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PubMed2003

Growth-related changes in cell body size and succinate dehydrogenase activity of spinal motoneurons innervating the rat soleus muscle.

Cell body sizes and oxidative enzyme (succinate dehydrogenase) activities of spinal motoneurons innervating the soleus muscle were determined in rats ranging in postnatal age from 3 to 13 weeks. The soleus motoneurons were labeled by a retrograde neuronal tracer, nuclear yellow. The mean cell body sizes of motoneurons increased from 3 to 7 weeks of age, while the mean succinate dehydrogenase activities of motoneurons decreased from 3 to 7 weeks of age. There were no changes in mean cell body size or mean succinate dehydrogenase activity of motoneurons from 7 to 13 weeks of age. An inverse relationship between cell body size and succinate dehydrogenase activity of motoneurons was observed, irrespective of age. These results indicate that motoneurons innervating the rat soleus muscle show the adult pattern of cell body size and succinate dehydrogenase activity at an earlier stage of postnatal growth, 7 weeks of age.

Aging↗
PubMed2006

Geographic variation in body size: the effects of ambient temperature and precipitation.

Latitudinal trends in body size have been explained as a response to temperature- or water-related factors, which are predictors of primary production. We used the first principal component calculated from three body parameters (weight, body length and the greatest length of the skull) of a sample of mammals from Israel and Sinai to determine those species that vary in size geographically, and whether such variation is related to annual rainfall, average minimum January temperature and average maximum August temperature. We used a conservative approach to discern the effects of precipitation and temperature by applying sequential regression. Variable priorities were assigned according to their bivariate correlation with body size, except for rainfall and its interactions that entered into the model last. Eleven species (Acomys cahirinus, Apodemus mystacinus, Canis lupus, Crocidura suaveolens, Gerbillus dasyurus, Hyaena hyaena, Lepus capensis, Meles meles, Meriones tristrami, Rousettus aegyptius and Vulpes vulpes) of the 17 species examined varied in size geographically. In five of them, rainfall was positively related to body size, while in one species it was negatively related to it. Contrary to the prediction of Bergmann's rule, mean minimum January temperature was positively related to body size in five species and negatively related to body size in two species (C. suaveolens and G. dasyurus). As predicted by Bergmann's rule, maximum June temperature was negatively related to body size in three species, and positively so in one (L. capensis). Primary production, particularly in desert and semi-desert areas, is determined mainly by precipitation. The above results indicate that, in our sample, primary production has an important effect on body size of several species of mammals. This is evident from the considerable proportion of the variability in body size explained by rain. However, low ambient temperatures may slow down and even inhibit photosynthesis. Hence, the observed positive relationships between average minimum January temperature and body size in four of the six species influenced by rain further support this conclusion.

Animals↗
PubMed1990

Body size and breast cancer prognosis: a critical review of the evidence.

There is currently controversy about the effect of body size on the prognosis of patients with breast cancer. In order to clarify the prognostic importance of body size, and to determine whether the effect varies across subgroups of patients, a critical appraisal of the published literature was undertaken. Thirteen cohort studies and one case-control study were identified that examined the prognostic effect of body size. Methodologic standards were developed that reflected those features of study design considered most important in studies of prognosis in breast cancer, and were independently applied to each report by each of the authors. When the effects of methodologic differences among the studies were controlled, a modest prognostic effect of body size was identified. This effect appeared to be greatest in postmenopausal women, in those with little or no involvement of axillary nodes, and to be independent of other prognostic factors. Additional investigation is recommended to determine the prognostic effects of body size in postmenopausal women with axillary node negative breast cancer and in women receiving systemic adjuvant therapy, and to determine the pathophysiological basis for these effects. Intervention studies to determine the effects of altering body size may also be indicated.

Body Constitution↗
PubMed2000

Initial studies on the contributions of body size and gastrointestinal passage rates to dietary flexibility among gorillas.

