Male Female Group Research Articles

The key role of lamb presence in affecting flight response in Sardinian mouflon (Ovis orientalis musimon)

Observations of the flight response in mammals are commonly used to test the behavioural response to predation risk. Such a response is likely to be stronger in more sensitive individuals such as females, and females with offspring in particular, as well as during such periods as the birth season. From August 2005 to July 2006 we recorded the flight distances of different mouflon group types in a natural population in Sardinia. The comparison of the flight distances of the groups (n groups=375, n mouflons=1303) provided evidence for the key role of lamb presence. Female groups with lambs fled at greater distances than male groups and female groups without lambs. This difference was linked to the females' priority to secure the survival of their offspring. Indeed, the uniformity of the flight distances of males and non-reproductive females was in contrast to the general expectations regarding ungulate species. In fact, smaller females were expected to be more sensitive to predation risk than larger males. The absence of major differences is probably due to the low sexual dimorphism of mouflon. Flight distances were shorter during the rut than during the lambing season, arguably because during the mating less time and energies were available for anti-predator behaviour. However, during the rut females with lambs still fled at greater distances than females without lambs, arguably because mothers took it as a priority to protect their parental investment rather then to find a potential mate.

線状に滞在するカップルに求められる他者との距離

The purpose of this research is to examine the effects of interpersonal distance from others on the emotions and behavior of couples staying along by the sea. An investigation to observe the behavior of actual couples, and an experiment to assess the opinions of the couples were carried out in the early evening and the nighttime. In the results, the following points were demonstrated. ・ Couples tended to stay together longer and more closely when the distance from others was large. This tendency appeared more strongly in the nighttime than in the early evening. Couples expected to maintain a private space of at least 2 to 3 meters on both sides. ・ Women tended to notice the proximity of others more in the early evening. This tendency was stronger when the others were groups of men rather than mixed male-female groups. ・ Generally in the evening, couples' behavior was not affected by the attributes of others. In some cases, couples moved even closer together when another couple approached than when no-one was near.

Grouping piglets by sex at weaning reduces aggressive behaviour

The aim of this work was to reduce aggressive behaviour when piglets are grouped at weaning. The experiment assessed whether it is better to group piglets by sex at weaning or to mix them in male–female groups. Large White piglets were weaned at 28 days and assigned to 4 conditions, with 6 groups of animals/condition: (L-MF) 4 males and 4 females reared together from birth, (A-M) 8 unfamiliar male piglets, (A-F) 8 unfamiliar female piglets, and (A-MF) 4 male and 4 female unfamiliar piglets. All groups were videotaped on days 28, 29, 31, 39 and 46 for 2 h. Aggressive interactions were quantified and scratches on each piglet were counted on days 27, 29 and 33. Feed consumption and piglets’ weights were quantified from birth to day 63. On days 27, 29 and 33, urine was collected between 7:00 and 8:00 for measurements of catecholamines and glucocorticoids. Fighting durations were longer in A-MF than in L-MF and both single-sex groups on day 29 ( p < 0.05), and than in L-MF and A-F on day 28 ( p < 0.05). Durations did not differ between L-MF and single-sex conditions. Fights were more severe and there were more scratches in the A-MF condition compared to the other three conditions. Conditions A-M and A-F did not differ. In the mixed-sex group, fights between two males tended to be more severe than fights between two females ( p < 0.1) or than mixed-sex fights ( p < 0.1); males initiated more aggression than females ( p < 0.05). The presence of females seemed to increase males’ aggressive behaviour in mixed-sex groups. Growth and food intake were slightly affected by treatments but were similar between conditions on day 63. A rise of noradrenaline levels was observed after weaning for the unfamiliar piglets ( p < 0.001). However, the grouping criterion by sex did not lead to changes in neuroendocrine activity. Grouping piglets by sex reduces aggressive behaviour at weaning and this should be taken into account in pig farms in order to improve animal welfare.

