Body Size Preferences Research Articles

Scaling laws of ambush predator 'waiting' behaviour are tuned to a common ecology.

The decisions animals make about how long to wait between activities can determine the success of diverse behaviours such as foraging, group formation or risk avoidance. Remarkably, for diverse animal species, including humans, spontaneous patterns of waiting times show random 'burstiness' that appears scale-invariant across a broad set of scales. However, a general theory linking this phenomenon across the animal kingdom currently lacks an ecological basis. Here, we demonstrate from tracking the activities of 15 sympatric predator species (cephalopods, sharks, skates and teleosts) under natural and controlled conditions that bursty waiting times are an intrinsic spontaneous behaviour well approximated by heavy-tailed (power-law) models over data ranges up to four orders of magnitude. Scaling exponents quantifying ratios of frequent short to rare very long waits are species-specific, being determined by traits such as foraging mode (active versus ambush predation), body size and prey preference. A stochastic-deterministic decision model reproduced the empirical waiting time scaling and species-specific exponents, indicating that apparently complex scaling can emerge from simple decisions. Results indicate temporal power-law scaling is a behavioural 'rule of thumb' that is tuned to species' ecological traits, implying a common pattern may have naturally evolved that optimizes move-wait decisions in less predictable natural environments.

Ecological traits influence the phylogenetic structure of bird species co-occurrences worldwide.

The extent to which species' ecological and phylogenetic relatedness shape their co-occurrence patterns at large spatial scales remains poorly understood. By quantifying phylogenetic assemblage structure within geographic ranges of >8000 bird species, we show that global co-occurrence patterns are linked - after accounting for regional effects - to key ecological traits reflecting diet, mobility, body size and climatic preference. We found that co-occurrences of carnivorous, migratory and cold-climate species are phylogenetically clustered, whereas nectarivores, herbivores, frugivores and invertebrate eaters tend to be more phylogenetically overdispersed. Preference for open or forested habitats appeared to be independent from the level of phylogenetic clustering. Our results advocate for an extension of the tropical niche conservatism hypothesis to incorporate ecological and life-history traits beyond the climatic niche. They further offer a novel species-oriented perspective on how biogeographic and evolutionary legacies interact with ecological traits to shape global patterns of species coexistence in birds.

Everyday translation: health practitioners’ perspectives on obesity and metabolic disorders in Samoa

Research in Samoa and the diaspora has documented the nutrition transition and related rising metabolic disorders. Research suggests cultural influences, including large body size preference, sedentarism, and dietary patterns, as well as political and economic influences, including changed labor patterns and food dependence, contribute to rising metabolic disorders. This article documents how Samoan health practitioners understand barriers to lifestyle change as primarily cultural rather than structural. They highlight differences between health, framed as individually oriented, and well-being, framed as socially oriented. Drawing from participant observation and semi-structured interviews, this article shows how health practitioners engage in ‘everyday translation’ by aiming to change the meaning of food, body, and wealth. Attention to everyday translation provides insights into the ambivalent ways interviewees identify culture as a barrier to health care. They avoid blaming patients, which has the paradoxical effect of suspending blame on individuals for not changing health behavior until cultural change occurs. This requires local leadership to effect community-wide change. When culture is recognized as the primary barrier to lifestyle change, health practitioners inadvertently reproduce structural inequalities in their daily interactions with patients. This has the effect of obscuring structural influences and promoting the idea that metabolic disorders are under individual control.

Obesity and body size perceptions in a Spanish Roma population

Background: Roma people are particularly vulnerable to developing overweight and obesity. Self-perception of body image may influence the prevalence of obesity in this ethnic minority.Aim: The objectives of this study are to estimate the prevalence of obesity, to analyse body size perceptions and preferences and to assess the relationship between body size perceptions and obesity in the Roma population.Subjects and methods: The analyses were carried out on 372 men, women and children from the Roma population residing in the Greater Bilbao region (Basque Country, Spain). In adults, a standard figural scale was used to analyse body size perceptions and preferences in this ethnic minority.Results: Overall 51.7% of adult and 24.4% of minor Roma individuals were obese. Both Roma men and women had inaccurate self-perceptions of their body size. Significant differences on body size perceptions were detected based on age, sex, nutritional status and socioeconomic characteristics.Conclusion: This Roma population presents one of the highest rates of obesity worldwide. Although a certain awareness of the correct weight status was appreciated, the inability of Roma individuals to see themselves as overweight or obese may be a significant factor on the high prevalence of obesity in this population.

