Encephalization of The Koala, Phascolarctos cinereus.

1998 ◽  
Vol 20 (3) ◽  
pp. 315
Author(s):  
C. De Miguel ◽  
M. Henneberg
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Brain Size ◽  
South Australia ◽  
Allometric Equation ◽  
Brain Weight ◽  
Phascolarctos Cinereus ◽  
Weight Relationship ◽  
Body Weights

Brain size relative to body size is considered to be an indicator of variously defined 'braininess' (=encephalization). Indices of encephalization are based on the ratio of the animal's actual brain size to its expected brain size calculated from an allometric equation derived from a brain size I body weight relationship in a series of taxa Freshly collected data on brain and body weights of 27 adult koalas (Phascolarctos cinereus) from South Australia are analysed here. Sex- averaged brain weight in this sample is 19.2 g and body weight is 8.0 kg. General equations for mammals produce encephalization values for the koala well below the mammalian average: EQ=38.9% ac- cording to Jerison's equation (1973), EQ= 49.7% applying Eisenberg's equation (1981) and EQ= 35.3% using Martin's equation (1990). When a 'basal' insectivore line is used, the koala appears to be progressive: IP =155.9% according to Stephan's equation (1972) and ICC= 131.7% using Martin's equation (1990). Use of 'basal' marsupial lines also indicates progressive encephalization of the koala: Pl=l l6.5% according to Pirlot's equation (1981}, E=108.4% following Nelson and Stephan's equation (1982) and E=107.9% using Haight and Nelson's equation (1987). These new results are clearly higher than the indices for the koala reported earlier by other authors (Nelson and Stephan 1982; Haight and Nelson 1987). It follows that choice of samples and equations influences conclusions regarding encephalization of a species.

A Scaled Ratio of Body Weight to Brain Weight as a Comparative Index for Relative Importance of Brain Size in Mammals of Widely Varying Body Mass

1972 ◽  
Vol 31 (1) ◽  
pp. 84-86 ◽  
Author(s):  
John Herschel
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Body Mass ◽  
Brain Size ◽  
Weight Ratio ◽  
Brain Weight ◽  
Relative Importance ◽  
Simple Body

Since very little can be determined about the relative importance of brain size in mammals from a simple body-weight/brain-weight ratio, a scaled ratio is proposed that takes into account the mathematical peculiarities of the cube/square relationship between body size and brain size in mammals of widely varying body masses. The values obtained from this scaled ratio appear to arrange these animals in an order more consistent with their observed intellectual capacities.

Brains of Australian Chiroptera I. Encephalization and Macromorphology

1981 ◽  
Vol 29 (5) ◽  
pp. 653 ◽  
Author(s):  
H Stephan ◽  
JE Nelson
Keyword(s):  
Body Weight ◽  
Allometric Equation ◽  
Brain Weight ◽  
Aerial Insectivore ◽  
Body Weights

Data on brain weights and body weights of 87 individuals representing 20 species of Australian Chiroptera were analysed. The allometric equation: log brain weight = 1.655 + 0.684 log body weight, which was derived from data on the vespertilionid species except Tylonycteris spp.. was used to calculate indices of encephalization for Australian Chiroptera. Vespertilionidae and Molossidae have the lowest indices; those of Emballonuridae, Rhinolophidae and Hipposideridae are slightly higher, that of Macroderma gigas is distinctly higher, and the highest are found in the Pteropodidae. Accompanying this scale of increasing encephalization are increases in hemisphere length, cover of the mesencephalic tectum, and cerebral and cerebellar fissuration. All of the aerial insectivore and foliage-gleaning species belong to the less encephalized Chiroptera, whereas all fruit eaters (alone or combined with other trophic roles) are highly encephalized. The intermediately encephalized Macroderma is a combined carnivore and foliage-gleaning species.

Avian Egg Morphometrics - Allometric Models of Egg Volume, Clutch Volume and Shape

1994 ◽  
Vol 42 (3) ◽  
pp. 307 ◽  
Author(s):  
PD Olsen ◽  
RB Cunningham ◽  
CF Donnelly
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Sexual Dimorphism ◽  
Clutch Size ◽  
Egg Volume ◽  
Simple Power ◽  
Wide Range ◽  
Body Weights ◽  
Body Sizes ◽  
Simple Power Function

This paper describes three comprehensive new models of the allometric relationships between egg volume, clutch volume and shape, and body weight. Mean egg dimensions, clutch sizes and adult body weights were obtained for 326 species, mainly of four bird types: raptors (including owls), shorebirds, frogmouths (including nightjars), and storks (including the New World vultures). These are groups in which there is a wide range of body sizes and of sexual dimorphism in body size (in direction and degree). Female body weight alone accounted for 92% of the variation in egg volume. Sexual dimorphism in body size, phylogenetic relationship, and clutch size were significant contributors to the model of egg volume; their addition increased the explained variance to over 98%. The model was curvilinear (quadratic) in form, rather than linear as assumed in previous models. Larger species laid smaller eggs than expected under a simple power function. For the fitted model, within bird types, generic groupings had parallel curvilinear slopes but differing intercepts. Between bird types, the slopes differed. Clutch volume was scaled to body weight; all the bird types had a common slope, which was curvilinear. Body weight and dimorphism accounted for 89.5% of the variation in clutch volume. For all bird types, eggs became proportionally longer in shape as body weight increased, according to a simple power law. The relevance of these relationships to hypotheses on the evolution and adaptive significance of sexual dimorphism and to the trade-off between egg size and clutch size is discussed briefly.