The effect of heritability on Bolton tooth-size discrepancy

The purpose of this study was to determine the possible effect of genetic factors on Bolton tooth-size discrepancy. Subjects who applied for orthodontic treatment and their siblings (106 females and 78 males) were included in the study. The ages of the subjects ranged from 13 to 21 years. The siblings were grouped according to gender: male-male (24 pairs), female-female (38 pairs) and male-female (30 pairs). Mesio-distal tooth size was measured using a pair of dividers with fine tips, and Bolton anterior and overall ratios were calculated. The effect of heritability on Bolton ratios was studied by means of Harvey's mixed model least-squared and maximum likelihood computer program (LSMLMW) model type II. Statistical analysis showed that heritability was effective on Bolton tooth-size discrepancy in all groups except the male-female group. Siblings of the same gender showed high heritability for anterior and overall ratios, but no statistically significant difference was observed in the siblings of different gender.

Avaliação da dieta habitual de crianças e adolescentes com sobrepeso e obesidade

OBJETIVO: Investigar a dieta habitual de crianças e adolescentes com sobrepeso e obesidade, atendidas no Ambulatório de Endocrinologia Pediátrica da Universidade Federal do Rio Grande do Norte. MÉTODOS: Foram constituídos os grupos sobrepeso (n=15), obesidade (n=30) e controle (n=21) de ambos os sexos. A avaliação antropométrica foi realizada utilizando-se o Índice de Massa Corporal e a dieta habitual por registro alimentar e analisada pelo Virtual Nutri 1.0. RESULTADOS: As calorias totais e fibra alimentar do grupo obesidade feminino foram inferiores e diferente significativamente do controle masculino. Observou-se elevada ingestão de proteínas nos grupos sobrepeso masculino e obesidade feminino. Uma correlação negativa foi verificada entre o Índice de Massa Corporal e a fibra alimentar no grupo obesidade feminino. CONCLUSÃO: As crianças e adolescentes com sobrepeso e obesidade da amostra estudada, possuem uma dieta habitual inadequada, com elevada ingestão de proteínas e lipídios e deficiente em fibras.

Men With Breast Cancer Have Better Disease-Specific Survival Than Women

Male breast cancer patients have better disease-specific survival than carefully matched female breast cancer patients. Retrospective study. University hospital. Each man in the breast cancer database at Columbia-Presbyterian Medical Center (New York, NY) between the years 1980 and 1998 was matched with a woman. Matching was done based on age and date of diagnosis, stage, and primary histologic findings. The overall survivals and disease-specific survivals of the male breast cancer group and female breast cancer group were compared. Fifty-three male patients were matched with an equal number of female breast cancer patients. The Kaplan-Meier curves demonstrated that there was no significant difference in overall survival. The 5- and 10-year survivals for women were 0.77 and 0.51, and for men 0.77 and 0.56. When the Kaplan-Meier curves for breast cancer-specific survival were compared, however, there was a significant difference in the 5- and 10-year survivals (P = .05, log-rank test). For women, the 5- and 10-year disease-specific survival was 0.81 and 0.7, respectively, while for men it was 0.9 and 0.9, respectively. In a Cox regression analysis for time to death from breast cancer, stage was the only predictor of death that approached significance (P = .06). While the overall survivals were equivalent, male breast cancer patients had significantly better disease-specific survivals compared with their female counterparts. Male patients were 4 times more likely to die of other causes than their breast cancer.

Comparison of different initiation protocols in the resistant hepatocyte model

Several models in rat liver have been developed to study multistage carcinogenesis, including the Solt-Farber resistant hepatocyte model. In this model, initiation consists of either a necrogenic dose of a hepatocarcinogen or a non-necrogenic dose in conjunction with partial hepatectomy (PH). As an alternative to PH, we investigated two different procedures: fasting for 96 h followed by refeeding, or the use of one-day-old neonates. Male Fisher 344 rats were injected p.o. with diethylnitrosamine (DEN) (0, 20, or 100 mg/kg) 24 h after refeeding or PH (controls received DEN alone with no proliferative stimulus). For the neonatal group, male and female Fisher 344 rats were treated with DEN (0 or 20 mg/kg, i.p.) at one day of age. All initiated animals were treated at the same age (11 weeks) with the following selection agents: three daily doses of 2-acetylaminofluorene (AAF) (30 mg/kg), followed by a single dose of carbon tetrachloride (2 ml/kg), followed by three additional daily treatments of AAF (30 mg/kg). Rats were euthanized 2 weeks after the last AAF injection. The PH, neonatal male, and neonatal female groups receiving DEN developed more gamma-glutamyl transpeptidase (GGT)-positive foci per cubic centimeter and foci per liver as compared to untreated rats receiving the same proliferative stimulus, whereas the fasting/refeeding group and the group receiving no proliferative stimulus did not. All DEN-treated groups receiving one of the proliferative stimuli had more foci per cubic centimeter than the DEN-treated group receiving no proliferative stimulus. The volume fractions of GGT-positive foci in the PH/DEN and neonatal male/DEN groups were higher than those of both the DEN-treated group receiving no proliferative stimulus and the groups receiving the same proliferative stimulus without DEN. In neonatal females-receiving DEN, the volume fraction was not different from either neonatal females not receiving DEN or DEN-treated rats receiving no proliferative stimulus. The volume fraction in the fasting/refeeding group was increased when DEN was administered at 100 mg/kg but not at 20 mg/kg. We conclude that the use of male neonatal rats can replace the PH in the Solt-Farber protocol. Fasting/refeeding was also effective at increasing the volume fraction of GGT-positive foci, but only at the higher dose of DEN.

