Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Allometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
PubMed1992

Growth, development and allometry of Philophthalmus nocturnus in the eyes of domestic chicks.

Fifty day-old chicks were each infected with 10 excysted metacercariae of Philophthalmus nocturnus Looss, 1907 around each orbit and growth, development and allometry were studied. The growth rate showed two phases over a period of 35 days, a limited lag phase lasting two days post-infection in which flukes did not exceed 440 microns in length, and a rapid phase during which growth was rapid and flukes reached a size of 3.008-3.504 mm on day 35. Five developmental stages were noticed during the course of development of the metacercaria to the egg-producing adult stage. Eggs appeared in the uterus on day 14 and oculate miracidia on day 25. The hindbody, testes and ovary showed positive allometric growth, the pharnyx less so, whereas negative allometric growth was shown by the forebody. Body width, oral sucker and ventral sucker were close to isometry, growing at the same rate as the body length.

Animals↗
PubMed1979

Primate facial allometry and interpretations of australopithecine variation.

Pilbeam and Gould have discussed African Plio-Pleistocene hominid evolution in the context of allometry (size-dependent morphological change). These authors demonstrate that some general aspects of australopithecine morphology (tooth, brain and body size) support the hypothesis that certain early African hominids were merely scaled variations of each other at different sizes. They also speculate that the methods applied to these very broad anatomical categories can be extended to more specific and detailed traits, especially in the face and cranium. Such traits underlie most taxonomic and phylogenetic discussions of the early African Hominidae, so it is useful to follow Pilbeam and Gould's lead, as we do here, and investigate the structural differences in the australopithecine face and cranimum in a quantificiable fashion.

Africa↗
PubMed1999

Allometry of the cranial base in prepubertal Korean subjects with class III malocclusions: finite element morphometry.

Sphenoethmoidal allometry could be associated with ethnic heterogeneity of the midfacial profile. Thirteen cranial base landmarks were digitized from cephalographs of 69 Korean and 73 European American prepubertal children exhibiting Class III malocclusion. Average geometries were normalized, and a color-coded finite element (FEM) program was used to localize differences in morphology. ANOVA indicated that mean Korean and European American cranial base configurations differed statistically (p < 0.01); this was also true for seven age groups tested (p < 0.001). For size-change, FEM analysis revealed that in the anterior cranial base, Korean sphenoethmoidal and sella turcica regions were smaller (=12%). Local increases in size were apparent for the posterior region of the Korean cranial base (=35%). For shape-change, Korean and European American cranial base configurations were isotropic with minor anisotropy in the sphenoethmoidal and spheno-occipital regions. A sphenoethmoidal mechanism of midfacial retrognathism appears to be implicated in the development of a skeletal Class III morphology.

Analysis of Variance↗
PubMedDate not supplied

Longitudinal study of ontogenetic allometry of oxygen uptake in boys and girls grouped by maturity status.

The utility of removing the confounding effect of body mass on oxygen uptake by simply dividing the measured values by mass has been questioned: Allometric transformation or calculation of covariance analysis have been proposed as more appropriate alternatives. This study hypothesized that scaling factors for individual youths differ with maturity status. Peak oxygen uptake (peak VO2) during exercise on a bicycle ergometer, stature and body mass were measured at annual intervals in 47 active boys and 31 active girls from 11 to 14 years of age. All subjects attended sport schools during the study. The children were classified into two maturity categories, early and average (for the sake of sample size and consistency between sexes), and late on the basis of individual stature velocities in boys and age at menarche in girls. Individual data for peak VO2 were normalized for differences in body mass by double logarithmic transformation and regression analysis (ontogenetic allometry). Individual allometric coefficients (mean +/- SD) for boys showing a good fit were, respectively, 0.799 +/- 0.239 and 0.536 +/- 0.141 in early and average maturing boys combined and in late maturing boys. Logarithmic transforms of VO2 and mass were highly related (r > 0.90) in 10 of 16 early and average maturers, and in 18 of 31 late maturers. Corresponding individual allometric coefficients in girls were more variable, and the logarithmic transforms of VO2 and mass were not highly related (r < 0.70). Similar results were obtained for the relationships between the logarithmic transforms of VO2 and stature. The evidence thus suggests that in boys scaling VO2 for body mass varies with maturity status of the individual, and that there is considerable inter-individual variation in scaling coefficients during early and mid-adolescence. The increase in peak VO2 in active girls 11-14 years is not related to the increase in body mass or stature in the majority.