Bone growth in the indigenous Nigerian pigs as a function of age, sex and body weight

1988 ◽  
Vol 110 (3) ◽  
pp. 597-604
Author(s):  
A. I. Essien ◽  
B. L. Fetuga
Keyword(s):  
Body Weight ◽  
Sex Differences ◽  
Bone Growth ◽  
Maximum Growth ◽  
Allometric Equation ◽  
Maximum Growth Rate ◽  
The Body ◽  
Intact Male ◽  
Body Weights ◽  
The Individual

SummaryThe left half carcasses of 64 female, 64 castrated male and 64 intact male indigenous Nigerian pigs were dissected in order to study the bone growth between birth and 672 days of age. Total bone weight as well as the weights and lengths of femur, tibia–fibula, humerus and radius–ulna were studied at 16 ages. While bone weights increased between 34 and 45 times from birth to the terminal age range, bone lengths on the average only quadrupled within the same period. Maximum growth in bone weight occurred at 112 days of age whereas bone length attained maximum growth rate at 56 days of age when the body weights had averaged 15·8 and 6·2 kg respectively.Beyond these body weights, the growth rates declined. Although sex differences for total bone weight were not significant, the individual long bones studied exhibited significant sex differences. Highly significant age and sex influences were obtained for the relative bone weights.The growth coefficients b determined for the individual bones and total bone using the logarithmically transformed allometric equation Y = oXb, ranged from an average of 0·76 for radius–ulna to O·80 for femur. Pooled values for total carcass bone was 0·84. The values agreed with those reported in literature with side weight as independent variable, and confirm bone to be early developing. Bone lengths were related more to body weight than to chronological age as judged by the R2 values. In all the bone traits studied, intact male pigs showed larger values than the castrated male and female pigs.

scholarly journals The size and endocrine activity of the pituitary in mice selected for large or small body-size

1962 ◽  
Vol 3 (3) ◽  
pp. 428-443 ◽  
Author(s):  
R. G. Edwards
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Small Body ◽  
Large Body ◽  
Primary Response ◽  
Endocrine Activity ◽  
Body Weights ◽  
Mouse Pituitary ◽  
Highly Correlated ◽  
Thyroid Secretion

Mice of two strains, N and C, were used in studies on body-size, pituitary size, and endocrine potency of the pituitary. Strain N had been selected for large (NL) and small (NS) body-size; strain C had also been selected for large body-size (CL) but had been crossed to an outbred strain segregating pituitary dwarfism.Pituitary weights and body-weights were highly correlated, the regression lines being common in NL and NS mice. Female pituitaries were considerably heavier than male pituitaries in CL mice. In relation to body-weight, CL pituitaries were consistently heavier than those of NL or NS mice.No differences were detected in the unit potency of gonadotrophins in the pituitaries of NL and NS mice as estimated by the uterine response of immature outbred mice to subcutaneous injections of pituitary tissue. The uptake of 131I into the thyroid was comparable in NL and NS mice per unit of body-weight, and the thyroid secretion rate was also similar using animals of the same body-weight. Immature mice of both lines responded by increased growth to injections of growth hormone or fresh mouse pituitary, though the response was greater in NS than in NL mice.The primary response to selection has probably been in the size of the pituitary rather than in its unit potency. The interrelationships between body-size, body components, organ size and endocrine levels are discussed.

scholarly journals The Composition of the Blood of the Shore Crab, Carcinus Moenas (Pennant), in Relation to Sex and Body Size

1959 ◽  
Vol 36 (3) ◽  
pp. 495-500
Author(s):  
A. B. GILBERT
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Frequency Distribution ◽  
Reproductive Activity ◽  
Ionic Concentration ◽  
Shore Crab ◽  
Protein Nitrogen ◽  
Body Weights ◽  
Total Ionic Concentration

1. The influence of sex and body weight on the concentration of the non-protein nitrogen (N.P.N.) in the blood of Carcinus moenas was investigated. 2. Blood N.P.N. decreased with body size in both sexes until a minimum was reached at a body weight of about 35 g. Thereafter it increased with increasing body weight. 3. For body weights less than 35 g. males had higher N.P.N. values than females; above this weight male values were lower. Statistically these differences were highly significant. 4. Frequency distribution of reproductive activity with body size showed peaks which correspond with those for total ionic concentration (Gilbert, 1959a, b) and with the troughs for N.P.N. 5. Results of the present work have been discussed in relation to those reported earlier for conductivity, total O.P., chloride and sulphate (Gilbert, 1959a, b).