Mosquito Prey Vulnerability in Intraguild Predation Between Ranatra filiformis and Anisops bouvieri: Implications in Biological Control

Wetlands are common habitats of a range of predatory water bugs (Heteroptera) constituting a guild that exhibit similar dietary choice including mosquito. Differences in body size and micro habitat preference among the heteropteran guild members provide a fair possibility of intraguild predation that can influence the regulatory effect on the prey species. This proposition was tested under laboratory conditions, using varying density of Ranatra filiformis (IG predator) and Anisops bouvieri (IG prey) as predators against mosquito larvae as shared prey. Compared to single predator system, mosquito larvae were proportionately less vulnerable to predation in intraguild predation (IGP), at low density of shared prey. In IGP system, vulnerability of shared prey increased with increase in density accompanied by a decline in mortality of IG prey. The mean mortality of shared prey and IG prey increased with the density of IG predator. It was apparent that the mosquito prey vulnerability was enhanced with increase in density of mosquito and R. filiformis while reducing the mortality of A. bouvieri partly. The interaction between R. filiformis and A. bouvieri as a part of IGP system indicate about the possible mechanism of coexistence of predators and prey in the wetlands. The density dependent effects on reduction and enhancement of shared prey (mosquito) mortality indicate that appropriate ratio of R. filiformis, A. bouvieri and mosquito larvae will be required to make biological regulation of wetland mosquitoes feasible.

Effect of fire on small mammals: a systematic review

Fire is a natural disturbance that exerts an important influence on global ecosystems, affecting vegetation distribution and structure, the carbon cycle and climate. However, human-induced changes to fire regimes may affect at-risk species groups such as small mammals. We examine the effect of fire on small mammals and evaluate the relative sensitivity to fire among different groups using a systematic review methodology that included critiquing the literature with respect to survey design and statistical analysis. Overall, small mammal abundance is slightly higher, and demographic parameters more favourable, in unburnt sites compared to burnt sites. This was more pronounced in species with body size range of 101–1000g and with habitat requirements that are sensitive to fire (e.g. dense ground cover): in 66.6 and 69.7% of pairwise comparisons, abundance or a demographic parameter were higher in unburnt than burnt sites. This systematic review demonstrates that there remains a continued focus on simple shifts in abundance with regards to effect of fire and small mammals, which limits understanding of mechanisms responsible for change. Body size and habitat preference were most important in explaining variation in small mammal species’ responses to fire.

Obesity in Somali Immigrant Women Due to Post-Migration Dietary Changes and Decreasing Self-Esteem?

The last-decade incidence of myocardial infarction (MI) has diminished dramatically in most age groups but not in middle-aged women in Sweden. There has been a large influx of immigrants and it has been shown that immigrant women have a higher BMI and are less physically active than Swedish women. Thereby they have a higher risk for heart disease. The aim of the study was to examine post-migration dietary changes, and knowledge about risks for heart diseases among Somali women. Furthermore, to examine the women’s perceptions of body image, self-esteem, and their knowledge about the positive effect of physical activity. The qualitative research method was used and eight Somali women aged 40 years or more, who have lived in Sweden longer than ten years, were interviewed with the help of a semistructured questionnaire. The study revealed that Somali migrated women in Sweden had changed their diet and experienced weight increase. They reported low self-esteem and little motivation for physical activity. They understood that they had a higher risk for heart disease as compared to Swedish women and they had, in general, a preference for big body size. The women of this study are, in combination with other risk factors, at a high risk of myocardial infarction. They all revealed a general knowledge about the relationship between obesity and inactivity and enhanced risks for heart disease. They had a preference for a larger female body image. They expressed low self-esteem, loneliness, and alienation from society. It is important to address the health issue among migrant Somali women in Sweden, but since this study had few informants, larger studies and more science is needed to further investigate the problem.