Adolescent↗
PubMed1999

Stand-level allometry in Pinus taeda as affected by irrigation and fertilization.

Changing environmental conditions have the potential to alter allometric relationships between plant parts, possibly leading to ecosystem-level feedbacks. We quantified allometric shifts in field-grown loblolly pine (Pinus taeda L.) in response to altered resource availability based on data from multiple harvests to correct for size-related changes in biomass partitioning. A replicated factorial arrangement of irrigation and fertilization treatments was applied for 4 years to an 8-year-old loblolly pine plantation on a well-drained, low fertility site in North Carolina. Destructive and nondestructive growth measurements were used to develop treatment-specific regressions to estimate stand-level biomass for ephemeral and perennial plant parts, both above- and belowground. Stand-level allometric analysis indicated that irrigation increased biomass partitioning to fine roots and decreased partitioning to foliage, relative to other plant parts. Fertilization increased partitioning to perennial tissues (coarse roots, taproots, and branches) and decreased partitioning to ephemeral tissues (foliage and fine roots). Changes in allometry were small (< 6 %) but statistically significant, indicating that biomass partitioning in loblolly pine changes with altered resource availability, but is probably under strong ontogenetic control.

Journal Article↗
PubMed1995

Log-linear allometry of fetal craniofacial growth in Down's syndrome.

Trisomy 21 develops as a result of nondisjunction of two homologous chromosomes during either the first or second meiotic division. One of the more important consequences of these genetic alterations is the predictable, although variable disturbance in the architecture of the craniofacial region [1]. Postnatal craniofacial morphology has been extensively studied in Down's syndrome (DS). However, little information is available on human prenatal development of the head and face in such patients. The time at which changes in craniofacial phenotype first emerge in Down's syndrome fetuses and at which physical growth begins to diverge from normal is unknown. To explore these questions, we compared prenatal craniofacial growth in 50 Down's syndrome fetuses with that of 555 fetuses judged to be "typical for body weight and age" using the method of log-linear allometry [2].

Cephalometry↗
PubMed2002

Population variation in sexual selection and its effect on size allometry in two dung fly species with contrasting sexual size dimorphism.

Body size is one of the most important quantitative traits under evolutionary scrutiny. Sexual size dimorphism (SSD) in a given species is expected to result if opposing selection forces equilibrate differently in both sexes. We document variation in the intensity of sexual and fecundity selection, male and female body size, and thus SSD among 31 and 27 populations of the two dung fly species, Scathophaga stercoraria and Sepsis cynipsea, across Switzerland. Whereas in S. cynipsea females are larger, the SSD is reversed in S. stercoraria. We comprehensively evaluated Fairbairn and Preziosi's (1994) general, three-tiered scenario, hypothesizing that sexual selection for large male size is the major driving force of SSD allometry within these two species. Sexual selection intensity on male size in the yellow dung fly, S. stercoraria, was overall positive, greater, and more variable among populations than fecundity selection on females. Also, sexual selection intensity in a given population correlated positively with mean male body size of that population for both the field-caught fathers and their laboratory-reared sons, indicating a response to selection. In S. cvnipsea, sexual selection intensity on males was lower overall and significantly positive, about equal in magnitude, but more variable than fecundity selection on females. However, there was no correlation between the intensity of sexual selection and mean male body size among populations. In both species, the laboratory-reared offspring indicate genetic differentiation among populations in body size. Despite fulfillment of all key prerequisites, at least in S. stercoraria, we did not find hypoallometry for SSD (Rensch's rule, i.e., greater evolutionary divergence in male size than female size) for the field-caught parents or the laboratory-reared offspring: Female size was isometric to male size in both species. We conclude that S. cynipsea does not fit some major requirements of Fairbairn and Preziosi's (1994) scenario, whereas for S. stercoraria we found partial support for it. Failure to support Rensch's rule within the latter species may be due to phylogenetic or other constraints, power limitations, erroneous estimates of sexual selection, insufficient genetic isolation of populations, or sex differences in viability selection against large size.