Androgenic influences on body size and composition of adult rhesus monkeys

1988 ◽  
Vol 255 (6) ◽  
pp. E857-E864 ◽  
Author(s):  
J. W. Kemnitz ◽  
K. K. Sladky ◽  
T. J. Flitsch ◽  
S. M. Pomerantz ◽  
R. W. Goy
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Rhesus Monkeys ◽  
Testosterone Propionate ◽  
Base Line ◽  
Lean Tissue ◽  
Anabolic Hormones ◽  
Crown Rump Length ◽  
Body Weights ◽  
Males And Females

The effects of daily treatment with testosterone propionate (TP, 2 mg/kg) and dihydrotestosterone propionate (DHTP, 2 mg/kg) were examined in rhesus monkeys in three experiments. In experiments 1 and 2, males and females gonadectomized in infancy, and female pseudohermaphrodites produced by prenatal exposure to TP or DHTP and gonadectomized postpubertally, were studied in conjunction with intact males (IM). The IM group was heavier in adulthood than the three gonadectomized groups, which did not differ in body weight from each other. Genetic males had greater crown-rump length than genetic females. Treatment of the gonadectomized groups with TP produced large increases in body mass (averaging approximately 50%) that were attributable to accretion of lean tissue. This effect did not differ significantly between males and females. In experiment 3, additional groups of males that had been castrated as infants were given daily injections with DHTP or oil. The DHTP treatment resulted in increases in body size that were not different from those seen following TP treatment. When TP and DHPT treatments were discontinued, body weights and dimensions reverted to base-line values. Increased body size induced by TP and DHTP was accomplished without reliable increases in food intake. Because testosterone (T) is metabolized to dihydrotestosterone (DHT), while DHT cannot be converted to T, these results show that both T and DHT are effective anabolic hormones in rhesus.

scholarly journals The effect of selection on brain and body size association in rats

1984 ◽  
Vol 43 (3) ◽  
pp. 289-298 ◽  
Author(s):  
William R. Atchley
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Weight Gain ◽  
Brain Size ◽  
Body Weight Gain ◽  
Genetic Correlations ◽  
Considerable Change ◽  
Evolutionary Divergence ◽  
Significant Divergence

SUMMARYChanges in brain size, body size and their co variance are reported from a long-term replicated directional selection experiment on body weight gain in rats. Two strains had been selected for increased and two for decreased weight gain between 3 and 9 weeks of age, and there were two randomly selected control lines. Selection produced significant changes in body weight in all selected lines. Divergence from the controls occurred in brain size in those strains selected for increased weight gain; no significant divergence was found for the strains selected for decreased weight gain. Divergence among unselected control lines suggests that genetic drift occurred in expression of brain size. Sexual dimorphism in response to selection results from sex differences in heritabilities and genetic correlations in relevant traits. In spite of considerable change in body size and brain size, no significant change in their covariation occurred either between the selection lines or between sexes. The relevance of these results to a brain and body size ‘scaling effect’ during evolutionary divergence is discussed.

Brain and Body Size Relations among Spotted Hyenas (Crocuta crocuta)

2018 ◽  
Vol 92 (1-2) ◽  
pp. 82-95
Author(s):  
Michael D. Mann ◽  
Lawrence G. Frank ◽  
Stephen E. Glickman ◽  
Arnold L. Towe
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Negative Relationship ◽  
Crocuta Crocuta ◽  
Spotted Hyena ◽  
Spotted Hyenas ◽  
Body Weights ◽  
Vertebrate Zoology ◽  
Males And Females ◽  
The Relationship

The relationship between brain size and body size across species “from mouse to elephant” is described by a function of positive slope. Almost uniformly, the relationship between brain size and body size within a species has a positive slope, though this is less steep than across species. The spotted hyena, Crocuta crocuta, differs from most other mammals in a number of ways including the fact that, on average, adult females weigh more than adult males and occasionally display greater body lengths. Brains of 5 female and 4 male hyenas were weighed in the field near Moyale in Northern Kenya, and body weights and body lengths were obtained from the same animals. When our analyses of brain/body relationships in these animals revealed an unanticipated negative relationship between brain size and body length, we extended our measurements to include intracranial volume in 19 skulls (8 females and 11 males) from the collection at the Museum of Vertebrate Zoology, University of California Berkeley; body weights and lengths were also available. A third dataset was formed by measuring intracranial volumes in 60 spotted hyena skulls (27 females and 33 males) in the Natural History Museum, London, UK; body lengths and intracranial volumes were available. Brain/body size slopes, in general, were not significantly different from zero except in 3 cases: brain weight/body length for Moyale males alone and males and females together, and cranial volume/body weight for Museum of Vertebrate Zoology males and females together. Although most of the slopes were not significantly different from zero, they were all negative, and a statistical test which combined probabilities from the 3 datasets supports the conclusion that there is a negative relationship between brain size and body size in spotted hyenas. Possible explanations for the negative slopes are discussed, including costs and benefits of large brains and large bodies and physiological mechanisms.

Sign in / Sign up

Export Citation Format

Share Document