Body size and shape responses to warming and resource competition

Body size is often hypothesized to facilitate or constrain morphological diversity in the cranial, appendicular, and axial skeletons. However, how overall body shape scales with body size (i.e., body shape allometry) and whether these scaling patterns differ between ecological groups remains poorly investigated. Here, we test whether and how the relationships between body shape, body size, and limb lengths differ among species with different locomotor specializations, and describe the underlying morphological components that contribute to body shape evolution among squirrel (Sciuridae) ecotypes. We quantified the body size and shape of 87 squirrel species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we first found that body shape and its underlying morphological components scale allometrically with body size, but these allometric patterns differ among squirrel ecotypes: chipmunks and gliding squirrels exhibited more elongate bodies with increasing body sizes whereas ground squirrels exhibited more robust bodies with increasing body size. Second, we found that only ground squirrels exhibit a relationship between forelimb length and body shape, where more elongate species exhibit relatively shorter forelimbs. Third, we found that the relative length of the ribs and elongation or shortening of the thoracic region contributes the most to body shape evolution across squirrels. Overall, our work contributes to the growing understanding of mammalian body shape evolution and how it is influenced by body size and locomotor ecology, in this case from robust subterranean to gracile gliding squirrels.

ALLEY, THOMAS R. Growth-produced Changes in Body Shape and Size as Determinants of Perceived Age and Adult Caregiving. CHILD DEVELOPMENT, 1983, 54, 241-248. The ethological hypothesis that parental caregiving can be elicited by certain physical characteristics of infants was investigated in 3 experiments. In Experiments 1 and 2, adults' responses to line drawings of humans varying only in size or body proportions showed that the reported tendency to protect others decreases as the size and shape of the recipient's body changes due to growth. In the third experiment, the rated cuddliness of the drawings varying in body proportions also decreased as their portrayed age increased. The changes in body proportions were found to be an effective source of information for relative age. These results support the ethological view that individuals who appear more youthful in terms of body size or shape are more likely to be recipients of adult caretaking.

The effects of transgenic compounds on non-target organisms remain poorly understood, especially in native insect species. Morphological changes (e.g., changes in body size and shape) may reflect possible responses to environmental stressors, like transgenic toxins. The dung beetle Canthon quinquemaculatus (Coleoptera: Scarabaeinae) is a non-target species found in transgenic crops. We evaluated whether C. quinquemaculatus individuals inhabiting corn fields cultivated with different seed types (conventional, creole and transgenic) present modifications in body shape compared to individuals inhabiting adjacent native forest fragments. We collected C. quinquemaculatus specimens across an agricultural landscape in southern Brazil, during the summer of 2015. Six populations were sampled: three maize crop populations each under a different seed type, and three populations of adjacent forests. After sampling, specimens were subjected to morphometric analyses to discover differences in body shape. We chose fifteen landmarks to describe body shape, and morphometric data were tested with Procrustes ANOVA and Discriminant Analysis. We found that body shape did not differ between individuals collected in conventional and creole crops with their respective adjacent forests (p > 0.05); however, transgenic crop populations differed significantly from those collected in adjacent forests (p < 0.05). Insects in transgenic maize are more oval and have a retraction in the abdominal region, compared with the respective adjacent forest, this result shows the possible effect of transgenic crops on non-target species. This may have implications for the ecosystem service of organic matter removal, carried out by these organisms.

Measurements of human body size and shape are an important source of information for a range of scientific fields and applications; however, practitioners still rely on traditional tools and methods which limit the kinds of measurements that can be taken. Recent literature has suggested that 3D imaging technology is a more sophisticated tool that could enable the comprehensive characterisation of human body shape. The aim of this programme of doctoral study was to determine whether shape anthropometrics can complement existing techniques in the assessment of human morphology. A novel analytical procedure was developed using geometric morphometrics and statistical shape analysis methods to extract numeric parameters from 3D imaging data, which describe scale-invariant characteristics of human torso shape. Though errors in anatomical landmark identification and participant scanning posture can affect the acquisition of shape anthropometrics, the developed methods were found to have high test-retest reliability, suitable for use within subsequent investigations. A series of investigations were conducted to determine whether shape measures provide additional information which is not captured by existing anthropometric techniques. The findings of these investigations suggest that body shape measures show a complex dependence on body size. Though certain shape features demonstrate a degree of allometric scaling and change with increases in body size, there are significant proportions of shape variation which cannot be explained by existing anthropometrics. These non-allometric variations in body shape have been shown to improve the estimation of subcutaneous abdominal adiposity in a small cohort of participants, and have demonstrated the potential for misclassification of individuals using existing indices, such as BMI and WHR. This programme of research provides a more detailed understanding of human morphological variation, which could inform the development of improved tools for characterising how body shape relates to its underlying mass distribution.

