest that song sung during a territorial encounter is of higher competitive value than song sung in an undisturbed situation and may, therefore, convey information about the motivation or quality of the territory holder. We conclude that testosterone facilitates context-dependent changes

Appraisal in a Team Context: Perceptions of Cohesion Predict Competition Importance and Prospects for Coping.

Science.gov (United States)

Wolf, Svenja A; Eys, Mark A; Sadler, Pamela; Kleinert, Jens

2015-10-01

Athletes' precompetitive appraisal is important because it determines emotions, which may impact performance. When part of a team, athletes make their appraisal within a social context, and in this study we examined whether perceived team cohesion, as a characteristic of this context, related to appraisal. We asked 386 male and female intercollegiate team-sport athletes to respond to measures of cohesion and precompetitive appraisal before an in-season game. For males and females, across all teams, (a) an appraisal of increased competition importance was predicted by perceptions of higher task cohesion (individual level), better previous team performance, and a weaker opponent (team level) and (b) an appraisal of more positive prospects for coping with competitive demands was predicted by higher individual attractions to the group (individual level). Consequently, athletes who perceive their team as more cohesive likely appraise the pending competition as a challenge, which would benefit both emotions and performance.

Comparison of reproductive traits of regular and irradiated male desert locust Schistocerca gregaria (Orthoptera: Acrididae: Evidence of last-male sperm precedence

Directory of Open Access Journals (Sweden)

Severin Dushimirimana

2012-02-01

The sterile insect technique (SIT is increasingly used to control pest insect populations. The success of SIT control programs depends on the ability to release sterile males and on the capacity of sterile males to compete with wild males to inseminate wild females. In this study, we evaluated the mating performance of Schistocerca gregaria (Försk. males irradiated with 4 Gray. We compared reproductive traits, such as duration of precopulation time, mating duration, quantity of sperm stored by females after copulation, number of females mated successively and postmating competition of irradiated males with non-irradiated males. Irradiated males were able to mate but the resulting number of offspring was dramatically reduced compared to the average number of offspring observed during a regular mating. During a single copulation, irradiated males transferred fewer sperm than regular males but, theoretically, this quantity is enough to fertilize all the eggs produced by a female during its reproductive life. Irradiated males also had the ability to remove sperm from a previous mating with unirraditated males. This new information on the mating strategies helps explain the post-copulation guarding behaviour of S. gregaria.

Linear models for assessing mechanisms of sperm competition: the trouble with transformations.

Science.gov (United States)

Eggert, Anne-Katrin; Reinhardt, Klaus; Sakaluk, Scott K

2003-01-01

Although sperm competition is a pervasive selective force shaping the reproductive tactics of males, the mechanisms underlying different patterns of sperm precedence remain obscure. Parker et al. (1990) developed a series of linear models designed to identify two of the more basic mechanisms: sperm lotteries and sperm displacement; the models can be tested experimentally by manipulating the relative numbers of sperm transferred by rival males and determining the paternity of offspring. Here we show that tests of the model derived for sperm lotteries can result in misleading inferences about the underlying mechanism of sperm precedence because the required inverse transformations may lead to a violation of fundamental assumptions of linear regression. We show that this problem can be remedied by reformulating the model using the actual numbers of offspring sired by each male, and log-transforming both sides of the resultant equation. Reassessment of data from a previous study (Sakaluk and Eggert 1996) using the corrected version of the model revealed that we should not have excluded a simple sperm lottery as a possible mechanism of sperm competition in decorated crickets, Gryllodes sigillatus.

Comparisons of Perceived Training Doses in Champion Collegiate-Level Male and Female Cross-country Runners and Coaches over the Course of a Competitive Season.

Science.gov (United States)

Barnes, Kyle R

2017-10-17

Session rating of perceived exertion (sRPE) is a practical tool for coaches to assess internal training load of their athletes. In a sport like cross-country running, that is individual in nature, but has a team training and competition component, information about the association between external and internal load is lacking. Furthermore, there is a need for studies that examine perception of training doses across multiple training cycles including the competitive season as well as between male and female athletes. Session RPE, duration, and training load (TL RPE  = sRPE × duration) of 25 highly trained male and female cross-country runners and their coaches were recorded for every training session (110 days) throughout a collegiate cross-country season. Intensity (sRPE), duration, and TL RPE were compared between coaches and runners by gender separately. Training sessions were also analyzed by those intended by the coaches to be easy, moderate, and hard as well as by training period. Data from 3024 training sessions were collected, 62% of which were considered "easy," 18% "moderate," and 20% "hard." Men and women rated coach-intended easy sessions significantly harder during each month of the season (effect size (ES) > 2.9, p sessions significantly higher than coaches (ES ≥ 1.0, p ≤ 0.002), whereas females rated hard intensity sessions significantly lower than coaches (ES > 0.5, p sessions (ES  0.05) or females and coach's moderate sessions (ES  0.05). Training intensity and TL RPE tended to increase throughout the season (p > 0.05), with a significant increase in moderate and hard intensity sessions in the last training period (p training throughout the cross-country season. Given the success of the athletes in this study, these results show how a simple system for monitoring training such as the sRPE method may improve control of training variables and provide a useful tool for coaches to evaluate training load placed on

Strong reproductive skew among males in the multiply mated swordtail Xiphophorus multilineatus (Teleostei).

Science.gov (United States)

Luo, J; Sanetra, M; Schartl, M; Meyer, A

2005-01-01

Male swordtails in the genus Xiphophorus display a conspicuous ventral elongation of the caudal fin, the sword, which arose through sexual selection due to female preference. Females mate regularly and are able to store sperm for at least 6 months. If multiple mating is frequent, this would raise the intriguing question about the role of female choice and male-male competition in shaping the mating system of these fishes. Size-dependent alternate mating strategies occur in Xiphophorus; one such strategy is courtship with a sigmoid display by large dominant males, while the other is gonopodial thrusting, in which small subordinate males sneak copulations. Using microsatellite markers, we observed a frequency of multiple paternity in wild-caught Xiphophorus multilineatus in 28% of families analyzed, but the actual frequency of multiple mating suggested by the correction factor PrDM was 33%. The number of fathers contributing genetically to the brood ranged from one to three. Compared to other species in the family Poeciliidae, both frequency and degree of multiple paternity were low. Paternity was found to be highly skewed, with one male on average contributing more than 70% to the offspring. Hence in this Xiphophorus mating system, typically one male dominates and sneaker males do not appear to be particularly effective. Postcopulatory mechanisms, however, such as sperm competition, are also indicated by our data, using sex-linked phenotypes among the offspring.

Distance running as an ideal domain for showing a sex difference in competitiveness.

Science.gov (United States)

Deaner, Robert O

2013-04-01

Men are over-represented in the arts, sciences, and sports. This has been hypothesized to reflect an evolved male predisposition for enduring competitiveness or long-term motivation to improve one's performance and "show-off." Evidence for this hypothesis is equivocal, however, because there are viable alternative explanations for men's dominance in most cultural display domains. Here, I argue that distance running is an ideal domain for addressing this issue. Distance running is ideal because it indicates enduring competitiveness, allows objective comparisons, and is accessible, acceptable, and popular for both men and women. I review recent studies and present new data showing that substantially more men than women run relatively fast in the U.S., that this sex difference in relative performance can be attributed, at least in part, to men's greater training motivation, and that this pattern has been stable for several decades. Distance running thus provides compelling evidence for an evolved male predisposition for enduring competitiveness. I conclude with suggestions regarding how variation in achievement motivation can be informed by considering how evolved predispositions interact with environmental and social conditions.

Life history differences favour evolution of male dimorphism in competitive games

NARCIS (Netherlands)

Smallegange, I.M.; Johansson, J.

2014-01-01

Many species exhibit two discrete male morphs: fighters and sneakers. Fighters are large and possess weapons but may mature slowly. Sneakers are small and have no weapons but can sneak matings and may mature quickly to start mating earlier in life than fighters. However, how differences in

Spine biomechanics associated with the shortened, modern one-plane golf swing.

Science.gov (United States)

Dale, R Barry; Brumitt, Jason

2016-06-01

The purpose of this study was to compare kinetic, kinematic, and performance variables associated with full and shortened modern backswings in a skilled group of modern swing (one-plane) golfers. Shortening the modern golf backswing is proposed to reduce vertebral spine stress, but supporting evidence is lacking and performance implications are unknown. Thirteen male golfers performed ten swings of each swing type using their own 7-iron club. Biomechanical-dependent variables included the X-Factor kinematic data and spine kinetics. Performance-related dependent variables included club head velocity (CHV), shot distance, and accuracy (distance from the target line). Data were analysed with repeated measures ANOVA with an a priori alpha of 0.05 (SPSS 22.0, IBM, Armonk, NY, USA). We found significant reductions for the X-Factor (p < 0.05) between the full and shortened swings. The shortened swing condition ameliorated vertebral compression force from 7.6 ± 1.4 to 7.0 ± 1.7 N (normalised to body weight, p = 0.01) and significantly reduced CHV (p < 0.05) by ~2 m/s with concomitant shot distance diminution by ~10 m (p < 0.05). Further research is necessary to examine the applicability of a shortened swing for golfers with low back pain.

High Prevalence of Dehydration and Inadequate Nutritional Knowledge Among University and Club Level Athletes.

Science.gov (United States)

Magee, Pamela Jane; Gallagher, Alison M; McCormack, Jacqueline M

2017-04-01

Although dehydration of ≥ 2% body weight (BW) loss significantly impairs endurance performance, dehydration remains prevalent among athletes and may be owing to a lack of knowledge in relation to fluid requirements. The aim of this study was to assess the hydration status of university/club level athletes (n = 430) from a range of sports/activities (army officer cadet training; bootcamp training; cycling; Gaelic Athletic Association camogie, football and hurling; golf; hockey; netball; rugby; running (sprinting and endurance); Shotokan karate and soccer) immediately before and after training/competition and to assess their nutritional knowledge. Urine specific gravity (USG) was measured immediately before and after exercise and BW loss during exercise was assessed. Nutritional knowledge was assessed using a validated questionnaire. 31.9% of athletes commenced exercise in a dehydrated state (USG >1.020) with 43.6% of participants dehydrated posttraining/competition. Dehydration was particularly prevalent (>40% of cohort) among karateka, female netball players, army officer cadets, and golfers. Golfers that commenced a competitive 18 hole round dehydrated took a significantly higher number of strokes to complete the round in comparison with their euhydrated counterparts (79.5 ± 2.1 vs. 75.7 ± 3.9 strokes, p = .049). Nutritional knowledge was poor among participants (median total score [IQR]; 52.9% [46.0, 59.8]), albeit athletes who were euhydrated at the start of exercise had a higher overall score in comparison with dehydrated athletes (55.2% vs. 50.6%, p = .001). Findings from the current study, therefore, have significant implications for the education of athletes in relation to their individual fluid requirements around exercise.

Characteristics of Anabolic-Androgenic Steroid-Free Competitive Male and Female Bodybuilders.

Science.gov (United States)

Elliot, Diane L.; And Others

1987-01-01

Comparison of steroid-free male and female bodybuilders with sedentary controls and runners revealed that the bodybuilders had lower percentages of body fat. One-third of the female bodybuilders reported menstrual abnormalities. Lipid values of bodybuilders were comparable to a group of lean, aerobically trained athletes. (Author/CB)

Sharing of science is most likely among male scientists.

Science.gov (United States)

Massen, Jorg J M; Bauer, Lisa; Spurny, Benjamin; Bugnyar, Thomas; Kret, Mariska E

2017-10-10

Humans are considered to be highly prosocial, especially in comparison to other species. However, most tests of prosociality are conducted in highly artificial settings among anonymous participants. To gain a better understanding of how human hyper-cooperation may have evolved, we tested humans' willingness to share in one of the most competitive fields of our current society: academia. Researchers were generally prosocial with 80% sharing a PDF of one of their latest papers, and almost 60% willing to send us their data. Intriguingly, prosociality was most prominent from male to male, and less likely among all other sex-combinations. This pattern suggests the presence of male-exclusive networks in science, and may be based on an evolutionary history promoting strong male bonds.

EDITORIAL: Physics competitions Physics competitions

Science.gov (United States)

Jordens, H.; Mathelitsch, L.

2009-11-01

1. Physics competitions: aims and realizations One aim of physics competitions is to increase the interest of young students, primarily at upper secondary level, to physics and natural sciences in general. A competition has motivational aspects known usually from sports events or games—comparing one's own ability with others, of course with the desire to be better and to win. If competitions reach nationwide and even international levels, additional stimulation is created. Competitions provide greatest attraction to possible winners, to the group of gifted people in a particular field. This implies that science contests are excellent tools for the promotion of talented students. Traditional teaching has been shown to have problems in supporting this group of students. Very often teachers are overstretched with the demands of teaching both low- and high-level students. Extracurricular activities are therefore a good chance to relieve the teacher, and to give talented students the opportunity for appropriate training and challenge. The competitions, however, have a broader impact and address more young people than one might guess from the statements above. Training courses and selection at school level give a larger group of students extra and, to some extent, complimentary education in physics. The degree of complexity of the tasks corresponds very often to the standards of the next level of education in the school system. Interestingly, many physics competitions have their origin in countries beyond the former Iron Curtain. They started as regional and national tournaments, were joined by neighbouring countries and have grown, in some cases, to events with participants from more than 80 countries. Although the features mentioned above are common to the different competitions, there are distinct differences between them [1]. The International Physics Olympiad (IPhO) is the oldest international physics competition for students at upper secondary level [2]. It dates

COMPETITIVENESS AND COMPETITIVE ORIENTATIONS: EVALUATION OF STUDENTS

Directory of Open Access Journals (Sweden)

G. Z. Efimova

2017-01-01

Full Text Available Introduction. Education of a competitive student is a strategically significant problem of the system of higher education in modern social and economic conditions. Personal competitiveness and competitive orientations – priority quality of future expert for successful future professional experience.The aim of the present research is to study factors of competitive orientations formation and criteria for evaluation of competitiveness of student’s youth in the Russian society.Methodology and research methods. Results of theoretical researches of Russian and foreign researchers are generalized; secondary analysis of data based on results of sociological researches and analysis of official statistical data are carried out. The results of the sociological survey undertaken in 2017 on the basis of statistical methods were processed and studied by the instrumentality of IBM SPSS Statistics 23 program; 1196 students of institutions of higher and secondary vocational education of the Tyumen region took part.Results and scientific novelty. It is stated that senior students feel themselves more competitive. It is revealed that a quarter of students who took part in the survey, generally men, count themselves competitive. A continuous distance of goal-setting is recorded among these respondents; in every third case they have plans of professional growth for five and more years that allows them to build attractive competitive strategy.The level of the competitiveness is directly connected with such indicators as “social stratum”, “overall life satisfaction”, “self-esteem of health”, “tendency to lead a healthy lifestyle” and “the level of trust in the surrounding people”. Mostly the students oriented on competition look into the future with confidence and optimism.Respondents focused on the competitiveness were more tend to demonstrate their abilities and cause admiration, have a creative approach towards work, be ready for surprises

Simultaneous Cooperation and Competition in the Evolution of Musical Behavior: Sex-Related Modulations of the Singer's Formant in Human Chorusing

Directory of Open Access Journals (Sweden)

Peter E. Keller

2017-09-01

Full Text Available Human interaction through music is a vital part of social life across cultures. Influential accounts of the evolutionary origins of music favor cooperative functions related to social cohesion or competitive functions linked to sexual selection. However, work on non-human “chorusing” displays, as produced by congregations of male insects and frogs to attract female mates, suggests that cooperative and competitive functions may coexist. In such chorusing, rhythmic coordination between signalers, which maximizes the salience of the collective broadcast, can arise through competitive mechanisms by which individual males jam rival signals. Here, we show that mixtures of cooperative and competitive behavior also occur in human music. Acoustic analyses of the renowned St. Thomas Choir revealed that, in the presence of female listeners, boys with the deepest voices enhance vocal brilliance and carrying power by boosting high spectral energy. This vocal enhancement may reflect sexually mature males competing for female attention in a covert manner that does not undermine collaborative musical goals. The evolutionary benefits of music may thus lie in its aptness as a medium for balancing sexually motivated behavior and group cohesion.

