Dimorphism In Shape Research Articles

Dental Anomalies and Cranio-Dental Ontogeny in a Captive Wild Boar Population From France.

Dental anomalies are frequent in boars and pigs, and they generally affect the first premolar loci. The prevalence of these dental anomalies was investigated in a large number of populations around the world. These studies mainly focused on the influence of domestication, size, sexual dimorphism or food hardness on these anomalies. However, they rarely considered ontogenetic aspects, while these are crucial for understanding their aetiology during animal growth and how the dental row-jaw complex is affected. Here, we studied the incidence of missing first upper and lower premolars in a French population of captive wild boars to discuss the functional and developmental reasons for missing teeth and to assess the impact of missing teeth on the growth of the dental row-jaw complex. Using the CT-scan data of the cranium and mandible of 24 wild boars investigated six times each during their growth, and presenting a balanced sex ratio, we recorded the number of missing teeth. We then quantified the shape of the upper and lower jaws using 3D geometric morphometrics. We found a similar prevalence of missing first premolar (37.5%) between the upper and the lower jaws, which is higher than the frequencies observed in most continental populations of wild boars. The increasing number of anomalies during ontogeny suggests a relaxed constraint on the dentition associated with a different feeding behaviour in captivity. The absence of first premolars does not appear to be associated with size variation or sexual dimorphism, nor does it affect the place of the dentition within the jaw, the latter being more influenced by the dimorphic shape of the canines and the timing of dental eruption.

Size as a determinant of robustness: Exploring sexual dimorphism in the size and shape of the snapping and cutting claws in Alpheus (caridea: Alpheidae)

This study investigates the role of static allometry in modulating sexual shape dimorphism in the snapping and cutting claws of Alpheus species. We hypothesize that the static allometry in adulthood can promote an exaggeration of existing sexual dimorphism in the snapping and cutting claws of Alpheus. Sexually mature pairs from three species (Alpheus angulosus, Alpheus carlae, and Alpheus nuttingi) were analyzed using geometric morphometric techniques. The increase in size claw enhances the robustness of both snapping and cutting claws. Since males carry larger weapons compared to females, the static allometry provides more robustness in their weapons. These findings support our hypothesis. Due to the effect of static allometry, male weapons exhibit a more robust pollex, while female weapons exhibit a more robust palm in the snapping claw. Sexual shape dimorphism is less pronounced in the cutting claw, although males display larger and more robust claws compared to females. Static allometry amplifies the sexual differences in Alpheus weapons, emphasizing the role of sexual selection in the evolution of claw morphology. The results suggest that sexual selection favors larger, more robust claws in males, thus enhancing their effectiveness in agonistic contests.

Sexual Dimorphism in Wing Shape and Its Impact on Conspecific Identification of Neotropical Fannia Species (Diptera: Fanniidae)

Neotropical species of the genus Fannia remain poorly known despite their potential collection as biological evidence in criminal investigations. This is partly due to taxonomic difficulties and a lack of specialists. Identifying neotropical species of Fannia relies mainly on the classical morphological characters of adult males, as females show high similarity between species. Here, landmark-based geometric morphometrics of the wing could constitute an additional tool for associating adult females with conspecifics in this genus. In this study, we used a reference dataset of males belonging to ten putative species of Fannia from Colombia and molecular data to test this hypothesis. We found a strong wing shape sexual dimorphism, resulting in an almost perfect sex assignment based solely on this trait. However, the differences in wing shape between sexes were greater than those between species, making conspecific identification difficult. Our data show that wing shape could only feasibly be used for identifying adult males and females of F. lamosca, and males of F. dorsomaculata and F. pseudoconstricta. Low discrimination scores among remaining species may be partly explained by high intraspecific variation, slight wing shape differences among closely related species, or sampling bias. Although this study provides the first wing size and shape comparison among neotropical Fannia species, more samples and species are needed to validate these findings and identify the potential factors influencing this trait. Furthermore, the wing shape sexual dimorphism across Fannia species suggests different life-history strategies between sexes and possible genetic canalization mechanisms.

Age Structure, Body Size, and Sexual Dimorphism in a High-Altitude Population of Pelophylax ridibundus (Pallas, 1771).

