Sexual segregation in western grey kangaroos: testing alternative evolutionary hypotheses

In sexually dimorphic ungulates, sexual segregation is hypothesized to have evolved because of sex-specific differences in body size and/or reproductive strategies. We tested these alternative hypotheses in kangaroos, which are ecological analogues of ungulates. Kangaroos exhibit a wide range of body sizes, particularly among mature males, and so the effects of body size and sex can be distinguished. We tested predictions derived from these hypotheses by comparing the distribution of three sex–sex size classes of western grey kangaroos Macropus fuliginosus, in different habitats, and the composition of groups of kangaroos, across seasons. In accordance with the predation risk-reproductive strategy hypothesis, during the non-breeding season, females, which were more susceptible to predation than larger males, and were accompanied by vulnerable young-at-foot, were over-represented in secure habitats. Large males, which were essentially immune to predation, occurred more often than expected in nutrient-rich habitat, and small males, which faced competing demands of predator avoidance and feeding, were intermediate between females and large males in their distribution across habitats. During the breeding season, females continued to be over-represented in secure habitats when their newly emerged pouch young were most vulnerable to predation. All males occupied these same habitats to maximize their chances of securing mates. Consistent with the social hypotheses, groups composed of individuals of the same sex, irrespective of body size, were over-represented in the population during the non-breeding season, while during the breeding season all males sought females so that mixed-sex groups predominated. These results indicate that body size and reproductive strategies are both important, yet independent, factors influencing segregation in western grey kangaroos.

Effects of tv time and other sedentary pursuits

Television (TV) viewing is the dominant recreational pastime at all ages, especially for children and adolescents. Many studies have shown that higher TV viewing hours are associated with higher body mass index (BMI), lower levels of fitness and higher blood cholesterol levels. Although the effect size estimated from observational studies is small (with TV viewing explaining very little of the variance in BMI), the results of intervention studies show large effect sizes. The potential mediators of the effect of higher TV viewing on higher BMI include less time for physical activity, reduced resting metabolic rate (for which there is little supporting evidence) and increased energy intake (from more eating while watching TV and a greater exposure to marketing of energy dense foods). Electronic games may have an effect on unhealthy weight gain, but are less related to increased energy intake and their usage is relatively new, making effect size difficult to determine. Thus, TV viewing does not explain much of the differences in body size between individuals or the rise in obesity over time, perhaps because of the uniformly high, but relatively stable, TV viewing hours. Reducing TV viewing hours is a difficult prospect because potential actions, such as social marketing and education, are likely to be relatively weak interventions, although the evidence would suggest that, if viewing could be reduced, it could have a significant impact on reducing obesity prevalence. Regulations to reduce the heavy marketing of energy dense foods and beverages on TV may be the most effective public health measure available to minimize the impact of TV viewing on unhealthy weight gain.

Mate choice in zebra finches: does corticosterone play a role?

The importance of stress as a factor in influencing life history strategies has received considerable attention in recent years, because it appears to have a substantial impact on an individual's behaviour and physiology. Birds respond to environmental and social stressors by the production of corticosterone, a glucocorticoid hormone released by the adrenal gland. In this experiment, we tested whether female zebra finches preferred males selected to produce low or high peak levels of circulating plasma corticosterone. Plasma corticosterone and testosterone levels of the males were recorded, as were morphometric measurements and perch activity. Spectrophotometric measurements were also taken from several putatively sexually selected regions of the males. The females preferred the males from the low corticosterone lines to the high corticosterone males. In addition to, and consistent with this effect, females preferred males with the lowest corticosterone titres. Male activity, testosterone level, body size and mass had no effect on female preference. Leg and beak brightness were important, however, as were the brightness and chromaticity of the male cheek patch. These results are discussed in relation to contemporary hypotheses in sexual selection, particularly in the context of stress-mediated signalling.

Challenges of negotiating obesity-related findings with African migrants in Australia : lessons learnt from the African migrant capacity building and performance appraisal project

Aim: To document sub-Saharan African migrants' and teachers' reaction to and acceptance of findings from African Migrant Capacity Building and Performance Appraisal initiative, and to examine the implications for any community-based obesity prevention program.

