Causes of male sexual trait divergence in introduced populations of guppies

Males from different populations of the same species often differ in their sexually selected traits. Variation in sexually selected traits can be attributed to sexual selection if phenotypic divergence matches the direction of sexual selection gradients among populations. However, phenotypic divergence of sexually selected traits may also be influenced by other factors, such as natural selection and genetic constraints. Here, we document differences in male sexual traits among six introduced Australian populations of guppies and untangle the forces driving divergence in these sexually selected traits. Using an experimental approach, we found that male size, area of orange coloration, number of sperm per ejaculate and linear sexual selection gradients for male traits differed among populations. Within populations, a large mismatch between the direction of selection and male traits suggests that constraints may be important in preventing male traits from evolving in the direction of selection. Among populations, however, variation in sexual selection explained more than half of the differences in trait variation, suggesting that, despite within-population constraints, sexual selection has contributed to population divergence of male traits. Differences in sexual traits were also associated with predation risk and neutral genetic distance. Our study highlights the importance of sexual selection in trait divergence in introduced populations, despite the presence of constraining factors such as predation risk and evolutionary history.

The long term effects of sports concussion on retired Australian football players: a study using Transranial Magnetic Stimulation

This study investigated corticomotor excitability and inhibition, cognitive functioning, and fine motor dexterity in retired elite and amateur Australian football (AF) players who had sustained concussions during their playing careers. Forty male AF players who played at the elite level (n=20; mean age 49.7±5.7 years) or amateur level (n=20; mean age 48.4±6.9 years), and had sustained on average 3.2 concussions 21.9 years previously, were compared with 20 healthy age-matched male controls (mean age 47.56±6.85 years). All participants completed assessments of fine dexterity, visuomotor reaction time, spatial working memory (SWM), and associative learning (AL). Transcranial magnetic stimulation (TMS) was used to measure corticospinal excitability: stimulus-response (SR) curves and motor evoked potential (MEP) 125% of active motor threshold (aMT); and intracortical inhibition: cortical silent period (cSP), short-interval intracortical inhibition (SICI), and long-interval intracortical inhibition (LICI). Healthy participants performed better in dexterity (p=0.003), reaction (p=0.003), and movement time (p=0.037) than did both AF groups. Differences between AF groups were found in AL (p=0.027) and SWM (p=0.024). TMS measures revealed that both AF groups showed reduced cSP duration at 125% aMT (p>0.001) and differences in SR curves (p>0.001) than did healthy controls. Similarly, SICI (p=0.012) and LICI (p=0.009) were reduced in both AF groups compared with controls. Regression analyses revealed a significant contribution to differences in motor outcomes with the three measures of intracortical inhibition. The measures of inhibition differed, however, in terms of which performance measure they had a significant and unique predictive relationship with, reflecting the variety of participant concussion injuries. This study is the first to demonstrate differences in motor control and intracortical inhibition in AF players who had sustained concussions during their playing career two decades previously.

Alcohol, masculinity, honour and male barroom aggression in an Australian sample

Introduction and Aims
The link between alcohol and men's aggression is well established, although growing evidence also points to individual and learned social factors. The aim of the present study was to investigate the relationships between male alcohol-related aggression (MARA) among young Australian men and heavy episodic drinking, trait aggression, masculinity, concerns about social honour and expected positive consequences of MARA.

Design and Methods
The total sample comprised 170 men aged 18–25 years who completed an online questionnaire exploring beliefs and attitudes towards MARA.

Results
Those who reported heavy episodic drinking were more likely to be involved in an incident of MARA. In addition, those who were involved in MARA had higher levels of trait aggression, concern for social honour and expected positive consequences of aggression in bars than did those without such involvement. The relationship between socially constructed masculinity factors (a combined variable reflecting masculinity, social honour and expected positive consequences) and MARA was mediated by heavy episodic drinking. Social honour accounted for almost all of the predictive power of masculinity factors. Heavy episodic drinking and trait aggression remained significant predictors of MARA in a multivariate model.

Discussion and Conclusions
The findings from the current study may assist in developing preventative techniques for young men which target masculinity concerns and the consequences of participating in MARA.

Breaker Morant's split personality: Australian male identity through opposing eyes

Breaker Morant was born in a workhouse to a widow. In Australia, he attempted to overcome the stigma associated with the British workhouse system by creating an alternative identity as a gentleman, a soldier and an Australian poet, but he died as a criminal convicted for murdering captured Boers.

Patterns and perceptions of physical activity and sedentary time in male transport drivers working in regional Australia

 Abstract

Objective: To objectively measure physical activity (PA) patterns and sedentary time, and explore perceptions of workplace PA opportunities in regional male transport workers.

Methods: A multi-method study involving 28 drivers (52.4±9.69years) working at a bus company in South-East Queensland, Australia. PA was measured using accelerometers (n=23) to determine the proportion of time spent in sedentary (<150 cpm), light (151–2,689 cpm) and moderate+ (≥2,690 cpm) intensity categories. Paired sample t-tests were used to evaluate differences between categories on a workday/off-workday (n=16), and during work/non-work time (n=15). Interviews were conducted with 28 drivers and six managers to explore perceptions and ideas relating to workplace PA opportunities.

Results: Sedentary time was significantly higher on off-work (64% of wear time) than work (52%) days (p<0.05), while the opposite was the case for light intensity time (off-workday=33%; workday=44%; p<0.05). On workdays, sedentary time was significantly lower when employees were working (44%) than when not working (60%; p<0.05). No significant differences were found for time spent in moderate+ PA. Driver perceptions indicated that PA opportunities (walking club and corporate gym membership) were being adopted by some drivers. However, at this depot, perceived health issues and organisational barriers (shift work and irregular driving routines), tended to preclude some drivers from engaging with these opportunities.

Conclusions: Findings contest the notion that a sedentary occupation such as driving necessitates an inactive work environment.

Implications: This research informs ongoing intervention efforts to target inactive drivers who are struggling to take advantage of existing workplace-related PA opportunities.

Restrained eaters consume more food only if they are impulsive and male

This study utilised the preload paradigm to evaluate whether dietary restraint, impulsivity, or their interaction significantly predicts heightened food consumption among male and/or female participants. Following a high calorie preload, 79 participants aged 18 to 40 (53 females and 26 males) completed a deceptive taste test and questionnaires measuring restraint and impulsivity levels. A series of hierarchical regressions were run, controlling for self-rated hunger levels. A significant negative association between level of restraint and food consumption post-preload was found for males, but this relationship was not significant for female participants. The hypothesis that impulsivity would directly predict heightened food consumption was not supported for either gender. However, impulsivity was found to significantly moderate the relationship between restraint and food intake in the male sample, but not the female, providing partial support for this hypothesis. Potential reasons for this gender-specific interaction effect of impulsivity and restraint for food consumption are discussed. More broadly, present findings highlight the need for further consideration of the role of impulsivity in undermining food intake of restrained eaters. Future research should also consider how preload effects may differ across gender.