DENSITY DEPENDENCE IN NORTHERN FUR SEALS (CALLORHINUS URSINUS)

This paper summarizes, updates, and interprets information on density-dependent dynamics of populations of the northern fur seal ( Callorhinus ursinus ). Density-dependent changes observed in these populations have involved various aspects of growth (body length, body weight, tooth weight, and size of other skeletal parts, especially the skull), survival, age at maturation, incidence of disease, and time spent foraging. For the population of northern fur seals on St. Paul Island of the Pribilof Islands, which was observed during a major increase and during two significant declines, density-dependent changes that occurred during the growth of the population were reversed during the declines. The Robben Island population in the western Pacific declined after 1965, and the decline was accompanied by changes similar to those observed during the declines on the Pribilof Islands. Although data are not available for all age and sex classes, it appears that most or all components of the populations exhibit similar changes. The overall implication of these changes is that current populations on Robben Island and the Pribilof Islands are reduced to levels below what could be supported by the resources available in their environments. Density dependence for this species is consistent with that of other large mammals, specifically in that vital rates for fur seals ate related to density in a nonlinear fashion.     

Correlation of tooth size and body size in living hominoid primates, with a note on relative brain size in Aegyptopithecus and Proconsul.

Second molar length and body weight are used to test the correlation between tooth size and body size in living Hominoidea. These variates are highly correlated (r= 0.942, p less than 0.001), indicating that tooth size can be used in dentally unspecialized fossil hominoids as one method of predicting the average body weight of species. Based on tooth size, the average body weight of Aegyptopithecus zeuxis is estimated to have been beteen 4.5 and 7.5 kg, which is corroborated by known cranial and postcranial elements. Using Radinsky's estimates of brain size, the encephalization quotient (EQ) for Aegyptopithecus was between 0.65 and 1.04. A similar analysis for Proconsul africanus yields a body weight between 16 and 34 kg, and an EQ between 1.19 and 1.96.     

AGING LIVE ANTARCTIC FUR SEALS AND SOUTHERN ELEPHANT SEALS

This study describes a method for extracting post-canine or incisor teeth from live antarctic fur seals ( Arctocephalus gazella ) and southern elephant seals ( Mirounga leonina ) respectively and their use to determine age in a field situation. Dental elevators were used to loosen the teeth from the alveolus and periodental ligament. Most teeth were removed within l-2 min and a total of 214 and 81 teeth were collected by this method from antarctic fur seals and southern elephant seals respectively. No seal recaptured at intervals up to a year after a tooth was extracted showed signs of infection or distress related to removal of the tooth. Teeth were thin-sectioned for the purpose of aging. In both species cementum growth layer groups were a more satisfactory indicator of age than dentinal growth layer groups. Estimates of age from cementum growth layers were confirmed for Antarctic fur seals using seals which had been tagged as pups up to 16 yr before sampling.     

An analysis of cercopithecoid odontometrics. I. The scaling of the maxillary dentition.

The relations between two tooth indices, post-canine area and incisor width in the upper jaw, and three variables, diet, body weight and body weight dimorphism, were examined separately for the males and females of 29 cercopithecoid species. Each species was assigned to one of three diet classes (folivore, frugivore, omnivore). Data on the other variable consisted of species means (log-transformed) obtained from published sources. The analytic techniques used were bivariate and multiple regression, the tooth indices being the dependent variables. All tooth indices scaled isometrically within diet classes, and all except female incisor width scaled with positive allometry across diet classes. In both sexes, the body weight adjusted mean incisor width of folivores was significantly smaller than that of either frugivores or omnivores. In the females, the body weight adjusted mean post-canine areas did not differ significantly across diet classes, while in the males the omnivores had a larger body weight adjusted mean post-canine area than either the folivores or frugivores. Female post-canine area was the only tooth index for which body weight dimorphism was a significant predictor. Extrapolations of these findings to other extant and to fossil primate species are discussed.     

Static intraspecific allometry of the dentition in Otoletnur crassicaudatus

Adult static intraspecific allometry of tooth size was evaluated in a sample of 66 Otolemur crassicaudatus (34 male, 32 female). Tooth areas were calculated from mesiodistal and buccolingual measurements of canines and postcanine teeth of both arcades and were scaled to four viscerocranial measurements: bimaxillary width; maxillo-alveolar length; mandibular length and bigonial width. Individual tooth crown areas were also scaled to total skull length, body length and body weight. From the log-transformed analyses it is concluded that postcanine tooth size was unrelated to body length or weight, and poorly correlated to skull length or jaw size. Although viscerocranial size appears to be independent of body size, these measures are well correlated to skull length. It is shown that the longer the skull, the shorter and narrower the maxilla, and the longer and broader the mandible. Canines are shown to scale negatively allometric to skull length, hence, large animals will have relatively small canines.     

