A multivariate dental sexing technique

This paper presents a method of sexing skeletal remains using dental measurements. A base sample from a population is sexed with reference to the postcranial skeleton and the dental measurements (buccal-lingual and mesial-distal diameters) are analyzed by the discriminant function technique. A linear function is derived, which will classify by sex the remaining portion of the population.     

Sexual dimorphism in the tooth-crown diameters of the deciduous teeth

Mesiodistal and buccolingual crown dimensions of the right deciduous teeth of 133 white children were analyzed for information on sexual dimorphism and sex discrimination using discriminant analysis. Even though consistent differences were found for only 15 out of 20 paired measurements, five of them significant at p = 0.05 or better, discriminant analysis showed the possibility of correctly sexing up to 75% of the juvenile sample, using a maximum of seven deciduous teeth.     

猕猴颊齿大小的性差研究初报

对28例太行山成年猕猴(♂10,♀18)的上、下颌颊齿齿冠面积进行测量。运用SPSS 10.0统计软件的多变量分析,选择有关颊齿变量建立性别判别函数。结果表明:猕猴颊齿具有明显的性差。选择不同的变量和选择不同的判别函数其性别正确判别率不同。上、下颌颊齿的性差有一定差异。使用逐步判别法建立判别函数,其性别正确判别率上颌颊齿为89.3%,下颌颊齿为92.3%。     

Sexual dimorphism and mechanics of the human hip: A multivariate assessment

The present research was undertaken to determine the effects of sexual dimorphism in the human pelvis and femur on the mechanics of human locomotion. The analysis was based on six biomechanical variables determined from 25 male and 32 female skeletal remains from the Dickson Mound site. Discriminant function analysis indicates that the mechanical variables which primarily contribute to dimorphism are the moment arm of the gluteus medius and the torque produced by the abductors at the hip. These mechanical aspects of hip function produce greater pressure on the femoral head in females.     

Classification and misclassification in sexing the Black femur by discriminant function analysis

Stepwise discriminant function analysis for sex assessment was applied to 130 North American Black femora. The measurements included femoral length and three midshaft dimensions likely to be preserved in archaeologically derived and forensic remains. The method correctly assigned sex for 76.4% of the sample (range 70.8–81.5%). This compares favorably with results achieved with other skeletal parts; it also compares favorably with results using the femur in sexing other racial groups. Among our other conclusions are: (1) a “general size factor” is one of major significance in correct classification and in misclassification of sex, and most misclassified individuals are anomalous for this factor; (2) the inconsistency in the relation between circumference and femoral length, which characterizes the remaining misclassified individuals, suggests that anomalous functional demands of body weight/musculature are at fault, and affect circumference more than length; and (3) discriminant function analysis of the same variables in Whites produced similar results, suggesting that sex overrides race in sex assessment; this was confirmed by cross-validating the predictive accuracy of Black discriminant function coefficients on White data, and vice versa.     

Comparison of four simple methods for estimating sexual dimorphism in fossils

Estimating sexual dimorphism in skeletal and dental features of fossil species is difficult when the sex of individuals cannot be reliably determined. Several different methods of estimating dimorphism in this situation have been suggested: extrapolation from coefficients of variation, division of a sample about the mean or median into two subsamples which are then treated as males and females, and finite mixture analysis (specifically for estimating the maximum dimorphism that could be present in a unimodal distribution). The accuracy of none of these methods has been thoroughly investigated and compared in a controlled manner. Such analysis is necessary because the accuracy of all methods is potentially affected by fluctuations in either sample size, sex ratio, or the magnitude of intrasexual variability. Computer modeling experiments show that the mean method is the least sensitive to fluctuations in these parameters and generally provides the best estimates of dimorphism. However, no method can accurately estimate low to moderate levels of dimorphism, particularly if intrasexual variability is high and sex ratios are skewed. © 1994 Wiley-Liss, Inc.     

A new method for assessing the sex of fragmentary skeletal remains: femoral shaft circumference

A simple discriminant function using midshaft femoral circumference for the determination of sex has been tested with 114 skeletons from the Libben Site, Ontario County, Ohio. The results have been shown to be 85% consistent with other, accepted means of determining sex. Femur circumference an be an aid to the sexual identification of poorly preserved and fragmentary skeletal remains.     

