High Degree Of Sexual Dimorphism Research Articles

Anthropometric evaluation of mandibular characteristics in the medieval Kurdish population of Girê Kortikê: Sex-based variations and comparative analysis

IntroductionThis research seeks to develop population-specific standards for skeletal sex determination, focusing on the medieval Kurdish population of Girê Kortikê and the mandible, a skull component presenting the highest degree of sexual dimorphism. This is the first study of its kind for this population. The research's primary objectives were to conduct anthropometric evaluations of several mandibular characteristics within this population, assess sex-based variations, determine relationships between various mandibular sizes, and contrast these findings with other existing studies. Materials and methodsA total of 121 mandibles (55 women, 66 men) were measured using 14 distinct anthropometric techniques, applying Pearson correlation coefficients, student's t-test, and principal component analysis (PCA) for comparison. ResultsThe study examined and discussed disparities between some chosen mandibular measurements and data from other populations. Statistically significant sex differences (p < 0.05) and correlations were identified in 12 of the anthropological measurements. The research found that the greater the height of the symphysis (GNI), the higher the foramen mentale height (FBB). Average measurements significantly deviated from the medieval Kurdish population when compared to populations in Santa Maria Xigui, Mexico (XIG), and Mexico City (MEX). ConclusionNo correlation was found between the height of the mandibular body (HML) and the mandible length (MLT). The study suggested distinct mandibular angle (MAN) sizes between sexes, indicating unique characteristics within the Girê Kortikê population, warranting further research for a more comprehensive evaluation. In conclusion, these findings emphasize the mandible's anatomical, historical, and cultural relevance in sex determination within the Girê Kortikê population.

Dimorphilus gyrociliatus (Annelida: Dinophiliformia) Dwarf Male Nervous System Represents a Common Pattern for Lophotrochozoa.

Dinophiliformia is a newly revealed clade within Annelida that is a sister group to Pleistoannelida. Dimorphilus gyrociliatus is a representative of this clade that has fascinated scientists with its high degree of sexual dimorphism. Both males and females are small, worm-like creatures that have specific ciliary structures: anterior ventral, posterior ventral, and dorsal ciliary fields in males, and prototroch, metatroch, and ventral ciliary fields in females. There are data on the morphology and development of the nervous system in Oweniidae, Sipunculida, Pleistoannelida, and even Dinophiliformia. However, data on the neuromorphology and development of D. gyrociliatus dwarf males are limited. Here, we present data on the distribution of cilia, sensory neurons, and the 5-HT-like immunoreactive system in 3D reconstructions and cross-sections. Immunochemical labeling with anti-acetylated tubulin and anti-5-HT antibodies and confocal microscopy were used to visualize the ciliary structures and neurons. The male has three ciliary fields: anterior ventral, posterior ventral, and dorsal. These include frontal ganglia, five commissures, two ventral and two dorsal bundles, and penial nerves. A total of fifty-seven neurons and only five 5-HT-like immunoreactive cells were described. Although the sensory neurons were not 5-HT-like immunoreactive, they had 5-HT innervation, which may indicate the role of 5-HT in perception. There may be homology between male and female ciliary structures. The dwarf male of D. gyrociliatus may have a reduced apical organ consisting of two sensory neurons and a 5-HT-like immunoreactive cell.

Delimiting the cryptic diversity and host preferences of Sycophila parasitoid wasps associated with oak galls using phylogenomic data.

Cryptic species diversity is a major challenge regarding the species-rich community of parasitoids attacking oak gall wasps due to a high degree of sexual dimorphism, morphological plasticity, small size and poorly known biology. As such, we know very little about the number of species present, nor the evolutionary forces responsible for generating this diversity. One hypothesis is that trait diversity in the gall wasps, including the morphology of the galls they induce, has evolved in response to selection imposed by the parasitoid community, with reciprocal selection driving diversification of the parasitoids. Using a rare, continental-scale data set of Sycophila parasitoid wasps reared from 44 species of cynipid galls from 18 species of oak across the USA, we combined mitochondrial DNA barcodes, ultraconserved elements (UCEs), morphological and natural history data to delimit putative species. Using these results, we generate the first large-scale assessment of ecological specialization and host association in this species-rich group, with implications for evolutionary ecology and biocontrol. We find most Sycophila target specific subsets of available cynipid host galls with similar morphologies, and generally attack larger galls. Our results suggest that parasitoid wasps such as Sycophila have adaptations allowing them to exploit particular host trait combinations, while hosts with contrasting traits are resistant to attack. These findings support the tritrophic niche concept for the structuring of plant-herbivore-parasitoid communities.

