Testicle size of orang-utans in relation to body size

Few data are available for assessing the relative testicle size of orang-utans, Pongo pygmaeus, so measures were obtained for 31 individuals of varying age. It was shown that the volume of the testicles, calculated from in situ measures of testicle length and breadth, closely approximates testicle weight when multiplied by the specific gravity of solid tissue. Growth curves for body weight and data published for wild specimens were evaluated to obtain the weight most characteristic of male Pongo, and the ratio of testicle weight to body weight was calculated. The mean ratio for individuals with fully adult stature is 0.034, similar to but smaller than that of humans at about 0.050, and larger than the ratios reported for 5 gorillas at 0.013. The testicles mature faster than the body, however, so the mean ratio for young adult orang-utans is about 0.056 and resembles the ratio for humans more closely than the full adults. The differences between the ratios for a monogamous gibbon species, orang-utans, and humans is accounted for when testicle size relative to the weight of the female is considered. This is consistent with a sperm dilution effect produced by variation in the size of the female reproductive tract. The small relative testicle size of the gorilla is anomalous and requires verification as does the application of female size to scale the testicles. © 1993 Wiley-Liss, Inc.     

Pelvic dimorphism in relation to body size and body size dimorphism in humans

Many mammalian species display sexual dimorphism in the pelvis, where females possess larger dimensions of the obstetric (pelvic) canal than males. This is contrary to the general pattern of body size dimorphism, where males are larger than females. Pelvic dimorphism is often attributed to selection relating to parturition, or as a developmental consequence of secondary sexual differentiation (different allometric growth trajectories of each sex). Among anthropoid primates, species with higher body size dimorphism have higher pelvic dimorphism (in converse directions), which is consistent with an explanation of differential growth trajectories for pelvic dimorphism. This study investigates whether the pattern holds intraspecifically in humans by asking: Do human populations with high body size dimorphism also display high pelvic dimorphism? Previous research demonstrated that in some small-bodied populations, relative pelvic canal size can be larger than in large-bodied populations, while others have suggested that larger-bodied human populations display greater body size dimorphism. Eleven human skeletal samples (total N: male = 229, female = 208) were utilized, representing a range of body sizes and geographical regions. Skeletal measurements of the pelvis and femur were collected and indices of sexual dimorphism for the pelvis and femur were calculated for each sample [ln(M/F)]. Linear regression was used to examine the relationships between indices of pelvic and femoral size dimorphism, and between pelvic dimorphism and female femoral size. Contrary to expectations, the results suggest that pelvic dimorphism in humans is generally not correlated with body size dimorphism or female body size. These results indicate that divergent patterns of dimorphism exist for the pelvis and body size in humans. Implications for the evaluation of the evolution of pelvic dimorphism and rotational childbirth in Homo are considered.     

Mammalian reproductive strategies: A generalized relation of litter size to body size

Summary A generalized relationship of litter size to mammalian body size was predicted by a graph model. The model was used to generate hypotheses explaining specific features of variation in gestation time, relative litter weight, birth weight, and reproductive capacity. The predictions were tested by means of data from the literature.Mammals were assumed to maximize neonatal survival of offspring to the limits allowed by litter weight per female body weight. Gestation time correlated negatively with the foetal growth rate of relative litter weight. Gestation time did not correlate with the foetal growth rate of individual offspring.Relative litter weight correlated negatively with adult body weight. This relationship was explained by the higher assimilation rate per unit weight relative to metabolic rate in small mammals.Birth weight correlated positively with body weight. However, small mammals produce larger offspring than predicted by the linear relationship of birth weight to body weight in large mammals. There is obviously a minimum birth weight which cannot be decreased without special arrangements for parental care.The prediction of the relationship of litter size to body size was derived from the relations of relative litter weight and birth weight to body weight. In small mammals (less than 1 kg) litter the correlation was negative. When litter size was compared with body length, the correlation was positive in small mammals (less than 30 cm) and negative in large mammals. In both sets of data there was a negative overall correlation between litter size and body size.Reproductive capacity, defined as the number of offspring per season, correlated negatively with life-span.     

Optimal diving behaviour for foraging in relation to body size

Overall, large animals dive longer and deeper than small animals; however, after the difference in body size is taken into account, smaller divers often tend to make relatively longer dives. Neither physiological nor theoretical explanations have been provided for this paradox. This paper develops an optimal foraging diving model to demonstrate the effect of body size on diving behaviour, and discusses optimal diving behaviour in relation to body size. The general features of the results are: (1) smaller divers should rely more heavily on anaerobic respiration, (2) larger divers should not always make longer dives than smaller divers, and (3) an optimal body size exists for each diving depth. These results explain the relatively greater diving ability observed in smaller divers, and suggest that if the vertical distribution of prey in the water column is patchy, there is opportunity for a population of diving animals to occupy habitat niches related to body size.     