Sex-specific plasticity, the differential response that the genome of males and females may have to different environments, is a mechanism that can affect the degree of sexual dimorphism. Two adaptive hypotheses have been proposed to explain how sex-specific plasticity affects the evolution of sexual size dimorphism. The adaptive canalization hypothesis states that the larger sex exhibits lesser plasticity compared to the smaller sex due to strong directional selection for a large body size, which penalizes individuals attaining sub-optimal body sizes. The condition-dependence hypothesis states that the larger sex exhibits greater plasticity than the smaller sex due to strong directional selection for a large body size favoring a greater sensitivity as an opportunistic mechanism for growth enhancement under favorable conditions. While the relationship between sex-specific plasticity and sexual dimorphism has been studied mainly in invertebrates, its role in long-lived vertebrates has received little attention. In this study we tested the predictions derived from these two hypotheses by comparing the plastic responses of body size and shape of males and females of the snapping turtle (Chelydra serpentina) raised under common garden conditions. Body size was plastic, sexually dimorphic, and the plasticity was also sex-specific, with males exhibiting greater body size plasticity relative to females. Because snapping turtle males are larger than females, sexual size dimorphism in this species appears to be driven by an increased plasticity of the larger sex over the smaller sex as predicted by the condition-dependent hypothesis. However, male body size was enhanced under relatively limited resources, in contrast to expectations from this model. Body shape was also plastic and sexually dimorphic, however no sex by environment interaction was found in this case. Instead, plasticity of sexual shape dimorphism seems to evolve in parallel for males and females as both sexes responded similarly to different environments.

1. Climate change has been occurring at unprecedented rates and its impacts on biological populations is beginning to be well documented in the literature. For many species, however, long‐term records are not available, and trends have not been documented. 2. Using museum specimens from southern USA, we show that the stream‐dwelling beetle Gyretes sinuatus has shown an 8% increase in body size and change in body shape (fineness ratio) from 1928 to 1988. Any directional morphological change observed over time could be an indicator of a microevolutionary response. 3. During these 60 years, there have also been changes in temperature, precipitation, and location of collection sites. Unlike the global trend, mean annual temperature in the region has decreased, and furthermore, total annual precipitation has increased. By investigating how these various ecological and geographical variables may affect body size and shape, we can examine which pressures may promote larger and/or thinner beetles. 4. Results indicate that mean annual temperature was the most predictive variable for the change in size and shape. We suggest there is an adaptive role for temperature on body size and shape of stream dwelling organisms. 5. We found that museum specimens can be invaluable resources of information when collection date and location information is available. We promote the use of such specimens for future studies of the morphological response to climate change.

Accessible Summary We held a group for people with Learning Disabilities who were overweight and unhappy about being so. The group ran for 9 weeks. It lasted 2 h and four adults came to the group. The group talked about how they felt about their bodies, why they ate and why it is sometimes hard to choose healthy food over unhealthy food. It helped people learn to accept their body size and shape. Summary The Clinical Psychology Service and the Dietetic and Nutrition Service for People with Learning Disabilities in Birmingham shared concerns about the effectiveness of services offered to service users who were overweight. In an effort to gain more understanding of the issues from a service user perspective and to ultimately provide more effective services, a body awareness group was established, structured according to the ‘Health at Every Size’ model. Four adults with learning disabilities attended a total of nine sessions held once a week for a period of 2 h. Topics were presented to the group in the form of group discussions or group activities, which included: personal and social attributions towards body shape and size; self-esteem; physical eating vs. emotional eating; relationship with food (e.g. understanding of choosing junk food over healthier options); negative messages people tell themselves about eating and factors that prevent people from engaging in a healthier lifestyle. This study aims to report the process of designing and facilitating the ‘Body Awareness Group’ and to critically review observations and findings in an effort to gain greater understanding of the role of food in this context.

The purpose of this study was to cross-culturally investigate the effect of body mass index (BMI) and body shapes on the perception of female body attractiveness and body size. A convenience sample of 107 American and 102 Russian female students completed questionnaire coordinated with a stimulus of 27 images of female body scans used by respondents to rate body size and attractiveness. Body sizes were categorised according to BMI. Three body shapes (hourglass, rectangle and pear) were defined within the stimulus. Russian respondents reported lower scores on body attractiveness than American respondents for all 27 images. Body scans with underweight BMIs were perceived as being the most attractive in both cultures. There was a significant difference of perceptions of body sizes between the Americans and the Russians.

Subterranean species show a distinct morphology, yet the adaptive significance of some traits, like body size and shape, is poorly understood and cannot be explained solely by distinct environmental conditions (darkness, less food). We predicted that in females some morphological changes may have co‐evolved with life history traits, and that co‐evolving life history traits provide at least part of the explanation for evolutionary changes of morphology. Using museum material we tested this prediction on the subterranean amphipod genus Niphargus. We studied six species found in springs and eight species found in cave lakes. We treated them as two ecologically distinct groups, and the major ecological differences between them were the availability of nutrients and the water currents. Cave species were found to be larger and stouter (as inferred from the shape of coxal plates, which are part of the marsupium), they had larger eggs and lower reproductive effort per brood, whereas the egg number and brood volume if corrected for the body size were not different. Using phylogenetic independent contrasts, we found a positive correlation between body shape and egg volume, a positive correlation between body size and egg volume, and a negative correlation between body size and reproductive effort per brood. We tentatively conclude that evolutions of morphology and life histories are functionally connected and that co‐evolving traits contribute to overall selective regime.