Large body size has been traditionally seen as the primary dietary adaptation of gorillas, facilitating their consumption of fibrous foods (Schaller ¿1963 The Mountain Gorilla; Watts ¿1990 Int. J. Primatol. 11:21-45). Nevertheless, recent research has emphasized frugivory among western lowland gorillas, as well as the influence of habitat and seasonality on gorilla diet and behavior across subspecies (Watts ¿1990 Int. J. Primatol. 11:21-45; Tutin et al. ¿1991 Philos. R. Soc. Trans. Lond. Biol. 334:179-186; Remis ¿1994 Ph.D. Thesis, ¿1997a Am. J. Primatol. 43:87-109, ¿1997b Am. J. Primatol. 43:111-133, ¿1998 Primate Locomotion: Recent Advances, p 95-(1)108, ¿1999 Primates 40:383-396; Nishihara ¿1995 Primates 36:151-168; Goldsmith ¿1999a Int. J. Primatol. 20:1-23, Goldsmith [1999b] Nonhuman Primates, p 58-63). This study provides preliminary data to address the physiological underpinnings of dietary flexibility among gorillas, and their consumption of a broad range of fibrous and tannin-rich foods. To date, little is known about the digestive physiology of the African apes (but see Milton ¿1984 Adaptations for Foraging in Nonhuman Primates, p 249-279, Milton [1984] ¿1999Evol. Anthropol. 8:11-20; Milton and Demment ¿1988 J. Nutr. 118:1082-1088; Lambert ¿1997 Ph.D. Dissertation), although gastrointestinal morphology and proportions are roughly similar among species ( Chivers and Hladik ¿1980 J. Morphol. 166:337-386). This study provides additional experimental data on the gastrointestinal passage times of gorillas (Gorilla gorilla gorilla) fed a captive diet in a zoological park setting and discusses results in relation to field research on gorilla feeding ecology. In this study, 480 small plastic markers were fed to six captive gorillas. The mean gut retention time (MRT) of the adult gorillas in this study was 50 hr, longer than the 31 hr reported for chimpanzees fed a similar diet (Lambert ¿1997 Ph.D. Dissertation). These data suggest that gorillas may retain foods in their gastrointestinal tracts longer than smaller hominoids, and that the large body size likely forms the primary basis for consumption of fiber. This research provides additional data to contribute to our understanding of the relationships of body size and morphology to ecology, and the evolution of body size, foraging strategy and social organization among the African apes.

Adaptation, Physiological↗
PubMed2004

Frugivory in polychrotid lizards: effects of body size.

As more data have become available on lizard diets in the past few decades, researchers have stressed the importance of lizards as pollinators and seed dispersers. Whereas large body size has been traditionally put forward as a major biological factor "allowing" herbivory and frugivory in lizards, a recent review of frugivory and seed dispersal by lizards showed that frugivory might be considered to be a typical island phenomenon, independent of body size. Here we show that frugivory is correlated with lizard body size among a group of syntopic Anolis species in Jamaica, with larger species eating more fruit. Additionally, the size of the fruits consumed is significantly related to lizard body size. Multiple regression analyses show that this is largely a pure body size effect as head shape or residual bite force are uncorrelated to overall fruit size. Moreover, we demonstrate that among polychrotid (Anolis-like) lizards in general, those that consume fruit are on average larger than those that do not. Lizards from the mainland were not significantly different in body size from island species. We thus suggest that fruit consumption in polychrotid lizards is mediated by large body size whether living on islands or not.

Animals↗
PubMed2003

Mothers influence offspring body size through post-oviposition maternal effects in the redbacked salamander, Plethodon cinereus.