Using interpubic distance for sexing manakins in the field

ABSTRACT Field methods for determining the sex of birds are often limited due to morphometric overlap between sexes, intermediate plumages, seasonality, and reliance on subjective age classification. Interpubic distance, characterized in birds as the distance between the distal ends of the pubic bones, has not been formally tested as a method for determining the sex of birds, despite references among parrot breeders and the frequent use of analogous measurements in mammals. We developed a harmless and easily performed field method for measuring interpubic distance in studies involving bird capture, and compared the interpubic distances of known sex White‐ruffed Manakins (Corapipo altera), Orange‐collared Manakins (Manacus aurantiacus), and Blue‐crowned Manakins (Lepidothrix coronata) to evaluate the possible use of this measurement to determine sex. Using interpubic distance ranges based on 85% confidence intervals where overlap existed between sexes, the sex of 92.8–100% of all manakins in our study was accurately determined with no misclassification. Interpubic distance performed better than plumage‐based methods that sexed 74.0% of all individuals and misclassified 1.5%. Using linear discriminant analysis, we developed classification equations that allowed us to accurately determine the sex of all individuals with 100% accuracy using mass and interpubic distance. Additionally, we compared the interpubic distances of female White‐ruffed Manakins to evaluate the potential to determine age and reproductive status. Despite an apparent relationship between interpubic distance, age and reproductive status, we concluded that interpubic distance has limited use for determining age and reproductive status due to extensive overlap (31.6–100%), but shows potential in other applications. Based on these results, we endorse the use of interpubic distance to determine the sex of manakins. We encourage further study to develop additional classification equations using different morphometric measurements and to test the efficacy of interpubic distance to determine sex in other bird species.     

Shape differences in the sacral alae

The great variability and complexity of sacral morphology has led to some confusion over the separate influences of phylogeny, population differences, and sexual dimorphism. Principal component analysis of Cartesian coordinates taken on the alae of one hundred human sacra reveals that allometric growth accounts for most variation in the extent and orientation of this region (termed basality). Sex differences related to functional contribution of the alae to the pelvic cavity account for the remainder of the variability. The requirement for extrastability in this region to support the large individual may obscure sexual dimorphism in the sacrum. This, in turn, may have influenced past observations on the sex criteria for this bone.     

Anthropometric analysis of the face in hypohidrotic ectodermal dysplasia: a family study

Sixteen individuals with hypohidrotic ectodermal dysplasia (HED) were compared to normal standards as well as to 16 unaffected family members by using a series of 20 anthropometric measurements of the head and face. Individuals with HED were generally smaller than normal controls or their unaffected relatives. However, this size reduction was not uniform. Instead, it was most evident in the anterior-posterior dimensions of the lower two-thirds of the face, in facial height, and in the size of the ears, nose, and mouth. A stepwise discriminant function analysis indicated that a function constructed from four variables (depth of the lower face, width of the nose, mandibular arc, and total facial height) could accurately classify 96.7% of the 32 individuals in the combined sample of affected and unaffected individuals. These findings demonstrated that the face of individuals with HED is unique and can be useful in its diagnosis. Additional studies are needed to determine if similar-though-less-pronounced facial abnormalities can be used to detect minimally affected gene carriers of this presumably X-linked condition.     

Mating system and demographic constraints on the opportunity for sexual selection

In monogamous systems the fitness difference between males due to competition for mates is limited to one female. This constraint presumably impedes the action of sexual selection relative to polygynous systems. In this paper, we use formal selection theory to show how population size and the adult sex ratio constrain the force of sexual selection and phenotypic evolution under monogamy and polygyny. The force of sexual selection is ultimately constrained by the number of males in a population and the theoretical limit to the rate of male phenotypic evolution is realized if a single male mates with one or many females. These results imply that the force of sexual selection is not strictly constrained by monogamy. The constraint on female phenotypic evolution is typically higher than the constraint on males under polygyny and similar to selection on males in monogamous systems. The sexual asymmetry in the force of selection under polygyny--not necessarily weak sexual selection on males of monogamous systems--may explain the prominence of sexual dimorphism in polygynous systems.     

Sexual size dimorphism and morphometric sexing in a North African population of Laughing Doves Spilopelia senegalensis

Like the majority of Columbiformes, the Laughing Dove Spilopelia senegalensis is sexually monomorphic in plumage, but seems to be slightly dimorphic in size. However, due to the lack of studies little is known about the sexual size dimorphism in this species. In this work, we used morphometric data on a sample of 61 Laughing Doves from southern Tunisia, and sexed using a DNA-based method, to assess size differences between males and females and to determine a discriminant function useful for sex identification. The results showed that wing length was the most dimorphic trait, which could be due to the effects of sexual selection. The best function for the discrimination between sexes included wing length and head length, which is comparable with findings on other dove species. This discriminant function accurately classified 89% of birds, providing a rapid and accurate tool for sex identification in the studied population. Further data from different populations are needed for firmer conclusions about the extent of sexual size dimorphism and the reliability of the morphometric sexing approach in this dove species.     