Methods: Two community forums were organised to discuss the research findings: one with 45 African community leaders from various African communities in Melbourne; and the other with 17 primary and secondary teachers from English Language Schools and Centres across Victoria. The dissemination focused on highlighting the rapid weight gain and obesity risks observed among African migrant children.

Results: Sub-Saharan African migrants' reaction to the findings was that of pride and satisfaction with large body size, seeing it as a job well done, reflecting their perceptions that obesity is not a disease. In addition, they highlighted the intergenerational conflict related to body size ideals between parents and teenage offspring, with the latter preferring model-like Australian body sizes.

Conclusion: Further research is required to examine the association between shifting preferences in body ideals and obesity among traditional communities, such as sub-Saharan African migrants. The understanding of how changes in body image perceptions may influence eating and exercise behaviours among sub-Saharan African migrants would assist in the development of obesity-related preventive interventional programs for this at-risk population.

Anthropometric risk factors for patellar tendon injury among volleyball players

Objective: Abnormal imaging in the patellar tendon reveals pathology that is often associated with knee pain. Anthropometric measures of body size and mass, such as height, weight and waist-to-hip ratio (WHR), have been individually associated with abnormal imaging. The aim of this study was to investigate the anthropometric factors that have the strongest relationship with abnormal imaging in volleyball players.

Methods: Height, weight, body mass index (BMI), waist girth, hip girth and WHR were measured in a cohort of 113 competitive volleyball players (73 men, 40 women). The univariate (ANOVA) and multivariable (discriminant function analysis) association between abnormal imaging and these anthropometric factors were investigated.

Results: No significant association was found in the female volleyball players. A significant univariate association was observed between abnormal imaging and heavier weight, greater BMI, larger waist and hip girth and larger WHR in the male volleyball players. Waist girth was the only factor that retained this association in a multivariable model (p<0.05).

Conclusions: Men with a waist girth greater than 83 cm seem to be at greater risk of developing patellar tendon pathology. There may be both mechanical and biochemical reasons for this increased risk.

Sex-specific developmental plasticity in response to yolk corticosterone in an oviparous lizard

Corticosterone exposure during prenatal development as a result of maternal upregulation of circulating hormone levels has been shown to have effects on offspring development in mammals. Corticosterone has also been documented in egg yolk in oviparous vertebrates, but the extent to which this influences phenotypic development is less studied. We show that maternal corticosterone is transferred to egg yolk in an oviparous lizard (the mallee dragon, Ctenophorus fordi Storr), with significant variation among clutches in hormone levels. Experimental elevation of yolk corticosterone did not affect hatching success, incubation period or offspring sex ratio. However, corticosterone did have a sex-specific effect on skeletal growth during embryonic development. Male embryos exposed to relatively high levels of corticosterone were smaller on average than control males at hatching whereas females from hormone-treated eggs were larger on average than control females. The data thus suggest that males are not just more sensitive to the detrimental effects of corticosterone but rather that the sexes may have opposite responses to corticosterone during development. Positive selection on body size at hatching for both sexes in this species further suggests that increased corticosterone in egg yolk may have sex-specific fitness consequences, with potential implications for sex allocation and the evolution of hormone-mediated maternal effects.

Waist circumference, waist-hip ratio and BMI and their correlation with cardiovascular risk factors in Australian adults

Objectives. To compare body mass index (BMI), waist circumference and waist–hip ratio (WHR) as indices of obesity and assess the respective associations with type 2 diabetes, hypertension and dyslipidaemia.

Design and setting. A national sample of 11 247 Australians aged ≥25 years was examined in 2000 in a cross-sectional survey.

Main outcome measures. The examination included a fasting blood sample, standard 2-h 75-g oral glucose tolerance test, blood pressure measurements and questionnaires to assess treatment for dyslipidaemia and hypertension. BMI, waist circumference and WHR were measured to assess overweight and obesity.

Results. The prevalence of obesity amongst Australian adults defined by BMI, waist circumference and WHR was 20.8, 30.5 and 15.8% respectively. The unadjusted odds ratio for the fourth vs. first quartile of each obesity measurement showed that WHR had the strongest relationship with type 2 diabetes, dyslipidaemia (women only) and hypertension. Following adjustment for age, however, there was little difference between the three measures of obesity, with the possible exceptions of hypertension in women, where BMI had a stronger association, and dyslipidaemia in women and type 2 diabetes in men, where WHR was marginally superior.