In the terrestrial salamander (Plethodon cinereus), previous work has shown that mother's body size is positively correlated to offspring size at the time of hatching even after controlling for the effects of egg size. This study was designed to determine whether maternal body size affects offspring size via pre-oviposition factors (e.g., yolk quality, jelly coat composition, or maternal genes) or post-oviposition factors (e.g., parental care behaviors, parental modification of environment). Gravid females were captured and induced to lay eggs in experimental chambers in which the environment was standardized. Fifteen clutches were exchanged, or cross-fostered, between female pairs differing in body size. Ten females whose eggs were taken away and then returned served as controls for the crossing treatment. Foster mothers did not significantly differ from control mothers in the time spent with eggs, body position, or number of egg movements during brooding. Average egg mass measured midway through development was not significantly correlated to the body size of either the genetic or foster mother, but was correlated to pre-oviposition oocyte size. At hatching, offspring body length was positively correlated to egg size and the foster mother's body size. This correlation suggests that in P. cinereus post-oviposition maternal effects have a greater impact on offspring size than other maternal factors incorporated into the egg prior to oviposition. While our study showed that larger mothers moved their eggs less often and tended to spend more time in contact with their eggs, further work needs to be done to identify the specific mechanisms through which larger mothers influence the body size of their offspring. This is the first experimental demonstration of post-oviposition maternal effects for any amphibian with parental care.

Animals↗
PubMed1998

Body size and risk of kidney stones.

A variety of factors influence the formation of calcium oxalate kidney stones, including gender, diet, and urinary excretion of calcium, oxalate, and uric acid. Several of these factors may be related to body size. Because men on average have a larger body size and a threefold higher lifetime risk of stone formation than women, body size may be an important risk factor for calcium oxalate stone formation. The association between body size (height, weight, and body mass index) and the risk of kidney stone formation was studied in two large cohorts: the Nurses' Health Study (NHS; n = 89,376 women) and the Health Professionals Follow-up Study (HPFS; n = 51,529 men). Information on body size, kidney stone formation, and other exposures of interest was obtained by mailed questionnaires. A total of 1078 incident cases of kidney stones in NHS during 14 yr of follow-up and a total of 956 cases in HPFS during 8 yr of follow-up were confirmed. In both cohorts, the prevalence of a stone disease history and the incidence of stone disease were directly associated with weight and body mass index. However, the magnitude of the associations was consistently greater among women. Specifically, the age-adjusted prevalence odds ratio for women with body mass index > or = 32 kg/m2 compared with 21 to 22.9 kg/m2 was 1.76 (95% confidence interval, 1.50 to 2.07), but 1.38 (95% confidence interval, 1.16 to 1.65) for the same comparison in men. For incident stone formation, the multivariate relative risks for the similar comparisons were 1.89 (1.51 to 2.36) for women and 1.19 (0.83 to 1.70) in men. Height was inversely associated with the prevalence of stone disease but was not associated with incident stone formation. These results suggest that body size is associated with the risk of stone formation and that the magnitude of risk varies by gender. Additional studies are necessary to determine whether a reduction in body weight decreases the risk of stone formation, particularly in women.

Adult↗
PubMed2003

Empirical evidence for an optimal body size in snakes.

The concept of optimal size has been invoked to explain patterns in body size of terrestrial mammals. However, the generality of this phenomenon has not been tested with similarly complete data from other taxonomic groups. In this study we describe three statistical patterns of body size in snakes, all of which indicate an optimal length of 1.0 m. First, a distribution of largest body lengths of 618 snake species had a single mode at 1.0 m. Second, we found a positive relationship between the size of the largest member of an island snake assemblage and island area and a negative relationship between the size of the smallest member of an island snake assemblage and island area. Best-fit lines through these data cross at a point corresponding to 1.0 m in body length, the presumed optimal size for a one-species island. Third, mainland snake species smaller than 1.0 m become larger on islands whereas those larger than 1.0 m become smaller on islands. The observation that all three analyses converge on a common body size is concordant with patterns observed in mammals and partial analyses of four other disparate animal clades. Because snakes differ so strikingly from mammals (ectotherms, gape-limited predators, elongate body shape) the concordant patterns of these two groups provide strong evidence for the evolution of an optimal body size within independent monophyletic groups. However, snakes differ from other taxonomic groups that have been studied in exhibiting a body size distribution that is not obviously skewed in either direction. We suggest that idiosyncratic features of the natural history of ectotherms allow relatively unconstrained distributions of body size whereas physiological limitations of endotherms constrain distributions of body size to a right skew.