Animals↗
PubMed1996

Allometry of anaerobic performance: a gender comparison.

Physiological variables must often be scaled for body size differences to permit meaningful comparisons between groups. Using multivariate allometric scaling (MAS), this study aimed to compare the anaerobic performance of adult males and females in 12 pairs matched for physical activity status. Peak power output (PPO) was assessed via a 30-s supramaximal cycle ergometer test. Fat-free mass (FFM) and thigh muscle and bone cross-sectional area (CSA) were determined anthropometrically and served as indicators of active musculature. The MAS revealed power functions of the form PPO = a.gender.FFMb (or CSAb). Common b exponents of 0.1 were identified for both FFM and CSA (negative allometry). Sex differences were found in absolute PPO (1,252 vs. 681 W, p < .05). Comparison of scaled PPO data via ANCOVA (FFM0.1 and CSA0.1 entered as covariates) did not eliminate the sex difference (adjusted means 1,243 vs. 690 W, p < .05). The results suggest that the superior anaerobic performance of males in this sample is independent of size of the involved musculature.

Adipose Tissue↗
PubMed1988

Allometry of the kidney: implications for the ontogeny of osmoregulation.

In reptiles, there are two pairs of kidneys at birth: the mesonephros and the metanephros. The metanephric kidney in reptiles, as in all amniote vertebrates, is retained as the functional kidney in adults. However, the reptilian mesonephros does not degenerate until after birth, and its function during this time is unknown. In neonates of the iguanid lizard Sceloporus jarrovi, the metanephric kidney is only 63% as large as predicted from the allometric relationship between kidney mass and body mass in adults. However, the kidney mass of neonatal lizards conforms to this prediction if the mesonephric and metanephric masses are combined. Some other amniote vertebrates appear to follow this pattern as well: in marsupials, which retain the mesonephros for a short period after birth, the sum of mesonephric and metanephric mass in neonates conforms to the allometry of kidney mass on body mass for adults. In contrast, the mesonephros of eutherian mammals is degenerate at birth and the metanephric kidney alone is of the predicted size. That the scaling of kidney mass in neonatal lizards and marsupials is the same as that of adults only if the mass of both the mesonephros and metanephros are combined suggests that the mesonephric kidney in these vertebrates plays a significant role in the regulation of water and ion balance during development and for at least a short time after birth.

Animals↗
PubMed1987

Static intraspecific maxillofacial allometry in the chacma baboon.

Adult static intraspecific allometry of jaw size and tooth area was evaluated in a sample of 104 Papio ursinus crania (52 male, 52 female). Tooth areas were calculated from mesiodistal and buccolingual measurements of all the teeth in both arcades and were scaled to four viscerocranial measurements: bimaxillary width, maxillo-alveolar length, mandibular length and bigonial width. Craniodental allometric analyses indicate that larger animals will tend to have proportionately shorter and narrower lower jaws. From the log-transformed interspecific analyses between P. ursinus and C. aethiops we conclude that males and females within each species share a common exponential value for jaw length. Hence increased sexual dimorphism for muzzle length in P. ursinus is attributable to increased divergence between the male and female slopes. Post-canine area was found to be significantly correlated to maxillary length and to canine size only in females, with exponential values similar to those reported for the same bivariate regressions in C. aethiops. A hypothesis of nutritional equivalence is advanced to account for these observations. Canine base area and the area of P3 were the only tooth areas that scaled in a positively allometric fashion to jaw size--but only in males. Hence the existence of a canine complex is confirmed in the male Chacma baboon, the size of which is related to jaw length.