Bone mineral density in elderly Chinese: effects of age, sex, weight, height, and body mass index.

To enhance our understanding of the relationship between bone mineral density (BMD) and sex, age, body mass index (BMI), weight, and height in elderly Chinese, we studied 258 males aged 50-80 years (mean +/- SD, 62.9 +/- 6.2 years) and 193 females aged 46-75 years (59.0 +/- 6.2 years). We measured BMD at the lumbar spine (L1-L4), hip (femoral neck, trochanter, and intertrochanter), and Ward's triangle. A significant difference of age-adjusted BMD among male-female groups (P < 0.0001) was observed. After adjustment for weight, the magnitude of the sex difference in BMD was reduced at all studied skeletal sites; for example, the difference declined from 18.3% to 5.5% at the spine. There were significant differences in BMD among age-stratified groups at all the sites in both sexes (P < 0.01), except for spine BMD in males (P = 0.928). Regression analysis suggested that, with aging, greater differences of BMD distribution exist in elderly females than in males. Weight accounted for the greatest proportion of age-adjusted BMD variation (e.g., at femoral neck, R(2) = 0.17 in males) among four variables: weight, height, BMI, and a principal component formed from weight and height. These results suggested that weight decreased the sex difference in BMD in elderly Chinese. Patterns of age-related BMD distribution and BMD change among different age groups differed between the sexes and between the studied sites. Weight accounted for most of the effect of two correlated variables (weight and height) on BMD in our sample.

Food and water consumption in assessment of acute oral toxicity of HEPALIP FORTE in rats

Body weight variations during toxicological testing can be one of the indicators of the test substance toxic effects. Data on food and water consumption are true indicators of the rate of growth of experimental animals (Stevens & Gallo, 1989). Daily recording of the food and water consumption was done during the acute toxicity testing of HEPALIP FORTE. The study was performed on Wistar rats. The active component of HEPALIP FORTE is EPL substance--essential phospholipids, a natural substance present in every living cell. Essential phospholipids in combination with vitamins have been used in the treatment of liver diseases, dyslipoproteinaemias and intoxications accompanied with liver failure. Statistical analysis of the body weight variations was performed separately, for males and females. The analysis failed to show any significant difference between the groups. There was a significant difference in water consumption between the male group 2M and female groups 3F and 2F in comparison with control groups. Statistical analysis of the variations of food consumption showed a significant difference in all male groups in comparison with control groups, and only in the 3F female group in comparison with a control group. Considering the absence of lethality and the lack of significant influence of the test substance on animal body weights, we concluded that the test substance was not acutely toxic in rats, if applied orally, in single doses of 300 mg/kg, 500 mg/kg and 1000 mg/kg. Significant differences found in food and water consumption suggest a need of their during the future chronic toxicity testing.