Tooth,chin, bone and body size correlations

Correlations of size of teeth, chin, bone and body were investigated in 118 males and 102 females of the Burlington Growth Centre. In the males, the mesiodistal widths of the mandibular lateral incisors and canines were independently related to the thickness of the cortex of the second metacarpal and to body weight. Bone cortex thickness was significantly related to metacarpal width in males and to body weight in females. Chin depth of the males was significantly related to bone width and to body height, and negatively related to tooth width when bone width or body weight was held constant in partial correlations. Bone width and length were significantly related to body height in both sexes.     

Allometric scaling in the dentition of primates and prediction of body weight from tooth size in fossils

Tooth size varies exponentially with body weight in primates. Logarithmic transformation of tooth crown area and body weight yields a linear model of slope 0.67 as an isometric (geometric) baseline for study of dental allometry. This model is compared with that predicted by metabolic scaling (slope = 0.75). Tarsius and other insectivores have larger teeth for their body size than generalized primates do, and they are not included in this analysis. Among generalized primates, tooth size is highly correlated with body size. Correlations of upper and lower cheek teeth with body size range from 0.90–0.97, depending on tooth position. Central cheek teeth (P and M) have allometric coefficients ranging from 0.57–0.65, falling well below geometric scaling. Anterior and posterior cheek teeth scale at or above metabolic scaling. Considered individually or as a group, upper cheek teeth scale allometrically with lower coefficients than corresponding lower cheek teeth; the reverse is true for incisors. The sum of crown areas for all upper cheek teeth scales significantly below geometric scaling, while the sum of crown areas for all lower cheek teeth approximates geometric scaling. Tooth size can be used to predict the body weight of generalized fossil primates. This is illustrated for Aegyptopithecus and other Eocene, Oligocene, and Miocene primates. Regressions based on tooth size in generalized primates yield reasonable estimates of body weight, but much remains to be learned about tooth size and body size scaling in more restricted systematic groups and dietary guilds.     

Response of wild subantarctic fur seal (Arctocephalus tropicalis) females to ketamine and tiletamine-zolazepam anesthesia

This study is the first to compare the anesthetic effects of two cyclohexamines on free-ranging subantarctic fur seal (Arctocephalus tropicalis) females. From April to July 1999, 107 females were immobilized for tooth extraction and blood sampling, using either ketamine (Ketalar, n = 58) alone or tiletamine-zolazepam (Zoletil 100, n = 49) mixture. Animals were injected intramuscularly at mean doses of 2.1 mg/kg for ketamine and 1.1 mg/kg for tiletamine-zolazepam mixture. Individual response to both drugs was highly variable. The dosage required to achieve a satisfactory level of anesthesia was smaller for subantarctic fur seals than for most other species of seals and was less for animals in better body condition. Few side effects were observed during the trials, aside from mild tremors caused by ketamine, and respiratory depression or prolonged apnea caused by tiletamine-zolazepam. We recommend use of ketamine, especially by those with little experience in anesthesia of fur seals. However, precautionary measures should be taken, such as using low doses for animals in good body condition and being prepared for anesthetic emergencies to avoid any casualties.     

Patterning the size and number of tooth and its cusps

Mice and rats, two species of rodents, show some dental similarities such as tooth number and cusp number, and differences such as tooth size and cusp size. In this study, the tooth size, tooth number, cusp size and cusp number, which are four major factors of the tooth patterning, were investigated by the heterospecific recombinations of tissues from the molar tooth germs of mice and rats. Our results suggest that the dental epithelium and mesenchyme determine the cusp size and tooth size respectively and the cusp number is co-regulated by the tooth size and cusp size. It is also suggested that the mesenchymal cell number regulates not the tooth size but the tooth number. The relationships among these factors in tooth patterning including micropatterning (cusp size and cusp number) and macropatterning (tooth size and tooth number) were analyzed in a reaction diffusion mechanism. Key molecules determining the patterning of teeth remains to be elucidated for controlling the tooth size and cusp size of bioengineered tooth.     