Animals↗
PubMed2006

Selection on body size and sexual size dimorphism differs between host species in a seed-feeding beetle.

Sexual size dimorphism varies substantially among populations and species but we have little understanding of the sources of selection generating this variation. We used path analysis to study how oviposition host affects selection on body size in a seed-feeding beetle (Stator limbatus) in which males contribute large ejaculates (nuptial gifts) to females. Females use nutrients in these ejaculates for egg production. Male body size, which affects ejaculate size, affects female fecundity and is thus under fecundity selection similar in magnitude to the fecundity selection on female body size. We show that when eggs are laid on a host on which larval mortality is low (seeds of Acacia greggii) fecundity predicts fitness very well and fecundity selection is the major source of selection on both male and female adult size. In contrast, when eggs are laid on a host on which larval mortality is high (seeds of Parkinsonia florida) fecundity poorly predicts fitness such that fecundity selection is relaxed on both male and female size. However, because egg size affects larval mortality on this poor host (P. florida) there is selection on female size via the female size --> egg size --> fitness path; this selection via egg size offsets the reduction in fecundity selection on female, but not male, body size. Thus, differences in host suitability (due to differences in larval mortality) affect the relative importance of two sources of selection on adult body size; fecundity selection on both male and female body size is lower on the poor quality host (P. florida) relative to the high quality host (A. greggii) whereas selection on female body size via effects of egg size on offspring survival (body size --> egg size --> fitness) is greater on the poor quality host relative to the high quality host. Because selection via the egg size path affects only females the difference in larval survival between hosts shifts the relative magnitude of selection on female vs. male size. Researchers working on other study systems should be alerted to the possible importance of subtle, but consequential, indirect selection on their study organisms.

Animals↗
PubMed2006

Body size changes among otters, Lutra lutra, in Norway: the possible effects of food availability and global warming.

Using museum data of adult specimens whose sex, age, and locality are known, we studied temporal and geographical body size trends among the otter, Lutra lutra, in Norway. We found that body size of the otters increased during the last quarter of the twentieth century, and suggest that this trend is related to increased food availability from fish farming and possibly also to energy saving due to elevated sea temperatures. Birth year and death year explained 38.8 and 43.5%, respectively, of the variation in body size. Body size of otters was positively related to latitude, thus conforming to Bergmann's rule.

Animals↗
PubMed1993

The role of body size in somatosensory testing.

To try to replicate our earlier findings of body size influences in somatosensory testing we measured thresholds of heat pain, warmth, cold and vibration in 66 young, normal-weight women. Our assumption was that true body measure effects have to be demonstrable even in a sample limited with regard to age and sex and without extreme body size variation (which may be linked to pathology). In the present sample, body size (a linear combination of height and weight) did not have a very strong relation with any of the somatosensory thresholds (slightly stronger for the warmth and cold thresholds than for the heat pain and vibration thresholds). Hence, we could not fully replicate our earlier findings of marked body size effects on warmth and cold thresholds obtained in a sample without such limits. A measure of the body fat content seemed to have some explanatory power, but only for the vibration thresholds. We conclude that body measures, age and sex may be confounded in a way that cannot always be sorted out by a posteriori analyses and should therefore be treated a priori as independent variables for purposes such as establishing normal values in somatosensory testing.

Adult↗
PubMed2006

Relationship between adiposity and body size reveals limitations of BMI.