Overweight, Obesity, and Perception of Body Image Among Slum Residents in Nairobi, Kenya, 2008–2009

IntroductionThe increase in cardiovascular diseases in sub-Saharan Africa has been attributed in part to the changes in lifestyle, and the prevalence of risk factors for cardiovascular disease is higher among urban populations than among nonurban populations. The objective of this study was to determine the prevalence of overweight and obesity and examine perceptions of body size differentiated by sex and other determinants among slum dwellers in Nairobi, Kenya.MethodsAnalysis included 4,934 adults randomly selected from the Korogocho and Viwandani slums of Nairobi. Height and weight were measured during interviews; body mass index (BMI) was calculated. Perceptions of current and ideal body image were determined by using 18 silhouette drawings of body sizes ranging from very thin to very obese. We used multivariate logistic regression analysis to determine predictors of underestimation of body weight among overweight and obese respondents.ResultsOverall, 43.4% of women and 17.3% of men in the study population were overweight or obese. More than half (53%) of those who were overweight or obese underestimated their weight; 34.6% of women and 16.9% of men did so. In all BMI categories, more than one-third of women and men preferred body sizes classified as overweight or obese.ConclusionThis study highlights the prevalence of overweight and obesity and the strong preference for larger body size among adults in the slums of Nairobi. Interventions to educate residents on the health risks associated with excess body weight are necessary as a part of strategies to reduce the prevalence of risk factors for cardiovascular disease in these settlements.

No evidence for size‐assortative mating in the wild despite mutual mate choice in sex‐role‐reversed pipefishes

Size-assortative mating is a nonrandom association of body size between members of mating pairs and is expected to be common in species with mutual preferences for body size. In this study, we investigated whether there is direct evidence for size-assortative mating in two species of pipefishes, Syngnathus floridae and S. typhle, that share the characteristics of male pregnancy, sex-role reversal, and a polygynandrous mating system. We take advantage of microsatellite-based “genetic-capture” techniques to match wild-caught females with female genotypes reconstructed from broods of pregnant males and use these data to explore patterns of size-assortative mating in these species. We also develop a simulation model to explore how positive, negative, and antagonistic preferences of each sex for body size affect size-assortative mating. Contrary to expectations, we were unable to find any evidence of size-assortative mating in either species at different geographic locations or at different sampling times. Furthermore, two traits that potentially confer a fitness advantage in terms of reproductive success, female mating order and number of eggs transferred per female, do not affect pairing patterns in the wild. Results from model simulations demonstrate that strong mating preferences are unlikely to explain the observed patterns of mating in the studied populations. Our study shows that individual mating preferences, as ascertained by laboratory-based mating trials, can be decoupled from realized patterns of mating in the wild, and therefore, field studies are also necessary to determine actual patterns of mate choice in nature. We conclude that this disconnect between preferences and assortative mating is likely due to ecological constraints and multiple mating that may limit mate choice in natural populations.

Body size preferences among young women in five Arab countries: a cross-cultural study

The aim of this study was to highlight body size preferences among university females in five Arab countries. The sample comprised 1134 females between 17 and 32 years old from universities in five Arab countries: Bahrain, Egypt, Jordan, Oman and Syria. A silhouette figure scale was used to examine body size preferences. There were significant differences between countries regarding female body size preferences (p<0.001) and for preferred body size for men (p<0.001). In general, the university females preferred a thinner body size for themselves than that perceived for men. There was a drastic change in body size preferences for women from plumpness to thinness. Sociocultural factors may play a role in the differences in the body size preferences between countries.