Sexual Dimorphism in Kisspeptin Signaling.

Kisspeptin (KP) and kisspeptin receptor (KPR) are essential for the onset of puberty, development of gonads, and maintenance of gonadal function in both males and females. Hypothalamic KPs and KPR display a high degree of sexual dimorphism in expression and function. KPs act on KPR in gonadotropin releasing hormone (GnRH) neurons and induce distinct patterns of GnRH secretion in males and females. GnRH acts on the anterior pituitary to secrete gonadotropins, which are required for steroidogenesis and gametogenesis in testes and ovaries. Gonadal steroid hormones in turn regulate the KP neurons. Gonadal hormones inhibit the KP neurons within the arcuate nucleus and generate pulsatile GnRH mediated gonadotropin (GPN) secretion in both sexes. However, the numbers of KP neurons in the anteroventral periventricular nucleus and preoptic area are greater in females, which release a large amount of KPs in response to a high estrogen level and induce the preovulatory GPN surge. In addition to the hypothalamus, KPs and KPR are also expressed in various extrahypothalamic tissues including the liver, pancreas, fat, and gonads. There is a remarkable difference in circulating KP levels between males and females. An increased level of KPs in females can be linked to increased numbers of KP neurons in female hypothalamus and more KP production in the ovaries and adipose tissues. Although the sexually dimorphic features are well characterized for hypothalamic KPs, very little is known about the extrahypothalamic KPs. This review article summarizes current knowledge regarding the sexual dimorphism in hypothalamic as well as extrahypothalamic KP and KPR system in primates and rodents.

Influence of incubation, diet, and sex on avian uncoupling protein expression and oxidative stress in market age broilers following exposure to acute heat stress

Genetic selection for rapid growth in broilers has inadvertently resulted in increased susceptibility to heat stress, particularly in male birds. Increased oxidative stress associated with hyperthermia may be reduced by avian uncoupling protein (avUCP), which has been proposed to modulate free radical production. However, the relationship between avUCP expression and current heat stress management strategies is unclear. Embryonic acclimation or thermal manipulation (TM) and dietary fat source are 2 heat stress interventions that may alter avUCP expression and oxidative stress, but the literature is inconclusive. The objective of this trial was to investigate the effect of TM and dietary fat source on avUCP gene expression and oxidative damage in the breast meat of market age broilers before and after acute heat challenge. The influence of bird sex was also evaluated as broilers exhibit a high degree of sexual dimorphism in growth and stress susceptibility. Concentration of thiobarbituric acid reactive substances (TBARS) was measured as a marker of oxidative damage. Embryonic TM occurred from incubation d 7 to 16 for 12 h daily at 39.5°C. Dietary treatments were applied during the finisher period using either poultry fat, soya oil, or olive oil supplemented at 4.5% in the diet. Acute heat stress (AHS) occurred on d 43 at 32°C for 4 h. Bird performance was decreased by TM, but no significant differences were noted between dietary fat source treatments. Neither avUCP nor TBARS concentrations were significantly influenced by TM or dietary fat source. Downregulation of avUCP was observed following AHS, concurrent with an increase in TBARS concentration. Male birds exhibited higher levels of both avUCP expression and TBARS compared to females and a significant interaction was noted for heat stress by sex, with avUCP expression being greatest in males prior to AHS. The increase in avUCP expression and TBARS concentrations in male birds may be associated with an increased susceptibility to stress arising from the increased growth rate noted for male broilers.