Male Sexual Behavior and Pheromone Emission Is Enhanced by Exposure to Guava Fruit Volatiles in Anastrepha fraterculus.

Directory of Open Access Journals (Sweden)

Guillermo E Bachmann

Full Text Available Plant chemicals can affect reproductive strategies of tephritid fruit flies by influencing sex pheromone communication and increasing male mating competitiveness.We explored whether exposure of Anastrepha fraterculus males to guava fruit volatiles and to a synthetic blend of volatile compounds released by this fruit affects the sexual performance of wild and laboratory flies. By means of bioassays and pheromone collection we investigated the mechanism underlying this phenomenon.Guava volatile exposure enhanced male mating success and positively affected male calling behavior and pheromone release in laboratory and wild males. Changes in male behavior appear to be particularly important during the initial phase of the sexual activity period, when most of the mating pairs are formed. Exposure of laboratory males to a subset of guava fruit volatiles enhanced mating success, showing that the response to the fruit might be mimicked artificially.Volatiles of guava seem to influence male mating success through an enhancement of chemical and physical signals related to the communication between sexes. This finding has important implications for the management of this pest species through the Sterile Insect Technique. We discuss the possibility of using artificial blends to improve the sexual competitiveness of sterile males.

Impact of specific training and competition on myocardial structure and function in different age ranges of male handball players.

Directory of Open Access Journals (Sweden)

Brahim Agrebi

Full Text Available Handball activity involves cardiac changes and demands a mixture of both eccentric and concentric remodeling within the heart. This study seeks to explore heart performance and cardiac remodeling likely to define cardiac parameters which influence specific performance in male handball players across different age ranges. Forty three players, with a regular training and competitive background in handball separated into three groups aged on average 11.78 ± 0.41 for youth players aka "schools", "elite juniors" 15.99 ± 0.81 and "elite adults" 24.46 ± 2.63 years, underwent echocardiography and ECG examinations. Incremental ergocycle and specific field (SFT tests have also been conducted. With age and regular training and competition, myocardial remodeling in different age ranges exhibit significant differences in dilatation's parameters between "schools" and "juniors" players, such as the end-diastolic diameter (LVEDD and the end-systolic diameter of the left ventricle (LVESD, the root of aorta (Ao and left atrial (LA, while significant increase is observed between "juniors" and "adults" players in the interventricular septum (IVS, the posterior wall thicknesses (PWT and LV mass index. ECG changes are also noted but NS differences were observed in studied parameters. For incremental maximal test, players demonstrate a significant increase in duration and total work between "schools" and "juniors" and, in total work only, between "juniors" and "seniors". The SFT shows improvement in performance which ranged between 26.17 ± 1.83 sec to 31.23 ± 2.34 sec respectively from "seniors" to "schools". The cross-sectional approach used to compare groups with prior hypothesis that there would be differences in exercise performance and cardiac parameters depending on duration of prior handball practice, leads to point out the early cardiac remodeling within the heart as adaptive change. Prevalence of cardiac chamber dilation with less hypertrophy remodeling

Impact of specific training and competition on myocardial structure and function in different age ranges of male handball players

Science.gov (United States)

Agrebi, Brahim; Tkatchuk, Vladimir; Hlila, Nawel; Mouelhi, Emna; Belhani, Ali

2015-01-01

Handball activity involves cardiac changes and demands a mixture of both eccentric and concentric remodeling within the heart. This study seeks to explore heart performance and cardiac remodeling likely to define cardiac parameters which influence specific performance in male handball players across different age ranges. Forty three players, with a regular training and competitive background in handball separated into three groups aged on average 11.78±0.41 for youth players aka “schools”, “elite juniors” 15.99±0.81 and “elite adults” 24.46±2.63 years, underwent echocardiography and ECG examinations. Incremental ergocycle and specific field (SFT) tests have also been conducted. With age and regular training and competition, myocardial remodeling in different age ranges exhibit significant differences in dilatation’s parameters between “schools” and “juniors” players, such as the end-diastolic diameter (LVEDD) and the end-systolic diameter of the left ventricle (LVESD), the root of aorta (Ao) and left atrial (LA), while significant increase is observed between “juniors” and “adults” players in the interventricular septum (IVS), the posterior wall thicknesses (PWT) and LV mass index. ECG changes are also noted but NS differences were observed in studied parameters. For incremental maximal test, players demonstrate a significant increase in duration and total work between “schools” and “juniors” and, in total work only, between “juniors” and “seniors”. The SFT shows improvement in performance which ranged between 26.17±1.83 sec to 31.23±2.34 sec respectively from “seniors” to “schools”. The cross-sectional approach used to compare groups with prior hypothesis that there would be differences in exercise performance and cardiac parameters depending on duration of prior handball practice, leads to point out the early cardiac remodeling within the heart as adaptive change. Prevalence of cardiac chamber dilation

Impact of specific training and competition on myocardial structure and function in different age ranges of male handball players.

Science.gov (United States)

Agrebi, Brahim; Tkatchuk, Vladimir; Hlila, Nawel; Mouelhi, Emna; Belhani, Ali

2015-01-01

Handball activity involves cardiac changes and demands a mixture of both eccentric and concentric remodeling within the heart. This study seeks to explore heart performance and cardiac remodeling likely to define cardiac parameters which influence specific performance in male handball players across different age ranges. Forty three players, with a regular training and competitive background in handball separated into three groups aged on average 11.78 ± 0.41 for youth players aka "schools", "elite juniors" 15.99 ± 0.81 and "elite adults" 24.46 ± 2.63 years, underwent echocardiography and ECG examinations. Incremental ergocycle and specific field (SFT) tests have also been conducted. With age and regular training and competition, myocardial remodeling in different age ranges exhibit significant differences in dilatation's parameters between "schools" and "juniors" players, such as the end-diastolic diameter (LVEDD) and the end-systolic diameter of the left ventricle (LVESD), the root of aorta (Ao) and left atrial (LA), while significant increase is observed between "juniors" and "adults" players in the interventricular septum (IVS), the posterior wall thicknesses (PWT) and LV mass index. ECG changes are also noted but NS differences were observed in studied parameters. For incremental maximal test, players demonstrate a significant increase in duration and total work between "schools" and "juniors" and, in total work only, between "juniors" and "seniors". The SFT shows improvement in performance which ranged between 26.17 ± 1.83 sec to 31.23 ± 2.34 sec respectively from "seniors" to "schools". The cross-sectional approach used to compare groups with prior hypothesis that there would be differences in exercise performance and cardiac parameters depending on duration of prior handball practice, leads to point out the early cardiac remodeling within the heart as adaptive change. Prevalence of cardiac chamber dilation with less hypertrophy remodeling was found

The Diet Quality of Competitive Adolescent Male Rugby Union Players with Energy Balance Estimated Using Different Physical Activity Coefficients

Directory of Open Access Journals (Sweden)

Tracy Burrows

2016-09-01

Full Text Available Objectives: The aims of the current study were to comprehensively assess the dietary intakes and diet quality of a sample of Australian competitive adolescent rugby union players and compare these intakes with National and Sports Dietitians Association (SDA Recommendations for adolescent athletes. A secondary aim investigated applying different physical activity level (PAL coefficients to determine total energy expenditure (TEE in order to more effectively evaluate the adequacy of energy intakes. Design: Cross-sectional. Methods: Anthropometrics and dietary intakes were assessed in 25 competitive adolescent male rugby union players (14 to 18 years old. Diet was assessed using the validated Australian Eating Survey (AES food frequency questionnaire and diet quality was assessed through the Australian Recommended Food Score. Results: The median dietary intakes of participants met national recommendations for percent energy (% E from carbohydrate, protein and total fat, but not carbohydrate intake when evaluated as g/day as proposed in SDA guidelines. Median intakes of fibre and micronutrients including calcium and iron also met national recommendations. Overall diet quality was classified as ‘good’ with a median diet quality score of 34 (out of a possible 73; however, there was a lack of variety within key food groups including carbohydrates and proteins. Non-core food consumption exceeded recommended levels at 38% of the daily total energy intake, with substantial contributions from takeaway foods and sweetened beverages. A PAL coefficient of 1.2–1.4 was found to best balance the energy intakes of these players in their pre-season. Conclusions: Adolescent rugby players met the percent energy recommendations for macronutrients and attained an overall ‘good’ diet quality score. However, it was identified that when compared to specific recommendations for athletes, carbohydrate intakes were below recommendations and these players in their

Attractive males have faster sperm in three-spined sticklebacks Gasterosteus aculeatus

Directory of Open Access Journals (Sweden)

Marion MEHLIS, Lukas K. HILKE, Theo C. M. BAKKER

2013-12-01

Full Text Available Recent studies have revealed that sexually selected traits may signal sperm quality and hence male fertilisation ability. There is also evidence that the expression of male sexual ornamentation and associated sperm characteristics depend on an individual’s ability to cope with oxidative stress. Carotenoids are known for their antioxidant properties and carotenoid-based ornaments might represent honest signals as these pigments can be traded off between the investment in sexual ornamentation, sperm function as well as immune response. In this study, we examined the relationship between sexual ornamentation (breeding coloration and sperm characteristics (e.g., velocity and morphology in the three-spined stickleback Gasterosteus aculeatus, an externally fertilising fish species, in which sperm competition commonly occurs. During the breeding season males are sperm limited and develop a conspicuous carotenoid-based coloration, which is under strong pre-copulatory sexual selection due to female mate choice and male-male competition. The results of the present study show that the expression of stickleback male breeding coloration is significantly positively associated with the linearity of sperm movement, whereas sperm morphology (head length to tail length ratio is significantly negatively related to the trajectory of sperm movement. Moreover, there is some support for the phenotype-linked fertility hypothesis as the intensity of male red breeding coloration is significantly positively correlated with sperm velocity, which is supposed to be an important determinant of fertilisation success in external fertilisers, indicating the honesty of the sexually selected nuptial red coloration [Current Zoology 59 (6: 761-768, 2013].

Inter-joint coordination between hips and trunk during downswings: Effects on the clubhead speed.

Science.gov (United States)

Choi, Ahnryul; Lee, In-Kwang; Choi, Mun-Taek; Mun, Joung Hwan

2016-10-01

Understanding of the inter-joint coordination between rotational movement of each hip and trunk in golf would provide basic knowledge regarding how the neuromuscular system organises the related joints to perform a successful swing motion. In this study, we evaluated the inter-joint coordination characteristics between rotational movement of the hips and trunk during golf downswings. Twenty-one right-handed male professional golfers were recruited for this study. Infrared cameras were installed to capture the swing motion. The axial rotation angle, angular velocity and inter-joint coordination were calculated by the Euler angle, numerical difference method and continuous relative phase, respectively. A more typical inter-joint coordination demonstrated in the leading hip/trunk than trailing hip/trunk. Three coordination characteristics of the leading hip/trunk reported a significant relationship with clubhead speed at impact (r joint coordination strategies have the great potential to use a biomechanical guideline to improve the golf swing performance of unskilled golfers.

Competitive anxiety in young athletes: differentiating somatic anxiety, worry, and concentration disruption.

Science.gov (United States)

Grossbard, Joel R; Smith, Ronald E; Smoll, Frank L; Cumming, Sean P

2009-03-01

The age-appropriate Sport Anxiety Scale-2 (SAS-2; Smith, Smoll, Cumming, & Grossbard, 2006) was used to assess levels of cognitive and somatic anxiety among male and female youth sport participants. Confirmatory factor analyses with a sample of 9-14 year old athletes (N=1038) supported the viability of a three-factor model of anxiety involving somatic anxiety, worry, and concentration disruption previously demonstrated in high school and college samples. Tests for factorial invariance revealed that the three-factor model was an equally good fit for 9-11 year olds and 12-14 year olds, and for both males and females. Gender and age were modestly related to anxiety scores. Worry about performing poorly was highest in girls and in older athletes, whereas boys reported higher levels of concentration disruption in competitive sport situations. Implications for emotional perception and for the study of competitive anxiety in young athletes are discussed.

Study of effect of radiation on the parameters of quality of sterile males of Ceratitis Ceratitis capitata (Wied.) and their improvement aroma therapy

International Nuclear Information System (INIS)

Nouira, Manel

2008-01-01

In this present work, we are interested in studying the various stages in the production of sterile males, the effect of different doses of irradiation on longevity, compatibility and competitiveness of these males. And the effect of exposure of adults and pupae of Ceratitis to different doses of essential oil of ginger on their compatibility and competitiveness. (Author)

Locomotion Characteristics and Match-Induced Impairments in Physical Performance in Male Elite Team Handball Players

DEFF Research Database (Denmark)

Michalsik, L B; Aagaard, Per; Madsen, K

2013-01-01

The purpose of this study was to determine the physical demands and match-induced impairments in physical performance in male elite Team Handball (TH) players in relation to playing position. Male elite TH field players were closely observed during 6 competitive seasons. Each player (wing players...

Short-term separation from groups by male Japanese macaques: costs and benefits in feeding behavior and social interaction.

Science.gov (United States)

Otani, Yosuke; Sawada, Akiko; Hanya, Goro

2014-04-01

To expand our understanding of fission-fusion behavior and determine its variability among primates, studies of both individual-based and group-based fission-fusion are necessary. We conducted a parallel tracking study of male and female Japanese macaques (Macaca fuscata yakui) during the non-mating season to clarify the general features of separate ranging by males of this species, an example of fission-fusion behavior, and to reveal its associated costs and benefits. Males frequently engaged in short-term separate ranging, leaving the company of females and ranging on their own for periods averaging 68 min in duration. However, the males did not venture outside the group's home range. When ranging separately from the group, males spent more time feeding, particularly on fruit, stayed longer in each feeding tree, and fed at a lower rate than when ranging with the group. These behavioral changes suggest that males can avoid within-group feeding competition by ranging alone. However, this behavior was also associated with higher traveling costs, and these separated males were more vulnerable to intergroup competition and had fewer opportunities for social interaction. The frequency of separate ranging was lower when highly clumped food plant species were the main food source. Lower-ranked males, who received more aggression when ranging with the group, exhibited a higher frequency of separate ranging. This behavioral flexibility with respect to group cohesion may allow males to reduce the costs of group living without completely losing the benefits. Specifically, by ranging alone, males may acquire sufficient feeding time without being disturbed by other group members. Conversely, when ranging with the group, males can access grooming partners and advantages in intergroup competition. © 2013 Wiley Periodicals, Inc.

Psychophysiological responses to competition and the big five personality traits.