Dental scaling in the callitrichinae

Callitrichines share several morphological features that appear to be derived among anthropoid primates. One view maintains that some of them are the consequence of a rapid reduction in body size in the common ancestor of callitrichines. This hypothesis predicts that callitrichines should have relatively large teeth for their body size in comparison to other platyrrhines. Dental metric data from 18 platyrrhine species, including 4 callitrichines, is used to test this hypothesis. Callitrichine tooth size is compared both to empirical regressions of tooth size against body weight for noncallitrichine platyrrhines and to a prediction of geometric similarity. In neither comparison do callitrichines as a group show significantly greater tooth size than other platyrrhines. In fact, three of the four genera seem to have relatively small teeth for their body size. While this study fails to support the hypothesis that the common ancestor of callitrichines underwent a rapid reduction in body size, it neither proves nor disproves the hypothesis that they are smaller than their last common ancestor.     

牙齿大小与颅骨大小的相关研究——上颌牙齿大小与颅围长等的相关研究

对上颌牙齿大小和颅骨大小进行了相关研究。全部上颌牙齿大小与上齿槽弓长和弓宽相关显著或非常显著,与颅围长(右I~2无显著相关,左I1、左I2、右I2、左M1、右M1和右PM1与中部面宽)相关显著或非常显著。在此基础上求出了17个以牙齿大小推算颅骨大小的回归方程。     

A First Look at Estimating Body Size in Dentally Conservative Marsupials

The relationship between body size and tooth size has been documented for recent primates and insectivores and resulting predictive equations used to estimate body size in fossil species. This relationship is an important one, as body size is related to a host of physiological and ecological factors. In this study, the relationship between body size and molar size in recent dentally conservative marsupials is examined and body size in Cretaceous marsupials is estimated. Body weight information and basic length, width, and area measurements were taken from the molars of individuals from 22 species of Didelphidae and Dasyuridae. Least squares regression analysis shows that, as in previous studies on eutherians, the first molar is generally the most highly correlated with body size. In fact, there is a strong relationship between body size and tooth size throughout the molar series, suggesting that a fairly accurate body size estimate could be obtained from molars other than the first molar. The inclusion of species that are morphologically divergent from the average morphotype may affect the analysis. Body mass estimated in Cretaceous marsupials indicates a range of sizes similar to that seen in Recent dentally primitive marsupials.     

Tooth growth in male Antarctic fur seals (Arctocephalus gazella) from South Georgia: an indicator of long-term growth history

Growth of upper canine teeth of male Antarctic fur seals ( Arctocephalus gazella ) which died of natural causes at Bird Island, South Georgia, was quantified from measurements of annual layers in longitudinal sections of teeth. Mean age at death was 7.69±0.07 years and this showed a small but significant increase through the period when samples were collected (1972/73–1988/89). There were significant correlations between morphometrics of teeth and those of seals, suggesting that tooth growth provided an indication of body growth. Tooth growth rate was lowest in seals which died early (age 4 years) and increased with age at death. Changes in the growth pattern of teeth suggested that fur seals which became sexually mature early also died early. Tooth growth layers deposited in each calendar year were compared with the expected layer depth based on a linear relationship between layer depth and age at which each layer was deposited. There was significant variation in the depth of tooth growth layers deposited in different years, suggesting that growth was greater in some years than others. No trends in cohort strengths were detected, but particularly poor years for growth were closely related to years in which reproductive performance was also observed to be low. Variations in growth from 1967/68 to 1987/88 were correlated significantly (P < 0.008) with the Southern Oscillation Index of climatic variation.     

Brief communication: Morphometric data for adult lion-tailed macaques (Macaca silenus)

Basic morphometric data were collected from 22 adult lion-tailed macaques (M. silenus) of both sexes. M. silenus is a rare primate species from which adequate morphometric data have not heretofore been available for comparative purposes. Data collected include measures of gross body size (weight; crown-rump and rump-heel length), and for males, measures of secondary sexual characteristics (canine tooth and testes size). Degree of sexual dimorphism was marked, with males significantly larger and heavier than females. The three body size measures were correlated for males but not for females. There was substantial variation among individual males in secondary sex characteristics measurements. The data indicate than lion-tailed macaque morphometrics are consonant with the general pattern of positive allometry for body size and sexual dimorphism characteristic of the primate order.     

Posterior tooth size, body size, and diet in South African gracile Australopithecines

A model relating relative size of the posterior teeth to diet is suggested for forest and savanna primates and Homo. Relative tooth size is calculated for the South African gracile australopithecine sample using posterior maxillary area sums and size estimates based on four limb bones. A number of limbs were shown to be non-hominid. Comparisons show the South African gracile sample apparently adapted to a very heavily masticated diet with relative tooth size significantly greater than any living hominoid. Periodic intensive utilization of grains and roots combined with scavenged animal protein are suggested as the most likely dietary reconstruction.     