Evidence of a Dietary Shift in Female Barbour's Map Turtle (Graptemys barbouri) to Exploit an Exotic Mollusk

Barbour's map turtle (Graptemys barbouri) is the species of map turtle with the highest degree of sexual dimorphism, with females attaining larger body sizes and having much greater head widths than males. Accordingly, females and males also feed on different riverine prey, with females historically feeding on native gastropods and bivalves and males predominantly feeding on soft-bodied macroinvertebrates. Here, we report on a diet shift in female Barbour's map turtle from native prey to an invasive mollusk, the Asian clam (Corbicula fluminea), in southwestern Georgia.

Non-alcoholic Fatty Liver Disease as a Canonical Example of Metabolic Inflammatory-Based Liver Disease Showing a Sex-Specific Prevalence: Relevance of Estrogen Signaling.

There is extensive evidence supporting the interplay between metabolism and immune response, that have evolved in close relationship, sharing regulatory molecules and signaling systems, to support biological functions. Nowadays, the disruption of this interaction in the context of obesity and overnutrition underlies the increasing incidence of many inflammatory-based metabolic diseases, even in a sex-specific fashion. During evolution, the interplay between metabolism and reproduction has reached a degree of complexity particularly high in female mammals, likely to ensure reproduction only under favorable conditions. Several factors may account for differences in the incidence and progression of inflammatory-based metabolic diseases between females and males, thus contributing to age-related disease development and difference in life expectancy between the two sexes. Among these factors, estrogens, acting mainly through Estrogen Receptors (ERs), have been reported to regulate several metabolic pathways and inflammatory processes particularly in the liver, the metabolic organ showing the highest degree of sexual dimorphism. This review aims to investigate on the interaction between metabolism and inflammation in the liver, focusing on the relevance of estrogen signaling in counteracting the development and progression of non-alcoholic fatty liver disease (NAFLD), a canonical example of metabolic inflammatory-based liver disease showing a sex-specific prevalence. Understanding the role of estrogens/ERs in the regulation of hepatic metabolism and inflammation may provide the basis for the development of sex-specific therapeutic strategies for the management of such an inflammatory-based metabolic disease and its cardio-metabolic consequences.

Correlation coefficients for predicting canine diameters from premolar and molar sizes

Background/purposeThe permanent canine is the most widely used tooth for sex estimation because it is the tooth with the highest degree of sexual dimorphism; however, there are several factors that can limit the analysis (e.g., pathologies, postmortem loss). The aim of this work was to analyse the correlation between the dimensions of the canines and those of the premolars and molars, and evaluate the correspondence of real and predicted canine dimensions by applying the equations developed. Materials and methodsThe sample was composed of digital models of 80 adult individuals from Temuco, Chile. The buccolingual and mesiodistal diameters of the canine, premolar and molar dental crowns were measured and Pearson's linear regression analysis was performed in order to determine the correlation between the diameters. The equations obtained from the reference subsample were applied to a validation subsample to predict canine dimensions from the dimensions of the postcanine teeth. ResultsFour regression equations were obtained, all for prediction of the size of the lower canines, whose correlation coefficient ranged from 0.701 to 0.738. The regression equations developed with the reference sample were tested on the validation sample using a Student's t-test for paired samples and the intraclass correlation coefficient. The differences between actual dental size and that predicted by the equations were not significantly different, and concordance analysis showed a moderate degree (0.485–0.585). ConclusionThere is a limited correlation of canine dimensions with respect to premolars and molars. The correspondence between the actual and predicted canines dimensions is moderate.

Divergent artificial selection for female reproductive investment has a sexually concordant effect on male reproductive success.

Depending on the genetic architecture of male and female fitness, sex‐specific selection can have negative, positive, or neutral consequences for the opposite sex. Theory predicts that conflict between male and female function may drive the breakdown of intrasexual genetic correlations, allowing sexual dimorphism in sexually antagonistic traits. Reproductive traits are the epitome of this, showing highly differentiated proximate functions between the sexes. Here we use divergent artificial selection lines for female reproductive investment to test how female‐specific selection on a sex‐limited trait affects male reproductive success in a precocial bird, the Japanese quail (Coturnix japonica). We demonstrate that selection for increased egg investment in females positively affects male reproductive success both in competitive and non‐competitive mating situations. This increased reproductive success was linked to a relatively larger left testis in males originating from lines selected for high female reproductive investment. Given that female quail have functional gonads only on their left side, this correlated response indicates that selection has acted on the shared developmental basis of male and female gonads. Our study thereby provides evidence for a positive genetic correlation between key reproductive traits in males and females despite a high degree of sexual dimorphism, and suggests that, in this system, selection on reproductive function is sexually concordant.

