Variation In Body Proportions Research Articles

Environmental signal in the evolutionary diversification of bird skeletons.

Characterizing how variation in the tempo and mode of evolution has structured the phenotypic diversity of extant species is a central goal of macroevolution1-3. However, studies are typically limited to a handful of traits4-6, providing incomplete information. We analyse morphological diversification in living birds, an ecologically diverse group7, documenting structural scales from 'pan-skeletal' proportions down to the localized three-dimensional shape changes of individual bones. We find substantial variation in evolutionary modes among avian subgroups and among skeletal parts, indicating widespread mosaicism and possible differences in the structure of the macroevolutionary landscape across Earth's main environments. Water-linked groups, especially Aequorlitornithes (waterbirds), have repeatedly explored a large portion of their total morphospace, emphasizing variation in body proportions and in the shape of bones close to the body core, which are functionally related to the mechanics of locomotion8. By contrast, landbirds (Inopinaves) evolved distinct, group-specific body forms early in the aftermath of the K-Pg and subsequently emphasized local shape variation, especially in the head and distal limb bones, which interact more directly with the environment. Passerines, which comprise more than half of all bird species, show a conservative evolutionary dynamic that resulted in low disparity across all skeletal parts. Evidence for early establishment of the morphospace of living birds is clear for some skeletal parts, including beaks and the combined skeletal morphology. However, we find little evidence for early partitioning of that morphospace, contrary to more specific predictions of 'niche-filling' models1,9. Nevertheless, early divergence among broad environmental types may have caused an early divergence of evolutionary modes, suggesting an important role for environmental divergence in structuring the radiation of crown-group birds.

The influence of climate and population structure on East Asian skeletal morphology

Recent studies have shown that global variation in body proportions is more complex than previously thought as some traits formerly associated with climate adaptation are better explained by geographic proximity and neutral evolutionary forces. While the recent incorporation of quantitative genetic methodologies has improved understanding of patterns related to climate in Africa, Europe, and the Americas, Asia remains underrepresented in recent and historic studies of body form. As ecogeographic studies tend to focus on male morphology, potential sex differences in features influenced by climate remain largely unexplored. Skeletal measurements encompassing the dimensions of the skull, pelvis, limbs, hands, and feet were collected from male (n = 459) and female (n = 442) remains curated in 13 collections across seven countries in East Asia (n = 901). Osteological data were analyzed with sex and minimum temperature as covariates adjusted by autosomal single-nucleotide polymorphism population genetic distance using univariate Bayesian linear mixed models, and credible intervals were calculated for each trait. Analysis supports a relationship between specific traits and climate as well as providing the magnitude of response in both sexes. After accounting for genetic distance between populations, greater association between climate and morphology was found in postcranial traits, with the relationship between climate and the skull limited primarily to breadth measurements. Larger body size is associated with colder climates with most measurements increasing with decreased temperature. The same traits were not always associated with climate for males and females nor correlated with the same intensity for both sexes. The varied directional association with climate for different regions of the skeleton and between the sexes underscores the necessity of future ecogeographic research to holistically evaluate body form and to look for sex-specific patterns to better understand population responses to environmental stresses.

Ontogenetic Development Related to Parental Care of a Neotropical Fish, Pterygoplichthys ambrosettii (Siluriformes: Loricariidae).

This study describes the main ontogenetic changes in the armored catfish Pterygoplichthys ambrosettii from newly hatched larva to adult. The relationship between the degree of development of newly hatched larvae and post-larvae and parental care is discussed. Ontogenetic series containing newly hatched larvae, post-larvae, and juveniles of P. ambrosettii were obtained from the Fish Culture Station of Universidade Estadual Paulista. Adult specimens were collected from the Preto River in the upper Paraná River basin. Morphological, osteological, morphometric, and meristic data and color pattern were analyzed. The species exhibited indirect development, with a distinct post-larval stage after the larval stage. Newly hatched larvae had a well-developed yolk sac and lacked pigmentation. The following characters underwent less change during development and can therefore be useful in taxonomical analyses: odontodes located posteriorly to the preopercle, number of plates on the lateral line, lower lip with three series of papillae, spots on the upper ray of the caudal fin, caudal fin similar to that of the adult, body ventrally covered with dermal plates and odontodes, small irregular spots on head, and typical ventral color pattern of the adult. The morphometric data revealed that most variation in body proportions occurred during less advanced developmental stages. Parental care influenced the ontogenetic development of newly hatched larvae.