Body size preference among Yoruba in three Nigerian communities

Following our previous observation of an aversion to weight reduction in Nigerians with type 2 diabetes, we measured several parameters of body dimensions and preferences in otherwise healthy adults in three communities to study the phenomenon further. The study population of 524 participants (304 F) was 99.8% of Yoruba ethnic origin with a mean age of 43.9 ± 17.2 years. Females had a significantly (p > 0.001) higher body mass index (BMI), waist circumference, hip circumference compared to the males; the values being 24.55 ± 5.5 vs. 21.75 ± 3.71 kg/m(2); 84.98 ± 12.67 vs. 80.92 ± 9.85 cm; 96.32 ± 12.94 vs. 89.36 ± 8.06 cm, respectively. There was a high level of satisfaction amongst respondents with their body size (Kendall's t = 0.52, p < 0.001) which they also predicted with a high degree of certainty even without the prior use of a weighing scale. The relationship between current body size (CBI) and BMI emerged as CBI = 1.22 + 0.32 BMI. In the 41% of respondents who expressed unhappiness with their current body size, there was a strong aversion for a smaller body size and the preference was often for a bigger body figure. Strikingly, many more women than men were less dissatisfied with their bigger body sizes. Stepwise regression indicated that CBI and gender were the two most important variables that best related to casual blood sugar (RBS) among the factors entered. The mathematical relationship between these variables that emerged was: [Formula: see text] where gender = 0 for male and 1 for female. The results suggest that larger body sizes were positively viewed in these communities consistent with our previous observations in type 2 diabetes.

Age, Body Size, Body Image, and Fit Preferences of Male Consumers

This study examines the influence of specific physical factors (body size), demographic factors (age), and psychosocial factors (body satisfaction, social physique anxiety, and drive for muscularity) on apparel-specific (jeans, khakis, dress shirts, and polo shirts) fit preferences of male consumers. Data were collected through an online survey administered to 141 men in the age group of 19-66 years. Results revealed that increase in body size significantly predicted preferences for apparel (jeans, dress, and polo shirts) with looser fits, and jeans with higher waistlines. Increase in age also predicted preferences for dress and polo shirts with looser fits and jeans with higher waists. With respect to the body-image-related factors, increase in body dissatisfaction predicted increased preferences for dress shirts with looser fits and khakis with higher waistlines. Contrary to expectations, increase in men's drive for muscularity predicted preferences for jeans with lower waistlines. This study offers important implications and creates actionable market information on fit strategy for male consumer segments.

Female mate preferences for male body size and shape promote sexual isolation in threespine sticklebacks

Female mate preferences for ecologically relevant traits may enhance natural selection, leading to rapid divergence. They may also forge a link between mate choice within species and sexual isolation between species. Here, we examine female mate preference for two ecologically important traits: body size and body shape. We measured female preferences within and between species of benthic, limnetic, and anadromous threespine sticklebacks (Gasterosteus aculeatus species complex). We found that mate preferences differed between species and between contexts (i.e., within vs. between species). Within species, anadromous females preferred males that were deep bodied for their size, benthic females preferred larger males (as measured by centroid size), and limnetic females preferred males that were more limnetic shaped. In heterospecific mating trials between benthics and limnetics, limnetic females continued to prefer males that were more limnetic like in shape when presented with benthic males. Benthic females showed no preferences for size when presented with limnetic males. These results show that females use ecologically relevant traits to select mates in all three species and that female preference has diverged between species. These results suggest that sexual selection may act in concert with natural selection on stickleback size and shape. Further, our results suggest that female preferences may track adaptation to local environments and contribute to sexual isolation between benthic and limnetic sticklebacks.

Cross-Cultural Variation in Mate Preferences for Averageness, Symmetry, Body Size, and Masculinity

Sexual selection has greatly influenced the evolved biology, psychology, and culture of humans and favors individuals who choose healthy and fertile mates. Physical traits that cue quality are generally preferred and perceived as attractive. However, because such traits often involve cost-benefit trade-offs, mate preferences are expected to vary among cultures as a function of local ecology and social environment and among individuals as a function of one’s personal experiences and life history. As such, it is essential to understand how ontogenetic and environmental factors influence mate preferences that may be locally adaptive and context specific. Here the authors review a growing body of comparative research, demonstrating predictable patterns in men’s and women’s preferences for facial averageness, facial symmetry, stature, body mass, and facial and vocal masculinity or femininity both between and within cultures. The authors consider potential factors influencing variation in preferences that include resource availability, disease prevalence, paternal investment, visual experience, and cultural norms.