Organochlorines in the free-ranging Hawaiian monk seal ( Monachus schauinslandi) from French Frigate Shoals, North Pacific Ocean

The Hawaiian monk seal ( Monachus schauinslandi) is an endangered species found only in the Hawaiian Island chain. The largest subpopulation, at French Frigate Shoals, has been in decline since 1989. In order to assess organochlorine (OC) levels in the Hawaiian monk seals, whole blood and blubber samples were collected in 1999 from 46 free-ranging Hawaiian monk seals at French Frigate Shoals, and were analyzed for eight dioxin-like polychlorinated biphenyls (PCBs) as well as six other PCB congeners, DDT and DDT metabolites. Average levels of the total PCBs in blood samples from adult male, juvenile and reproductive female groups were 4800, 4000 and 3000 ng/g lipid wt., respectively, whereas 3200, 1300 and 1200 ng/g, respectively, in blubber from the three corresponding groups. p, p′-DDE was the only DDT detected in blubber samples, and no DDTs were detected in blood samples. Concentrations of the total PCBs in adult males were significantly higher than the levels measured in either reproductive females or juveniles. There were significant correlations between age and blubber p, p′-DDE, estimated mass and total blood PCBs or blubber p, p′-DDE, and body condition and total blood PCBs. Although it is clear that the Hawaiian monk seal has been exposed to OCs, it is unclear what biological effects, if any, these xenobiotics may have on the animals.

Social relationships and social structure of the mound-building mouse ( Mus spicilegus ) in intraspecific cage groups

The social relationships of Mus spicilegus were studied in intraspecific cage groups for a month during the reproductive period to clarify the role of intraspecific aggressiveness in shaping social structure and in reproduction. The mound-building mice were captured from a wild population in northern Bulgaria. A total of 13 groups, 5 male, 4 female, and 4 male–female groups, were tested. Each group consisted of five unfamiliar adults. The experiments were carried out in 100×100-cm glass cages. The patterns of behaviour and the dominant–subordinate structure within each group were investigated. A dominance index for every individual in the group was calculated. During the period of establishment of the hierarchical structure in the groups a high level of aggressiveness was registered among individuals. About half of the subdominants and subordinates were found dead, with or without obvious marks of injury. Male–male interactions were more aggressive compared to these of females. Dominant–subordinate relationships between individuals of the same sex were observed in the mixed groups. A link between dominance rank and reproduction was established. The dominant male and the dominant female formed a pair and started to breed. Based on these findings it can be assumed that the aggressiveness of M. spicilegus is an adaptation to its life in the fields, where dominance is likely to be an essential factor in individual reproductive success. It is likely that the successful rearing of offspring in natural populations, which are exposed to strong biotic and abiotic impact, necessitates the existence of monogamous relationships.

Evidence for dramatically increased bone turnover in spontaneously hypertensive rats

Using the 3H-tetracycline model, whole-body skeletal bone resorption was compared among male and female spontaneously hypertensive (SHR) rats and normotensive Wistar Kyoto (WKy) and Sprague-Dawley (SD) rats. Immature animals undergoing rapid skeletal growth and bone sculpting showed a tendency for decreased indices of skeletal resorption in females compared with males. By 24 weeks of age, the indices of the rate of resorption and extent of metabolically reactive bone in male rats were decreased a mean of 68% and 74%, respectively, compared with values obtained at 8 weeks. By comparison, values for 24-week-old females decreased only 26% and 56%, respectively, evidence for a significantly elevated level of resorptive activity in mature females compared with males in each of the 3 rat strains. Within-sex comparisons of 24-week-old animals indicated that bone resorptive activity was similar between normotensive male and normotensive female groups. By comparison, the resorptive activity was significantly increased in both male and female hypertensive rats compared with normotensive controls. This condition was exaggerated in female hypertensive rats, which showed an approximate 81% and 44% increase in the indices of rate of resorption and extent of metabolically reactive bone compared with normotensive WKy controls. The results indicate a marked sexual dichotomy in the decline of skeletal bone resorptive activity following maturation and slowing of skeletal growth. They further indicate a significant elevation of whole skeleton bone turnover in male SHR rats and dramatically increased bone turnover in female SHR rats.

Group founding and breeding structure in the subsocial spider stegodyphus lineatus (Eresidae)

Co-operative behaviour may evolve by enhancing the genetic similarity of group members. Increased group similarity is thought to be the basis for the 'subsocial route' of social evolution in the spider family Eresidae. Two processes may promote the similarity of individuals within populations or breeding groups, namely philopatry in stable environments and founder events in a stochastic environment. We show that both processes led to genetic differentiation within and among populations of the subsocial spider Stegodyphus lineatus. Within populations we distinguished between the genetic structure caused by random mating and philopatry in old breeding groups and that caused by newly founded groups consisting of sibs. Such sib-groups suggest that new breeding groups are established primarily by single females. The different gene coancestries among breeding groups resulted in high variances among single-locus data. The results imply that sex-specific dispersal behaviour (random male mating-dispersal or female group founding) had different impacts on the population structure. This type of population structure, where within-population philopatry and founder events may lead to differential proliferation of breeding groups, is very similar to that presumed for social spiders, and is also one that could provide the conditions for interdemic selection.