Observations of the mating behavior and dentition of the round stingray,Urolophus halleri

Synopsis The mating behavior and dentition ofUrolophus halleri, the round stingray was examined. Males frequently bite females during the mating period but most male biting does not result in copulation. In bites that do not lead to copulation, males bite the posterior (or occasionally the medial) portion of the females' disc but females often free themselves from these bites. In bites that precede copulation, males bite the anterior portion of the females' disc and females do not struggle to free themselves. Thus, females may exert some form of choice when they are bitten. Mature males have sexually dimorphic dentition that may aid in holding females. A principal component analysis (PCA) showed that in juvenile males, the relative size of the teeth decrease while the relative thickness of the disc increases as body size enlarges; adult males displayed no clear pattern. In adult females, there is a relative decrease in tooth size and increase in relative disc thickness as body size enlarges. The relative increase in females disc thickness in areas where they are bitten may function to minimize the amount of damage due to non-copulatory biting. There is no indication that biting functions to induce female receptivity but it may allow females and males to acquire information about potential mates. Thus, copulatory biting functions to maintain contact during copulation while the function of non-copulatory biting is less clear.     

Lateral angle: a method for sexing using the petrous bone

We report on the results of applying the so-called lateral angle method for sex determination on skeletal remains. The lateral angle denotes the angle of the internal auditory canal in relation to the medial surface of the petrous part of the temporal bone. The method involves making a small cast of the proximal part of the internal acoustic canal and determining the angle at which the canal opens up to the surface of the petrous bone. The method has the great advantage of utilizing one of the sturdiest bone elements of the human skeleton, and may thus be especially suited for analyses of very fragmented skeletal remains or cremated bones, where the petrous bone may still be readily recognizable. The method was tested using a forensic sample of 113 petrous bones with known sex. Intra- and interobserver testing was also performed. We found a statistically significant difference in angle size between males and females (mean angle size of males, 39.3 degrees ; mean angle size of females, 48.2 degrees ; P < 0.001). There was no bilateral difference in angle size. In blind trials, 83.2% of petrous bones were assigned to the correct sex. We also tested the lateral angle method against an archaeological skeletal sample. True sex was not known for this sample; instead, sexing had been carried out by assessing pelvic and cranial morphology in independent trials. We found a higher concordance between the lateral angle and "pelvic" sex than for lateral angle and "cranial" sex. Finally, we note that subadult sexing may also be possible with this method.     

太行山猕猴肩胛骨和肱骨的性别判别

测量了 2 6例 (♀ 1 6,♂ 1 0 )成年太行山猕猴肩胛骨和肱骨的 1 5项变量。通过运用SPSS1 0 0单因子方差分析 ,结果显示 ,有 9项变量在两性间达到了显著差异水平 ;采用多变量判别分析方法对有关变量建立判别函数 ,结果显示 ,采用强迫引入法和逐步判别法 ,判别正确率分别为 1 0 0 0 0 %和 92 3 0 %;运用主成分分析 ,进一步说明肩胛骨和肱骨在性别判别中有一定的作用     

Univariate and multivariate analysis on phenotypic divergence in Phleum

Summary An analysis of phenotypic and genetic variability was performed on Phleum ambiguum populations obtained by vegetative propagation and grown in different environments. The investigation on a single character and the canonical analysis on several plant traits indicate that, while genetic variability (h²) is essentially constant, phenotypic variance and covariance are affected by different environments and successive clonations. The observed changes seem not to be reversible when plants, transferred to a different environment, are returned to the original one. Within-clones variability seems to be affected by environmental conditions without being directly related to them. The results reported seem to be in good agreement with the phenotypic divergence hypothesis.     

A novel method for sexing live adult Alphitobius diaperinus

This work aimed to identify discriminant morphological characteristics in Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae) adults that enable live males and females to be distinguished. The method of sexing proposed here is based on dimorphism of the 8th abdominal sternite and is 100% accurate. The method allows differentiation of the sexes non-destructively.