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.

SourceResearch connectionFrom yearThrough year

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

At least 37 records · Page 2Linked to original sources

PubMed1995

Organ and cell allometry in Hawaiian Drosophila: how to make a big fly.

The importance of body size in predicting many aspects of an animal's biology has become well established in recent years. However, little is known about how body size evolves at the cellular level. Some published data suggest that it is cell number and not cell size that accompanies changes in organ and body size across taxa. We examined organ and cell allometry in the wing, eye and basitarsus of adult Hawaiian Drosophila, ranging in body length from 0.2 mm to 0.8 mm. Linear measurements of all three structures exhibit a positive allometry with body length. Exponents of the allometric equation were 0.96, 0.55 and 1.50 for wing, eye and basitarsus, respectively. Surface markers were used to quantify cell size of each organ. The allometric exponents for cell size as a function of organ size were 0.53, 0.68 and 0.33 for wing, eye and basitarsus, respectively. In contrast to reports in the literature on other systems, our results for Hawaiian Drosophila indicate that cell size may contribute between one third and two thirds to evolutionary changes in organ and body size.

Animals↗

PubMed1993

Allometry of base pair specific-DNA contents in Tetrapoda.

Cells of 82 species of Tetrapoda were stained with DNA base pair specific fluorochromes (Hoechst 33258 and olivomycin) and studied by means of flow cytometry. The genome size range was about 50-fold. The class Amphibia, which had the widest range of genome size variation (about 20-fold), exhibited linear allometry in their base pair specific DNA contents (bps-C-values), i.e., the more DNA they had, the lower the quotient of AT-pairs (C(AT) = 0.13 + 0.87 x C(GC), r = +0.998). Data for Mammalia, pooled with amphibians, fell on the same allometric line at the lower extreme end of genome size range, supporting the correlation. Reptilia-Aves (or Reptilia alone) pooled with Amphibia did not conform with this relationship. Reptilia-Aves form their own line (zone); pooled with Mammalia, this group showed no regularities in the relationship of their bps-DNA contents. Besides revealing the allometry of bps-C-values, these data indicate an integral genomic feature, localization within the same regression line, which Mammalia share with Amphibia but not with recent Reptilia (and Aves). These data also suggest that the relationship between DNA base frequencies and genome size is nonlinear (reciprocal); to obtain a linear relationship, the bps-C-values should be used. It is also concluded that caution is needed when DNA-content is measured for comparative purposes using a fluorescent dye which is known to be base-pair specific. DNA content values obtained with fluorochromes with different specificity may differ as much as by a factor of 1.8, the average discrepancy level is about 14%.

Animals↗

PubMed1994

Allometry of muscle, tendon, and elastic energy storage capacity in mammals.

This paper considers the structural properties of muscle-tendon units in the hindlimbs of mammals as a function of body mass. Morphometric analysis of the ankle extensors, digital flexors, and digital extensors from 35 quadrupedal species, ranging in body mass from 0.04 to 545 kg, was carried out. Tendon dimensions scale nearly isometrically, as does muscle mass. The negative allometry of muscle fiber length results in positive allometric scaling of muscle cross-sectional areas in all but digital extensors. Maximum muscle forces are predicted to increase allometrically, with mass exponents as high as 0.91 in the plantaris, but nearly isometrically (0.69) in the digital extensors. Thus the maximum amount of stress a tendon may experience in vivo, as indicated by the ratio of muscle and tendon cross-sectional areas, increases with body mass in digital flexors and ankle extensors. Consequently, the capacity for elastic energy storage scales with positive allometry in these tendons but is isometric in the digital extensors, which probably do not function as springs in normal locomotion. These results suggest that the springlike tendons of large mammals can potentially store more elastic strain energy than those of smaller mammals because their disproportionately stronger muscles can impose higher tendon stresses.

Animals↗

PubMed1987

Growth allometry of the organs in giant transgenic mice.

We have analyzed the absolute and relative (allometric) growth of a series of internal organs in giant transgenic (MTrGH) and littermate control mice to determine the general and organ-specific effects of the altered hormonal environment on growth in these rodents. Comparison of cross-sectional growth allometries of organ weights and external body dimensions between the two samples was based on analyses of covariance. We report significantly increased growth in all of the organs and measurements examined except for the brain. Coefficients of growth allometry differ significantly from isometric values in a number of cases, and thus, the adult transgenic mice exhibit body proportions different from those of the adult controls. Most of these shape differences reflect general allometric size increase, but the liver and spleen of the transgenics undergo special enlargement or growth. These results indicate that the primary effect of elevated GH and IGF-I levels is increased overall growth, but in the relative proportions set by the intrinsic controls of individual organs and body regions.