Creativity and Sex Composition: An Experimental Illustration

An experiment is reported in which the effect of sex composition on the creativity of brainstorming groups is investigated. It was hypothesized that mixed sex groups would be more creative than either homogeneous male or homogeneous female groups. Fifteen groups, consisting of four members each two males and two females; four females; four males, took part in the experiment. The experimenter noted the number of ideas generated per person, as well as the different associations with these ideas, and the number of different angles from which the task was approached. After finishing the exercise, subjects completed a post-experimental questionnaire. Results show that heterogeneous groups produced more creative outcomes than homogeneous groups. Also, they rated their process more positively. These findings are discussed in relation to the type of task used, and in relation to the general notion that heterogeneous groups are likely to produce more creative outcomes yet suffer from more process problems as compared to homogeneous groups.

Social Organisation in the Rufous Bettong, Aepyprymnus Rufescens

This study examined association patterns and reproductive behaviour in a sexually monomorphic potoroid marsupial, the rufous bettong, Aepyprymnus rufescens. A total of 29 individuals was marked, and 22 of these were observed regularly over a six-month period; these 22 individuals accounted for almost all the animals using the study area. Rufous bettongs at this site were predominantly solitary (71% of sightings were of single animals) and groups, when they formed, were generally small (maximum of six individuals). Most groups of two were male-female pairs, and unisex groups occurred significantly less often than expected. These male-female groups formed as a result of sexual investigations of females by males, and were shore-lived. Analysis of the frequency with which particular males and females were seen together (excluding occasions when females were in oestrus) showed that most males did not persistently associate with any particular female. Instead, they appeared to maintain transitory contact with as many females as possible. However, three pairs were regularly seen together, suggesting that some males may maintain especially close contact with particular females. Females as they approached oestrus were followed continually by several males, with one male following very closely and preventing others from approaching. In two well-studied cases, the male who defended priority of access to the female was the same individual who had most often associated with that female when not in oestrus. These males demonstrated intimate knowledge of the nesting locations of the females and were able to join them very early each evening, and defended them against other males with little overt aggression. The mating system in this population appears to be promiscuous, but with a hint of monogamy arising from the tendency of some males to persistently investigate and ultimately to guard sexual access to certain individual females.

The effects of sex, season and habitat availability on patterns of habitat use by fallow deer (Dama dama)

Diurnal habitat use by fallow deer Dama dama was studied between 1986–9 by direct observations from transects of eight populations in sites of differing environmental structure and composition. Sites chosen differed in the overall proportion of woodland cover, and ranged from virtually continuous woodland areas in the New Forest, southern England, to open agricultural sites with only scattered woodland copses.Within both New Forest and agricultural areas, individuals in male groups and female groups showed similar patterns of habitat use. In the New Forest, the habitat used most overall by both sexes was open woodland, with extensive use also made of grassland, woodland clearings and closed woodland. In agricultural areas, most extensive use was made of closed woodland, with open woodland, arable land and grassland used to a lesser extent. Individuals in mixed‐sex groups in the New Forest but not in agricultural areas made more extensive use of grasslands than those in single‐sex groups.Individuals in female groups in the New Forest showed pronounced seasonal variation in habitat use with utilization of open woodland higher in autumn and winter and grassland higher in spring and summer. Individuals in female groups in agricultural areas showed little seasonal variation in habitat use. There were insufficient data to investigate seasonal variation in habitat use by individuals in male and mixed‐sex groups.Availability of habitat types varied widely between study sites. Use of either open or closed woodland remained high in each site reflecting increased selection for woodland resources when they were of limited availability. Fallow deer appeared able to satisfy their ecological and behavioural requirements from a variety of environments through: (i) changing strength of selection of particular habitats to compensate for differing availability; and (ii) substitution of one habitat in one area for a different habitat in another area which offered the same effective resources. This flexibility in resource use parallels observed plasticity in other aspects of fallow behavioural ecology.