Behavioural variation in juvenile Arctic charr in relation to body size

Young Arctic charr Salvelinus alpinus , derived from one male and one female only from Lake Ölvesvatn in northern Iceland (a stock that has been popular in Icelandic aquaculture), showed large variance in body size, primarily as a consequence of variable egg size. Shortly after the onset of exogenous feeding, large fish (0·11–0·14 g) were more active and fed mainly from the water surface. Small fish (0·06–0·09 g) moved less and made fewer foraging attempts. They spent most of the time on the bottom, and foraged equally on the bottom and surface. These findings can be used to improve growth and performance of juveniles in rearing tanks.     

Airway thermal volume in humans and its relation to body size

Serikov, Vladimir B., E. Heidi Jerome, Neal W. Fleming,Peter G. Moore, Frederick A. Stawitcke, and Norman C. Staub.Airway thermal volume in humans and its relation to body size.J. Appl. Physiol. 83(2): 668-676, 1997.The objective of this study was to investigate the influence ofvolume ventilation(E) andcardiac output () on the temperature of the expiredgas at the distal end of the endotracheal tube in anesthetized humans.In 63 mechanically ventilated adults, we used a step decrease in thehumidity of inspired gas to cool the lungs. After change from humid todry gas ventilation, the temperature of the expired gas decreased. Weevaluated the relationship between the inverse monoexponential timeconstant of the temperature fall (1/) and eitherE or . WhenE wasincreased from 5.67 ± 1.28 to 7.14 ± 1.60 (SD) l/min(P = 0.02), 1/ did not changesignificantly [from 1.25 ± 0.38 to 1.21 ± 0.51 min¹,P = 0.81]. In the 11 patients in whom changed during the study period(from 5.07 ± 1.81 to 7.38 ± 2.45 l/min,P = 0.02), 1/ increasedcorrespondingly from 0.89 ± 0.22 to 1.52 ± 0.44 min¹(P = 0.003). We calculated the airwaythermal volume (ATV) as the ratio of the measured values to 1/ and related it to the body height (BH):ATV (liters) = 0.086 BH (cm)  9.55 (r = 0.90).

     

The metabolic rate of roach in relation to body size and temperature

Standard and routine metabolic rates of roach Rutilus rutilus for a wide size and temperature range (3–200 g, 5–23° C) were analysed by automated, computerized intermittent flow respirometry. The mass exponent b ranged from 0·68 to 0·82 for standard metabolism, and from 0·65 to 0·92 for routine metabolism depending on the experimental temperature. For routine metabolism b was lowest at 10° C. At both decreasing and increasing temperatures, b increased significantly. Roach were exponentially temperature-dependent for both metabolic levels. For roach <20 g, however, an asymptotic relationship was observed between temperature and routine metabolic rate. The 'flattening of the curve' in the latter case may be explained by reduced spontaneous activities at the lower threshold of the preferred temperature range.     

Physiological energetics of the ascidian Styela clava in relation to body size and temperature

The ascidian Styela clava is widely distributed in northern China and is thought to be important in the functioning of estuarine systems. This ascidian may experience highly variable physiological conditions, and its physiological responses to these are of interest considering its ecological role. This study presents data on the physiological parameters in relation to body size and temperature (12-28 degrees C) of S. clava. Respiration, excretion, feces, ingestion and absorption energy were positive related to size and its mass exponents (b-values) varied from 0.2930 to 0.7488. Respiration energy increased with increasing, but critical values were found at 20 degrees C for energy of ingestion and absorption, while 24 degrees C for energy in feces and excretion. At the range of 16-24 degrees C, the scope for growth, gross and net growth efficiencies of ascidians increased with increasing temperature. The energy budget equations of different sized ascidians were obtained at different temperatures. Excretion energy shared a minimal fraction in ingestion energy (1.30-2.47%), the ratios of feces energy and respiration energy to ingestion energy were 46.53-64.27% and 10.26-80.75%, respectively. The physiological data obtained in the present study indicated that S. clava could adjust its energy budget according to the environment and its physiological conditions to meet their nutritional and energetic demands. In the range of experimental temperature (12-28 degrees C), 16-20 degrees C was suitable for the rearing of S. clava to achieve optimum development, while deficient metabolic adjustment induced a negative scope for growth of S. clava at 28 degrees C.     