Aging↗

PubMed1988

Dimensions and allometry of testes, epididymides and spermatozoa in the domestic dog (Canis familiaris).

Dimensions of the testes, epididymides and spermatozoa were measured from a sample of 104, mainly cross-bred, domestic dogs ranging in body mass from 5 to 48 kg. Allometric analyses in relation to body mass indicated isometric changes in testicular mass but epididymal mass and the mass of the cauda epididymidis and sperm numbers in the cauda showed significant positive allometry. Total sperm length, seminiferous tubule diameter and the relative proportion of tissues in the testis showed no significant correlation with body mass, but sperm principal piece length showed a low correlation with body mass. We suggest that the positive allometry of epididymal mass and sperm numbers is related to promiscuous mating and sperm competition in stray dogs.

Animals↗

PubMed1980

[Allometry and the original and modified Janoschek growth function. (author's transl)].

After a summary of the author's work on the allometry principle with regard to the original and generalized Bertalanffy and Gompertz functions of organic growth attention is drawn to the analogous topic concerning the Janoschek growth function. At first the Janoschek function is resettled a little as to fit also for starting growth with values unequal to zero. After giving the main characteristics illustrated by graphs the allometric principle is applied to the growth function enforcing a repetition of all derivations due to the changed structure against the growth function proper. Secondly, the increase ansatz is changed with integration now leading to curves of finite growth time. Examples for allometry are added taking up values of recent investigations thus allowing for comparison. Finally an approximation method for the calculation of the inflexion points rounds up the paper.

Biometry↗

PubMed1978

Multivariate dental allometry in primates.

Disagreement is current over the question of whether relatively large teeth in some large primates are a natural outcome of growth trends instead of an indication of intrinsic differences. A cross-primate survey of dental scaling relative to skull (and inferred body) size is given in this study, using a principal component technique to measure the multivariate growth relation between two sets of data: dental size and cranial size. Cheek teeth are strongly positively allometric in restriced taxonomic groups, especially in cercopithecoids. Conversely, the allometry drops to an almost linear proportional growth relation when variation in diet is controlled.

Animals↗

PubMed1980

Postnatal growth allometry of the extremities in Cebus albifrons and Cebus apella: a longitudinal and comparative study.

Cebus albifrons and Cebus apella, partially sympatric capuchin monkeys from South America, are known to differ substantially in adult body mass and bodily proportions. C. apella possesses a robust, stocky build in contrast to the more gracile, relatively longer limbed body design of C. alblfrons. Average birth weights and adult body lengths of these two congeners, however, are remarkably similar and do not serve to distinguish them. This study examines longitudinal growth rates and patterns of ontogenetic scaling in the extremities (humerus, radius, hand, femur, tibia, foot) in order to document the nature and magnitude of skeletal changes associated with increasing age and body mass. Our data indicate that the growth rates of the six skeletal components of the limbs differ only slightly and somewhat inconsistently between the two species. Body mass, however, increases at a consistently faster rate in C. apella. Relative to body mass, therefore, the extremities of C. albifrons scale much faster than those of C. apella. This implies that at any given postnatal body mass, C. alblfrons is longer limbed that C. apella. Conversely, C. apella is heavier than C. albifrons at any given limb length or age. We suggest that such differences in body mass distribution are causally related to differences in locomotor behavior and foraging strategies. Specifically, the relatively long-limbed C. albifrons is probably more cursorial and tends to travel longer distances each day than C. apella. C. apella is a much more deliberate quadruped and is also characterized by especially vigorous and powerful foraging and feeding behaviors. We also compare our results to other (mostly cross-sectional) studies of skeletal growth allometry in nonhuman primates.

Animals↗

PubMed1981

Allometry of primate hair density and the evolution of human hairlessness.

Allometric analyses of hair densities in 23 anthropoid primate taxa reveal that increasingly massive primates have systematically fewer hairs per equal unit of body surface. Considering the absence of effective sweating in monkeys and apes, the negative allometry of relative hair density may represent an architectural adaptation to thermal constraints imposed by the decreasing ratios of surface area to volume in progressively massive primates. Judging by estimates of body volume, denudation of the earliest hominids should have progressed to a considerable extent prior to their shift from a forest to a grassland habitat during the Pliocene. We propose that, lacking a reflective coat of hair, the exploitation of eccrine sweating emerged as the primary mechanism for adaptation to the increased heat leads of man's new environment and permitted further reduction of the remnant coat to its present vestigial condition.