Strong Competition Does Not Always Predict Play Asymmetry: The Case of South American Sea Lions (Otaria flavescens)

AbstractAlthough play fighting has been studied for over a century in both human and non‐human animals, quantitative data on marine mammals are still scarce. Here, we investigated play fighting in South American sea lions (Otaria flavescens), one of the most sexually dimorphic species with an extreme polygynous mating system, high levels of both intra‐ and inter‐sexual competition. All these features make South American sea lions a good model species to test some predictions on play fighting. Our results indicate play is restricted to juveniles, being inhibited among adults, and as to be expected in a species that shows a high degree of sexual dimorphism, it is mainly expressed in males. Even though playful interactions were punctuated by competitive behaviours, animals played in a highly symmetric way and were able to adjust their competitive playful interactions in a flexible manner and so reduce the risk of escalation to a minimum level. They were highly selective in their choice of playmates by limiting the number of players per session and playing more with age‐matched companions and friends. All these factors taken together are probably at the basis of the low risk of escalation recorded during the study. This result is predictive of a high ability and motivation of these animals to engage in play behaviour which can have a possible role not only in the acquisition of dominance status, but also in establishing and maintaining social relationships, an unexpected role in a so highly competitive species.

Gigantopithecus blacki: a giant ape from the Pleistocene of Asia revisited

Gigantopithecus blacki is the largest hominoid that ever lived. The consensus view is that it is a specialized pongine and late-surviving member of the Sivapithecus-Indopithecus lineage. It is known primarily from Early and Middle Pleistocene cave sites in southern China, dating from 2.0Ma to almost 300ka. The cause of its extinction in the late Middle Pleistocene is unknown, but ecological change or the arrival of Homo erectus may have been contributing factors. Gigantopithecus is highly specialized in its dentognathic anatomy, with a unique combination of features that distinguish it from all other hominoids. Based on the size of its dentition and mandible, a reasonable estimate of its body mass would be 200-300kg. There was a progressive increase in dental size from the Early Pleistocene to the Middle Pleistocene, and possibly a shift towards greater complexity of the cheek teeth. Gigantopithecus exhibits a relatively high degree of sexual dimorphism, implying a high level of male-male competition, but the relatively small canines in both sexes suggest that these teeth were not important in agonistic behaviors. The species inhabited a subtropical monsoon forest with a closed canopy and dense understory. Foraging was focused on the forest floor and its diet included a broad range of C3 plants, including fruits, leaves and stems, and possibly tubers. The cheek teeth and jaws were adapted for processing a wide variety of bulky, fibrous, and abrasive food items, but the small incisors indicate that incisal preparation was not an important part of its feeding repertoire.

PATTERNS OF SEXUAL DIMORPHISM AND PHENETIC VARIETYAMONG THE POPULATIONS OF THE GOLDEN JACKAL (Canis aureus) IN BULGARIA: INSIGHTS FROM CRANIOMETRIC DATA

Abstract A population craniometric analysis of the golden jackal ( Canis aureus ) from Bulgaria was carried out using 18 linear skull and dental parameters. The analysis included 106 individuals (52 males and 54 females), originating from 3 geographic populations with different density. Age variation, sexual dimorphism and geographic variation of the size of the cranium were assessed order to resolve the phenetic similarity of the Bulgarian golden jackal populations. The obtained data confirmed the high degree of sexual dimorphism of the skull. The multivariate statistical assessment of the population skull features in the adult Bulgarian golden jackals, performed separately by gender, demonstrated that at population level in both sexes they have resolution ability and can be used for classification of the individuals to certain geographic populations of the species in Bulgaria. Moreover, the patterns of population craniological variation manifested low degree of craniological similarity among the golden jackals inhabiting the Eastern (Southern and South-western Bulgaria) and Western (Dalmatia, Croatia) Balkans, whereupon revealing their craniometric heterogeneity in the Balkan Peninsula. Thus, it is necessary to use the morphometric data in combination with other methods to establish the phenetic similarity between golden jackal populations, especially at subspecies rank in the Balkan Peninsula.