Ejaculate traits in relation to male body size in the eastern mosquitofish Gambusia holbrooki

In the present study, the correlation between sperm number, sperm quality (speed, viability, longevity and length), sperm bundles quality (size and dissolving rate) and male body size has been tested in the eastern mosquitofish Gambusia holbrooki a poecilid species characterized by coercive mating tactics where males do not possess obvious ornaments, and the body size is the key determinant of pre‐copulatory male mating success. The results do not tally with theoretical predictions. Indeed, no correlation between male body size and either sperm or sperm‐bundle traits has been found, evidencing the lack of the theoretically expected trade‐off between the investment in characters involved in mate acquisition and the investment in ejaculate quality. An explanation for the observed pattern comes from the extremely dynamic mating system of G. holbrooki, characterized by variable size‐related male mating success and strong post‐copulatory selective pressure, with all males facing a similar high level of sperm competition. In this situation, a higher investment in growth and maintenance at the expense of ejaculate quality is not expected. These results underscore the necessity to comprehend detailed information on species’ reproductive biology and reproductive environment to understand both the evolution of ejaculate characteristics and possible deviations from theoretical predictions.     

Characteristics of the alula in relation to wing and body size in the Laridae and Sternidae

The alula is a small structure present on the leading edge of bird wings and is known to enhance lift by creating a small vortex at its tip. Alula size vary among birds, but how this variation is associated with the function of the alula remains unclear. In this study, we investigated the relationship between the size and shape of the alula and the features of the wing in the Laridae and Sternidae. Laridae birds have generally longer wings and greater loadings than Sternidae birds. The two families differed in the relationships between body size or wing length and the size or shape of the alula. In the Laridae, the aspect ratio of the alula was smaller in the species that have relatively longer wings, but the pattern was opposite in the Sternidae. The aspect ratio of the alula was greater in the species that are relatively heavier in the Sternidae but not in the Laridae. Combined, these results suggest that the species with high loading potential and long wings exhibit long alula. We hypothesize that heavier species may benefit from having longer alula if they perform flights with higher attack angles than lighter species, as longer alula would better suppress flow separation at higher attack angles. Our results suggest that the size and shape of the alula can be explained in one allometric landscape defined by wing length and loading in these two closely related families of birds with similar wing shapes.     

Growth response of pikeperch larvae in relation to body size and zooplankton abundance

The most critical period at onset of feeding in pikeperch Stizostedion lucioperca is short (<5 days at 20° C). The larvae are sensitive to prey density during the first week of exogenous feeding. First-feeding larvae of 6.5 mm total length ( L_T ) needed prey densities of >585 prey l⁻¹ to maintain mass (C_maint), whereas 5 days older larvae of 7 mm L _T C_maint= 55 prey l⁻¹ and for 11 mm L _T larvae C_maint<10 prey 1⁻¹. Changes in specific growth rates for larvae of 7 and 11 mm were similar to a type-II functional response curve reaching a specific growth rate of 26 and 30% day⁻¹, respectively, at 1000 prey l⁻¹, whereas the 6·5 mm larvae showed a linear growth response reaching a specific growth rate of only 9% day ⁻¹ at 1000 prey l⁻¹. The results suggest that prey density is a limiting factor, which might contribute to the high variation between year-class Strengths.     

Bony pelvic canal size and shape in relation to body proportionality in humans

Obstetric selection acts on the female pelvic canal to accommodate the human neonate and contributes to pelvic sexual dimorphism. There is a complex relationship between selection for obstetric sufficiency and for overall body size in humans. The relationship between selective pressures may differ among populations of different body sizes and proportions, as pelvic canal dimensions vary among populations. Size and shape of the pelvic canal in relation to body size and shape were examined using nine skeletal samples (total female n = 57; male n = 84) from diverse geographical regions. Pelvic, vertebral, and lower limb bone measurements were collected. Principal component analyses demonstrate pelvic canal size and shape differences among the samples. Male multivariate variance in pelvic shape is greater than female variance for North and South Africans. High‐latitude samples have larger and broader bodies, and pelvic canals of larger size and, among females, relatively broader medio‐lateral dimensions relative to low‐latitude samples, which tend to display relatively expanded inlet antero‐posterior (A‐P) and posterior canal dimensions. Differences in canal shape exist among samples that are not associated with latitude or body size, suggesting independence of some canal shape characteristics from body size and shape. The South Africans are distinctive with very narrow bodies and small pelvic inlets relative to an elongated lower canal in A‐P and posterior lengths. Variation in pelvic canal geometry among populations is consistent with a high degree of evolvability in the human pelvis. Am J Phys Anthropol 151:88–101, 2013. © 2013 Wiley Periodicals, Inc.