Conclusions. Waist circumference, BMI and WHR identified different proportions of the population, as measured by both prevalence of obesity and cardiovascular disease (CVD) risk factors. Whilst WHR had the strongest correlations with CVD risk factors before adjustment for age, the three obesity measures performed similarly after adjustment for age. Given the difficulty of using age-adjusted associations in the clinical setting, these results suggest that given appropriate cut-off points, WHR is the most useful measure of obesity to use to identify individuals with CVD risk factors.

Differences in height explain gender differences in the response to the oral glucose tolerance test - the AusDiab study

Aim To determine the extent of gender-related differences in the prevalence of glucose intolerance for the Australian population and whether body size may explain such differences.

Methods Cross-sectional data were collected from a national cohort of 11 247 Australians aged ≥ 25 years. Glucose tolerance status was assessed according to both fasting plasma glucose (FPG) and 2-h plasma glucose (2hPG) levels following a 75-g oral glucose tolerance test (OGTT). Anthropometric and glycated haemoglobin measurements were also made.

Results Undiagnosed diabetes and non-diabetic glucose abnormalities were more prevalent among men than women when based only on the FPG results (diabetes: men 2.2%, women 1.6%, P = 0.02; impaired fasting glycaemia: men 12.3%, women 6.6%, P < 0.001). In contrast 16.0% of women and 13.0% of men had a 2hPG abnormality (either diabetes or impaired glucose tolerance, P = 0.14). Women had a mean FPG 0.3 mmol/l lower than men (P < 0.001), but 2hPG 0.3 mmol/l higher (P = 0.002) and FPG-2hPG increment 0.5 mmol/l greater (P < 0.001). The gender difference in mean 2hPG and FPG-2hPG increment disappeared following adjustment for height. For both genders, those in the shortest height quartile had 2hPG levels 0.5 mmol/l higher than the tallest quartile, but height showed almost no relationship with the FPG.

Conclusions Men and women had different glycaemic profiles; women had higher mean 2hPG levels, despite lower fasting levels. It appeared that the higher 2hPG levels for women related to lesser height and may be a consequence of using a fixed glucose load in the OGTT, irrespective of body size.

The Pacific OPIC Project (Obesity Prevention In Communities) : action plans and interventions

Background: The Pacific OPIC Project (Obesity Prevention In Communities) includes whole-of-community intervention programs in four countries (Fiji, Tonga, New Zealand, Australia) aimed at reducing the prevalence of overweight and  obesity in youth.

Development of Action Plans: At each intervention site, preliminary interviews  were conducted with youth to identify the potential socio-cultural barriers and  facilitators to healthy eating and regular physical activity in order to attain and sustain a healthy body size. This and other information was presented at a 2-day workshop with community stakeholders, including youth. The participants then prioritised the components for a draft action plan which was later consolidated through further community consultation.

Action Plan objectives: Each action plan had two overall aims: to build  community capacity and to promote healthy weight. The first three objectives in each action plan were on capacity building, social marketing messages, and evaluation. Next were a set of four to five behavioural objectives with associated strategies involving programs, events, social marketing and environmental  change. Lastly, each site had one or two innovative or developmental objectives.

Progress: Interventions began in all sites from 2005, with the action plans guiding implementation priorities. The initial behavioural objective for targeting in Fiji was eating regular breakfast and meals throughout the day, for Tonga it was physical activity, and for Australia and New Zealand it was increasing water consumption and decreasing consumption of sweet drinks.

Conclusions: The action plans have provided the basis for community engagement in the project, the guide to the implementation of activities and the template for the evaluation plan.