This study aimed to describe the morphological characteristics and age structure of a P. ridibundus population sampled from a high altitude. For this purpose, a total of 54 adult frogs (33 males and 21 females) were collected from Şavşat district, Artvin province, Türkiye. The samples were aged based on skeletochronology method. Furthermore, von Bertalanffy growth curve models were constructed using SVL and weight data. To assess sexual size and shape dimorphism, the measurements of 23 different morphological characters were analyzed using univariate and multivariate statistical techniques. The mean SVL and weight were found to be 78.05 mm and 60.87 g for males and 93.95 mm and 109.61 g for females. The mean age was 3.67 years and 4.05 years for males and females, respectively. The maximum age was found to be 6 years for both sexes. Growth curve models revealed a significant relationship between age, SVL, and weight. A clear female-biased sexual size dimorphism was found in all morphological characters. However, SVL-adjusted values indicated that males had larger head and limb structures resulting from evolutional and sexual pressures associated with reproduction and male-male competition. The shape dimorphism was found only in forelimbs, and it was male-biased and was related to clasping in amplexus.

Seasonal dimorphism as an expression of sexual dimorphism: Influence of gonad maturity on the body shape of a rocky intertidal polyplacophoran

Seasonal dimorphism in the body shape of marine invertebrates has been poorly explored compared to vertebrates. We aim to investigate through traditional (body length/width ratio, dorsal elevation ratio and angle of elevation) and geometric (centroid size and shape geometric configurations) morphometrics the effect of gonad maturity (via the gonadosomatic index [GSI] and gonad development stages [GDS]) on changes in body shape in males and females of two latitudinally different populations of the broadcast-spawning intertidal mollusc Chiton articulatus. We confirmed that C. articulatus does not present external sexual dimorphism since sex does not have a significant effect on body shape (1%); instead, dimorphism was seasonal and related to the reproductive season, and varied across populations, probably because in the subtropical zone additional energy is invested in shell (scleritome) bending at the same time as the gonad matures, which is opposite of what occurs in the tropical zone. C. articulatus shows a narrower body shape (i.e., diminished body width) during its gonad maturity compared to the rest of the GDS and is corroborated by a body length/width ratio that contributes the greatest variation in the geometric shape descriptors (18%), just below the centroid size (24%). The expression of centroid size differences shows a correspondence with the change in body dimensions expressed by the three morphometric ratios during gonad maturity. The use of traditional body ratios over time may be useful in polyplacophoran molluscs as a proxy tool to estimate gonad maturity and to provide a reliable indication of the reproductive season.

Gradual exacerbation of obstetric constraints during hominoid evolution implied by re-evaluation of cephalopelvic fit in chimpanzees.

Under the obstetrical dilemma hypothesis, sexual dimorphism in pelvic shape is a solution to accommodate high fetopelvic constraints. It is therefore unclear why chimpanzees display a human-like pattern of pelvic sexual dimorphism despite having easier births enabled by small neonates and capacious pelvic canals. Here we reassessed chimpanzee fetopelvic fit using three-dimensional simulations, revealing a similarly constricted midpelvis as in humans, with even narrower outlet dimensions. Geometric morphometric analyses confirm that female chimpanzees have larger pelvic canals than males despite a smaller body size and a morphology that maximizes pelvic dimensions favourable for parturition, particularly in smaller-bodied individuals. Together with evidence for increased neurological immaturity at birth relative to monkeys, our findings imply substantial obstetric constraints in chimpanzees and possibly other apes. We therefore propose that difficult birth did not arise abruptly in Homo with increasing encephalization but evolved gradually through a series of obstetric compromises from an already constricted birth canal shared across anthropoid primates. Specifically, we propose that obstetric selection pressures exacerbated incrementally with the stiffening of the symphysis that accompanied body size increase in hominoids, while subsequent adaptations to bipedalism shortened the ilium. The resulting contorted birth canal required obligatory fetal rotation, thus greatly increasing birth difficulty.

Molecular characterization, carbohydrate metabolism and tolerance to abiotic stress of Eremothecium coryli endophytic isolates from fruits of Momordica indica.