Science.gov (United States)

Binboga, Erdal; Guven, Senol; Catıkkaş, Fatih; Bayazıt, Onur; Tok, Serdar

2012-06-01

This study examines the relationship between psychophysiological arousal, cognitive anxiety, and personality traits in young taekwondo athletes. A total of 20 male and 10 female taekwondo athletes (mean age = 18.6 years; ± 1.8) volunteered for the study. The Five Factor Personality Inventory and the state scale of the Spielberger State-Trait Anxiety Inventory (STAI) were used to measure personality and cognitive state anxiety. Electrodermal activity (EDA) was measured twice, one day and approximately one hour prior to the competition, to determine psychophysiological arousal. Descriptive statistics, Pearson product-moment correlations, and stepwise regression were used to analyze the data. Several "Big Five" facets were related to the EDA delta scores that were measured both one day and one hour before the competition. Two stepwise regressions were conducted to examine whether personality traits could significantly predict both EDA delta scores. The final model, containing only neuroticism from the Big Five factors, can significantly explain the variations in the EDA delta scores measured one day before the competition. Agreeableness can significantly explain variations in the EDA delta scores measured one hour before the competition. No relationship was found between cognitive anxiety and the EDA delta scores measured one hour before the competition. In conclusion, personality traits, especially agreeableness and neuroticism, might be useful in understanding arousal responses to competition.

Natural bodybuilding competition preparation and recovery: a 12-month case study.

Science.gov (United States)

Rossow, Lindy M; Fukuda, David H; Fahs, Christopher A; Loenneke, Jeremy P; Stout, Jeffrey R

2013-09-01

Bodybuilding is a sport in which competitors are judged on muscular appearance. This case study tracked a drug-free male bodybuilder (age 26-27 y) for the 6 mo before and after a competition. The aim of this study was to provide the most comprehensive physiological profile of bodybuilding competition preparation and recovery ever compiled. Cardiovascular parameters, body composition, strength, aerobic capacity, critical power, mood state, resting energy expenditure, and hormonal and other blood parameters were evaluated. Heart rate decreased from 53 to 27 beats/min during preparation and increased to 46 beats/min within 1 mo after competition. Brachial blood pressure dropped from 132/69 to 104/56 mmHg during preparation and returned to 116/64 mmHg at 6 mo after competition. Percent body fat declined from 14.8% to 4.5% during preparation and returned to 14.6% during recovery. Strength decreased during preparation and did not fully recover during 6 months of recovery. Testosterone declined from 9.22 to 2.27 ng/mL during preparation and returned back to the baseline level, 9.91 ng/mL, after competition. Total mood disturbance increased from 6 to 43 units during preparation and recovered to 4 units 6 mo after competition. This case study provides a thorough documentation of the physiological changes that occurred during natural bodybuilding competition and recovery.

Pre-game hydration status, sweat loss, and fluid intake in elite Brazilian young male soccer players during competition.

Science.gov (United States)

Da Silva, Rafael P; Mündel, Toby; Natali, Antonio J; Bara Filho, Mauricio G; Alfenas, Rita C G; Lima, Jorge R P; Belfort, Felipe G; Lopes, Priscila R N R; Marins, João C B

2012-01-01

In this study, we assessed the pre-game hydration status and fluid balance of elite young soccer players competing in a match played in the heat (temperature 31.0 ± 2.0 ° C, relative humidity 48.0 ± 5.0%) for an official Brazilian soccer competition. Fluid intake was measured during the match, as were urine specific gravity and body mass before and after the game to estimate hydration status. Data were obtained from 15 male players (age 17.0 ± 0.6 years, height 1.78 ± 0.06 m, mass 65.3 ± 3.8 kg); however, data are only analysed for 10 players who completed the full game. The mean (± s) sweat loss of players amounted to 2.24 ± 0.63 L, and mean fluid intake was 1.12 ± 0.39 L. Pre-game urine specific gravity was 1.021 ± 0.004, ranging from 1.010 to 1.025. There was no significant correlation between sweat loss and fluid intake (r = 0.504, P = 0.137) or between urine specific gravity and fluid intake (r = -0.276, P = 0.440). We conclude that young, native tropical soccer players started the match hypohydrated and replaced about 50% of the sweat lost. Thus, effective strategies to improve fluid replacement are needed for players competing in the heat.

Competitive balance in national European soccer competitions

NARCIS (Netherlands)

Haan, M.A.; Koning, R.H.; van Witteloostuijn, A.; Albert, Jim; Koning, Ruud H.

2007-01-01

According to popular belief, competitive balance in national soccer competitions in Europe has decreased due to the Bosman ruling and the introduction of the Champions League. We test this hypothesis using data from 7 national competitions, for a host of indicators. We find some evidence for

Charlie's Words: Supporting Gifted Male Athletes Using Athletes' Journals

Science.gov (United States)

Kent, Richard

2012-01-01

A gifted student-athlete, Charlie Bloomfield is introduced to athlete's journals by his coaches at Burke Mountain Academy (Vermont), an elite American ski school. Used by Olympians and professionals alike, journals provide athletes with ways to organize and reflect on training and competitions. Athlete's journals help gifted male athletes address…

Relative Age Affects Marathon Performance in Male and Female Athletes

OpenAIRE

Connick, Mark J.; Beckman, Emma M.; Tweedy, Sean M.

2015-01-01

Marathon runners are ranked in 5-year age groups. However the extent to which 5-year groupings facilitates equitable competition has not been evaluated. The aim of this study was to evaluate the effect of relative age in male and female marathon running. Marathon finishing times for the top ten male (aged 20-69 years) and female athletes (aged 20-64 years) were obtained from the 2013 New York and Chicago marathons. Intra-class and inter-class validity were evaluated by comparing performances ...

Male Sexual Behavior and Pheromone Emission Is Enhanced by Exposure to Guava Fruit Volatiles in Anastrepha fraterculus

Science.gov (United States)

Bachmann, Guillermo E.; Segura, Diego F.; Devescovi, Francisco; Juárez, M. Laura; Ruiz, M. Josefina; Vera, M. Teresa; Cladera, Jorge L.; Fernández, Patricia C.

2015-01-01

Background Plant chemicals can affect reproductive strategies of tephritid fruit flies by influencing sex pheromone communication and increasing male mating competitiveness. Objective and Methodology We explored whether exposure of Anastrepha fraterculus males to guava fruit volatiles and to a synthetic blend of volatile compounds released by this fruit affects the sexual performance of wild and laboratory flies. By means of bioassays and pheromone collection we investigated the mechanism underlying this phenomenon. Results Guava volatile exposure enhanced male mating success and positively affected male calling behavior and pheromone release in laboratory and wild males. Changes in male behavior appear to be particularly important during the initial phase of the sexual activity period, when most of the mating pairs are formed. Exposure of laboratory males to a subset of guava fruit volatiles enhanced mating success, showing that the response to the fruit might be mimicked artificially. Conclusions Volatiles of guava seem to influence male mating success through an enhancement of chemical and physical signals related to the communication between sexes. This finding has important implications for the management of this pest species through the Sterile Insect Technique. We discuss the possibility of using artificial blends to improve the sexual competitiveness of sterile males. PMID:25923584

Reflections on Competition, Competition Regulation and the Current Crises

DEFF Research Database (Denmark)

Buch-Hansen, Hubert; Wigger, Angela

2013-01-01

competition came to enjoy such an exalted status in Europe and then challenges conventional wisdom by bringing into focus the downsides of competition. It argues that excessive competition and neoliberal competition regulation have contributed to intensify the economic, political, social and environmental...

The influence of parenting practices and parental presence on children's and adolescents' pre-competitive anxiety.

Science.gov (United States)

Bois, Julien E; Lalanne, Julien; Delforge, Catherine

2009-08-01

We examined parental influence on athletes' pre-competitive anxiety. The effect of parental presence during competition was studied as was the role of parenting practices. Data were collected from a sample of 341 athletes (201 basketball players and 140 tennis players) before an official competition. Analysis of variance indicated that the presence of both parents was associated with higher pre-competitive anxiety for all participants, except male tennis players. The absence of both parents did not result in less anxiety. A second analysis of variance revealed that females tennis players at provincial and national level perceived greater parental pressure than most other participants. Canonical correlation analysis showed a positive relationship between pre-competitive anxiety and parenting practices for tennis players, but not for basketball players. Directive behaviours and pressure were positively associated with pre-competitive anxiety for all tennis players, whereas praise and understanding was negatively related to anxiety for female tennis players only.

Participation of irradiated Anopheles arabiensis males in swarms following field release in Sudan

International Nuclear Information System (INIS)

Ageep, Tellal B; Alsharif, Bashir; Ahmed, Ayman; Salih, Elwaleed HO; Ahmed, Fayez TA; El Sayed, Badria B; Damiens, David; Gilles, Jeremie RL; Lees, Rosemary S; Diabaté, Abdoulaye

2015-01-01

BACKGROUND: The success of the SIT depends on the; release of large numbers of sterile males, which are able to; compete for mates with the wild male population within the; target area. The processes of colonisation, mass production; and irradiation may reduce the competitiveness of sterile; males through genetic selection, loss of natural traits and; somatic damage. In this context, the capacity of released; sterile Anopheles arabiensis males to survive, disperse and; participate in swarms occurring at varying distances from; the release site was studied using mark-release-recapture; techniques.; METHODS: In order to assess their participation in; swarms, irradiated and marked laboratory-reared male; mosquitoes were released 50, 100 or 200 m from the; known site of a large swarm on three consecutive nights.; Males were collected from this large swarm on subsequent; nights. Over the three days a total of 8,100 males were released.; Mean distance travelled (MDT), daily probability of; survival and estimated population size were calculated; from the recapture data. An effect of male age at the time; of release on these parameters was observed.; RESULTS: Five per cent of the males released over three; days were recaptured. In two-, three- and four-day-old; males, MDT was 118, 178 and 170 m, and the daily survival; probability 0.95, 0.90 and 0.75, respectively. From the; recapture data on the first day following each release, the; Lincoln index gives an estimation of 32,546 males in the; natural population.; DISCUSSION: Sterile An. arabiensis males released into; the field were able to find and participate in existing; swarms, and possibly even initiate swarms. The survival; probability decreased with the age of male on release but; the swarm participation and the distance travelled by older; males seemed higher than for younger males. The inclusion; of a pre-release period may thus be beneficial to male competitiveness; and increase the attractiveness of adult sexing

Heightened aggression and winning contests increase corticosterone but decrease testosterone in male Australian water dragons.

Science.gov (United States)

Baird, Troy A; Lovern, Matthew B; Shine, Richard

2014-07-01

Water dragons (Intellegama [Physignathus] lesueurii) are large (to >1m) agamid lizards from eastern Australia. Males are fiercely combative; holding a territory requires incessant displays and aggression against other males. If a dominant male is absent, injured or fatigued, another male soon takes over his territory. Our sampling of blood from free-ranging adult males showed that baseline levels of both testosterone and corticosterone were not related to a male's social tactic (territorial versus non-territorial), or his frequency of advertisement display, aggression, or courtship behavior. Even when we elicited intense aggression by non-territorial males (by temporarily removing territory owners), testosterone did not increase with the higher levels of aggression that ensued. Indeed, testosterone levels decreased in males that won contests. In contrast, male corticosterone levels increased with the heightened aggression during unsettled conditions, and were higher in males that won contests. High chronic male-male competition in this dense population may favor high testosterone levels in all adult males to facilitate advertisement and patrol activities required for territory maintenance (by dominant animals), and to maintain readiness for territory take-overs (in non-territorial animals). Corticosterone levels increased in response to intense aggression during socially unstable conditions, and were higher in contest winners than losers. A positive correlation between the two hormones during socially unstable conditions suggests that the high stress of contests decreased androgen production. The persistent intense competition in this population appears to exact a high physiological cost, which together with our observation that males sometimes lose their territories to challengers may indicate cycling between these two tactics to manage long-term energetic costs. Copyright © 2014 Elsevier Inc. All rights reserved.

Low Risk of Injuries in Young Adolescents Participating in Top-Level Karate Competition.

Science.gov (United States)

Arriaza, Rafael; Inman, David; Arriaza, Alvaro; Saavedra, Miguel A

2016-02-01

Prospective studies on injuries in martial arts competition are scarce, especially those involving young practitioners, but the upsurge of children and adolescents taking part in organized training and competition in these sports requires clarification of the injury risk that they represent for youths. Top-level karate competition for young adolescents (cadets, or 14- to 15-year-olds) has a low injury rate and can be safely promoted. Descriptive epidemiological study. Prospective recording of the injuries resulting from all bouts in 3 consecutive World Karate Championships (2009, 2011, and 2013) for cadets was performed. Data were collected prospectively in situ with checklists that described competitor sex, bout category, and weight as well as injured area, diagnosis, mechanism of injury, severity, and treatment. A total of 1020 bouts were reviewed, 671 in the male category and 349 in the female category. A total of 61 injuries were recorded. Of those, only 3 were time-loss injuries. During the 2009 and 2011 championships, there was 1 injury per 25.6 fights, while during the 2013 championship the number of injuries increased, with 1 injury per 10 fights (P = .003). There was no statistical difference in the total injury rate between the male and female categories (P = .71), with an odds ratio of 1.16 (95% CI, 0.52-2.55). The injury rate for cadet top-level karate competition found in this prospective study is much lower than the rates previously published for karate or other martial arts competitions, but there seems to be a marked increase as more championships are held, which is a matter of concern. © 2015 The Author(s).

Environmental structure and competitive scoring advantages in team competitions

Science.gov (United States)

Merritt, Sears; Clauset, Aaron

2013-10-01

In most professional sports, playing field structure is kept neutral so that scoring imbalances may be attributed to differences in team skill. It thus remains unknown what impact environmental heterogeneities can have on scoring dynamics or competitive advantages. Applying a novel generative model of scoring dynamics to roughly 10 million team competitions drawn from an online game, we quantify the relationship between the structure within a competition and its scoring dynamics, while controlling the impact of chance. Despite wide structural variations, we observe a common three-phase pattern in the tempo of events. Tempo and balance are highly predictable from a competition's structural features alone and teams exploit environmental heterogeneities for sustained competitive advantage. Surprisingly, the most balanced competitions are associated with specific environmental heterogeneities, not from equally skilled teams. These results shed new light on the design principles of balanced competition, and illustrate the potential of online game data for investigating social dynamics and competition.

Treatment of Travel Expenses by Golf Course Patrons: Sunk or Bundled Costs and the First and Third Laws of Demand

OpenAIRE

Matt, Brown; Daniel, Rascher; Chad, McEvoy; Mark, Nagel

2007-01-01

To attract golf patrons, sport managers must understand consumption patterns of the golfer. Importantly, the treatment of travel costs must be understood. According to the Alchian-Allen (1964) theorem, golfers treat travel costs as bundled costs (third law of economic demand) whereas classical consumer theory indicates that golfers treat travel costs as sunk costs (first law of economic demand). The purpose of this study was to determine if golf patrons treated travel costs as sunk costs o...

Specific Physical Training in Elite Male Team Handball.