Animals↗

PubMed1981

Sexual dimorphism and allometry in primate ossa coxae.

Five measurements were taken on the ossa coxae of 454 adult primates representing Ceboidea, Cercopithecoidea and Hominoidea. Sex differences in these variables and their relationships to overall body size and sexual dimorphism were tested by means of Student's T-test and regression analysis. The study attempts to clarify the nature of primate pelvic sexual dimorphism, including allometric effects, and more specifically, test the assertion made by Mobb and Wood (1977) that sexual dimorphism in body size in not an important determinant in pelvic sex differences. Variables that contribute to the size of the birth canal tend to be larger in females than males in all taxa studied except two. In these, Hylobates and Alouatta, there were no significant differences between the sexes for any of the five variables. In general, sexual dimorphism in variables contributing to the size of the birth canal was correlated (r approximately or equal to 0.8) with sexual dimorphism in body size. Furthermore, the coefficients of allometry underlying pelvic sex differences were shown to be moderately correlated (r approximately or equal to 0.5) with sexual dimorphism in size. The influence of other adaptive factors on primate pelvic sexual dimorphism are also briefly discussed.

Animals↗

PubMed1981

On the definition of variables in studies of primate dental allometry.

Cranial and dental measurements are taken on 253 adult female primates from 32 species. Regression equations are calculated to determine allometric relationships between anterior tooth size, posterior tooth size, and body size. When cranial length or skull length is used as the measure of general size, the results of the equations differ from when body weight is the reference dimension. Similarly, using different definitions of posterior tooth size (such as mandibular second molar length and maxillary postcanine area) alters results substantially. The same occurs with different definitions of anterior tooth size. It has been common in studies of primate dental allometry to generalize from the specific variables measured to broad functional interpretations. However, highly correlated variables cannot be substituted one for another in allometric analyses without important changes in the results of the equation. Interpretation of allometric data is more highly restricted to the precise variables measured in a particular study than has been generally recognized.

Animals↗

PubMed1982

Allometry and adaptation in the catarrhine postcranial skeleton.

Seven measurements were taken on the postcranial skeleton of 249 specimens representing ten species of catarrhine primates and tested to determine their relationship with size. Size was measured as skeletal weight on each individual. It was found that the interspecific line based on the entire sample was in some cases determined not only by morphological adjustments for size variation but also by changes in locomotor adaptations of differently sized species within the sample. It is suggested that it is consequently preferable to study allometric relationships within a species or within a group of species that differ in size but are similar in their mode of locomotion. The allometric analysis reveals some interesting patterns within the data. Limb lengths scaled with either negative allometry or isometry over the entire sample. Within the species groups isometry was the rule except for pongid femurs, which showed negative scaling. Humerus length scaled at the same rate in pongids as in cercopithecoids but had a slightly higher intercept value. While colobines and cercopithecines scaled at similar rates for all seven dimensions, the colobine line was shifted to a position above that for cercopithecines in every case. It is suggested that this is a result of adaptation for leaping in the former group. Other implications of the allometric results are discussed.

Adaptation, Physiological↗

PubMed1983

The allometry of relative cusp size in hominoid mandibular molars.

The crown area (MCBA) and cusp areas of mandibular molars of Homo sapiens (M-1 = 131; M-2 = 71), Gorilla (M-1 = 25) and Pongo (M-1 = 24) were studied to determine whether the relative size of the mesial and distal cusps are related to overall crown size. Allometric trends were assessed by examining the correlation between relative cusp areas and MCBA and by calculating the slope of the regression line of log cusp area and log MCBA. With the exception of the metaconid in the Homo sapiens M-2S, the results of the intraspecific analyses provide little evidence of an allometric trend for relative reduction of the mesial cusps with increasing crown size. None of the samples provide consistent or reliable evidence of such a trend for the protoconid, nor do the M-1 samples provide evidence for such a trend for the metaconid. The evidence from the distal cusps is also mixed: positive allometry for the entoconid for the Homo sapiens M-2S and for the hypoconulid for the Homo sapiens M-1S, with no departure from isometry in either Gorilla or Pongo. The interspecific data provide no evidence of any trend for the mesial cusps to decrease or the distal cusps to increase in importance in larger teeth. If one accepts the proposition that the static allometric trends observed in this study are reasonable analogues for any allometric relationships within, or between, fossil hominid taxa, then the evidence presented above does not support the hypothesis that the reduction of the trigonid, which is observed in the "robust" australopithecines, is an allometric phenomenon.