AN INITIAL EVALUATION OF THE USE OF BIVARIATE MATCHING IN DIF ANALYSES FOR FORMULA SCORED TESTS12

This study evaluated the use of bivariate matching as a solution to the problem of studying DIF with formula scored tests. This problem specifically involves including in or excluding from a formula scored matching criterion formula scored items to-be-studied for a DIF analysis. Using SAT Verbal data with large and small samples both Male-Female and Black-White group comparisons were investigated. MH D-DIF values and DIF category classifications based on bivariate matching were compared with MH D-DIF values and categories based on rights scored and formula scored matching criteria. When large samples were used, MH D-DIF values based on the bivariate matching criterion were ordered very similarly to MH D-DIF values based on the other criteria. The DIF category classifications were almost identical. However, with small samples the MH D-DIF values based on the bivariate matching criterion displayed only moderate correlations with MH D-DIF values from the other criteria. In addition, the DIF category classifications based on the bivariate matching criterion showed fewer high DIF items than those based on the rights or formula scored matching criteria. As a secondary result, this study documented the differences between formula and rights scored criteria in DIF analyses of formula scored tests. These results showed that the substitution of a rights scored criterion in a DIF analysis of a formula scored test resulted in MH D-DIF values that were ordered very similarly as those based on the proper formula scored criterion. The MH D-DIF values based on the rights score criterion were, however, different in magnitude from those based on the formula scored criterion. The differences were related to item difficulty and were greater for comparisons with larger ability differences.

Sex Differences in Giraffe Feeding Ecology: Energetic and Social Constraints

AbstractSex ratios of giraffe groups differ in different habitats, with open vegetation having female‐biased groups, and tall, thick vegetation having male‐biased groups. On a ranch in south‐central Kenya, we quantified habitat differences of male and female giraffe groups and showed that the preference for open habitats by female groups was limited to groups with young. We suggest that this difference is due to the avoidance of predators of young giraffes. We also showed that rates of giraffe feeding peaked at intermediate feeding heights equal to approximately 60% of adult giraffe height. In the dense habitats with a variety of tree heights used by male groups and female groups without young, both male and female giraffes fed most at heights where they could feed fastest. However, in the open habitats used by female groups with young, females fed mostly at heights below optimum because these habitats are dominated by short food plants. On the other hand, the dominant males accompanying these female groups fed at heights above optimum on rare tall trees, possibly to increase intrasexual vigilance. Apparently, both male and female giraffes sometimes forfeit feeding efficiency tor short‐term reproductive gains.

RIGIDITY: A COMPARISON BY AGE AND GENDER

This study compared personality rigidity in young adults (ages 17 to 21), older adults (21 to 72), male and female groups. A probability sample of 295 community-college psychology students were administered a 39-item, true false rigidity questionnaire. The following research hypotheses were formulated: Rigidity is related functionally to age and gender, with males being more rigid than females, young being more rigid than old, and young male and young female groups being more rigid than old male and old female groups. Measures of central tendency and dispersion as well as one-tailedttests were used to analyze the data. The following significant differences at the .05 level were found: The male group was more rigid than the female group; and the young male group was more rigid than the young female group. Since no significant differences existed between old males and old females, it was concluded that rigidity differences may diminish with age.

Agonistic and grooming behavior of captive crowned lemurs (Lemur coronatus) during the breeding season

Captive breeding of rare and endangered prosimians may be enhanced by an increased understanding of all aspects of their seasonal mating behavior. In this study, the agonistic and grooming behaior of captiveL. coronatus were studied during their annual breeding season. Between October and March, selected aspects of agonistic and grooming behavior of four male-female groups were recorded. Males initiated significantly more allogrooming than females. The frequency of this behavior pattern increased significantly in the weeks of estrus. Females performed significantly more agonistic behavior patterns than males. The mean frequency of agonistic interactions decreased significantly during the breeding season. In successfully reproducing groups males showed much less agonism towards females, than they did in unsuccessful groups. Inter-specific comparisons demonstrated that the patterns of agonistic interactions during the breeding season are very different among closely related species of lemurids. The conclusions drawn from this study are that captive breeding of crowned lemurs may be enhanced by keeping permanent multi-male, multi-female groups.