Science.gov (United States)

Wagner, Herbert; Gierlinger, Manuel; Adzamija, Nermin; Ajayi, Samuel; Bacharach, David W; von Duvillard, Serge P

2017-11-01

Wagner, H, Gierlinger, M, Adzamija, N, Ajayi, S, Bacharach, DW, and von Duvillard, SP. Specific physical training in elite male team handball. J Strength Cond Res 31(11): 3083-3093, 2017-Specific physical training in elite team handball is essential for optimal player's performance; however, scientific knowledge is generally based on temporary training studies with subelite athletes. Therefore, the aim of the study was to analyze the effects of specific physical training in an elite male handball team over the entire season. Twelve players of a male handball team from the First Austrian Handball League conducted a 1-year specific physical training program in addition to their normal (team handball techniques and tactics) weekly training. Performance was measured with 5 general and 4 specific tests as well as game statistics during competition. Repeated measures analysis of variances and paired sample t-test were used to analyze differences in performance during training. We found a significant increase in oxygen uptake, offense time, defense time, fast break time, and jump height in the specific tests. Game performance statistics revealed a lower throwing percentage in the hosting team (59%) compared with the rival teams (63%). Our results indicated that specific endurance and agility are an acceptable modality in elite male team handball. However, performance in competition is strongly influenced by specific techniques and tactics. We recommend to strength and conditioning professionals that they tailor strength and power training, coordination and endurance as specific as possible, using free weights, agility exercises that include change in direction and jumps as well as short (10-15 seconds) high-intensity intervals.

Training practices and ergogenic aids used by male bodybuilders.

Science.gov (United States)

Hackett, Daniel A; Johnson, Nathan A; Chow, Chin-Moi

2013-06-01

Bodybuilding involves performing a series of poses on stage where the competitor is judged on aesthetic muscular appearance. The purpose of this study was to describe training practices and ergogenic aids used by competitive bodybuilders and to determine whether training practices comply with current recommendations for muscular hypertrophy. A web-based survey was completed by 127 competitive male bodybuilders. The results showed that during the off-season phase of training (OFF), the majority of respondents performed 3-6 sets per exercise (95.3%), 7-12 repetition maximum (RM) per set (77.0%), and 61- to 120-seconds recovery between sets and exercises (68.6%). However, training practices changed 6 weeks before competition (PRE), where there was an increased number of respondents who reported undertaking 3-4 sets per exercise at the expense of 5-6 sets per exercise (p competitions (56 of 73 respondents), whereas dietary supplementation was used by all respondents. The findings of this study demonstrate that competitive bodybuilders comply with current resistance exercise recommendations for muscular hypertrophy; however, these changed before competition during which there is a reduction resistance training volume and intensity. This alteration, in addition to an increase in aerobic exercise volume, is purportedly used to increase muscle definition. However, these practices may increase the risk of muscle mass loss in natural compared with amateur bodybuilders who reportedly use drugs known to preserve muscle mass.

First report of satellite males during breeding in Leptodactylus latrans (Amphibia, Anura

Directory of Open Access Journals (Sweden)

Gabriel Laufer

2014-05-01

Full Text Available The occurrence of satellite males is a common behaviour across anuran taxa. Satellite males take peripheral positions to calling males and adopt tactics in an attempt to intercept females that are attracted to calling males to increase their own mating success. Satellite males could have an inexpensive form of mate-locating, avoiding predators, and saving energy. Furthermore, this strategy could play an important role in the genetic structure of populations. The genus Leptodactylus consists of approximately 70 described species that are widely distributed in South America. The literature on the biology of this genus is extensive; however, we found only two reports on the existence of multi-male mating behavior in the genus (L. chaquensis and L. podicipinus. Herein, we report intrasexual competition in the form of satellite behavior in Leptodactylus latrans, where multiple satellite males were observed in close vicinity to a calling male.

Rapid diversification of male genitalia and mating strategies in Ohomopterus ground beetles.

Science.gov (United States)

Takami, Y; Sota, T

2007-07-01

We analysed evolutionary diversification and covariation in male genitalia and four mating traits related to sexual selection, i.e. testis size, spermatophore size, copulation duration and post-copulatory guarding duration, in Ohomopterus ground beetles using phylogenetically independent contrasts. Male genital size and mating duration have evolved more rapidly than body size and the other traits studied. Male genital size was negatively correlated with copulation duration, suggesting that elongated male genitalia may enable decreased time investment in a single copulation because it is more effective at facilitating spermatophore deposition. Male genital size was positively correlated with spermatophore size, suggesting coevolution between offensive and defensive male mating tactics because the elongated male genitalia may be advantageous in displacement of rivals' plug-like spermatophores, and decreased mating duration may intensify sperm competition. Thus, the remarkable diversity of male genitalia in Ohomopterus may have been facilitated by the interplay between inter- and intrasexual selection processes.

Frequency and direction of competitive anger in contact sports.

Science.gov (United States)

Robazza, B; Bertollo, M; Bortoli, L

2006-09-01

The purpose of the present study was to investigate whether athletes involved in physical contact sports may interpret their feelings of anger as facilitative of performance, and to examine differences in the interpretation of anger as a function of the type of sport (team vs individual) or the competitive skill level (high vs low). A modified version of the State-Trait Anger Expression Inventory was administered to 100 Italian adult male athletes practicing rugby or individual combat sports (judo, freestyle wrestling, or Greco-Roman wrestling). The questionnaire was intended to measure the frequency and the direction (i.e., the facilitative-debilitative interpretation) of competitive anger. Many athletes engaged in contact sports tended interpret their competitive anger as facilitative of performance rather than debilitative. The type of sport and the athlete's standard level can mediate the individual's interpretation of the effects of anger symptoms upon performance. Competitors can interpret their anger as helpful to energize behavior and channel physical and mental resources for skill execution. Practitioners should assist athletes in gaining control over anger rather than attempting to suppress it.

Retail competition

International Nuclear Information System (INIS)

1998-01-01

Retail competition as the cornerstone of a competitive electricity marketplace was the subject of the seventh in the series of policy discussion papers developed at the Market Design Conference. Concern was expressed that because of the complexities involved in market design and technical implementation, the retail competition may lag behind other elements of the implementation of the new market design. A variety of key issues were debated, including the role of physical versus financial contracts, the form of retail competition and financial settlement systems in the short term, the requirement to separate 'competitive' (metering, billing, maintenance, consumer education) from non-competitive' (the transmission wires) services and the role of municipal electric utilities. It was agreed that the IMO should play an important role in defining and enforcing the separation of services, and that as a general rule, the development of policy in this area should be guided by the principle of maximizing the potential for competition

Return to Golf After Lumbar Fusion.

Science.gov (United States)

Shifflett, Grant D; Hellman, Michael D; Louie, Philip K; Mikhail, Christopher; Park, Kevin U; Phillips, Frank M

Spinal fusion surgery is being increasingly performed, yet few studies have focused on return to recreational sports after lumbar fusion and none have specifically analyzed return to golf. Most golfers successfully return to sport after lumbar fusion surgery. Case series. Level 4. All patients who underwent 1- or 2-level primary lumbar fusion surgery for degenerative pathologies performed by a single surgeon between January 2008 and October 2012 and had at least 1-year follow-up were included. Patients completed a specifically designed golf survey. Surveys were mailed, given during follow-up clinic, or answered during telephone contact. A total of 353 patients met the inclusion and exclusion criteria, with 200 responses (57%) to the questionnaire producing 34 golfers. The average age of golfers was 57 years (range, 32-79 years). In 79% of golfers, preoperative back and/or leg pain significantly affected their ability to play golf. Within 1 year from surgery, 65% of patients returned to practice and 52% returned to course play. Only 29% of patients stated that continued back/leg pain limited their play. Twenty-five patients (77%) were able to play the same amount of golf or more than before fusion surgery. Of those providing handicaps, 12 (80%) reported the same or an improved handicap. More than 50% of golfers return to on-course play within 1 year of lumbar fusion surgery. The majority of golfers can return to preoperative levels in terms of performance (handicap) and frequency of play. This investigation offers insight into when golfers return to sport after lumbar fusion surgery and provides surgeons with information to set realistic expectations postoperatively.

COMPARATIVE ANALYSIS OF COMPETITIVE STATE ANXIETY AMONG TEAM SPORT AND INDIVIDUAL SPORT ATHLETES IN IRAN

OpenAIRE

Soltani Hossein; Hojati Zahra; Reza Attarzadeh Hossini Seyed

2016-01-01

Purpose: With respect to the fact that every sport field has its own special nature, the aim of present study was to compare competitive state anxiety among team sport and individual sport athletes in Iran. Material: The statistic sample included 120 male athletes, 60 athletes in individual sports (wrestling, taekwondo and karate) and 60 athletes in team sports (futsal, volleyball and basketball). The research instrument employed was the Persian version of the Competitive State Anxiety Invent...

Competitive intelligence as an enabler for firm competitiveness: An overview

Directory of Open Access Journals (Sweden)

Alexander Maune

2014-06-01

Full Text Available The purpose of this article is to provide an overview, from literature, about how competitive intelligence can be an enabler towards a firm’s competitiveness. This overview is done under the background of intense global competition that firms are currently experiencing. This paper used a qualitative content analysis as a data collection methodology on all identified journal articles on competitive intelligence and firm competitiveness. To identify relevant literature, academic databases and search engines were used. Moreover, a review of references in related studies led to more relevant sources, the references of which were further reviewed and analysed. To ensure reliability and trustworthiness, peer-reviewed journal articles and triangulation were used. The paper found that competitive intelligence is an important enabler of firm competitiveness. The findings from this paper will assist business managers to understand and improve their outlook of competitive intelligence as an enabler of firm competitiveness and will be of great academic value.

Competitiveness and survival of two strains of Glossina palpalis gambiensis in an urban area of Senegal.

Science.gov (United States)

Bassène, Mireille Djimangali; Seck, Momar Talla; Pagabeleguem, Soumaïla; Fall, Assane Gueye; Sall, Baba; Vreysen, Marc J B; Gimonneau, Geoffrey; Bouyer, Jérémy

2017-12-01

In the Niayes area, located in the west of Senegal, only one tsetse species, Glossina palpalis gambiensis Vanderplank (Diptera: Glossinidae) was present. The Government of Senegal initiated and implemented an elimination programme in this area that included a sterile insect technique (SIT) component. The G. p. gambiensis strain (BKF) mass-reared at the Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES) in Burkina Faso was used for the SIT component. Studies conducted in 2011 in four localities in the Niayes area (Pout, Sébikotane, Diacksao Peul and the Parc de Hann) showed that the BKF strain demonstrated inferior survival in the ecosystem of the Parc de Hann, a forested area in the city centre of the capital Dakar. Therefore, G. p. gambiensis flies from the Niayes area (SEN strain) were colonized. Here we compared the competitiveness and survival of the two strains (BKF and SEN) in the Parc de Hann. Released sterile males of the SEN colony showed a daily mortality rate of 0.08 (SD 0.08) as compared with 0.14 (SD 0.08) for the BKF flies but the difference was not significant (p-value = 0.14). However, the competitiveness of the SEN males was lower (0.14 (SD 0.10)) as compared with that of the BKF males (0.76 (SD 0.11)) (p-value competitiveness of the BKF males is deemed more important for the SIT component, as their shorter survival rates can be easily compensated for by more frequent fly releases.

Developmental environment mediates male seminal protein investment in Drosophila melanogaster.

Science.gov (United States)

Wigby, Stuart; Perry, Jennifer C; Kim, Yon-Hee; Sirot, Laura K

2016-03-01

Males of many species fine-tune their ejaculates in response to sperm competition risk. Resource availability and the number of competitors during development can also strongly influence sperm production. However, despite the key role of seminal proteins in mediating reproductive processes, it is unclear whether seminal protein investment is dependent on the developmental environment.We manipulated the developmental environment of Drosophila melanogaster by rearing flies at low and high density. As expected, this resulted in large and small (i.e. high and low condition) adult phenotypes, respectively.As predicted, large males produced more of two key seminal proteins, sex peptide (SP) and ovulin, and were more successful at obtaining matings with both virgin and previously mated females. However, there was only a weak and non-significant trend for large males to transfer more absolute quantities of SP at mating, and thus, small males ejaculated proportionally more of their stored accessory gland SP resources.Males transferred more receptivity-inhibiting SP to large females. Despite this, large females remated more quickly than small females and thus responded to their developmental environment over and above the quantity of SP they received.The results are consistent with two non-mutually exclusive hypotheses. First, flies might respond to condition-dependent reproductive opportunities, with (i) small males investing heavily in ejaculates when mating opportunities arise and large males strategically partitioning SP resources and (ii) small females remating at reduced rates because they have higher mating costs or need to replenish sperm less often.Second, flies may be primed by their larval environment to deal with similar adult population densities, with (i) males perceiving high density as signalling increased competition, leading small males to invest proportionally more SP resources at mating and (ii) females perceiving high density as signalling abundant

A comparison of two methods to assess audience-induced changes in male mate choice

Institute of Scientific and Technical Information of China (English)

Madlen ZIEGE; Carmen HENNIGE-SCHULZ; Frauke MUECKSCH; David BIERBACH; Ralph TIEDEMANN; Bruno STREIT; Martin PLATH

2012-01-01

Multidirectional communicative interactions in social networks can have a profound effect on mate choice behavior.Male Atlantic molly Poecilia mexicana exhibit weaker mating preferences when an audience male is presented.This could be a male strategy to reduce sperm competition risk:interacting more equally with different females may be advantageous because rivals might copy mate choice decisions.In line with this hypothesis,a previous study found males to show a strong audience effect when being observed while exercising mate choice,but not when the rival was presented only before the choice tests.Audience effects on mate choice decisions have been quantified in poeciliid fishes using association preference designs,but it remains unknown if patterns found from measuring association times translate into actual mating behavior.Thus,we createl five audience treatments simulating different forms of perceived sperm competition risk and determined focal males' mating preferences by scoring pre-mating (nipping) and mating behavior (gonopodial thrusting).Nipping did not reflect the pattern that was found when association preferences were measured,while a very similar pattern was uncovered in thrusting behavior.The strongest response was observed when the audience could eavesdrop on the focal male's behavior.A reduction in the strength of focal males' preferences was also seen after the rival male had an opportunity to mate with the focal male's preferred mate.In comparison,the reduction of mating preferences in response to an audience was greater when measuring association times than actual mating behavior.While measuring direct sexual interactions between the focal male and both stimulus females not only the male's motivational state is reflected but also females' behavior such as avoidance of male sexual harassment [Current Zoology 58 (1):84-94,2012].

Pre- and Postcopulatory Traits of Salvator Male Lizards in Allopatry and Sympatry

Directory of Open Access Journals (Sweden)

Sergio Naretto

2016-01-01

Full Text Available The reproductive traits of males are under influence of sexual pressures before and after copulation. The strength of sexual selection varies across populations because they undergo varying competition for mating opportunities. Besides intraspecific pressures, individuals seem to be subjected to pressures driven by interspecific interactions in sympatry. Lizards may vary their reproductive strategies through varying sexual characters, body size, gonadal investment, and sperm traits. We evaluated the reproductive traits, involved in pre- and postcopulatory competition, in allopatric and sympatric populations of Salvator lizards. We observed a spatial gradient of male competition among populations, with the following order: allopatric zone of S. rufescens; sympatric zone; and allopatric zone of S. merianae. Accordingly, variation in secondary sexual character, the relative testis mass, and the length of sperm component was observed between allopatry and sympatry in each species, suggesting differences in the investment of reproductive traits. However, we found that these two Salvator species did not differ in secondary sexual characters in sympatry. Interestingly, the trade-off between testes and muscle varied differently from allopatry to sympatry between these Salvator species, suggesting that the influence of social context on reproductive traits investment would affect lizard species differently.

Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish.