Yeasts are unicellular fungi that occur in a wide range of ecological niches, where they perform numerous functions. Furthermore, these microorganisms are used in industrial processes, food production, and bioremediation. Understanding the physiological and adaptive characteristics of yeasts is of great importance from ecological, biotechnological, and industrial perspectives. In this context, we evaluated the abilities to assimilate and ferment different carbon sources, to produce extracellular hydrolytic enzymes, and to tolerate salt stress, heavy metal stress, and UV-C radiation of two isolates of Eremothecium coryli, isolated from Momordica indica fruits. The two isolates were molecularly identified based on sequencing of the 18S-ITS1-5.8S-ITS2 region. Our isolates were able to assimilate nine carbon sources (dextrose, galactose, mannose, cellobiose, lactose, maltose, sucrose, melezitose, and pectin) and ferment three (glucose, maltose, and sucrose). The highest values of cellular dry weight were observed in the sugars maltose, sucrose, and melezitose. We observed the presence of hyphae and pseudohyphae in all assimilated carbon sources. The two isolates were also capable of producing amylase, catalase, pectinase, and proteases, with the highest values of enzymatic activity found in amylase. Furthermore, the two isolates were able to grow in media supplemented with copper, iron, manganese, nickel, and zinc and to tolerate saline stress in media supplemented with 5% NaCl. However, we observed a decrease in CFU at higher concentrations of these metals and NaCl. We also observed morphological changes in the presence of metals, which include changes in cell shape and cellular dimorphisms. The isolates were sensitive to UV-C radiation in the shortest exposure time (1min). Our findings reinforce the importance of endophytic yeasts for biotechnological and industrial applications and also help to understand how these microorganisms respond to environmental variations caused by human activities.

Unveiling the third dimension of tooth shape: 2D versus 3D geometric morphometry of human post-canine dentition

Abstract Introduction: Geometric morphometry is an effective tool for studying teeth morphology for quantifying variations in dental shape across individuals and populations. This study aims to analyse the dimorphism of human post-canine maxillary and mandibular tooth shape by utilising 2D and 3D landmark data and compare the effectiveness of both methods in detecting allometry and shape characteristics. Methods: Pre-treatment dental casts (N = 160) from patients aged 13–20 were digitised, and 2D and 3D anatomic landmarks on maxillary and mandibular post-canine teeth were marked. The data were evaluated using principal component analysis, discriminant function analysis, and regression analysis of shape coordinates with centroid size using MorphoJ morphometric software. Results: Principal component analysis revealed that 20–30% of the principal components explained 80% variation in tooth shape. The maxillary second molar and mandibular second premolar had the largest differences in variance between 2D and 3D data. The two-cusp type mandibular second premolar and maxillary second molar displayed the highest variation in 3D analysis. The mandibular second premolar (two-cusp type) had the highest overall accuracy in classifying sex, followed by the maxillary first and second molars. Conclusion: 3D data collection offers advantages over 2D methods, but it has limitations and trade-offs. It can be time-consuming and expensive and require specialized equipment or software. 2D methods may miss important depth axis variation or capture biological variation. Researchers must carefully consider the benefits and limitations of both methods before choosing. This study provides valuable insight into post-canine tooth shape dimorphism and contributes to existing knowledge in the field.

Sexual dimorphism and allometry in human scapula shape.

Scapula shape is highly variable across humans and appears to be sexually dimorphic-differing significantly between biological males and females. However, previous investigations of sexual dimorphism in scapula shape have not considered the effects of allometry (the relationship between size and shape). Disentangling allometry from sexual dimorphism is necessary because apparent sex-based differences in shape could be due to inherent differences in body size. This study aimed to investigate sexual dimorphism in scapula shape and examine the role of allometry in sex-based variation. We used three-dimensional geometric morphometrics with Procrustes ANOVA to quantify scapula shape variation associated with sex and size in 125 scapulae. Scapula shape significantly differed between males and females, and males tended to have larger scapulae than females for the same body height. We found that males and females exhibited distinct allometric relationships, and sexually dimorphic shape changes did not align with male- or female-specific allometry. A secondary test revealed that sexual dimorphism in scapula shape persisted between males and females of similar body heights. Overall, our findings indicate that there are sex-based differences in scapula shape that cannot be attributed to size-shape relationships. Our results shed light on the potential role of sexual selection in human shoulder evolution, present new hypotheses for biomechanical differences in shoulder function between sexes, and identify relevant traits for improving sex classification accuracy in forensic analyses.