Animals↗
PubMed1994

MAINTENANCE OF DYNAMIC STRAIN SIMILARITY AND ENVIRONMENTAL STRESS FACTOR IN DIFFERENT FLOW HABITATS: THALLUS ALLOMETRY AND MATERIAL PROPERTIES OF A GIANT KELP

We have focused on the giant kelp Nereocystis luetkeana to examine the mechanical scaling of benthic marine organisms loaded in tension by hydrodynamic forces. If we consider simply the allometry of the kelp's morphological characters, we conclude that their stipes are underscaled relative to the blade area they support (i.e. that the kelp do not maintain stress or elastic similarity as they grow). However, a closer look at the characteristics of these kelp in the field reveals (1) that they have different blade shapes (and hence drag coefficients) and stipe material properties in different hydrodynamic environments, and (2) that they show a decrease in drag coefficient as they become larger. One consequence of these adjustments of blade and stipe morphology is that the maximum stresses in N. luetkeana stipes, when the kelp are pulled by peak tidal currents in their respective habitats, are similar for kelp of different sizes and for kelp from different sites. Hence, sessile organisms such as these kelp can, via their growth responses in different mechanical environments, show a phenomenon analogous to dynamic strain similarity. In addition, N. luetkeana also maintain a constant environmental stress factor, the ratio of the stress required to break a component of an organism (in this case the stipe) at some stage in its life to the maximum stress normally encountered in the habitat by that component during that stage (in this case, stress due to the drag on a kelp exposed to the peak tidal currents typical of the site at which it lives), both between habitats and as they grow.

Journal Article↗
PubMed1976

[Allometry and linear correlation coefficients binding the volumes of the different pituitary gland lobes, of the pituitary gland, of the subfornical organ and of the pineal gland to body weight and to hypothalamic volume in Rodents and in a Lagomorphe].

The morphometric study of the hypophysis, of the subfornical organ and of the pineal gland of 41 Rodents and one Lagomorphe shows that the anterior lobe of the hypophysis as well as the total hypophysis are better correlated to body weight than to the volume of the hypothalamus, while it is the contrary for the pars nervosa. The volume of the intermediate lobe varies very much from one species to another for the same body weight. The high value of the allometry coefficient of the pineal gland on somatic weight (1.25) is due to the fact that the heavy Rodents of our temperate climates have a large epiphysis while the small african Rodents possess a small pineal gland.

Animals↗
PubMed1992

Ontogenetic allometry of ossified fetal limb bones.

The skeletal components of fetal limbs change in both size and shape throughout gestation. Relative growth of different bones, as well as differences between homologous bones of the upper and lower limbs, are not well known for all stages of fetal development. This study used human fetal skeletal material (N = 57) ranging in age from 19 to 40 weeks gestation, and in body mass from 290g to 4650g. Measurements of maximal length and minimal width were taken from the six major long bones: femur, tibia, fibula, humerus, radius, and ulna. These data were log transformed, and growth rates determined from least squares regression of bone length or bone width on body mass and on crown-to-rump length. The results indicated that growth rates are equivalent among bones within a limb, whereas homologous bones in the upper and lower limb grew at different rates. In general, the upper limb bones display negative allometry and the lower limb bones display isometric growth in relation to body mass and crown-to-rump length. Further, there was no difference between growth rates of length and width relative to body mass. The negative slopes of upper-to-lower limb bones in relation to mass confirm the conclusion that lower limb bones grow faster than the upper limb bones from 19 weeks gestation to birth. These results, together with results from similar studies of other periods of fetal development, provide a unified picture of the prenatal growth in human skeletal limbs.

Bone and Bones↗
PubMed1992

Growth allometry of organs, muscles and bones in mice from lines divergently selected on the basis of plasma insulin-like growth factor-I.