Leptin pharmacokinetics in male mice

Pharmacokinetics of leptin in mammals has not been studied in detail and only one study has examined more than one time point in non-mutant mice and this was in a female mice. This is the first study to describe leptin distribution over a detailed time course in normal male mice. A physiologic dose (12 ng) of radiolabelled leptin was injected into adult male mice via the lateral tail vein and tissues were dissected out and measured for radioactivity over a time course of up to two hours. Major targets were the digestive tract, kidneys, skin and lungs. The brain was not a major target, and 0.15% of the total dose was recovered from the brain 5 min after administration. Major differences appear to exist in the distribution of leptin between the male and female mice, indicating a high degree of sexual dimorphism. Although the half-lives were similar between male and female mice, almost twice the proportion of leptin was recovered from the digestive tract of male mice in comparison to that reported previously for females. This would seem to indicate a major difference in leptin distribution and possibly function between males and females.

Osteometric sex estimation from the os coxa in a Thai population

The coxal bone shows a very high degree of sexual dimorphism both morphologically and metrically. However, despite a number of recent studies on sex estimation from the skeleton in Thailand, no osteometric methods of sexing the Thai os coxa have been proposed. Therefore, the aim of this study was to develop a standard sex estimation method for a Thai population by examining the efficacy of six coxal bone measurements and eight indices obtained from 200 Thai skeletons. Independent samples t-tests revealed statistically significant differences between males and females for all but one of the measurements. The equation with the highest correct allocation accuracy was based on four measurements (pubis length, ischium length, total height and acetabulum diameter) and had a predicted and cross-validated accuracy of 96.9% and a tested accuracy of 97.5% on a holdout sample of 40 individuals. The single variable equation with the highest correct allocation accuracy of 94.4% and a tested accuracy of 97.5% was for the ischiopubic index, which is calculated from ischium length and pubis length. Percentage accuracies in predicting sex from these equations were higher than many previous studies, suggesting high levels of sexual dimorphism in the Thai os coxa.

Extending Afrotropical endemism: Discovery of Prosapanesia Kieffer (Hymenoptera: Bethylidae) from the Oriental region with the description of two new species

Pristocerinae is one of the five subfamilies of Bethylidae exhibiting high degree of sexual dimorphism. Prosapanesia Kieffer, a rarely collected pristocerine genus is recorded for the first time from the Oriental region. Two new species based on females, Prosapanesia emarginatasp. nov. and P. orientaliasp. nov. are described with world key to the known female species. The generic diagnosis for both male and female are revised. The distribution of Prosapanesia and its congeners is commented.

Conversion of palatal rugae pattern to scanable Quick Response code in an Arabian population

Backgroud/purposePalatal rugae (PR) are situated in the anterior part of the hard palate and possess unique and stable characteristics that can be used in human identification. Their pattern of orientation is established early in life and remains stable thereafter. The purposes of this study were to convert PRP into alphanumeric codes in order to generate scanable Quick Response (QR) codes, to demonstrate uniqueness of PRP using the codes in the study population, and to determine the sexual dimorphism of PRP in the study population. Materials and methodsOrthodontic dental casts of 256 Saudi male and female patients were photographed after ensuring standardization. Individual rugae characteristics, strength and their displacement from incisive papilla and midpalatine raphe were recorded in the form of an alphanumeric code which was subsequently converted to a QR code. Computer assisted check was performed for possible match in the 256 alpha numeric codes while QR codes were scanned using a bar code scanner to determine uniqueness. Sexual dimorphism of palatal rugae (PR) was also analysed. ResultsAll alphanumeric codes of the study population were unique. Mean number of PR in males and females differed significantly (P = 0.0001). Differences in rugae characteristics and strengths in males and females were also present. ConclusionThe alphanumeric and QR code of the rugae pattern are unique for each individual and can be used for digital record keeping and person identification. A high degree of sexual dimorphism in PR exists in the studied Arab population studied.