The aims of this study were to assess 1) whether the stature-adjusted body mass index (BMI) is a valid proxy for adiposity across both athletic and nonathletic populations, and 2) whether skinfold measurements increase in proportion to body size, thus obeying the principle of geometric similarity. The research design was cross-sectional, allowing the relationship between skinfold calliper readings (at eight sites and between specific athletic and nonathletic groups, n = 478) and body size (either mass, stature, or both) to be explored both collectively, using proportional allometric MANCOVA, and individually (for each site) with follow-up ANCOVAs. Skinfolds increase at a much greater rate relative to body mass than that assumed by geometric similarity, but taller subjects had less rather than more adiposity, calling into question the use of the traditional skinfold-stature adjustment, 170.18/stature. The best body-size index reflective of skinfold measurements was a stature-adjusted body mass index similar to the BMI. However, sporting differences in skinfold thickness persisted, having controlled for differences in body size (approximate BMI) and age, with male strength- and speed-trained athletes having significantly lower skinfolds (32% and 23%, respectively) compared with controls. Similarly, female strength athletes had 29% lower skinfold measurements compared to controls, having controlled for body size and age. These results cast serious doubts on the validity of BMI to represent adiposity accurately and its ability to differentiate between populations. These findings suggest a more valid (less biased) assessment of fatness will be obtained using surface anthropometry such as skinfolds taken by experienced practitioners following established procedures.

Adiposity↗
PubMed2006

Climate change, body size evolution, and Cope's Rule in deep-sea ostracodes.

Causes of macroevolutionary trends in body size, such as Cope's Rule, the tendency of body size to increase over time, remain poorly understood. We used size measurements from Cenozoic populations of the ostracode genus Poseidonamicus, in conjunction with phylogeny and paleotemperature estimates, to show that climatic cooling leads to significant increases in body size, both overall and within individual lineages. The magnitude of size increase due to Cenozoic cooling is consistent with temperature-size relationships in geographically separated modern populations (Bergmann's Rule). Thus population-level phenotypic evolution in response to climate change can be an important determinant of macroevolutionary trends in body size.

Animals↗
PubMed2006

Cope's rule in cryptodiran turtles: do the body sizes of extant species reflect a trend of phyletic size increase?

Cope's rule of phyletic size increase is questioned as a general pattern of body size evolution. Most studies of Cope's rule have examined trends in the paleontological record. However, neontological approaches are now possible due to the development of model-based comparative methods, as well as the availability of an abundance of phylogenetic data. I examined whether the phylogenetic distribution of body sizes in extant cryptodiran turtles is consistent with Cope's rule. To do this, I examined body size evolution in each of six major clades of cryptodiran turtles and also across the whole tree of cryptodirans (n = 201 taxa). Extant cryptodiran turtles do not appear to follow Cope's rule, as no clade showed a significant phyletic body size trend. Previous analyses in other extant vertebrates have also found no evidence for phyletic size increase, which is in contrast to the paleontological data that support the rule in a number of extinct vertebrate taxa.

Animals↗
PubMed1977

Sexual dimorphism in metacarpal dimensions and body size of Mexican school children.

The hypothesis that patterns of sexual dimorphism in transverse dimensions of the metacarpal only reflect sex differences in body size was investigated in a sample of 324 Mexican school children 6.00-10.99 years of age. Several patterns of sexual dimorphism in second metacarpal dimensions are seen with regard to stature and weight. Sex differences in medullary diameter and percent cortical area are not related to sexual dimorphism in body size, while sex differences in cortical thickness are related to, but not fully explained by, differences in body size. Dimorphism in metacarpal diaphyseal diameter is related to differences in body size, but, at a constant body size and age, boys still have significantly larger diaphyseal diameters than girls. Finally, sexual dimorphism in cortical area is closely associated with sex differences in body size.

Age Factors↗
PubMed2000

Ethnic differences in perceptions of body size in middle-aged European, Maori and Pacific people living in New Zealand.