Allometric Variation in Modern Humans and the Relationship Between Body Proportions and Elite Athletic Success

In many sports, greater height and arm span are purportedly linked to athletic success. While variation in body proportions has been explored across an array of scientific disciplines, studies focusing on humans of tall stature outside of clinical cases are limited. We investigated body size proportions in a sample of elite athletes, employing data on recruits for the National Basketball Association (NBA, n=2,990), mixed martial arts (MMA) fighters (mixed-sex, n=1,284), as well as a control sample of healthy young adults who are not professional athletes, represented here by male (n=4,082) and female (n=1,986) recruits for the United States Army, to test two hypotheses: 1) There is a significant difference in arm span to height ratios between elite professional athletes and the control population, and 2) There is a significant relationship between arm span to height ratio and athletic success within the NBA and MMA. We find that NBA players are significantly taller, with absolutely and relatively wider arm spans than MMA fighters and the control population. Additionally, we find that basketball players are significantly more likely to be drafted earlier in the NBA, and MMA fighters are significantly more likely to have a better loss to win ratio, if their arm span to height ratio falls above the regression line. However, we note that arm span and height, as well as athletic success, are impacted by a myriad of factors, and some of the most successful professional athletes do not have particularly long arms relative to their height.

Intraspecific variation in body size and shape in an Andean highland anole species, <i>Anolis ventrimaculatus</i> (Squamata: Dactyloidae)

Variation in body characteristics related to lizard locomotion has been poorly studied at the intraspecific level in Anolis species. Local adaptation due to habitat heterogeneity has been reported in some island species. However, studies of mainland species are particularly scarce and suggest different patterns: high variability among highland lizards and poorly differentiated populations in one Amazonian species. We characterized inter population variation of body size and shape in the highland Andean Anolis ventrimaculatus, an endemic species from Western Colombia. A total of 15 morphometric variables were measured in specimens from the reptile collection of the Instituto de Ciencias Naturales, Universidad Nacional, Colombia. The study included individuals from seven different highland localities. We found size and shape sexual dimorphism, both of which varied among localities. Patterns of variation in body proportions among populations were different in both males and females, suggesting that either sexual or natural selective factors are different in each locality and between sexes. Since this species exhibits a fragmented distribution in highlands, genetic divergence may also be a causal factor of the observed variation. Ecological, behavioral, additional morphological as well as phylogenetic data, may help to understand the evolutionary processes behind the geographic patterns found in this species.

The use of biocultural data in interpreting sex differences in body proportions among rural Amazonians.

Variation in height and body proportions is relatively well-understood at the inter-population level, but less is known about intra-population variation. This study explores intra-population variation in body proportions among 172 (88 female; 84 male) adult rural Amazonians. We test the hypotheses that: (1) stunting is associated with changes in proportions and fatness; (2) the sexes express different proportions in response to similar environmental stress; and (3) female growth is negatively affected by the costs of reproduction. We examined height, sitting height, and total leg length in subsamples based on sex and nutritional status (stunted/nonstunted) in relation to biocultural factors including access to food and healthcare and female reproductive history parameters. Differences in proportions were examined using the Quick-Test (Tsutakawa and Hewett: Biometrics 33 (1977) 215-219); correlation analyses were used to detect associations between anthropometric data and body fatness, and female reproductive history parameters. We found significantly higher rates of stunting among females (X(2) = 5.31; P = 0.02; RR = 1.4). Stunted individuals exhibited relatively shorter legs than nonstunted individuals (P = 0.02), although this was not found in within-sex analyses. A significant negative correlation was found between leg length index and fatness (P < 0.01). Lastly, females exhibited relatively shorter legs than males (P = 0.0003) and, among females, height and leg length were significantly positively correlated with age-at-first-birth (P < 0.02) suggesting that adolescent pregnancy may negatively affect growth in this population. Our findings provide insights for the study of intra-population variation in body proportions and highlight the importance of biocultural data in interpreting the pattern of variation observed in living and past populations.