An unusual, new, sexually dimorphic species of Gryon Haliday (Hymenoptera: Scelionidae) from India

Gryon ingens (Hymenoptera: Scelionidae) discovered recently in India and possessing an unusually elongate metasoma is described as a new species. With the exception of the length of the metasoma, the species characters match those of Gryon. The large and elongate eggs of the reduviid host of G. ingens sp. n. account for its unusually long habitus. The high degree of sexual dimorphism, which includes colour, encountered in this instance is atypical of this genus.

Assessment of sexual dimorphism using digital orthopantomographs in South Indians.

Introduction:The identification of human skeletal remains plays a crucial role in forensic investigation and its accuracy depends on the available parts of the skeleton. The mandible is the hardest and strongest bone of the skull, which exhibits a high degree of sexual dimorphism and helps to identify the sex in human remains. The aim of this study was to develop discriminant function to determine sex from the mandibular radiographs in a South Indian (Visakhapatnam) population.Materials and Methods:This retrospective study consisted of 384 (192 males and 192 females) digital orthopantomographs (OPGs) divided into five groups according to age. Ten mandibular variables were measured using Planmeca Romexis software. The data were tabulated and subjected to discriminant function analyses using Statistical Package for the Social Sciences (SPSS) software (version 20.0) package.Results:All the parameters showed a significant sexual dimorphism (P < 0.001) except for the gonial angle. An overall accuracy of 75.8% was achieved and coronoid height (CrH) was the single best parameter providing an accuracy of 74.1%.Conclusion:All the mandibular variables except for the gonial angle (GA) were found to be reliable in determining the sex in South Indians for forensic purposes.

Gender determination by radiographic analysis of mental foramen in the Maharashtra population of India.

Context:Identification of gender is of primary importance in forensic investigations when only fragment of skull remains. Mandible is a hard bone and exhibits a high degree of sexual dimorphism. Gender differences were observed in the height of mandible, gonial angle, bigonial breadth, bicondylar breadth, and position of mental foramen (MF).Aims of the Study:The purpose of this study is to evaluate gender differences in distances from superior border of MF (SMF) and inferior border of MF (IMF) to the lower border of mandible (LBM) and height of mandible in the Maharashtra population.Materials and Methods:A total of 400 patients (200 males and 200 females) were considered for the study. The panoramic radiographs of patients were captured using Xtropan 2000 system and Carestream (T-Mat GIRA) films. The distance from SMF and IMF to the LBM and the height of mandible was measured.Statistical Analysis Used:Unpaired t-test was applied to calculate the differences between the genders.Results:The distance from SMF and IMF to LBM and height of mandible was more in males when compared to females, which was statistically significant.Conclusion:The distances from SMF and IMF to the LBM and height of the mandible showed sexual dimorphism in the Maharashtra population of India.

Sexual dimorphism in Iranian population using diagonal distances on the facial and occlusal surfaces of mandibular first molar

Background: Measurements of diagonal distances of teeth were one of the major tools in assessment of sexual dimorphism in various populations. Various research and studies were aimed at achieving the perfect results in forensic context. Aims: The study was aimed to assess the degree of sexual dimorphism in permanent mandibular molar of Iranians using diagonal diameters. Objectives: To evaluate the applicability of diagonal measurements in sex determination. Materials and Methods: The study sample consisted of 30 Iranians students of age group between 15 to 25 years that included 15 male samples and 15 female samples ie of 1: 1 ratio. Diagonal distances on the occlusal surfaces and diagonal dimensions on the facial surface were considered. Calculations were done using manual Vernier calliper recorded dimensions were larger in males than in females. Results: The mean values and standard deviation of all recorded dimensions were larger in males than in females. Conclusion of Study: The results showed that occlusal and facial diagonal diameters of molars can be used for sex determination as they present a high degree of sexual dimorphism.