Perceived influence of significant others on body shape of female and male college students

Phenotypic variation plays a critical role in determining the structural organisation and ecological function of wild populations. Animal groups are often structured according to factors such as species, sex, body size and parasite load, but it is unclear whether body shape also influences patterns of social organisation, and thus contributes to population phenotypic structure. Here, we use geometric morphometric analyses to determine whether wild-caught shoals of a freshwater fish, the western rainbowfish (Melanotaenia australis), are structured according to body size and shape. Using randomisation analyses, we show that the level of variation in size and shape observed in natural group assemblages is lower than that expected under a null model of random shoal composition. In addition, we found evidence of further phenotypic structuring along an upstream-downstream environmental gradient. The putative benefits of morphological assortment include a reduction in predation risk (due to prey oddity and predator confusion effects) and increased hydrodynamic or foraging efficiency. We suggest that morphological variation is a neglected component of population social organisation that can affect population processes, such as patterns of gene flow, and ecological interactions, such as predator-prey dynamics.

Effect of body image on gestational weight gain in overweight and obese women

The common pattern of replicated evolution of a consistent shape-environment relationship might reflect selection acting in similar ways within each environment, but divergently among environments. However, phenotypic evolution depends on the availability of additive genetic variation as well as on the direction of selection, implicating a bias in the distribution of genetic variance as a potential contributor to replicated evolution. Allometry, the relationship between shape and size, is a potential source of genetic bias that is poorly understood. The threespine stickleback, Gasterosteus aculeatus, provides an ideal system for exploring the contribution of genetic variance in body shape allometry to evolutionary patterns. The stickleback system comprises marine populations that exhibit limited phenotypic variation, and young freshwater populations which, following independent colonization events, have often evolved similar phenotypes in similar environments. In particular, stickleback diversification has involved changes in both total body size and relative size of body regions (i.e., shape). In a laboratory-reared cohort derived from an oceanic Alaskan population that is phenotypically and genetically representative of the ancestor of the diverse freshwater populations in this region, we determined the phenotypic static allometry, and estimated the additive genetic variation about these population-level allometric functions. We detected significant allometry, with larger fish having relatively smaller heads, a longer base to their second dorsal fin, and longer, shallower caudal peduncles. There was additive genetic variance in body size and in size-independent body shape (i.e., allometric elevation), but typically not in allometric slopes. These results suggest that the parallel evolution of body shape in threespine stickleback is not likely to have been a correlated response to selection on body size, or vice versa. Although allometry is common in fishes, this study highlights the need for additional data on genetic variation in allometric functions to determine how allometry evolves and how it influences phenotypic evolution.

Understanding human body type and shape variations is of fundamental importance in various ergonomic applications in a wide range of industries. This article provides a comprehensive analysis of the body types in various countries using the most recent national sizing standards. A set of integrated and internationally compatible size tables are then derived, which provide a valuable reference for analysis of body shape variation. This study covered both female and male sizing standards of the US, Europe, China, Japan and some other countries. The statistical analysis showed that size frequency varies from various countries with significant differences in body types and shapes. The standards of China and Japan covered the smaller body dimensions and sizes, as reflected in the relatively narrow torso and hips. The Europe and US standards covered the relatively large body dimensions and size ranges; the body shapes are plumper and wider than those of other countries.

In populations with limited resources, high-reproductive effort may lead to poor nutritional status of the mother (the maternal depletion syndrome), whereas in well-nourished populations woman's body weight tends to increase after each pregnancy. However, in affluent populations, women's body shape may change due to mobilization of polyunsaturated fatty acids (PUFAs) from the lower parts of their bodies to meet the needs of the developing child (the "covert maternal depletion"). We studied relationships between reproductive history traits and body size and shape for 296 rural, parous women in good nutritional status (mean body mass index, BMI = 27.9, SD = 5.94), aged 22-85 (mean 47.8, SD = 16.34) from southern Poland. Body mass adjusted for age, age of menarche, body height, and similarly adjusted BMI were each positively related to the number of children born by a woman (R = 0.13, P = 0.02 and R = 0.13, P = 0.02, respectively). Waist and hip circumferences, adjusted for confounders, did not show statistically significant relationships with the number of children. Moreover, groups with low and high parity did not significantly differ in hip/BMI and waist/BMI ratios, which were proposed to be indicators of covert form of maternal depletion (after controlling for overall body fatness and age). In conclusion, parity caused a slightly higher body mass and BMI later in life. However, parity did not lead to covert maternal depletion, perhaps because women in this population have relatively high-dietary intake of PUFAs.