Heritability of permanent tooth size

The aim of this investigation was to quantify the relative contributions of genetic and environmental influences to the observed variability of permanent tooth size in a group of Australian Aboriginals. Tooth size data were obtained from dental casts of Aboriginals living at Yuendumu in the Northern Territory of Australia. The custom of polygyny practised by these people enabled the analysis of associations between full-siblings and half-siblings. Phenotypic variability of tooth size was partitioned into four variance components; between sides, between fathers, between mothers and between offspring. From these components, the relative genetic and environmental contributions were quantified and heritability estimates for tooth size derived. Additional estimates of heritability were obtained by regression analysis from a small sample of parent-offspring data. Results of the analyses suggested that about 64% of the total variability of permanent tooth size could be attributed to genetic factors, while a further 6% was due to common environment. Although the findings confirm a relatively strong genetic component, they emphasise the importance of non-genetic influences in the determination of tooth size variability.     

Tooth wear and the position of the mental foramen

Variation in the position of the mental foramen with respect to the teeth ("apparent" position) seems to be associated with race, but in the determination of this position, factors which affect the disposition of the teeth plainly have a bearing on the results. The apparent position was investigated in a sample of southern Chinese skulls of known age which were classified by the degree of tooth wear. Controlling for "true" position and size of the mandible, a highly significant correlation between wear and position was found, age and tooth size having no significant contribution as additional explanatory variables. The effect of tooth wear on the apparent position of the foramen may partly explain racial variation.     

Factors affecting weaning weight in Antarctic fur seals Arctocephalus gazella at South Georgia

Summary Relationships between size, body condition, age and feeding-attendance patterns during pup rearing of female Antacrtic fur seals Arctocephalus gazella and their effects on the timing of birth and weaning, pup weight, growth and condition were studied at South Georgia in 1981–1982. Twenty-seven (6 male, 21 female) mother-pup pairs were followed from birth to weaning. The analysis of maternal effects was limited to female pups because of the small sample size of male weaners. High weaning weight was associated with those female pups whose mothers spent more time ashore attending their offspring. Weaning weight showed no relationship with perinatal duration, number of feeding trips to sea, days at sea or date of weaning. A further 63 mother-pup pairs were analysed for the effects of maternal body condition (weight/length), age and timing of birth on offspring body weight and condition. Pup weight and condition were weakly correlated with maternal age in female pups. Male pups born earlier in the season were heavier and in better condition. Maternal and offspring body weight and condition were unrelated. For the Antarctic fur seal population at South Georgia where the food supply was apparently not limiting in summer, maternal condition and foraging time were subordinate to maternal care on land (as expressed by attendance duration) in determining offspring weight at weaning.     

Macaca thibetana at Mt. Emei,China: I. A cross-sectional study of growth and development

Six free-ranging groups of Macaca thibetana were studied at Mt. Emei, in southwest China. Patterns of growth and development observed during the study are described for this species for the first time. Data were collected mainly during the birth season of 1986. Food handouts made possible the measurement of body weight and sitting height. Changes in fur color and growth of forehead hair were noted. Dark hair appeared on the broad white forehead of infants at the end of the third month. A triangular patch formed about 30 days later, and full cover developed within 4.5 to 5 months. For the first 1 or 2 weeks, the fur was blackish; it then became yellow, and by the age of 3.5–4.5 months, it was brown or blackish, i.e., adult color. Growth data on body weight and sitting height for different age-sex classes were collected. For adult males, body weight was 18 kg, sitting height (SH) 55 cm, and ponderal index 33. For adult female, body weight was 13 kg, sitting height 47 cm, and ponderal index 27. Females were considered to be adult at age 5 years.     

Inheritance of tooth size in Australian aboriginals

The purpose of this study was to clarify the question of inheritance of tooth size, with particular reference to the role of the sex chromosomes. Data were obtained from the dental casts of Aboriginals living at Yuendumu in the Northern Territory of Australia, who had participated in a longitudinal growth study extending over 20 years. The compilation and verification of comprehensive genealogical records gathered over a number of years enabled the analysis of family data. Product-moment correlation coefficients between different full-sibling and half-sibling pairs were calculated for permanent tooth size. Values of individual and average correlation for both mesiodistal and buccolingual tooth diameters conformed with the theoretical correlations expected assuming polygenic inheritance. However, no evidence of sex chromosomal involvement was found.