Nutritional, developmental, and genetic influences on relative sitting height at high altitude

The study explores how nutritional status, developmental exposure to high-altitude hypoxia, and genetic ancestry influence relative sitting height in two groups of high-altitude Bolivian children aged 8 through 13 years of age: 253 rural Aymara children of very low socioeconomic status and 273 children of upper socioeconomic status from the capital city of La Paz. The rural Aymara children on average have longer trunks relative to stature, but there is also overlap in body proportions between the two groups of children. The 20% of each sample in the region of overlap was examined to investigate influences on relative sitting height. Nutritional effects on relative sitting height are suggested by the finding that Aymara children with relatively long legs are taller, heavier, and fatter than other Aymara children. Developmental and genetic influences on relative sitting height are suggested by the finding that high relative sitting heights in elite urban children are associated with a greater percentage of time lived at high altitude and with parents born in Bolivia. Separating developmental and ancestry effects is difficult because the two are closely interconnected in the urban children. The results of this study suggest that influences on growth in relative trunk and leg length are similar to those that affect other aspects of growth in Andean populations. They also highlight the fact that because relative sitting height gradually decreases prior to adolescence and then increases, the interpretation of variation in body proportions in children is not always straightforward.

Body proportions in ancient Andeans from high and low altitudes

Living human populations from high altitudes in the Andes exhibit relatively short limbs compared with neighboring groups from lower elevations as adaptations to cold climates characteristic of high-altitude environments. This study compares relative limb lengths and proportions in pre-Contact human skeletons from different altitudes to test whether ecogeographic variation also existed in Andean prehistory. Maximum lengths of the humerus, radius, femur, and tibia, and femoral head breadth are measured in sex-specific groups of adult human skeletons (N = 346) from the central (n = 80) and the south-central (n = 123) Andean coasts, the Atacama Desert at 2,500 m (n = 102), and the southern Peruvian highlands at 2,000-3,800 m (n = 41). To test whether limb lengths vary with altitude, comparisons are made of intralimb proportions, limb lengths against body mass estimates derived from published equations, limb lengths against the geometric mean of all measurements, and principal component analysis. Intralimb proportions do not statistically differ between coastal groups and those from the Atacama Desert, whereas intralimb proportions are significantly shorter in the Peruvian highland sample. Overall body size and limb lengths relative to body size vary along an altitudinal gradient, with larger individuals from coastal environments and smaller individuals with relatively longer limbs for their size from higher elevations. Ecogeographic variation in relation to climate explains the variation in intralimb proportions, and dietary variation may explain the altitudinal cline in body size and limb lengths relative to body size. The potential effects of gene flow on variation in body proportions in Andean prehistory are also explored.

The Low Prevalence of Weight-for-Height Deficits in Brazilian Children Is Related to Body Proportions

Compared with children from other regions, Latin American children living in poverty have much lower prevalences of weight-for-height deficits than would be expected given the observed rates of stunting. This study was aimed at investigating whether variations in body proportions, particularly abdominal circumference, could explain this paradoxical finding. In a cross-sectional study, children aged 12-35 mo (n = 197) were studied in Southern Brazil. Half of these children were from a high socioeconomic status (SES) group whose growth closely resembled that of the National Center for Health Statistics (NCHS)/WHO reference; the other half were from low income families. The following 11 anthropometric measurements were collected: weight, height, sitting height/crown-rump length, head, chest, upper arm and abdominal circumference, triceps, biceps, subscapular and suprailiac skinfolds. These measures were compared between the two groups of children and with values for North American children [mostly from Second National Health and Nutrition Examination Survey (NHANES II)]. For nearly all measures, low SES Brazilian children tended to be smaller than both high SES and North American children. However, when body proportionality was assessed by dividing the measurements by the child's height, these differences tended to disappear or even to change direction, as was the case for head, chest and abdominal circumferences. Mean abdominal circumference was virtually identical between low and high SES children, and the former had larger abdomens for a given height. Despite slight differences in measuring techniques, Brazilian children had larger abdomens than North Americans. These findings may explain in part why deprived Latin American children have higher weights for their height compared with the NCHS/WHO reference.

Body mass in lowland gorillas: a quantitative analysis.