Adult↗

PubMed1986

Ecological significance of hypometabolism in nonhuman primates: allometry, adaptation, and deviant diets.

The "Kleiber relationship" describes the interspecific allometry between body size and metabolism. Like other allometric relationships, the Kleiber relationship not only summarizes scaling effects across species but also provides a standard by which species can be compared. One well-noted deviation from the Kleiber relationship is "hypometabolism": metabolic rates below that expected for a given size. It has been suggested in the literature that hypometabolism may be a primitive mammalian trait, a thermoregulatory adaptation, an adaptation to arboreal folivory, or an adaptation to a diet that is deviant for body size. Data on primate physiology and behavior are used to evaluate these hypotheses. Only the deviant-diet hypothesis is supported by the data on nonhuman primates. Indeed, the Jarman-Bell relationship, which is the basis for this hypothesis, provides a more coherent explanation of correlated features of animal physiology and behavior than do the alternative models. Hypometabolism may be an energy-conserving adaptation to a variety of nutritional stresses. The present analysis underscores the point that metabolic rate, like foraging behavior, should be thought of as evolutionarily labile.

Adaptation, Physiological↗

PubMed1987

Allometry of the limb long bones of insectivores and rodents.

In an attempt to investigate the relationships between allometry and locomotory adaptations, we studied the long limb bones of 45 species of insectivores and rodents. Animals ranged from a few grams to about 50 kilograms. Diameter and length of the bones and body mass (when known) were recorded. Regressions of diameter to length, diameter to body mass, and length to body mass were calculated by the least-squares and Model II, or major axis, methods. The results obtained do not agree with the predictions of either the theory of geometric similarity or the theory of elastic similarity. The discrepancies could be due to the fact that animals studied exhibit various modes of locomotion. Moreover, the allometric relationships of the different locomotor patterns are better reflected in insectivores and rodents than in other groups of mammals. The use of a single regression analysis seems to be inadequate when the sample includes a large range of body sizes.

Animals↗

PubMed1988

Allometry of the perivascular spaces of the putamen in aging.

The equation of simple allometry was used to study the relative growths of the diameters of the perivascular spaces (PSs), the diameters of the arterial vessels and their wall thicknesses in specimens of the putamen from 24 subjects aged 62 to 90 years. Our findings supported the view that the diameters of the PSs were mainly related to the dimensions of their arteries, especially in the elderly, and that they grew isometrically with arterial diameters. In addition, the diameters of the PSs were basically independent of age.

Aged↗

PubMed1987

Relative growth of adenomatous polyps of the colon. Stereology and allometry of multiple polyposis.

The volume of the adenomatous mucosa (V), the area of the surface epithelium (Ss), the area of the glandular epithelium (Sg), and the Sg: Ss ratio were calculated in a series of 14 adenomatous polyps (APs) of a case of multiple polyposis of the colon. The equation of simple allometry was used to study the relative growth of the four series of values. Ss grew isometrically with size; Sg overgrew Ss and accounted for most of the increase in V. The Sg:Ss ratio increased with Sg and V.

Colonic Polyps↗

PubMed1984

Growth and allometry in primate masticatory muscles.

A study of the dry weight of primate and non-primate masticatory musculature permitted possible allometric and ontogenetic influences on this musculature to be explored. Using weight as an indicator of adult body size, all of the masticatory muscles examined (anterior temporalis, posterior temporalis, masseter, medial pterygoid, lateral pterygoid, digastrics, and total adductor mass) are isometric. This is true even when prosimians and non-primates are removed from consideration, leaving only adult anthropoid primates. Thus, size-related changes do not affect the masticatory musculature of anthropoids differently from the musculature of examined prosimians and non-primates. However, other measures of body size (skull length, head and body length) reveal a different picture. Yet, irrespective of the indicator of body size chosen, the allometric properties of the masticatory muscles appear similar and the fluctuations of the various muscle indices therefore reflect functional changes, and are not caused by allometry. Exudate-eating and frugivory are discussed in relation to body size and the development of the mandibular depressor muscles. The logs of the masticatory muscles do not show a significant correlation with age, except when species are followed across age grades. For the five anthropoid species for which this is possible, the medial and lateral pterygoid and digastric muscles are still not correlated with age. When all examined species are considered, some muscle ratios correlate significantly with age. Following anthropoid species across age grades singles out an early surge in growth of the medial pterygoid muscle over the masseter muscle, a situation which was apparent also in the general age correlation.

Age Factors↗