Sexual dimorphism in the dwarf round ray Urotrygon nana.

This paper presents information on the morphological, morphometric, and dental sex differences in the dwarf round ray Urotrygon nana. We recorded 12 morphological traits, sex, the distribution pattern of dermal denticles, the number of tooth rows, and the tooth shape of 466 individuals. The disc width of females ranged from 50 to 172 mm and that of males ranged from 53 to 135 mm. A neuronal classification model and a correspondence analysis showed that female disc width was 21.5% broader, and the distance from the rostrum to the anus was 17.7% longer than that of males, whereas males presented 19.5% greater distance between the nostrils, 9.7% greater preorbital snout length, 6.8% greater cloaca to caudal-fin length, 2.7% greater interorbital distance, and 1.1% greater total length than females. The disc of adult males, including the abdominal cavity area, was densely covered with dermal denticles, which were slightly larger than those observed in females. Females presented homodont dentition with molariform teeth and a smooth lozenge-shaped crown with rounded margins. Males exhibited homodonty but with tooth morphology variations in individuals of different sizes (from molariforms to sharper cusp teeth). There were changes in disc shape (from subcircular to oval), distribution and size of dermal denticles (more abundant and larger), and tooth shape (from molariform to monocuspid teeth) during male development, from neonates to adults. U. nana exhibited sexual dimorphism in size, disc shape, number and shape of teeth, and distribution and size of dermal denticles.

Sexual dimorphism in the Hungarian golden jackal population: analysing body and skull size and shape

Defining species within the Canidae family is challenging due to morphological convergence, behavioral plasticity, traditional taxonomic limitations, and possible hybridisation. This challenge is timely with the recent population and range expansion of the golden jackal (Canis aureus). Exploring their morphological data and sexual dimorphism is essential for identifying factors driving their success in new habitats. The proven hybridization of golden jackals with dogs and wolves may affect species description, population dynamics, and genetic diversity, impacting conservation strategies. This study, for the first time, conducts a morphometric analysis of golden jackals in Somogy County, Hungary, to prove sexual size dimorphism (SSD) in body and skull and sexual shape dimorphism (SShD) in skull across juvenile and adult age groups. 719 golden jackals (362 females and 357 males) were collected between January 2021 and January 2023. Descriptive statistics revealed significant SSD in body and skull measurements among both age groups, with males generally larger than females, particularly in body mass (11.72% in juveniles and 13.37% in adults). Most skull dimensions differed significantly between sexes and age groups, except for foramen magnum height, foramen magnum width, and postorbital breadth among juveniles and foramen magnum height and postorbital breadth among adults. We used principal component analyses (PCA) on raw dimension data and the log shape ratio method to extract shape information. Linear discriminant analysis (LDA) explored skull SShD between sexes. Notably, our study achieved over 71% accuracy in sex classification, illustrating the clear presence of SShD of the skull in golden jackals across both age groups. Our study provides a comprehensive database of golden jackals in the overpopulated Hungarian habitat, which will be helpful for further research on ecology, behavior, and conservation management.

Mapping the genetic basis for sex determination and growth in hybrid tilapia (Oreochromis mossambicus × O. niloticus)

Tilapia growth and sex are key traits for aquaculture. Elucidating their molecular mechanisms can enable molecular breeding and accelerate genetic gain. To uncover the genetic basis underlying these traits for molecular breeding, we generated an F2 family by crossing Mozambique and Nile tilapia. The growth and sex traits of 284 F2 fish were recorded at 150 days post hatch. These F2 individuals exhibited sexual dimorphism in weight, body shape, and lip thickness, and were genotyped with RAD-sequencing. A high-density linkage map, consisting of 22 linkage groups with 38,102 SNPs was constructed. Association mapping revealed that QTL containing the amhy gene from male Nile tilapia largely determined sex, modulated by minor-effect loci. For growth-related traits, QTL and association analyses discovered that body weight or total length was predominantly controlled by a large-effect locus, while body shape was determined by several minor-effect loci. Analysis of transcriptomics in the liver and muscle identified novel candidate genes, including dusp2, rtn4r, bhmt1, adamts12 and s100p, for growth. These findings provide tools for sex-specific molecular breeding and valuable information for understanding the genomic architecture of growth and body shape variation. Assessing the sex-specific effects on growth can further refine selective breeding in aquaculture.