Science.gov (United States)

Hurtado-Gonzales, Jorge L; Uy, J Albert C

2010-12-23

Intense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs). Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata), striped (parae), structural-coloured (blue) and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs. Our study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations) by 1) directly monopolizing access to females, and 2) modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males. Strong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct males exhibiting clear differences in their levels of

Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish

Directory of Open Access Journals (Sweden)

Uy J Albert C

2010-12-01

Full Text Available Abstract Background Intense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs. Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata, striped (parae, structural-coloured (blue and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs. Results Our study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations by 1 directly monopolizing access to females, and 2 modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males. Conclusions Strong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct

Social network predicts loss of fertilizations in nesting males of a fish with alternative reproductive tactics

OpenAIRE

Cardoso, Sara D.; Faustino, Ana Isabel Soares; Costa, Silvia S.; Valério, Fábio; Gonçalves, David; Oliveira, Rui Filipe

2016-01-01

Material suplementar está disponível online em doi: 10.1007/s10211-016-0249-9, disponibilizado a todos os utilizadores autorizados. Alternative reproductive tactics (ARTs) evolve when there is strong intra-sexual competition between conspecifics for access to mates. Typically, larger Bbourgeois^ males reproduce by securing the access to reproductive resources while smaller Bparasitic^ males reproduce by stealing fertilizations from larger males. A number of factors can influ...

Male coercion and convenience polyandry in a calopterygid damselfly

Directory of Open Access Journals (Sweden)

A. Cordero

2002-08-01

Full Text Available Copulation in odonates requires female cooperation because females must raise their abdomen to allow intromission. Nevertheless in Calopteryx haemorrhoidalis haemorrhoidalis (Odonata males commonly grasp ovipositing females and apparently force copulations. This has been interpreted as a consequence of extreme population density and male-male competition. We studied this behavior at two sites on a river that had different densities over three years. As predicted, at high densities most matings were forced (i.e. not preceded by courtship, but at low density most were preceded by courtship. Courtship matings were shorter at high density, but density did not affect the duration of forced matings. Females cooperated in forced matings even if they had very few mature eggs. Furthermore, females mated more times if they experienced higher male harassment during oviposition, and at low density second and subsequent matings were more likely to be forced. We interpret these results to mean that females engage in "convenience polyandry", because they gain more by accepting copulation than by resisting males. The results also suggest that females might trade copulations for male protection, because under extreme population density harassment by males is so intense that they can impede oviposition.

Competitive Intelligence.

Science.gov (United States)

Bergeron, Pierrette; Hiller, Christine A.

2002-01-01

Reviews the evolution of competitive intelligence since 1994, including terminology and definitions and analytical techniques. Addresses the issue of ethics; explores how information technology supports the competitive intelligence process; and discusses education and training opportunities for competitive intelligence, including core competencies…

Healthy Competition and Unsound Comparison: Reforming Educational Competition in Singapore

Science.gov (United States)

Christensen, Søren

2015-01-01

It is frequently claimed that the "competition state" responds to external competition by making competition increasingly central to its internal processes as well. This article discusses education reform in Singapore as departing from the opposite position. In Singapore "excessive" competition in education is now targeted by…

Polygyny, mate-guarding, and posthumous fertilization as alternative male mating strategies.

Science.gov (United States)

Zamudio, K R; Sinervo, B

2000-12-19

Alternative male mating strategies within populations are thought to be evolutionarily stable because different behaviors allow each male type to successfully gain access to females. Although alternative male strategies are widespread among animals, quantitative evidence for the success of discrete male strategies is available for only a few systems. We use nuclear microsatellites to estimate the paternity rates of three male lizard strategies previously modeled as a rock-paper-scissors game. Each strategy has strengths that allow it to outcompete one morph, and weaknesses that leave it vulnerable to the strategy of another. Blue-throated males mate-guard their females and avoid cuckoldry by yellow-throated "sneaker" males, but mate-guarding is ineffective against aggressive orange-throated neighbors. The ultradominant orange-throated males are highly polygynous and maintain large territories; they overpower blue-throated neighbors and cosire offspring with their females, but are often cuckolded by yellow-throated males. Finally, yellow-throated sneaker males sire offspring via secretive copulations and often share paternity of offspring within a female's clutch. Sneaker males sire more offspring posthumously, indicating that sperm competition may be an important component of their strategy.

Information content and acoustic structure of male African elephant social rumbles.

Science.gov (United States)

Stoeger, Angela S; Baotic, Anton

2016-06-08

Until recently, the prevailing theory about male African elephants (Loxodonta africana) was that, once adult and sexually mature, males are solitary and targeted only at finding estrous females. While this is true during the state of 'musth' (a condition characterized by aggressive behavior and elevated androgen levels), 'non-musth' males exhibit a social system seemingly based on companionship, dominance and established hierarchies. Research on elephant vocal communication has so far focused on females, and very little is known about the acoustic structure and the information content of male vocalizations. Using the source and filter theory approach, we analyzed social rumbles of 10 male African elephants. Our results reveal that male rumbles encode information about individuality and maturity (age and size), with formant frequencies and absolute fundamental frequency values having the most informative power. This first comprehensive study on male elephant vocalizations gives important indications on their potential functional relevance for male-male and male-female communication. Our results suggest that, similar to the highly social females, future research on male elephant vocal behavior will reveal a complex communication system in which social knowledge, companionship, hierarchy, reproductive competition and the need to communicate over long distances play key roles.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game.

Science.gov (United States)

Fransson, Dan; Vigh-Larsen, Jeppe Foged; Fatouros, Ioannis G; Krustrup, Peter; Mohr, Magni

2018-03-01

We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12) participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement ( p ≤ 0.05) at 0 h post-match with knee flexors (14 ± 3%) and hip abductors (6 ± 1%) demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05) for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin) and 24 h into recovery (creatine kinase), respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02). In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Fatigue Responses in Various Muscle Groups in Well-Trained Competitive Male Players after a Simulated Soccer Game

Directory of Open Access Journals (Sweden)

Fransson Dan

2018-03-01

Full Text Available We examined the degree of post-game fatigue and the recovery pattern in various leg and upper-body muscle groups after a simulated soccer game. Well-trained competitive male soccer players (n = 12 participated in the study. The players completed the Copenhagen Soccer Test, a 2 x 45 min simulated soccer protocol, following baseline measures of maximal voluntary contractions of multiple muscle groups and systemic markers of muscle damage and inflammation at 0, 24 and 48 h into recovery. All muscle groups had a strength decrement (p ≤ 0.05 at 0 h post-match with knee flexors (14 ± 3% and hip abductors (6 ± 1% demonstrating the largest and smallest impairment. However, 24 h into recovery all individual muscles had recovered. When pooled in specific muscle groups, the trunk muscles and knee joint muscles presented the largest decline 0 h post-match, 11 ± 2% for both, with the performance decrement still persistent (4 ± 1%, p ≤ 0.05 for trunk muscles 24 h into recovery. Large inter-player variations were observed in game-induced fatigue and recovery patterns in the various muscle groups. Markers of muscle damage and inflammation peaked 0 h post-match (myoglobin and 24 h into recovery (creatine kinase, respectively, but thereafter returned to baseline. Intermittent test performance correlated with creatine kinase activity 24 h after the Copenhagen Soccer Test (r = -0.70; p = 0.02. In conclusion, post-game fatigue is evident in multiple muscle groups with knee flexors showing the greatest performance decrement. Fatigue and recovery patterns vary markedly between muscle groups and players, yet trunk muscles display the slowest recovery.

Pediatric Injuries at an Annual Motocross Competition: Rates and Severity.

Science.gov (United States)

Williams, Brendan A; McFadden, James P; Teurlings, Tyler L; Blakemore, Laurel C

Pediatric motocross injuries occur frequently and with significant associated morbidity; however, data are limited regarding injury occurring during competition. North Central Florida hosts an annual motocross competition with numerous pediatric competitors. We sought to evaluate the rate and severity of injuries sustained at this event over a multiyear period. Our primary hypothesis was that motocross injury rates and severity in competition exceed that of other competitive sports in this age group. A retrospective review was performed to identify pediatric patients (17 and younger) presenting to a single Level 1 Trauma Center as a result of injury sustained at an annual motocross competition from 2009 to 2012. Demographic, diagnostic, and treatment data were collected including injuries, procedural interventions, and length of hospital stay. Rate, type, and severity of injury were evaluated and compared with established norms of other competitive sports in a similar age group. Over a 4-year period, 51 pediatric motocross competitors sustained 75 injuries. Injured riders were 14.2±2.51 years (range, 8 to 17 y) old and 92% (47/51) male. Forty (78%) patients sustained at least 1 orthopaedic injury and 17 (33%) patients suffered polytrauma. The majority of injuries occurred in the upper extremity (36%). Twenty-four (47%) patients required procedural intervention, 15 of which were operative. Thirty-nine (76%) patients necessitated surgical specialty care. Average injury severity score was 6.5 (1 to 75) and 1 death occurred. The injury rate for pediatric motocross riders in this study was 19.9 injuries per 1000 competitors. High rates of injury occur among pediatric patients in competitive motocross, exceeding those seen in other competitive sports in a comparable age group. Significant morbidity and at least 1 fatality were demonstrated in the group studied. The majority of patients suffer at least 1 orthopaedic injury and nearly all patients require pediatric

Relationships between recall of perceived exertion and blood lactate concentration in a judo competition.

Science.gov (United States)

Serrano, M A; Salvador, A; González-Bono, E G; Sanchís, C; Suay, F

2001-06-01

Relationships between perceived exertion and blood lactate have usually been studied in laboratory or training contexts but not in competition, the most important setting in which sports performance is evaluated. The purpose of this study was to examine the relationships between psychological and physiological indices of the physical effort in a competition setting, taking into account the duration of effort. For this, we employed two Ratings of Perceived Exertion (RPE and CR-10) and lactic acid plasma concentration as a biological marker of the effort performed. 13 male judo fighters who participated in a sports club competition provided capillary blood samples to assay lactate concentrations and indicated on scale their Recall of Perceived Exertion in the total competition and again in just the Last Fight to compare the usefulness of RPE and CR-10 in assessing discrete bouts of effort and a whole session. Analysis showed that perceived exertion or the effort made during the whole competition was positively and significantly related to maximal lactate concentration and lactate increase in competition, thus extending the validity of this scale to sports contests. The Recall of Perceived Exertion scores were not significantly correlated with the duration of effort.

EDITORIAL: Physics competitions Physics competitions

Science.gov (United States)

Jordens, H.; Mathelitsch, L.

2010-07-01

This editorial opens the second special section on physics competitions in European Journal of Physics. In the first section last year, we asked for feedback on the idea of such a section and on the content of the articles. We received no answer whatsoever, which can be interpreted in two ways: the section is not interesting enough to raise motivation for feedback, or the reader is satisfied. Having no indication which scenario is the correct one, we are optimistic and favour the second. The section at hand contains three articles. Again, as last year, the organizer of the annual Olympiad reports on tasks and outcomes of this competition. The Olympiad took place in Merida, Mexico, and was by far the largest event with 316 contestants from 68 countries. Again, the predominance of Asian/Chinese students was manifest, showing how serious the training is taken by both their authorities and students. Unfortunately, the winners of the last International Young Physicists' Tournament (IYPT), the team from Korea, did not accept the offer to report on their prize-winning contribution. We are thankful that two students from Austria, who achieved second place with their team, took over and reported on the task which they presented in the finals of the competition. It connects the fields of sport and physics and explains a special move in skateboarding. The third contribution introduces a different competition, 'International Conference of Young Scientists'. On one hand, as in the Olympiad, it addresses individuals, not teams. On the other, as in the IYPT, students have several months to prepare and also the quality of the presentation is an important element of the judgment. In fact, this competition comes closer to real scientific research compared to the other events. Finally and again, we hope that this section will serve several purposes: To show the competitions as a very important tool in the support of gifted students. To raise awareness amongst university teachers, and

Power market competition

International Nuclear Information System (INIS)

Kelly, J.

1998-01-01

In the Unites States the prospect of greater competition in wholesale power market was immediately eclipsed by talk of retail competition. Attempts to move to retail competition have been costly and complex. Prudent public policy and economic analyses suggest that retail competition not be implemented until it can first be demonstrated that effective competition exists in wholesale power markets [it

Lunabotics Mining Competition

Science.gov (United States)

Mueller, Rob; Murphy, Gloria

2010-01-01

This slide presentation describes a competition to design a lunar robot (lunabot) that can be controlled either remotely or autonomously, isolated from the operator, and is designed to mine a lunar aggregate simulant. The competition is part of a systems engineering curriculum. The 2010 competition winners in five areas of the competition were acknowledged, and the 2011 competition was announced.

Interspecific competition influences the organization of a diverse sessile insect community

Science.gov (United States)

Cornelissen, Tatiana; de Carvalho Guimarães, Carla Daniele; Rodrigues Viana, João Paulo; Silva, Bárbara

2013-10-01

Interspecific competition has played a major role in determining the effects of species interactions in terrestrial communities and the perception of its role on shaping population dynamics and community structure has changed throughout the years. In this study, we evaluated the existence of interspecific competition in the herbivore community of the dioecious plant Baccharis pseudomyriocephala (Asteraceae), which holds a diverse community of gall-forming insects. Sixty plants were studied and gall richness and abundance among plants were evaluated. To address whether a plant already occupied by a gall species is preferred or avoided by another gall species, null models were used for all 60 plants combined and for male and female plants separately. Our results have shown that the 11 species of gall-formers found on B. pseudomyriocephala co-occur less than expected by chance alone, indicating that interspecific competition might be an important force structuring the insect community in this tropical host plant, regardless of plant gender.

Last mated male sperm precedence in doubly mated females is not ...

Indian Academy of Sciences (India)

Home; Journals; Journal of Genetics; Volume 92; Issue 2. Last mated male sperm precedence in doubly mated females is not ubiquitous: evidence from sperm competition in laboratory populations of Drosophila nasuta nasuta and Drosophila nasuta albomicans. B. Shruthi S. R. Ramesh. Research Note Volume 92 Issue 2 ...

The evolution of gonad expenditure and gonadosomatic index (GSI) in male and female broadcast-spawning invertebrates.

Science.gov (United States)

Parker, Geoff A; Ramm, Steven A; Lehtonen, Jussi; Henshaw, Jonathan M

2018-05-01

Sedentary broadcast-spawning marine invertebrates, which release both eggs and sperm into the water for fertilization, are of special interest for sexual selection studies. They provide unique insight into the early stages of the evolutionary succession leading to the often-intense operation of both pre- and post-mating sexual selection in mobile gonochorists. Since they are sessile or only weakly mobile, adults can interact only to a limited extent with other adults and with their own fertilized offspring. They are consequently subject mainly to selection on gamete production and gamete success, and so high gonad expenditure is expected in both sexes. We review literature on gonadosomatic index (GSI; the proportion of body tissue devoted to gamete production) of gonochoristic broadcast spawners, which we use as a proxy for gonad expenditure. We show that such taxa most often have a high GSI that is approximately equal in both sexes. When GSI is asymmetric, female GSI usually exceeds male GSI, at least in echinoderms (the majority of species recorded). Intriguingly, though, higher male GSI also occurs in some species and appears more common than female-biased GSI in certain orders of gastropod molluscs. Our limited data also suggest that higher male GSI may be the prevalent pattern in sperm casters (where only males release gametes). We explore how selection might have shaped these patterns using game theoretic models for gonad expenditure that consider possible trade-offs with (i) somatic maintenance or (ii) growth, while also considering sperm competition, sperm limitation, and polyspermy. Our models of the trade-off between somatic tissue (which increases survival) and gonad (which increases reproductive success) predict that GSI should be equal for the two sexes when sperm competition is intense, as is probably common in broadcast spawners due to synchronous spawning in aggregations. Higher female GSI occurs under low sperm competition. Sperm limitation appears

Home ranges and satellite tactics of male green swordtails (Xiphophorus helleri) in nature.