Body proportions and tissue composition (e.g., relative contributions of muscle, skin, bone, and adipose to total body mass) were determined through dissection of four adult captive lowland gorillas. The relative contribution of bone varies little among the four animals (10.2-13.4%) despite considerable range in body weights (99.5-211 kg). In tissue composition, three animals have on average 37.3% muscle relative to body mass. Maximum estimates of body fat range between 19.4-44%. Differences in age, sex, and life history events partially explain the observed variation in body proportions and tissue composition among the four animals. Although gorillas are considered extremely sexually dimorphic in body weight and canine size, differences in tissue are not as dramatic as body mass differences suggest. This study found sex differences mostly in the upper body; males have relatively heavier forelimbs, including heavier deltoid, trunk-binding, and deep back muscles compared to the younger female. The old, obese female had one half the muscle tissue of the other three animals (16% vs. 37.3%), and twice the body fat (44%); forelimbs and upper body musculature were relatively well-developed to compensate for the restricted hip-joint movement due to arthritis. Data on the variation in tissue composition and body proportions in gorillas provide a basis for comparison with other hominoids, including humans. For example, compared to highly dimorphic orangutans, gorillas have more muscle, less adipose tissue, lighter forelimbs and heavier hindlimbs. Such analyses complement studies of the skeleton and contribute to our understanding of human evolution and adaptation.

An investigation of the structure of sizing systems

Most apparel sizing systems are based on one or two body dimensions and rely on assumptions about proportional body relationships to project other dimensions necessary to design the garment pattern. Garments from these systems will not fit a population with large variations in body proportions. Using nonlinear optimization methods and anthropometric data of US Army women three multidimensional sizing systems were derived that are designed to provide improved fit for women from the USA, a population with much variation. These systems range from an optimized linear system with a regular grade to an unconstrained optimized system with a grade break at each size. The optimized sizing systems compare favorably with D5585‐94 in their ability to accommodate variation in the population based on a mathematical test of the aggregate loss of each system. Issues related to pattern grading, size selection, and calculation of stock keeping units are discussed.

Intraspecific morphological variation in a freshwater copepod (Crustacea) in relation to geographic distribution and environment

Intraspecific variation in morphology was studied by means of morphometric analysis in 52 populations of the freshwater planktonic copepod Cyclops scutifer G.O. Sars from Eurasia and North America. The species showed very conservative morphology over wide geographic areas and subspecies could not be established. Variations occurred irregularly, and morphologically very similar forms were found widely separated on different continents. Correlation analysis revealed that many morphological relations were correlated with environmental factors such as depth, temperature, and trophic condition. Variations in body proportions were thus related to environmental factors rather than to geographic distance.

Population‐specific stature reconstruction for medieval Trondheim, Norway

AbstractTemporal changes in average stature are often used as a measure of a past population's adaptation, or lack of it. Traditionally, stature estimates have been calculated using formulae derived from limb proportions of cadavers. However, many authors have noted the problem of regional or population variation in body proportions of such reconstructed ratios. Before differences in stature can be attributed to environmental adaptation, ‘ethnic’ or population differences in limb ratios must be taken into account. The present paper calculates the stature of a medieval Norwegian skeletal sample using archaeological plan femur length and dry bone femur length. The author presents a variety of formulae and compares the stature derived from these calculations to the stature derived from archaeological plans. The Trondheim statures are then compared to stature reconstructions of other contemporary populations.

Body Proportionality and Head and Length `Sparing' in Growth-Retarded Neonates: A Critical Reappraisal

Despite the popular current distinction between "proportional" and "disproportional" intrauterine growth retardation, it has never been shown that variation in body proportions is greater among growth-retarded than nongrowth-retarded infants of the same birth weight, nor that proportionality is distributed bimodally among growth-retarded infants. Based on a cohort of 8719 neonates born between 1980 and 1986 of mothers with concordant (+/- 7 days) menstrual dating and early ultrasound estimates of gestational age, we used a continuous measure of birth weight for gestational age to define four study groups: nongrowth retarded (n = 5163) and mild (n = 411), moderate (n = 226), and severe (n = 147) intrauterine growth retardation. Compared with non-growth-retarded infants of the same gestational age, growth-retarded infants had substantially lower lengths, head circumferences, and proportionality ratios, and the magnitude of the deficits increased significantly with increasing degrees of growth retardation. When the comparison was based on birth weight rather than gestational age, however, growth-retarded infants had slightly but significantly greater lengths and head circumferences, with increased variability in body proportions, but no evidence of the bimodality that would characterize two distinct subtypes. The analysis suggests that proportionality among intrauterine growth-retarded infants represents a continuum, with progressive disproportionality as severity of growth retardation increases. Moreover, despite evidence of some "sparing," the absolute magnitudes of the deficits in length and head growth remain substantial.