Sexual Dimorphism: The Interrelation of Shape and Color

Sex-typicality displayed as sexual dimorphism of the human face is a key feature enabling sex recognition. It is also believed to be a cue for perceiving biological quality and it plays an important role in the perception of attractiveness. Sexual dimorphism of human faces has two main components: sexual shape dimorphism of various facial features and sexual color dimorphism, generally manifested as dimorphism of skin luminance, where men tend to be darker than women. However, very little is known about the mutual relationship of these two facets. We explored the interconnection between the dimorphism of face shape and dimorphism of face color in three visually distinct populations (Cameroonian, Czech, and Vietnamese). Our results indicated that populations which showed a significant dimorphism in skin luminance (Cameroon, Vietnam) had low levels of sexual shape dimorphism, while a population with higher levels of sexual shape dimorphism (Czech Republic) did not exhibit a significant dimorphism of skin luminance. These findings suggest a possible compensatory mechanism between various domains of sexual dimorphism in populations differing in the levels of shape and color dimorphism.

Transcriptomic signatures and genomic regions associated with growth in the flatfish Senegalese sole

Growth performance is a complex genetic trait that interacts with several environmental variables and life-history attributes, most notably sex and reproduction. Thus, unveiling the genetic architecture of growth remains as a major challenge particularly in flatfish in which sexual dimorphism seems to be a common feature. In this study, we investigated the gene expression profiles and genomic windows associated with growth in the Senegalese sole (Solea senegalensis), which exhibits a female-biased size dimorphism. For this purpose, three fast-growing (FG) and two slow-growing (SG) genetic families were selected according to their breeding values for weight at harvest. Principal component analysis (PCA) using 17 morphometric traits showed that main variation (92.5%) was explained by size and shape. While phenotypic variation clearly separated the FG and SG groups, some differences associated with sex were still observable. Females exhibited greater weight, higher ventral body heights and less elliptical body shapes than males supporting sexual dimorphism both in size and shape. RNA-seq analysis identified 693, 12645 and 1059 differentially expressed transcripts (DETs) between FG and SG in muscle, liver, and brain, respectively. It should be noted a major effect of sex in muscle and liver with 7428 and 15715 DETs, respectively. In these two tissues, >50% of DETs for growth were also co-regulated by sex. Functional analysis using DETs for growth and sex unveiled intricate interactions between vitellogenesis, reproductive status, and growth-related transcriptional networks, particularly in muscle and liver tissues. Main transcriptional enriched pathways associated with growth were closely related to energy provision, cell cycle and signaling. Analysis of sex-specific and growth×sex interacting DETs between males and females highlighted lipid metabolism, macrophagy regulation, cell cycle, DNA and RNA metabolism, ribosome biogenesis, energy provision and maintainance of cellular homeostasis as the most relevant pathways driving sexual dimorphism. A variants analysis using RNA pool-seq data identified eleven genomic windows associated with growth distributed across the genome. Main gene candidates (pptc7, taz, abcd1, tfe3, nfix, ptcd2, prkaa1), whose expression was highly modified by growth, were involved in mitochondrial homeostasis, regulation of mitochondrial activity, energy production and regulation of musculoskeletal system. All these data improve our understanding of the intricate genetic architecture governing growth in sole.

Male proboscis monkey cranionasal size and shape is associated with visual and acoustic signalling

The large nose adorned by adult male proboscis monkeys is hypothesised to serve as an audiovisual signal of sexual selection. It serves as a visual signal of male quality and social status, and as an acoustic signal, through the expression of loud, low-formant nasalised calls in dense rainforests, where visibility is poor. However, it is unclear how the male proboscis monkey nasal complex, including the internal structure of the nose, plays a role in visual or acoustic signalling. Here, we use cranionasal data to assess whether large noses found in male proboscis monkeys serve visual and/or acoustic signalling functions. Our findings support a visual signalling function for male nasal enlargement through a relatively high degree of nasal aperture sexual size dimorphism, the craniofacial region to which nasal soft tissue attaches. We additionally find nasal aperture size increases beyond dental maturity among male proboscis monkeys, consistent with the visual signalling hypothesis. We show that the cranionasal region has an acoustic signalling role through pronounced nasal cavity sexual shape dimorphism, wherein male nasal cavity shape allows the expression of loud, low-formant nasalised calls. Our findings provide robust support for the male proboscis monkey nasal complex serving both visual and acoustic functions.