Ecological and life-history factors influencing the evolution of maternal antibody allocation : a phylogenetic comparison

Maternally derived yolk antibodies provide neonates with immune protection in early life at negligible cost to mothers. However, developmental effects on the neonate's future immunity are potentially costly and thus could limit yolk antibody deposition. The benefits to neonatal immunity must be balanced against costs, which may depend on neonate vulnerability to pathogens, developmental trajectories and the immunological strategies best suited to a species' pace of life. We measured yolk antibodies and life-history features of 23 species of small Neotropical birds and assessed the evidence for each of several hypotheses for life history and ecological effects on the evolution of yolk antibody levels. Developmental period and yolk antibodies are negatively related, which possibly reflect the importance of humoral immune priming through antigen exposure, and selection to avoid autoimmunity, in species with a slower pace of life. There is also a strong relationship between body size and yolk antibody concentration, suggesting that larger species are architecturally equipped to produce and transfer higher concentrations of antibodies. These results suggest that developmental effects of maternally derived antibodies, such as imprinting effects on B-cell diversity or autoimmune effects, are important and deserve more consideration in future research.

Patterns of physical activity for adolescent girls in Fiji and Tonga

Behavioural patterns are determined in part by sociocultural factors such as values, expected behaviours and sociopolitical organisation. This paper presents the patterns of physical activity reported by Tongan and Fijian females aged 12-18 years and possible explanations for these patterns. The paper draws on interviews conducted in a wider study of adolescents patterns of eating, physical activity and body size in Tonga, Fiji, New Zealand and Australia. The study examined sociocultural factors that could promote or protect against obesity from the perspective of adolescents in order to develop culturally-appropriate strategies for healthy lifestyles. Twenty four indigenous Fijian and 24 Tongan females aged 12-18 years were interviewed by females who were fluent in participants first languages. Researchers from Australia, Tonga and Fiji analysed the data separately and then together in order to capture cultural nuances and enhance cultural validity. This analysis revealed similarities and differences in both cultural groups. Limitations to physical activity identified by Tongan and Fijian girls included the time spent in household chores and parental restrictions.Fijian girls also identified concern about personal safety as a constraint. These findings are examined in relation to sociocultural factors that appear to limit opportunities for young females to be physically active.

The Pacific OPIC project (Obesity Prevention in Communities) - objectives and designs

Background: Evidence on how to reduce the increasing prevalence of youth obesity is urgently needed in many countries.The Pacific OPIC Project (Obesity Prevention In Communities) is a series of linked studies in four countries (Fiji, Tonga, New Zealand, Australia) which is designed to address this important problem.
Objectives: The studies aim to: 1) determine the overall impact of comprehensive, community-based intervention programs on overweight/obesity prevalence in youth; 2) assess the feasibility of the specific intervention components and their impacts on eating and physical activity patterns; 3) understand the socio-cultural factors that promote obesity and how they can be infl uenced; 4) identify the effects of food-related policies in Fiji and Tonga and how they might be changed; 5) estimate the overall burden of childhood obesity (including loss of quality of life); 6) estimate the costs (and cost-effectiveness) of the intervention programs, and; 7) increase the capacity for obesity prevention research and action in Pacific populations.
Design: The community studies use quasi-experimental designs with impact and outcome assessments being measured in over 14,000 youth across the intervention and control communities in the four sites. The multi-strategy, multi-setting interventions will run for 3 years before fi nal follow up data are collected in 2008. The interventions are being informed by socio-cultural studies that will determine the family and societal infl uences on food intake, physical activity and body size perception.
Progress and conclusions: Baseline studies have been completed and interventions are underway. Despite the many challenges in implementing and evaluating community-based interventions, especially in the Pacifi c, the OPIC Project will provide rich evidence about what works and what does not work for obesity prevention in youth from European and Pacific backgrounds.

Quantum music

The purpose of the research was to examine the human response system to aid the development of improvised music and mulit-media artwork. It was found that there are many predictable responses to external stimuli within the human body and that music and performance would benefit if this knowledge was applied.

Factors influencing reported food intake

A study was conducted to investigate the possible influence of body size and composition, errors in portion size estimation, level of satisfaction with body size and degree of dietary restraint on the level of reported food intake obtained using both a food frequency questionnaire and weighed food record. The findings suggest that in dietary studies based on weighed food records, 'weight consciousness', as determined using a measure of dietary restraint, could be more important than influence of body size in determining the level of reported intake.

Adenosine receptor agonists as potential therapeutic agents

Adenosine is a naturally occurring compound within the human body. It is known to exert a wide range of physiological effects. A range of compounds which elict a similar response to adenosine in vivo have been synthesised and evaluated as cardioprotective agents.