Invasive moss alters patterns in life-history traits and functional diversity of spiders and carabids

Invasive plants can modify terrestrial habitats and affect the natural faunal composition. In acidic coastal dunes the invasive moss Campylopus introflexus can form dense carpets that largely replace native vegetation. As shown in a previous study, moss invasion affects habitat structure and ground-dwelling arthropod diversity. We suggested that including the functional diversity concept in the analysis of moss invasion impacts may offer further insights. We used pitfall trap data to compare trait composition and functional diversity of spiders and carabids in (a) invaded, moss-rich (C. introflexus) and (b) native, lichen-rich (Cladonia spp.) acidic coastal dunes. Moss invasion induced shifts in the trait values body size and feeding preference (carabids) and hunting mode (spiders): Species were smaller in native sites, and the percentages of web-building spiders and phytophagous beetles were reduced in invaded sites. Furthermore, moss invasion led to a more heterogeneous trait composition for spiders, and changed functional diversity of both arthropod groups, although with the opposite effects: While spiders were functionally more diverse in invaded sites, moss invasion reduced carabid beetles’ functional diversity. We also observed changes in the relationship between species richness and functional diversity that indicate a high functional similarity for spiders but a lower one for carabid beetles in native grey dunes. C. introflexus invasion not only alters the arthropod diversity and assemblage structure of endangered acidic coastal dunes but also interferes at a functional level. These results provide further insight into the way plant invasions might alter the structure and function of ecosystems.

Visual Diet versus Associative Learning as Mechanisms of Change in Body Size Preferences

Systematic differences between populations in their preferences for body size may arise as a result of an adaptive ‘prepared learning’ mechanism, whereby cues to health or status in the local population are internalized and affect body preferences. Alternatively, differences between populations may reflect their ‘visual diet’ as a cognitive byproduct of mere exposure. Here we test the relative importance of these two explanations for variation in body preferences. Two studies were conducted where female observers were exposed to pictures of high or low BMI women which were either aspirational (healthy, attractive models in high status clothes) or non-aspirational (eating disordered patients in grey leotards), or to combinations thereof, in order to manipulate their body-weight preferences which were tested at baseline and at post–test. Overall, results showed good support for visual diet effects (seeing a string of small or large bodies resulted in a change from pre- to post-test whether the bodies were aspirational or not) and also some support for the associative learning explanation (exposure to aspirational images of overweight women induced a towards preferring larger bodies, even when accompanied by equal exposure to lower weight bodies in the non-aspirational category). Thus, both influences may act in parallel.

Incongruence between the sexes in preferences for body and dorsal fin size in Xiphophorus variatus

Female preference for male fin enhancements in poeciliid fishes may be driven by a preexisting perceptual bias for increased male lateral projection area (LPA). This hypothesis suggests that a male with enlarged body and/or fin size projects a larger image onto the female's retina at a given viewing distance, eliciting a greater sensory and thus behavioral response out of the female than a smaller male. Given the shared sensory/neural systems of opposite sex conspecifics, we might expect the LPA bias to also be present in males of at least some poeciliid species. However, we need not expect congruence between the sexes in the state of the bias over evolutionary time. To examine whether the sexes share a bias for sailfin-like dorsal fins, a trait not present in their evolutionary history, the bias favoring increased dorsal fin size and LPA observed in female Xiphophorus variatus, among other poeciliids, was investigated by testing male preference for dummy females varying in dorsal fin size, body size, and dorsal fin:body size ratio. In three sets of simultaneous choice experiments, males preferred females of larger body size when fin size was held constant and when total LPA was held constant, but showed no preference for larger fins when body size was held constant. The LPA bias is therefore less permissive in males than females with selection favoring a male's ability to discriminate between female body size – an indicator of fertility/fecundity – and fin size, which offers no known fitness benefits.