Sexual dimorphism analysis in permanent human mandibular canines by geometric morphometrics

Sex estimation of unknown human remains is a common form of assessment in bioarchaeological and forensic practice. When remains are poorly preserved, teeth become important. Research regarding the use of teeth for sex estimation mainly uses odontometrics. Nevertheless, to date, few studies have aimed to systematically evaluate sexual dimorphism in tooth shape. The purpose of this study is to analyze and describe sexual dimorphism in the mandibular canine. Landmarks and semilandmarks were placed on the occlusal, mesiodistal and buccolingual views of mandibular canines of 56 individuals (37 males and 19 females) from the “Prof. Dr. Rómulo Lambre” collection. Moreover, the impact of dental wear in morphometric analyses on sexual dimorphism was explored. The shape of male and female canines differed significantly in the three views analyzed. Female canines showed a larger crown in relation to its root, while male canines showed greater roots in relation to their crown. While female canines showed a large development of the cingulum, male’s teeth exhibited less development of this trait. For these reasons, this study constitutes a first approach to show the usefulness of shape for estimating the sex of canine teeth. These differences might be the result of dissimilarities in the total amount of dentin and enamel due to the effect of sex-linked genes in the growth of these tissues.

Description of Pauronemoides siddiqii n. gen., n. sp. (Tylenchomorpha, Paurodontidae), a morphological and molecular phylogenetic study

Summary Three populations of Pauronemoides siddiqii n. gen., n. sp. were recovered from three different locations in northwestern and northern Iran from bark and soil samples. The new genus was described and illustrated based upon morphological and molecular characteristics. Pauronemoides n. gen. belongs to the family Paurodontidae and is characterised by the medium-sized body, asymmetrical knobs in stylet base, stem-like extension into intestine, post-vulval uterine sac (PUS) absent or rudimentary, different tail tip shape between sexes, and bursa enveloping tail or reaching to the tail end. The type species, Pauronemoides siddiqii n. gen., n. sp., is mainly characterised by 752-1281 μm body length in females and 660-1085 μm in males, six equally-sized lips, stylet 9-11 μm long with asymmetrical knobs, six incisures in lateral fields forming five bands, three of which (two outers and one central) are wider, and variably lengthened stem-like extension projecting into the intestine. Vulva situated posteriorly (V = 87.7-91.7%), PUS absent. Conical tail with widely rounded end, having a small mucron at tip in females, males with conical tail ending to a narrower tip and bursa enveloping tail completely. The type species of the new genus was compared with all known species of the genera Prothallonema, Paurodontus, Paurodontoides and Paurodontella. Pauronemoides siddiqii n. gen., n. sp. resembles Prothallonema macrocellum and P. mucronatum by having the bulb extension penetrating into the intestine, dimorphism in tail shape of both sexes and bursa enveloping tail, and Paurodontella iranica by tail shape dimorphism between sexes and bursa ending near tail tip. Therefore, the above-mentioned species are transferred to the new genus as Pauronemoides macrocellus n. gen., n. comb. (= Prothallonema macrocellum), P. mucronatus n. gen., n. comb. (= Prothallonema mucronatum) and P. iranicus n. gen., n. comb. (= Paurodontella iranica). In addition to morphological comparisons, molecular phylogenetic analyses were performed using two sequences of small subunit (SSU), and three partial sequences of D2-D3 expansion segments of the large subunit (LSU) rDNA, and the resulting topologies were discussed.