Science.gov (United States)

Franck, D; Klamroth, B; Taebel-Hellwig, A; Schartl, M

1998-05-01

Dominance relationships were studied between marked or otherwise individually recognizable male green swordtails in a creek at Lake Catemaco and in a tributary of the Rio Atoyac (Veracruz, Mexico). The Atoyac population is unique because of a high degree of polymorphism, including both macromelanophore spotting and a micromelanophore tailspot pattern. During the dry season males living in the same area maintained a linear social hierarchy for periods of many days. The subordinate males settled down either in the same home ranges or in home ranges largely overlapping with that of dominant males. Although dominant males untiringly chased the subordinate males away, they returned persistently and achieved the status of non-tolerated satellites. Females were less stationary and presumably passed through many male home ranges during their feeding activities. The data clearly demonstrate that green swordtails live in complex social systems in which male-male competition and probably also female mate choice are likely to be essential factors for individual reproductive success.

Heart rate variability and pre-competitive anxiety in BMX discipline.

Science.gov (United States)

Mateo, Manuel; Blasco-Lafarga, Cristina; Martínez-Navarro, Ignacio; Guzmán, José F; Zabala, Mikel

2012-01-01

Altered neural mechanisms implying autonomic functioning have been described related to anxiety. Pre-competitive stress may be considered as an anxiety-state associated with disorders (i.e. somatic and cognitive alterations, and self-confidence worsening) that severely impair sport performance, conditioning short-lasting strength-related disciplines like BMX. From the psychological perspective, coaches use questionnaires like CSAI-2R to identify these alterations. However, with the emergence of psycho-physiological and non-linear approaches, recent studies suggest that HRV analysis provides a non-invasive tool to assess them. Hence, our purpose was to analyze how BMX competition affects subjective perception of anxiety, and if this emotional alteration is reflected in HR dynamics, analyzed both linear and nonlinearly, exploring the evolution of this relationship in a 2-day competition. Eleven male athletes from the BMX Spanish National Team were assessed from baseline HRV the morning of a training session (rT) and on two successive days of competition (rC1 and rC2), repeating HRV recording with CSAI-2R 20 min prior to training (aT) and competition (pre-competitive: aC1 and aC2). Repeated measures MANOVA showed significant vagal slow-down responses in aC1 and aC2 comparing not only with aT, but also comparing with rT, rC1 and rC2, coinciding with significant greater scores for the somatic and cognitive anxiety (SA and CA) in aC1 and aC2 versus aT. Pearson analysis showed a large and positive correlation between α1 and SA in C1, and close to it between SampEn and CA in aC2; both were confirmed by Bland-Altman chart analysis. Our results confirm that HRV analysis provide a complementary tool to assess competitive pressure.

Effect of Resistance Tube Exercises on Kicking Accuracy, Vertical Jump and 40-Yard Technical Test in Competitive Football Players – An Experimental Study

Directory of Open Access Journals (Sweden)

Tirumala Alekhya

2014-09-01

Full Text Available Purpose. Kicking, jumping and agility are important skills in football. These activities require adequate lower limb strength, which can be enhanced with resistance training. The objective of the study was to evaluate the effect of resistance tube exercises on kicking accuracy, vertical jump performance and 40-yard technical test results in competitive football players. Methods. The study involved 23 competitive football players (11 males, 12 females aged from 18-20 years recruited from three different universities in Belgaum, Karnataka, India. Back heel kick accuracy, vertical jump height and 40-yard technical test time were evaluated before and after a 2-week resistance tube exercise program. Results. Significant improvements in post-intervention kicking accuracy were found when males and females were treated as a single group (p = 0.01. Vertical jump height also showed a highly significant post-intervention improvement in the males and for the combined group of males and females (p = 0.001. The 40-yard technical test values significantly improved in the females and in the combined results for males and females (p = 0.001. Conclusions. The two-week resistance tube exercise program was found to have an effect on kicking accuracy, vertical jump height and 40-yard technical test performance in competitive football players. Resistance tube exercises can thus be included as a component of a regular strength training program for such athletes.

Male mating rate is constrained by seminal fluid availability in bedbugs, Cimex lectularius.

Directory of Open Access Journals (Sweden)

Klaus Reinhardt

Full Text Available Sexual selection, differences in reproductive success between individuals, continues beyond acquiring a mating partner and affects ejaculate size and composition (sperm competition. Sperm and seminal fluid have very different roles in sperm competition but both components encompass production costs for the male. Theoretical models predict that males should spend ejaculate components prudently and differently for sperm and seminal fluid but empirical evidence for independent variation of sperm number and seminal fluid volume is scarce. It is also largely unknown how sperm and seminal fluid variation affect future mating rate. In bedbugs we developed a protocol to examine the role of seminal fluids in ejaculate allocation and its effect on future male mating rate. Using age-related changes in sperm and seminal fluid volume we estimated the lowest capacity at which mating activity started. We then showed that sexually active males allocate 12% of their sperm and 19% of their seminal fluid volume per mating and predicted that males would be depleted of seminal fluid but not of sperm. We tested (and confirmed this prediction empirically. Finally, the slightly faster replenishment of seminal fluid compared to sperm did not outweigh the faster decrease during mating. Our results suggest that male mating rate can be constrained by the availability of seminal fluids. Our protocol might be applicable to a range of other organisms. We discuss the idea that economic considerations in sexual conflict research might benefit from distinguishing between costs and benefits that are ejaculate dose-dependent and those that are frequency-dependent on the mating rate per se.

[Risk of injury in and adolescent and junior competitive karate].

Science.gov (United States)

Müller-Rath, R; Miltner, O; Mamarvar, M; Mumme, T

2005-12-01

Increasing professionalism in competitive karate has led to a specific injury pattern. The aim of our study was to investigate the injury pattern in junior competitive karate and to evaluate the prophylactic effect of fist padding. During the 4 (th) Junior World Championships of the World Karate Confederation (WKC) 2004 235 karate fights were observed and injury-related data were recorded. Fist padding was used in 183 fights, 52 fights were carried out without. In 22 % of all fights we saw an injury. Most of them were mild injuries of the head and face: 32 bruises of the face (13 with epistaxis), 7 facial lacerations and 3 concussions (mild brain injury). 14 fights were stopped due to an injury. Only in the category male 18 - 20 years a higher rate of injuries was seen without fist padding (shobu ippon) compared to shobu sanbon (with fist padding). The injury pattern of junior competitive karate is comparable to senior karate. Fist padding does not generally reduce the incidence or severity of injuries.

Competition

NARCIS (Netherlands)

Bridoux, F.; Vodosek, M.; Den Hartog, D.N.; McNett, J.M.

2014-01-01

Competition traditionally refers to the actions that firms take in a product market to outperform rivals in attracting customers and generating revenues. Yet, competition extends beyond product markets to other arenas such as factor markets, where firms compete for resources, and the political

Temperature-specific competition between invasive mosquitofish and an endangered cyprinodontid fish.

Directory of Open Access Journals (Sweden)

Gerard Carmona-Catot

Full Text Available Condition-specific competition is widespread in nature. Species inhabiting heterogeneous environments tend to differ in competitive abilities depending on environmental stressors. Interactions between these factors can allow coexistence of competing species, which may be particularly important between invasive and native species. Here, we examine the effects of temperature on competitive interactions between invasive mosquitofish, Gambusia holbrooki, and an endemic Iberian toothcarp, Aphanius iberus. We compare the tendency to approach heterospecifics and food capture rates between these two species, and examine differences between sexes and species in aggressive interactions, at three different temperatures (19, 24 and 29°C in three laboratory experiments. Mosquitofish exhibit much more aggression than toothcarp. We show that mosquitofish have the capacity to competitively displace toothcarp through interference competition and this outcome is more likely at higher temperatures. We also show a reversal in the competitive hierarchy through reduced food capture rate by mosquitofish at lower temperatures and suggest that these two types of competition may act synergistically to deprive toothcarp of food at higher temperatures. Males of both species carry out more overtly aggressive acts than females, which is probably related to the marked sexual dimorphism and associated mating systems of these two species. Mosquitofish may thus impact heavily on toothcarp, and competition from mosquitofish, especially in warmer summer months, may lead to changes in abundance of the native species and displacement to non-preferred habitats. Globally increasing temperatures mean that highly invasive, warm-water mosquitofish may be able to colonize environments from which they are currently excluded through reduced physiological tolerance to low temperatures. Research into the effects of temperature on interactions between native and invasive species is thus of

Competition in Japan

OpenAIRE

Michael E. Porter; Mariko Sakakibara

2004-01-01

This article examines competition in Japan and its link to postwar economic prosperity. While Japan's industrial structure and competition policy seem to indicate that competition in Japan has been less intense, the empirical evidence does not support this conclusion. The sectors in which competition was restricted prove to be those where Japan was not internationally successful. In the internationally successful sectors, internal competition in Japan was invariably fierce. While the level of...

Competitive bidding in Medicare: who benefits from competition?

Science.gov (United States)

Song, Zirui; Landrum, Mary Beth; Chernew, Michael E

2012-09-01

To conduct the first empirical study of competitive bidding in Medicare. We analyzed 2006-2010 Medicare Advantage data from the Centers for Medicare and Medicaid Services using longitudinal models adjusted for market and plan characteristics. A $1 increase in Medicare's payment to health maintenance organization (HMO) plans led to a $0.49 (P service plans included, higher Medicare payments increased bids less ($0.33 per dollar), suggesting more competition among these latter plans. As a market-based alternative to cost control through administrative pricing, competitive bidding relies on private insurance plans proposing prices they are willing to accept for insuring a beneficiary. However, competition is imperfect in the Medicare bidding market. As much as half of every dollar in increased plan payment went to higher bids rather than to beneficiaries. While having more insurers in a market lowered bids, the design of any bidding system for Medicare should recognize this shortcoming of competition.

Competitive Priorities and Competitive Advantage in Jordanian Manufacturing

OpenAIRE

Awwad, Abdulkareem S.; Al Khattab, Adel A.; Anchor, J.R

2013-01-01

The purpose of this research was to explore and predict the relationship between the competitive priorities (quality, cost, flexibility and delivery) and the competitive advantage of firms in the Jordanian Industrial Sector. A population of 88 Jordanian manufacturing firms, registered on the Amman Stock Exchange, was targeted using a cross-sectional survey employing a questionnaire method of data collection. The results of the data analysis indicate a significant relationship between competit...

Male sexual polymorphism, alternative reproductive tactics, and androgens in combtooth blennies (pisces: blenniidae).

Science.gov (United States)

Oliveira, R F; Canario, A V; Grober, M S

2001-09-01

In species in which intense intermale competition for the access to females is present males of lower competitive ability may adopt alternative reproductive tactics (ART) to get access to mates. These ART translate in many cases into male sexual polymorphism, with individuals following distinctly different tactics. Usually two alternative male morphs can be recognized in species with ART: (1) bourgeois males that compete for access to mates invest in typically male behaviors, such as building elaborated nests or displaying ornaments; and (2) parasitic males that take advantage of the success of the bourgeois males in attracting females and attempt "sneaker" fertilizations (e.g., sneaker and satellite males). In combtooth blennies (Blenniidae) the co-occurrence of ART and male sexual polymorphism has been described for two temperate species: the peacock blenny, Salaria pavo, and the Azorean rock-pool blenny, Parablennius sanguinolentus parvicornis. Interestingly, while in the peacock blenny the alternative male morph adopts a sneaker tactic, in the rock-pool blenny parasitic males act as satellites to nest-holder males. Thus, this variation in the ART expressed in these two closely related species allows for a comparative study of the proximate and ultimate factors affecting the expression of the two ART. In this article we summarize the available information on androgen levels in bourgeois and parasitic males of natural populations of the two species and of recent studies on the effect of exogenous administration of androgens on tactic switching in parasitic males of the two species. The information is discussed within the frame of the relative plasticity hypothesis, which predicts that plastic alternative morphs should show differences in hormone levels and that the administration of sex steroids should be effective in promoting the switch from the parasitic to bourgeois tactic. The evidence is only partly consistent with this hypothesis. Alternatively, a social

The effects of competition and implicit power motive on men's testosterone, emotion recognition, and aggression.

Science.gov (United States)

Vongas, John G; Al Hajj, Raghid

2017-06-01

A contribution to a special issue on Hormones and Human Competition. We investigated the effects of competition on men's testosterone levels and assessed whether androgen reactivity was associated with subsequent emotion recognition and reactive and proactive aggression. We also explored whether personalized power (p Power) moderated these relationships. In Study 1, 84 males competed on a number tracing task and interpreted emotions from facial expressions. In Study 2, 72 males competed on the same task and were assessed on proactive and reactive aggression. In both studies, contrary to the biosocial model of status (Mazur, 1985), winners' testosterone levels decreased significantly while losers' levels increased, albeit not significantly. Personalized power moderated the effect of competition outcome on testosterone change in both studies. Using the aggregate sample, we found that the effect of decreased testosterone levels among winners (compared to losers) was significant for individuals low in p Power but not for those with medium or high p Power. Testosterone change was positively related to emotion recognition, but unrelated to either aggression subtype. The testosterone-mediated relationship between winning and losing and emotion recognition was moderated by p Power. In addition, p Power moderated the direct (i.e., non-testosterone mediated) path between competition outcome and emotion recognition and both types of aggression: high p-Power winners were more accurate at deciphering others' emotions than high p-Power losers. Finally, among high p-Power men, winners aggressed more proactively than losers, whereas losers aggressed more reactively than winners. Collectively, these studies highlight the importance of implicit power motivation in modulating hormonal, cognitive, and behavioral outcomes arising from human competition. Copyright © 2017 Elsevier Inc. All rights reserved.

Relationships between triathlon performance and pacing strategy during the run in an international competition.

Science.gov (United States)

Le Meur, Yann; Bernard, Thierry; Dorel, Sylvain; Abbiss, Chris R; Honnorat, Gérard; Brisswalter, Jeanick; Hausswirth, Christophe

2011-06-01

The purpose of the present study was to examine relationships between athlete's pacing strategies and running performance during an international triathlon competition. Running split times for each of the 107 finishers of the 2009 European Triathlon Championships (42 females and 65 males) were determined with the use of a digital synchronized video analysis system. Five cameras were placed at various positions of the running circuit (4 laps of 2.42 km). Running speed and an index of running speed variability (IRSVrace) were subsequently calculated over each section or running split. Mean running speed over the first 1272 m of lap 1 was 0.76 km·h-1 (+4.4%) and 1.00 km·h-1 (+5.6%) faster than the mean running speed over the same section during the three last laps, for females and males, respectively (P international competitions, even if high levels of motivation and direct opponents lead them to adopt an aggressive strategy.

The Literature Review of a New Form of Competitiveness Called City Competitiveness

Directory of Open Access Journals (Sweden)

Osman EROĞLU

2014-06-01

Full Text Available With globalization, the rapid development of information technologies and the rapid changes in the economic structure, the country’s borders at a time increasingly depreciate and the importance of city competitiveness reveals. Although it is an ongoing debate around the world whether cities compete with each other, city competitiveness is a new form of competitiveness. Cities compete with each other to increase their competitiveness. City competitiveness is defined as having better values compared to other cities. In this study, a new form of competitiveness called city competitiveness is examined.