OBJECTIVES: The aim of this study was to compare perceptions of body size in European, Maori and Pacific Islands people with measured body mass index (BMI), waist-to-hip ratio and change in BMI since age 21 y. Socio-demographic factors that influenced perceptions of body size were also investigated. DESIGN: Cross-sectional survey. METHODS: Participants were 5554 workers, aged > or =40 y, recruited from companies in New Zealand during 1988-1990. RESULTS: Prevalences of BMI>25 kg/m2 were: Europeans, 64.7% men, 47.2% women; Maori, 93.2% men, 80.6% women; and Pacific Islanders, 94.1% men, 92.9% women. Similarly, prevalences of BMI >30 kg/m2 were: Europeans, 14.4% men, 14.6% women; Maori, 55.0% men, 41.9% women; and Pacific Islanders, 55.1% men, 71.7% women. At each perception of body size category, Maori and Pacific Islands men and women had a higher BMI than European men and women, respectively. BMI increased with increasing perception of body size in all gender and ethnic groups. Since age 21, increases in BMI were highest in Pacific Islands people and increased with increasing perceptions of body size category in all ethnic and gender groups. BMI adjusted odds (95% CI) of being in a lower perception category for body size were 1.70 (1.38-2.12) in Maori and 8.99 (7.30-11.09) in Pacific people compared to Europeans, 1.27 (1.13-1.42) times higher for people with no tertiary education, 1.41 (1.25-1.59) times higher in people with low socioeconomic status, and 0.94 (0.92- 0.95) for change in BMI since age 21. CONCLUSION: Nutritional programs aimed at reducing levels of obesity should be ethnic-specific, addressing food and health in the context of their culture, and also take into account the socioeconomic status of the group. On the population level, obesity reduction programs may be more beneficial if they are aimed at the maintenance of weight at age 21.

Adult↗
PubMed1997

Vocal tract length and formant frequency dispersion correlate with body size in rhesus macaques.

Body weight, length, and vocal tract length were measured for 23 rhesus macaques (Macaca mulatta) of various sizes using radiographs and computer graphic techniques. linear predictive coding analysis of tape-recorded threat vocalizations were used to determine vocal tract resonance frequencies ("formants") for the same animals. A new acoustic variable is proposed, "formant dispersion," which should theoretically depend upon vocal tract length. Formant dispersion is the averaged difference between successive formant frequencies, and was found to be closely tied to both vocal tract length and body size. Despite the common claim that voice fundamental frequency (F0) provides an acoustic indication of body size, repeated investigations have failed to support such a relationship in many vertebrate species including humans. Formant dispersion, unlike voice pitch, is proposed to be a reliable predictor of body size in macaques, and probably many other species.

Acoustics↗
PubMed2003

Temperature dependent larval resource allocation shaping adult body size in Drosophila melanogaster.

Geographical variation in Drosophila melanogaster body size is a long-standing problem of life-history evolution. Adaptation to a cold climate invariably produces large individuals, whereas evolution in tropical regions result in small individuals. The proximate mechanism was suggested to involve thermal evolution of resource processing by the developing larvae. In this study an attempt is made to merge proximate explanations, featuring temperature sensitivity of larval resource processing, and ultimate approaches focusing on adult and pre-adult life-history traits. To address the issue of temperature dependent resource allocation to adult size vs. larval survival, feeding was stopped at several stages during the larval development. Under these conditions of food deprivation, two temperate and two tropical populations reared at high and low temperatures produced different adult body sizes coinciding with different probabilities to reach the adult stage. In all cases a phenotypic trade-off between larval survival and adult size was observed. However, the underlying pattern of larval resource allocation differed between the geographical populations. In the temperate populations larval age but not weight predicted survival. Temperate larvae did not invest accumulated resources in survival, instead they preserved larval biomass to benefit adult weight. In other words, larvae from temperate populations failed to re-allocate accumulated resources to facilitate their survival. A low percentage of the larvae survived to adulthood but produced relatively large flies. Conversely, in tropical populations larval weight but not age determined the probability to reach adulthood. Tropical larvae did not invest in adult size, but facilitated their own survival. Most larvae succeeded in pupating but then produced small adults. The underlying physiological mechanism seemed to be an evolved difference in the accessibility of glycogen reserves as a result of thermal adaptation. At low rearing temperatures and in the temperate populations, glycogen levels tended to correlate positively with adult size but negatively with pupation probability. The data presented here offer an explanation of geographical variation in body size by showing that thermal evolution of resource allocation, specifically the ability to access glycogen storage, is the proximate mechanism responsible for the life-history trade-off between larval survival and adult size.

Adaptation, Physiological↗