Growth allometry was examined over the range 6 to 112 days of age in male and female mice from lines selected for low (L) or high (H) plasma concentrations of insulin-like growth factor-I (IGF-I). Plasma IGF-I concentrations were greater in the H line than in L line mice from 28 days of age. H line mice also had greater liveweights and weights of the heart, kidneys, pancreas, lungs, liver, brain and testes from 21-28 days of age. Changes in weights of these organs reflected the general pattern of body growth, there being no consistent effects of selection line on allometric growth coefficients. Ovarian weights were not different between the lines. For muscle weights, (gastrocnemius, quadriceps femoris), the weights or lengths of bones (tibia, femur) and the nose-anus and anus-tail lengths, allometric growth coefficients were generally higher (P less than .05) in L line females than in L line males or H line mice of either sex. The allometric growth coefficient for spleen was significantly (P less than .05) greater in H line mice than in L line mice with the result that spleen weights were 30% higher in H line mice from 28 days of age. This is consistent with results from mice treated with, or transgenic for, IGF-I and suggests a specific effect of this hormone on growth of the spleen. Thymus weights were also greater in H line than in L line mice and developmental patterns of thymus weight closely paralleled those of circulating IGF-I.

Animals↗
PubMed1991

Multiphasic growth and allometry.

Multiphasic growth assumes increase in body weight, or in other body measures, to be a result of more than one growth phase. Therefore, the concept of allometry can be extended from relation between body measures to relation between phases of growth. For two phases of growth, body weight (W) and tail length (L) can be partitioned into W1 + W2 and L1 + L2. Here, W1 and W2 correspond to phases 1 and 2 of weight and L1 and L2 to phases 1 and 2 of length, where each phase is described by a logistic function. Diphasic functions were applied to growth curves for body weight and for tail length of mice that were progeny of a transgenic male mated to random-bred NMRI females. A group of 20 female and male mice with high body weight at week 12, assumed to be transgenic, and a group of 20 with normal body weight, assumed to be non-transgenic, were selected for comparison. Body weight and tail length were measured about weekly from 3 to 26 weeks of age. Allometric relations between phases for weight (W1 and W2) and tail length (L1 and L2) are presented using predicted values based on estimated parameters of the diphasic growth functions. Differences between ages at maximum gain and ratios of duration of phases were analyzed. Growth in second phase of body weight appeared to be unrelated to growth in first phase of body weight and unrelated to growth in tail length. Growth in each phase of tail length appeared to be close to a simple allometric relation with growth in first phase of body weight. It is now feasible to study multiphasic allometric relations of growth between phases of one body measure and between phases of different body measures by comparing estimates of parameters of the multiphasic growth function.

Animals↗
PubMedDate not supplied

Allometry of hepatic weight growth in human staged fetuses.

The growth of the hepatic weight was correlated to fetal parameters of maturity (gestational age, crown-rump length and weight) in 70 human fetuses ranging from 14 to 39 weeks post-conception using the allometric method. The growth of the hepatic weight presents moderate positive allometry relative to age and C-R length, and isometry relative to fetal weight. The coefficiens of correlation are very high (p less than 0.001, Table 1). This study presents growth curves of the hepatic weight useful in medical branches such as anatomy, forensic medicine, fetopathology, medical imagery, onstetrics and pediatrics.

Female↗
PubMedDate not supplied

Brain and body growth and allometry in the Mongolian gerbil (Meriones unguiculatus).

A new four-parameter version of Pütter's curve (Pütter, 1920), recently developed by Jolicoeur and Pirlot (1988), is applied to cross-sectional data on brain and body growth in 127 male and 136 female Mongolian gerbils (Meriones unguiculatus) ranging from birth up to approximately 2 years in postnatal age. The physical development of the gerbil is more rapid than that of the white rat and of the domestic rabbit even though its behavioral development is known to be somewhat slower. Like other recent studies on rats, rabbits and humans, the present analysis indicates that complex allometry (curvature of log-log relationships) is more widespread in the quantitative development of mammals than generally realized.

Age Factors↗