MEASURING SPORT-SPECIFIC PHYSICAL ABILITIES IN MALE GYMNASTS: THE MEN'S GYMNASTICS FUNCTIONAL MEASUREMENT TOOL

Science.gov (United States)

Kenyon, Lisa K.; Elliott, James M; Cheng, M. Samuel

2016-01-01

Purpose/Background Despite the availability of various field-tests for many competitive sports, a reliable and valid test specifically developed for use in men's gymnastics has not yet been developed. The Men's Gymnastics Functional Measurement Tool (MGFMT) was designed to assess sport-specific physical abilities in male competitive gymnasts. The purpose of this study was to develop the MGFMT by establishing a scoring system for individual test items and to initiate the process of establishing test-retest reliability and construct validity. Methods A total of 83 competitive male gymnasts ages 7-18 underwent testing using the MGFMT. Thirty of these subjects underwent re-testing one week later in order to assess test-retest reliability. Construct validity was assessed using a simple regression analysis between total MGFMT scores and the gymnasts’ USA-Gymnastics competitive level to calculate the coefficient of determination (r2). Test-retest reliability was analyzed using Model 1 Intraclass correlation coefficients (ICC). Statistical significance was set at the p<0.05 level. Results The relationship between total MGFMT scores and subjects’ current USA-Gymnastics competitive level was found to be good (r2 = 0.63). Reliability testing of the MGFMT composite test score showed excellent test-retest reliability over a one-week period (ICC = 0.97). Test-retest reliability of the individual component tests ranged from good to excellent (ICC = 0.75-0.97). Conclusions The results of this study provide initial support for the construct validity and test-retest reliability of the MGFMT. Level of Evidence Level 3 PMID:27999723

Sperm competition selects for sperm quantity and quality in the Australian Maluridae.

Science.gov (United States)

Rowe, Melissah; Pruett-Jones, Stephen

2011-01-25

When ejaculates from rival males compete for fertilization, there is strong selection for sperm traits that enhance fertilization success. Sperm quantity is one such trait, and numerous studies have demonstrated a positive association between sperm competition and both testes size and the number of sperm available for copulations. Sperm competition is also thought to favor increases in sperm quality and changes in testicular morphology that lead to increased sperm production. However, in contrast to sperm quantity, these hypotheses have received considerably less empirical support and remain somewhat controversial. In a comparative study using the Australian Maluridae (fairy-wrens, emu-wrens, grasswrens), we tested whether increasing levels of sperm competition were associated with increases in both sperm quantity and quality, as well as an increase in the relative amount of seminiferous tubule tissue contained within the testes. After controlling for phylogeny, we found positive associations between sperm competition and sperm numbers, both in sperm reserves and in ejaculate samples. Additionally, as sperm competition level increased, the proportion of testicular spermatogenic tissue also increased, suggesting that sperm competition selects for greater sperm production per unit of testicular tissue. Finally, we also found that sperm competition level was positively associated with multiple sperm quality traits, including the proportion of motile sperm in ejaculates and the proportion of both viable and morphologically normal sperm in sperm reserves. These results suggest multiple ejaculate traits, as well as aspects of testicular morphology, have evolved in response to sperm competition in the Australian Maluridae. Furthermore, our findings emphasize the importance of post-copulatory sexual selection as an evolutionary force shaping macroevolutionary differences in sperm phenotype.

Field Assessment of 3 Years of Release of sub-sterile males of Ectomyelois ceratoniae (Lepidoptera: Pyralidae)

International Nuclear Information System (INIS)

Jouda, Mediouni; Dhouibi, M.H.

2005-01-01

A weekly long-season release program was conduced in a pomegranate orchard during three years. Irradiation was done using a 60Co source with a dose rate of 46Gy/min. The gamma radiation substerilising dose adopted for this program was 400 Gy. The efficiency of these releases was investigated at the harvest. Releases of the sub-sterile male insects precede the beginning of the wild population activity. The monitoring of the wild pest population was accomplished using a series of Delta traps baited with the sexual pheromone. Traps were kept in the field the whole season. Trapping results and sampling data were used in order to study the insect population's dynamics. We studied reared irradiated male dispersion, their competitiveness into the field and attractiveness of irradiated virgin female. At the harvest, we determined the fruit infestation-rate both in the treated orchard and in the control. Irradiated male dispersion was studied using 24 delta traps. Six levels of male capture were chosen. These levels were 20, 40, 60, 80, 100 and 120 m from the point release. Results showed that irradiation at the substerilising dose 400 Gy don't affect the male's ability of flying. Moreover, we observed that irradiated males are able to reach traps placed at 120 m from the released point. The maximum of insect capture is obtained with levels 40m and 80m. This result is very important and has a practical implementation. In fact, in order to get a homogeneous distribution into the field, distances between 40m and 80 m should be kept between the release-lines. Male's competitiveness was carried out into two cages. The cages were installed on two middle size trees and were covered with a mosquito-net. A delta trap was hung into each cage. The trap was baited with two virgin non- irradiated females. Four ratios of irradiated to normal males were investigated: 1:1, 2.5:1, 5:1 and 10:1. Experimentations were replicated five times for each ratio. Results showed that substeriles

Effects of Gamma Radiation on Reproduction and Mating Competitiveness in the Cotton Leaf Worm Spodoptera Littoralis (Boisd.)

International Nuclear Information System (INIS)

Sallam, H. A.; Alm El-Din, M. M. S.; El-Dessouki, S. A.; El-Awady, S. M.

2004-01-01

Full-grown male pupae of the cotton leaf worm Spodoptera littoralis (Boisd.) were gamma irradiated with low doses of 100, 125, 150 Gy. The fecundity of normal females crossed with treated males decreased with the increase of the dose given to males. The reduction in egg hatch was significant at all tested doses. The percentage of mated females was not clearly affected. However, the reduction observed in either percentage of inseminated female or the average number of spermatophores per mated female was increased by increasing the dose to males. Males irradiated by low doses of 125 and 150 Gy were fully competitive against untreated males for mating with normal females. Increasing the ratio of irradiated males to normal males from 1:1 to 5:1 decreased the rate of egg viability among P 1 and their successive filial generations. (Authors)

Central dopamine D2 receptors regulate growth-hormone-dependent body growth and pheromone signaling to conspecific males.

Science.gov (United States)

Noaín, Daniela; Pérez-Millán, M Inés; Bello, Estefanía P; Luque, Guillermina M; Casas Cordero, Rodrigo; Gelman, Diego M; Peper, Marcela; Tornadu, Isabel García; Low, Malcolm J; Becú-Villalobos, Damasia; Rubinstein, Marcelo

2013-03-27

Competition between adult males for limited resources such as food and receptive females is shaped by the male pattern of pituitary growth hormone (GH) secretion that determines body size and the production of urinary pheromones involved in male-to-male aggression. In the brain, dopamine (DA) provides incentive salience to stimuli that predict the availability of food and sexual partners. Although the importance of the GH axis and central DA neurotransmission in social dominance and fitness is clearly appreciated, the two systems have always been studied unconnectedly. Here we conducted a cell-specific genetic dissection study in conditional mutant mice that selectively lack DA D2 receptors (D2R) from pituitary lactotropes (lacDrd2KO) or neurons (neuroDrd2KO). Whereas lacDrd2KO mice developed a normal GH axis, neuroDrd2KO mice displayed fewer somatotropes; reduced hypothalamic Ghrh expression, pituitary GH content, and serum IGF-I levels; and exhibited reduced body size and weight. As a consequence of a GH axis deficit, neuroDrd2KO adult males excreted low levels of major urinary proteins and their urine failed to promote aggression and territorial behavior in control male challengers, in contrast to the urine taken from control adult males. These findings reveal that central D2Rs mediate a neuroendocrine-exocrine cascade that controls the maturation of the GH axis and downstream signals that are critical for fitness, social dominance, and competition between adult males.

Productive and Unproductive Competition

DEFF Research Database (Denmark)

Guerra, Alice; Luppi, Barbara; Parisi, Francesco

Conventional theories of competition classify contests as being either “productive,” when the competitive efforts generate a surplus for society, or “unproductive,” when competition generates no social surplus and merely distributes already existing resources. These two discrete categories of com...... and socially optimal levels of competition in the full range of intermediate cases, as well as in the extremum cases of destructive and super-productive competition.......Conventional theories of competition classify contests as being either “productive,” when the competitive efforts generate a surplus for society, or “unproductive,” when competition generates no social surplus and merely distributes already existing resources. These two discrete categories...... of competition create a division of real-world situations into analytical categories that fails to recognize the entire spectrum of competitive activities. Taking the existing models of productive and unproductive competition as benchmark idealizations, this paper explores the relationship between the privately...

THE PATTERN OF IPPON APPEARANCE IN MAJOR JUDO COMPETITIONS IN THE PERIOD 2008 - 2009

Directory of Open Access Journals (Sweden)

Rosu Daniel

2010-08-01

Full Text Available AbstractPurpose: Determining the trends manifested in the current competition judo, in relation to the incidence of the Ippon.Methods: 26 major judo competitions during 2008-2009 are analysed in terms of the incidence of Ippon, based on gender, age, weight category and the importance of competition.Results: Ippon appears, on average, at 55.52% of the meetings of males and 51.95% of the meetings of the females. Independent Samples T-test shows that these averages are significantly different at p = 0.033.In men's competitions Ippon represents an increasing share to the extent that increases the weightcategory: 52.34% in light categories, 57.15% in medium categories, 59.98% in heavy categories. One Way Anova shows that these differences are significant at p = 0.002. The lowest frequency of Ippon occurs in light female categories: 48.90%. The Independent Samples T-test shows that between this value and the frequency of53.91% corresponding to the occurrence of Ippon in the middle categories, there are also statistically significantdifferences at p = 0.025.Conclusions: in Judo competitions Ippon occurs following a normal statistical law, yet, some variables such as sex and the weight category can significantly influence the frequency of its occurrence. The age and the importance of the competition do not significantly influence the frequency of Ippon in the competition.

Salivary hormones and anxiety in winners and losers of an international judo competition.

Science.gov (United States)

Papacosta, Elena; Nassis, George P; Gleeson, Michael

2016-01-01

The purpose of this study was to investigate the responses of salivary hormones and salivary secretory immunoglobulin A (SIgA) and anxiety in winners and losers during an international judo competition. Twenty-three trained, male, national-level judo athletes provided three saliva samples during a competition day: morning, in anticipation of competition after an overnight fast, mid-competition, and post-competition within 15 min post-fight for determination of salivary cortisol, salivary testosterone, salivary testosterone/cortisol ratio, SIgA absolute concentrations, SIgA secretion rate and saliva flow rate. The competitive state anxiety inventory questionnaire was completed by the athletes (n = 12) after the first saliva collection for determination of somatic anxiety, cognitive anxiety and self-confidence. Winners were considered 1-3 ranking place (n = 12) and losers (n = 11) below third place in each weight category. Winners presented higher anticipatory salivary cortisol concentrations (p = 0.03) and a lower mid-competition salivary testosterone/cortisol ratio (p = 0.003) compared with losers with no differences for salivary testosterone. Winners tended to have higher SIgA secretion rates (p = 0.07) and higher saliva flow rates (p = 0.009) at mid-competition. Higher levels of cognitive anxiety (p = 0.02) were observed in the winners, without differences according to the outcome in somatic anxiety and self-confidence. The results suggest that winners experienced higher levels of physiological arousal and better psychological preparedness in the morning, and as the competition progressed, the winners were able to control their stress response better.

The crunch factor's role in golf-related low back pain.

Science.gov (United States)

Cole, Michael H; Grimshaw, Paul N

2014-05-01

The golf swing exposes the spine to complex torsional, compressive, and shearing loads that increase a player's risk of injury. The crunch factor (CF) has been described as a measure to evaluate the risk of low back injuries in golfers and is based on the notion that lateral flexion and axial trunk rotation jointly contribute to spinal degeneration. However, few studies have evaluated the appropriateness of this measure in golfers with low back pain (LBP). To objectively examine the usefulness of the CF as a measure for assessing the risk of low back injury in golfers. Field-based research using a cross-sectional design. This research used three-dimensional motion analysis to assess the golf swings of 12 golfers with LBP and 15 asymptomatic controls. Three-dimensional kinematics were derived using Vicon Motus, and the CF was calculated as the instantaneous product of axial trunk rotation velocity and lateral trunk flexion angle. Maximum CFs and their timings were not significantly different between the symptomatic and asymptomatic groups. Furthermore, for those golfers who produced higher CFs (irrespective of the group), the increased magnitude could not be attributed to an increased axial angular trunk velocity or lateral flexion angle, but rather to a concomitant increase in both of these variables. The findings suggested that although the fundamental concepts that underpin the CF seem sensible, this measure does not appear to be sensitive enough to distinguish golfers with LBP from the asymptomatic players. Copyright © 2014 Elsevier Inc. All rights reserved.

Athletes Perception of Coaches’ Leadership Style and Tendency to Cooperate among Competitive Teams

Directory of Open Access Journals (Sweden)

João Lameiras

Full Text Available Abstract The purpose of the present study was to discover the relationships between athletes’ perceived coach behaviors during training and competition, and cooperation via Bayesian network (BN. Professional male atheletes from several team sports (N = 158 completed the Portuguese version of the Leadership Scale for Sport and the Questionário de Cooperação Desportiva to assess cooperation. Relationships were identified between perceived coach behaviors in training and competition environments and with athletes tendency to cooperate. Overall, the findings support that in sports, coaching behaviours congruent with the athletes’ individual needs and adapted to the situational demands may promote prosocial behaviour.

Mixing, entropy and competition

International Nuclear Information System (INIS)

Klimenko, A Y

2012-01-01

Non-traditional thermodynamics, applied to random behaviour associated with turbulence, mixing and competition, is reviewed and analysed. Competitive mixing represents a general framework for the study of generic properties of competitive systems and can be used to model a wide class of non-equilibrium phenomena ranging from turbulent premixed flames and invasion waves to complex competitive systems. We demonstrate consistency of the general principles of competition with thermodynamic description, review and analyse the related entropy concepts and introduce the corresponding competitive H-theorem. A competitive system can be characterized by a thermodynamic quantity—competitive potential—which determines the likely direction of evolution of the system. Contested resources tend to move between systems from lower to higher values of the competitive potential. There is, however, an important difference between conventional thermodynamics and competitive thermodynamics. While conventional thermodynamics is constrained by its zeroth law and is fundamentally transitive, the transitivity of competitive thermodynamics depends on the transitivity of the competition rules. Intransitivities are common in the real world and are responsible for complex behaviour in competitive systems. This work follows ideas and methods that have originated from the analysis of turbulent combustion, but reviews a much broader scope of issues linked to mixing and competition, including thermodynamic characterization of complex competitive systems with self-organization. The approach presented here is interdisciplinary and is addressed to the general educated readers, whereas the mathematical details can be found in the appendices. (comment)

Seasonal variation in male alternative reproductive tactics.