Some Characteristics of the Pelagic Redfish (Sebastes Mentella Travin) from Weather Station Alfax

The existence of a permanent pelagic population of the redfish Sebastes mentella Travin in the Irminger Sea has been confirmed as a result of successful angling trials carried out by ships occupying Weather Station Alfa (62°N, 33°W) during the years 1962 to 1965. No specimens of S. marinus or ‘intermediate’ forms were found amongst the 207 specimens returned to the laboratory. The sample was predominantly female (7:1) although males were found in equal or greater numbers in the period late December to March. All females were sexually mature and all males were approaching or had reached full sexual maturity. Captures were made at depths ranging from 50 to 350 m but chiefly between 100 and 150 m in the summer. Fishing was most successful during the periods May to August and December to March. There was considerable but continuous variation in body proportions and age/length relationships. Much less variation occurred in the numbers of vertebrae and of pyloric caeca. Allowing one pair of growth rings to one year's growth, it is thought that the ages ranged from approximately 15 to 57 years, with a mean age of 31 years and it is believed that sexual maturity in females occurs between 15 and 25 years of age. Fecundity, which varies according to size (length), ranges from approximately 20,000 to 150,000. No evidence was obtained to show the relationship of this population to any other redfish population nor is there any clear evidence to demonstrate migration or movement. The seasonal variation in the number of males caught at Station Alfa may possibly be due to either horizontal or vertical migration.

Some Aspects of the Life History and Ecology of the Salamander Leurognathus

Leurognathus inhabits trout streams in the southern Appalachian Mountains from southwestern Virginia to northeastern Georgia. These salamanders have a discontinuous distribution; they are strangely absent from some drainages. Specimens are best collected by diverting the flow of water so that a part of the stream bed is drained. This area is then carefully searched and the routed animals captured with the use of a funnel-shaped trap made of screen or fine-mesh hardware cloth. Some individuals attain a maximum snout-vent length of 78 mm and a weight of 13 grams. Generally males are larger than females, have a relatively wider head, less vomerine teeth, enlarged maxillary teeth, a larger and papillated cloaca, and an enlarged (but not conspictious) mental gland. Spawning occurs chiefly in June. Eggs are attached to the underside of a rock located in the main current. They average about 40 per clutch and hatch in about three months. Hatchlings average 11 mm in snoutvent length. The larval stage may be as short as 10 months or as long as 20 months. The average size at metamorphosis varies seasonally and geographically. It ranges from 25 to 38 mm; the over-all average is near 30 mm. Males reach sexual maturity when about 50 mm in snout-vent length and at least two years of age. Females mature when they are three years old and about 55 mm in size. Maximum size is probably approached at the age of five years. There is no evidence that either sex prefers a special habitat or that the sex ratio is other than one to one. Leurognathus are mainly noctural and secretive. They spend much time under rocks and feed almost exclusively on the larval or nymphal forms of aquatic insects. Much geographic and individual variation in body proportions and in coloration and markings occurs in this species. One of the most interesting types of variation involves the absence of dark pigment. These specimens are mostly whitish-yellow but may have dark blotches over both venter and dorsum. Some completely lack dark markings, but all have normal colored eyes and soles of the feet. The incidence of albinistic specimens has gradually increased from less than one per cent in 1954 to nine per cent in 1960. No albinistic larvae have been found. The smallest specimen showing such albinism measured 39 mm from snout to vent. However, some specimens as small as 45 mm were among the most albinistic ones collected. Thus a very conspicuous change in phenotype may occur in individuals and in populations within a relatively short period of time. A survey of the morphological features and adaptive trends of desmognathine salamanders supports retention of the genus Leurognathus. This content downloaded from 207.46.13.86 on Sun, 16 Oct 2016 04:35:27 UTC All use subject to http://about.jstor.org/terms 2 THE AMERICAN MIDLAND NATURALIST 67(1)