Sexual dimorphism and female ecomorphology in Anolis (Squamata: Anolidae): knowledge of female morphology increases the understanding of Anolis diversification

Abstract The study of sexual dimorphism in Anolis lizards brings the opportunity to understand how this phenomena interacts with adaptive radiation to produce broader diversity. We explored this phenomenon in 43 Anolis species from northwestern South America. Morphometric analysis with body size and shape, and lamellae number, were used to estimate the indexes of size dimorphism, and dimorphism in other ecomorphological traits. Almost half of these species exhibit differences between sexes in all traits, and body size relates to size dimorphism but not to shape dimorphism. When female and male data are analyzed separately, we found four and five morphotypes, respectively. Males and females of 10 species exhibit a huge difference in morphology, and the two sexes in these species were assigned to different morphotypes. In addition, SURFACE analyses reveal that the morphology of sexes evolved towards slightly different adaptive regimes, numbers and patterns, suggesting that the lower female morphological diversity highlights the more conservative nature of the female niches. Finally, our study demonstrates the need for ecological information to explain morphological patterns in dimorphic species, and to further understand the mechanisms that drive the evolution of morphological diversity in this genus.

Life-history of masked water snakes (Homalopsis buccata) in Java: implications for the sustainability of harvesting

Context Masked water snakes (Homalopsis buccata, Homalopsidae) thrive in the muddy edges of agricultural ponds and canals in densely populated areas of West Java, Indonesia, and are harvested by local farmers to protect fish stocks and to provide meat, skins, and medicines for commercial use. Aims Here, we aimed to quantify sexual dimorphism and reproductive biology of H. buccata, so as to deepen our knowledge of the species’ inherent ability to withstand commercial harvests. Methods We examined carcasses of 4286 snakes at six processing sites to quantify biological attributes (e.g. sexual dimorphism in body size and shape, seasonality of reproduction, fecundity, reproductive frequency), with emphasis on traits that affect the ability of snake populations to withstand this intensive harvesting. Key results The snakes we examined were primarily adults (<1% juvenile), with approximately equal numbers of males and females except in January (when females comprised >90% of specimens). Females grow larger than males, and they are more heavy-bodied but shorter-tailed than are males of the same snout–vent length. Reproduction is seasonal in both sexes, with testis volumes decreasing to a minimum over the period August to November (late dry season) when most adult-size females were gravid. Litter sizes ranged from 1 to 37 (mean 12), increasing with maternal body size, with ~75% of females reproducing each year. Conclusions On the basis of these results, we infer that the life history of H. buccata (viviparity, high fecundity, frequent reproduction, rapid maturation) renders it inherently resilient to harvesting, especially because that offtake is based on males as well as females. Because a lack of sustainability is evident only in hindsight, regular monitoring of the trade could assure that any problems are detected rapidly. Implications To further buffer these populations from the impact of harvest, hunting could be restricted during January (a time when gravid females are disproportionately vulnerable) and the largest snakes (females, with high fecundity and reproductive frequency) could be excluded from harvests.

The effects of the industrial transition on lower limb bone structure: A comparison of the inhabitants of Pecos Pueblo and present-day Indigenous peoples of New Mexico.

Comparisons between Indigenous peoples over time and within a particular geographic region can shed light on the impact of environmental transitions on the skeleton, including relative bone strength, sexual dimorphism, and age-related changes. Here we compare long bone structural properties of the inhabitants of the late prehistoric-early historic Pecos Pueblo with those of present-day Indigenous individuals from New Mexico. Femora and tibiae of 126 adults from Pecos Pueblo and 226 present-day adults were included in the study. Cross-sectional diaphyseal properties-areas and second moments of area-were obtained from past studies of the Pecos Pueblo skeletal sample, and from computed tomography scans of recently deceased individuals in the present-day sample. Femora and tibiae from Pecos individuals are stronger relative to body size than those of present-day Indigenous individuals. Present-day individuals are taller but not wider, and this body shape difference affects cross-sectional shape, more strongly proximally. The tibia shows anteroposterior strengthening among Pecos individuals, especially among males. Sexual dimorphism in midshaft bone shape is stronger within the Pecos Pueblo sample. With aging, Pecos individuals show more medullary expansion but also more subperiosteal expansion than present-day individuals, maintaining bone strength despite cortical thinning. Higher activity levels, carried out over rough terrain and throughout adult life, likely explain the relatively stronger lower limb bones of the Pecos individuals, as well as their greater subperiosteal expansion with aging. Greater sexual dimorphism in bone structure among Pecos individuals potentially reflects greater gender-based differences in behavioral patterns.