Science.gov (United States)

Monroe, M J; Amundsen, T; Utne-Palm, A C; Mobley, K B

2016-12-01

Genetic parentage analyses reveal considerable diversity in alternative reproductive behaviours (e.g. sneaking) in many taxa. However, little is known about whether these behaviours vary seasonally and between populations. Here, we investigate seasonal variation in male reproductive behaviours in a population of two-spotted gobies (Gobiusculus flavescens) in Norway. Male two-spotted gobies guard nests, attract females and care for fertilized eggs. We collected clutches and nest-guarding males early and late in the breeding season in artificial nests and used microsatellite markers to reconstruct parentage from a subset of offspring from each nest. We hypothesized that mating, reproductive success and sneaking should be more prevalent early in the breeding season when competition for mates among males is predicted to be higher. However, parentage analyses revealed similar values of mating, reproductive success and high frequencies of successful sneaking early (30% of nests) and late (27% of nests) in the season. We also found that multiple females with eggs in the same nest were fertilized by one or more sneaker males, indicating that some males in this population engage in a satellite strategy. We contrast our results to previous work that demonstrates low levels of cuckoldry in a population in Sweden. Our results demonstrate marked stability in both the genetic mating system and male alternative reproductive tactics over the breeding season. However, sneaking rates may vary geographically within a species, likely due to local selection influencing ecological factors encountered at different locations. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Dancing in the Dark: Competition over the "Meaning of Competition"

OpenAIRE

Metcalfe John Stanley

2009-01-01

Competing concepts of competition provide a sharp divide between theories of economic order and theories of economic transformation. The shift from competition as a state of affairs and competition as a creative process provides the divergence of perspective that is the topic of this paper. We link the Smith Marshall approach of rivalry and open competition to the more modern evolutionary view based on variation cum selection perspectives on innovation and the adaptive role of market processe...

Competitive intelligence: An instrument to enhance South Africa’s competitiveness

Directory of Open Access Journals (Sweden)

Wilma Viviers

2014-10-01

Full Text Available The case for Competitive Intelligence (CI as an instrument that can enhance the competitiveness of South African companies and South Africa as a country is strong. Various global competitive rankings measurements have indicated over a number of years the areas in which competitiveness is lacking. Moreover, these rankings have indicated that South Africa has failed to improve its position year on year. The fact that the world is becoming increasingly competitive for South African entities is undisputed. Coupled with a fluctuating exchange rate and the country’s geographical proximity, this poses unique challenges facing South African managers who have to deal with various regulations and legislative matters. In order to create and sustain an effective knowledge economy and to enhance global competitiveness, South Africa however has to put appropriate strategies/measures in place to stimulate, encourage and grow knowledge practices. Competitive Intelligence (CI as a means of making more sense of the competitive business environment and to identify opportunities and risks in time to act upon can be effectively used as a means to enhance competitiveness. Valuable lessons from successful CI practices in the business sector and government can be learnt from elsewhere in the world. CI should be investigated and adapted for South Africa’s business environment. It is therefore the aim of this article to first attempt to describe the role of CI in enhancing competitiveness, specifically in South Africa and secondly, to stimulate thought on how to secure momentum in enhancing CI as an academic field by developing relevant CI courses as well as demonstrating the value of CI to companies in South Africa through research and collaboration between academics and the private and public sectors.

COMPETITIVENESS THROUGH INFORMATION

Directory of Open Access Journals (Sweden)

Raluca Daniela RIZEA

2013-10-01

Full Text Available Intelligence competitiveness has already started to build its road in the company’s long term strategies. Nonetheless, business executives continue to look for ways to apply information technology strategically to their businesses. Using information managers manage to communicate, to convey their knowledge about markets, competitors, products, services and operations. Even if data and information are all over there are few amounts of managers that realize the importance of them to the success of the business. This article will review competitive forces and competitive information systems strategies for gaining competitive advantages, explain concepts of value chain, value co-opetition (competition and cooperation, and discuss innovation strategy. Co-opetition is a strategy whereby companies cooperate and compete at the same time with their competitors, complementors (i.e. hardware and software businesses, customers, suppliers. The article discuss an important dimension of information system, identifies competitive advantages and enhancing competitive strategies thought information systems.

A prospective epidemiological study of injury incidence and injury patterns in a Hong Kong male professional football league during the competitive season

Directory of Open Access Journals (Sweden)

Justin Wai-Yuk Lee

2014-10-01

Full Text Available The aim of this study was to investigate the match and training injury incidence, injury patterns and severity, and their monthly variation in a Hong Kong male professional football league. The study design was a prospective cohort study. Seven teams in the Hong Kong Football Association first division league and 152 players from 10 professional teams participated in this study. On a weekly basis throughout the 9-month season, time-loss injuries and individual exposure were collected from injury recorders team visits. Operational injury definitions and procedures followed the recommendations of a football consensus. The overall injury incidence was 7.4 injuries/1000 player hours and 296 injuries were recorded. The relative risk of match injury was 17 times greater than the risk of training injury [relative ratio (RR, 17.3; 95% confidence injury (CI, 11.6–25.7; p < 0.001]. Ankle sprain was the most common injury type (16.2% of all injuries and 52% of these injuries were recurrent. Thigh strain was the second most common injury type with 82% of the injuries involving the hamstring muscle and 80% of hamstring strains were noncontact injuries. During the competitive season, the relative risk of injury was highest in October (RR, 6.8; 95% CI, 6.7–6.9; p < 0.001 and February (RR, 4.7; 95% CI, 4.3–5.2; p < 0.001. This highlighted that Hong Kong professional football has a high match injury incidence. The relative risk of injury was highest at the beginning of the competitive season. A prospective multicentre epidemiological study is warranted to examine regional differences in injury risks. Coaches, players, health professionals, and researchers should join their efforts to investigate the effect on injury incidence and injury pattern associated with the duration and content of the preseason period, and the number of friendly matches held during preseason.

Sex and aggregation pheromone transport after methyl eugenol consumption in male Bactrocera papayae

International Nuclear Information System (INIS)

Hee, Alvin K.W.; Tan, K.H.

2000-01-01

Amongst at least 52 sibling species complexes in the Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), B. papayae (formerly Mal B) Drew and Hancock (Drew and Hancock 1994) is beginning to emerge as an economically important insect pest which poses a severe threat to the fruit cultivation in both subtropical and tropical countries. In Malaysia, B. papayae is one of the most damaging pests which infests many commercially grown fruits (Tan and Lee 1982). Like the Oriental fruit fly and its sibling species complex, B. carambolae Drew and Hancock, B. papayae is also strongly attracted to, and compulsively feeds on, methyl eugenol (ME) (Tan 1993). Chemical analyses revealed that in B. papayae males, ME is converted to phenylpropanoids which are then selectively accumulated in the rectal gland. Of the three major volatile substances, 2-allyl-4,5-dimethoyphenol (allyl-DMP) was detected in higher quantities relative to the trans-coniferyl alcohol (4-(3-hydroxy-E-propenyl)-2-methoxyphenol) (CF) and cis-3,4-dimethoxycinnamyl alcohol (cis-DMC) (Nishida et al. 1988a, 1988b). Behavioural studies have also shown that allyl-DMP and CF function as male sex and aggregation pheromone in B. papayae (Tan and Nishida 1996, Hee and Tan 1998). Allyl-DMP was found to be the most attractive compound and cis-DMC the least attractive to the males (Tan 1996). Consumption of ME enhances the mating competitiveness of males. This is demonstrated by the strong attraction of females to conspecific ME-fed males in wind tunnel experiments (Hee and Tan 1998). In male-male mating competition for virgin females, males that fed on ME performed significantly better (Shelly and Dewire 1994, Tan and Nishida 1996). Thus it appears that ME-fed males produced signals that were more attractive. However, the characterisation and understanding of the functions of these phenylpropanoids have not been accompanied by studies of their physiological mode of transport in male flies. The current

Putting competition into perspective

International Nuclear Information System (INIS)

Jones, L. III.

1993-01-01

This paper examines the current level of competition in the electric industry in the context of the history of the industry and the development of electric markets in other counties. The topics of the paper include competition in the history of the American electric industry, the current state of competition, the competitive situation in Texas, competition in other electric markets, and competitive changes in the US market

Toward Value Co-Creation: Increasing Women’s Presence in Management Positions through Competition against a Set Target

Directory of Open Access Journals (Sweden)

Irene Comeig

2017-10-01

Full Text Available Despite empirical evidence that women’s presence in management positions is a source of value co-creation for firms, these positions are still male-dominated. Some evidence from experimental economics suggests that one reason for this imbalance is that women shy away from competition. However, most of these studies have focused on competition systems that pit individuals against each other. We present an economic laboratory experiment that compares competition against others with competition against a set target. The crucial difference is that whereas the former involves competing against opponents, the latter does not. Our results show that significantly more women are willing to compete against a set target than against others. Furthermore, there is no reduction in men’s participation and no general efficiency reduction. Our findings suggest that firms that aim at value co-creation and sustainability through a gender-neutral promotion mechanism should introduce competition against a set target and reduce competition against others. This paper contributes to dispelling stereotypes about women’s reluctance to compete.

Characteristics of muscle dysmorphia in male football, weight training, and competitive natural and non-natural bodybuilding samples.

Science.gov (United States)

Baghurst, Timothy; Lirgg, Cathy

2009-06-01

The purpose of this study was to identify differences in traits associated with muscle dysmorphia between collegiate football players (n=66), weight trainers for physique (n=115), competitive non-natural bodybuilders (n=47), and competitive natural bodybuilders (n=65). All participants completed demographic questionnaires in addition to the Muscle Dysmorphia Inventory (Rhea, Lantz, & Cornelius, 2004). Results revealed a significant main effect for group, and post hoc tests found that the non-natural bodybuilding group did not score significantly higher than the natural bodybuilding group on any subscale except for Pharmacological Use. Both the non-natural and natural bodybuilding groups scored significantly higher than those that weight trained for physique on the Dietary Behavior and Supplement Use subscales. The collegiate football players scored lowest on all subscales of the Muscle Dysmorphia Inventory except for Physique Protection where they scored highest. Findings are discussed with future research expounded.

Multinationals and Institutional Competitiveness

DEFF Research Database (Denmark)

Hull Kristensen, Peer; Morgan, Glenn

This article discusses how institutional competitiveness and multinationals are mutually enriching concepts. Seen from the perspective of Multinationals, institutional competitiveness becomes expressed at two levels. At the level of corporate HQs institutional competitiveness proves itself...... competitiveness of Liberal Market Economies and Coordinated Markets Economies under the current competitive regime....

Male and female breeding strategies in a cooperative primate.

Science.gov (United States)

Yamamoto, Maria Emilia; Araujo, Arrilton; Arruda, Maria de Fatima; Lima, Ana Karinne Moreira; Siqueira, Jose de Oliveira; Hattori, Wallisen Tadashi

2014-11-01

Marmosets are cooperative breeders organized as extended family groups, but breeding is generally restricted to a single pair. Breeding competition is fierce in female marmosets; males, on the other hand, show low levels of intragroup aggression. We investigated male and female breeding strategies and the resulting reproductive output in 9 wild groups. Reproductive output, tenure of breeding animals, identification of the breeding system, breeding position replacements, migration and infanticide were recorded; also, we recorded grooming and aggression. Replacement of the breeding male or female was observed on nine occasions. On four occasions, the son of the breeding male inherited the breeding post, but we never observed inheritance of a breeding post by a daughter. Mostly, females attained a breeding post by immigrating to a group that had a breeding vacancy. Our results showed that Callithrix jacchus males and females use different strategies to attain a breeding position and maintain it for as long as possible. These strategies prolong the tenure of the breeding position, which is the best way to produce a large number of offspring. This article is part of a Special Issue entitled: Neotropical Behaviour. Copyright © 2014 Elsevier B.V. All rights reserved.

Selective attention in peacocks during assessment of rival males.

Science.gov (United States)

Yorzinski, Jessica L; Patricelli, Gail L; Bykau, Siarhei; Platt, Michael L

2017-03-15

Males in many species compete intensely for access to females. In order to minimize costly interactions, they can assess their rivals' competitive abilities by evaluating traits and behaviors. We know little about how males selectively direct their attention to make these assessments. Using Indian peafowl ( Pavo cristatus ) as a model system, we examined how males visually assess their competitors by continuously tracking the gaze of freely moving peacocks during the mating season. When assessing rivals, peacocks selectively gazed toward the lower display regions of their rivals, including the lower eyespot and fishtail feathers, dense feathers, body and wings. Their attention was modified based on the rivals' behavior such that they spent more time looking at rivals when rivals were shaking their wings and moving. The results indicate that peacocks selectively allocate their attention during rival assessment. The gaze patterns of males assessing rivals were largely similar to those of females evaluating mates, suggesting that some male traits serve a dual function in both intra- and intersexual selection. However, males spent more time than females looking at the upper eyespots and this could indicate that the upper eyespots function more in close-up rival assessment than mate choice. © 2017. Published by The Company of Biologists Ltd.

Studies on the control of the Mediterranean fruit fly, Ceratitis capitata Wiedemann, using gamma radiation. Part of a coordinated programme on fruit fly eradication or control by the sterile-male technique

International Nuclear Information System (INIS)

Wakid, A.M.

1975-01-01

Wheat bran and molasses were used in larval medium of the Mediterranean fruit fly, Ceratitis capitata instead of the dried carrot previously used in Egypt. The new larval medium consists of wheat bran, molasses, yeast, sodium benzoate, hydrochloric acid and tap water. This substitution reduced the production costs of pupae in our laboratories. The adults produced from this medium showed almost similar emergence, fecundity, fertility and longevity as those produced from carrot medium. New large larval breeding cabinet was constructed which improved the larval production and can help in mass production purposes. Large oviposition cage was also used instead of the small ones previously used in Egypt. Six field cages made of wire screen, glass and wood were constructed to conduct semi field experiments on the competitiveness of the irradiated males. Competitiveness decreased with increased dose, doses of 5-9 krad led to almost similar reduction in egg hatch. Ratios of 13:13:1:1 and 2:2:1:1 (treated males : treated females : untreated males : untreated females) were tested in the field cages. There was no clear indication of whether male competitiveness of a particular dose was affected by the ratio of irradiated males to untreated males and females. Generally competitiveness of the irradiated males decreased by time. Flight range of the irradiated (9 krad) tagged flies was found to be 700 m within an orchard. Flies released in an orchard did not reach another orchard 700 m far from the release point

Cooperative and Competitive Contextual Effects on Social Cognitive and Empathic Neural Responses

Directory of Open Access Journals (Sweden)

Minhye Lee

2018-06-01

Full Text Available We aimed to differentiate the neural responses to cooperative and competitive contexts, which are the two of the most important social contexts in human society. Healthy male college students were asked to complete a Tetris-like task requiring mental rotation skills under individual, cooperative, and competitive contexts in an fMRI scanner. While the participants completed the task, pictures of others experiencing pain evoking emotional empathy randomly appeared to capture contextual effects on empathic neural responses. Behavioral results indicated that, in the presence of cooperation, participants solved the tasks more accurately and quickly than what they did when in the presence of competition. The fMRI results revealed activations in the dorsolateral prefrontal cortex (dlPFC and dorsomedial prefrontal cortex (dmPFC related to executive functions and theory of mind when participants performed the task under both cooperative and competitive contexts, whereas no activation of such areas was observed in the individual context. Cooperation condition exhibited stronger neural responses in the ventromedial prefrontal cortex (vmPFC and dmPFC than competition condition. Competition condition, however, showed marginal neural responses in the cerebellum and anterior insular cortex (AIC. The two social contexts involved stronger empathic neural responses to other’s pain than the individual context, but no substantial differences between cooperation and competition were present. Regions of interest analyses revealed that individual’s trait empathy modulated the neural activity in the state empathy network, the AIC, and the dorsal anterior cingulate cortex (dACC depending on the social context. These results suggest that cooperation improves task performance and activates neural responses associated with reward and mentalizing. Furthermore, the interaction between trait- and state-empathy was explored by correlation analyses between individual