Pre-pregnancy Body Size Dissatisfaction and Excessive Gestational Weight Gain

Body size dissatisfaction has been documented as a risk factor for obesity, but little is known about the effect of body size dissatisfaction on excessive gestational weight gain. The objective of the study was to determine the association of pre-pregnancy body size dissatisfaction with excessive gestational weight gain in Iranian pregnant women. This case-control study compared pre-gravid body satisfaction status in 182 women with excessive gestational weight gain and 180 women who gained weight within the guidelines of the Institute of Medicine. All the participants of the study were 35-41 weeks gestational age and received prenatal care in Shahid Akbarabadi Hospital. The women were asked to think back to their pre-pregnant state and report their body size satisfaction status measured by the Body Image Assessment for Obesity (BIA-O). According to this measurement, the women were divided into three categories: dissatisfied women with a thinner body size preference, dissatisfied women with a heavier body size preference and satisfied women. Among women with excessive gestational weight gain, 56.6% preferred a thinner body size, while 53.9% of those with adequate gestational weight gain were satisfied with their pre-gravid body sizes. After adjusting for cofounders, those with a thinner body size preference were more likely to gain weight excessively during pregnancy when compared to satisfied women (OR: 2.17, 95% CI: 1.17-4.02). Our result showed that thinner body size preference was associated with excessive gestational weight gain. Further studies are needed to investigate whether changes in women's feelings about their body sizes will decrease the proportion of women with excessive gestational weight gain.

Relationship between body size and habitat complexity preference in age‐0 and ‐1 year winter flounder Pseudopleuronectes americanus

The interaction between body size, habitat complexity and interstice width on habitat preference of age-0 and -1 year Pseudopleuronectes americanus was examined using continuous remote video observation. The habitat choices of juvenile P. americanus were recorded over a 6 h period in tanks with four treatments: bare sand, sand with low complexity cobble, sand with intermediate complexity cobble and sand with high complexity cobble. Both age-0 and -1 year fish preferred cobble to bare sand. Within cobble treatments, age-0 year fish preferred intermediate complexity cobble, with a 1.59 ratio of interstitial space to body width. The largest age-1 year fish (123-130 mm standard length, L(S) ) preferred low complexity cobble. While a significant preference was not detected, medium age-1 year fish (83-88 mm L(S) ) tended to select low complexity cobble, whereas small age-1 year fish (73-82 mm L(S) ) tended to select low and intermediate cobble, with an interstitial space to body width ratio of 1.05. For medium and large age-1 year fish, there was an increased selection of low complexity cobble, corresponding to larger interstitial space to body size ratios. This study indicates that juvenile P. americanus prefer complex habitat to unstructured habitat and that this preference is mediated by a relationship between fish body size and the size of structure interstices. These results contribute to the growing body of knowledge of complex habitat selection and drivers of habitat choice in flatfishes.

A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice

Mating preferences for genetic compatibility strictly depend on the interplay of the genotypes of potential partners and are therein fundamentally different from directional preferences for ornamental secondary sexual traits. Thus, the most compatible partner is on average not the one with most pronounced ornaments and vice versa. Hence, mating preferences may often conflict. Here, we present a solution to this problem while investigating the interplay of mating preferences for relatedness (a compatibility criterion) and large body size (an ornamental or quality trait). In previous experiments, both sexes of Pelvicachromis taeniatus, a cichlid fish with mutual mate choice, showed preferences for kin and large partners when these criteria were tested separately. In the present study, test fish were given a conflicting choice between two potential mating partners differing in relatedness as well as in body size in such a way that preferences for both criteria could not simultaneously be satisfied. We show that a sex-specific trade-off occurs between mating preferences for body size and relatedness. For females, relatedness gained greater importance than body size, whereas the opposite was true for males. We discuss the potential role of the interplay between mating preferences for relatedness and body size for the evolution of inbreeding preference.