Dimorphism In Shape Research Articles

A new species of sea urchin associating clingfish of the genus Dellichthys from New Zealand (Teleostei, Gobiesocidae)

A new species of clingfish, Dellichthys trnskii sp. n. is described on the basis of 27 specimens, 11.9–46.0 mm SL, collected from intertidal and shallow coastal waters of New Zealand. It is distinguished from its only congener, D. morelandi Briggs, 1955 by characters of the cephalic sensory system and oral jaws, snout shape, and colouration in life. A rediagnosis is provided for D. morelandi, which is shown to exhibit sexual dimorphism in snout shape.

Subtle variation in size and shape of the whole forewing and the red band among co-mimics revealed by geometric morphometric analysis in Heliconius butterflies.

Heliconius are unpalatable butterflies that exhibit remarkable intra‐ and interspecific variation in wing color pattern, specifically warning coloration. Species that have converged on the same pattern are often clustered in Müllerian mimicry rings. Overall, wing color patterns are nearly identical among co‐mimics. However, fine‐scale differences exist, indicating that factors in addition to natural selection may underlie wing phenotype. Here, we investigate differences in shape and size of the forewing and the red band in the Heliconius postman mimicry ring (H. erato phyllis and the co‐mimics H. besckei, H. melpomene burchelli, and H. melpomene nanna) using a landmark‐based approach. If phenotypic evolution is driven entirely by predation pressure, we expect nonsignificant differences among co‐mimics in terms of wing shape. Also, a reinforcement of wing pattern (i.e., greater similarity) could occur when co‐mimics are in sympatry. We also examined variation in the red forewing band because this trait is critical for both mimicry and sexual communication. Morphometric results revealed significant but small differences among species, particularly in the shape of the forewing of co‐mimics. Although we did not observe greater similarity when co‐mimics were in sympatry, nearly identical patterns provided evidence of convergence for mimicry. In contrast, mimetic pairs could be distinguished based on the shape (but not the size) of the red band, suggesting an “advergence” process. In addition, sexual dimorphism in the red band shape (but not size) was found for all lineages. Thus, we infer that natural selection due to predation by birds might not be the only mechanism responsible for variation in color patterns, and sexual selection could be an important driver of wing phenotypic evolution in this mimicry ring.

Quantifying the shape variation of the elytra in Patagonian populations of the ground beetle Ceroglossus chilensis (Coleoptera: Carabidae)

Elytra shape variation was analyzed from two forest systems in the Chilean Patagonia, one composed of Nothofagus dombeyi and N. nitida and a second-growth stand of N. pumilo. Geometric morphometrics analysis and multivariate analyses were used on the complete elytra having the shape information (outline) of the trait. The results show several shape variations on the mid bottom of the elytra and confirm the local adaptation of the Patagoninan population at different traits with the results found at the abdominal section of previous studies of the same species, nevertheless, here we found a complete absence of sexual shape dimorphism using the elytra as a trait of sexual differentiation. A positive allometry was found, however, this was not related with sexual dimorphism differentiation but rather with to the forest and second-growth forest.

Glucosylsphingosine concentration in the blood of Gaucher patients reflects the severity of GBA mutations - data from a large global cohort

The Oryzias woworae species group, composed of O. asinua, O. wolasi, and O. woworae, is widely distributed in southeastern Sulawesi, an island in the Indo-Australian Archipelago. Deep-elongated body shape divergence is evident among these three species to the extent that it is used as a species-diagnostic character. These fishes inhabit a variety of habitats, ranging from upper streams to ponds, suggesting that the body shape divergence among the three species may reflect adaptation to local environments. First, our geometric morphometrics among eight local populations of this species group revealed that the three species cannot be separated by body shape and that riverine populations had more elongated bodies and longer caudal parts than lacustrine populations. Second, their phylogenetic relationships did not support the presence of three species; phylogenies using mitochondrial DNA and genomic data obtained from RNA-Seq revealed that the eight populations could not be sorted into three different clades representing three described species. Third, phylogenetic corrections of body shape variations and ancestral state reconstruction of body shapes demonstrated that body shape divergence between riverine and lacustrine populations persisted even if the phylogenies were considered and that body shape evolved rapidly irrespective of phylogeny. Sexual dimorphism in body shape was also evident, but the degree of dimorphism did not significantly differ between riverine and lacustrine populations after phylogenetic corrections, suggesting that sexual selection may not substantially contribute to geographical variations in body shape. Overall, these results indicate that the deep-elongated body shape divergence of the O. woworae species group evolved locally in response to habitat environments, such as water currents, and that a thorough taxonomic reexamination of the O. woworae species group may be necessary.

Sexual Dimorphism in the Mandible Shape of <i>Neospondylis upiformis</i> (Coleoptera: Cerambycidae)

Sexes of adult Cerambycidae (Coleoptera) are usually discriminated by the greater length of male antennae. However, in Spondylidinae, adult antennae are short and the difference between sexes is negligible and difficult to appraise. Only two species belong to this subfamily in North America, one of these being Neospondylis upiformis (Mannerheim), a species rarely caught in eastern North America. Unexpectedly, we collected numerous specimens of Neospondylis upiformis on Anticosti Island, Quebec, which appears as a hotspot for this species in eastern Canada. We show that sexual dimorphism in the mandible shape of N. upiformis (Mannerheim) can be used to discriminate sexes. Females have robust mandibles with a sharp cutting inner edge while males have thin mandibles and a well-rounded inner edge. There was no overlap between sexes in all measures done on mandibles, showing that mandible shape was a reliable criterion for sexing N. upiformis. We also tested previously reported criteria using antennae, as well as other characteristics such as body size, and show that they can hardly discriminate between sexes in N. upiformis. We also present illustrations of male and female genitalia, which is rarely available for Cerambycidae.

Sexual dimorphism in facial shape among Malaysian ancestries (Malay/Chinese/Indian) in Section 13 Shah Alam-Malaysia

Sexual dimorphism in facial shape among Malaysian ancestries (Malay/Chinese/Indian) in Section 13 Shah Alam-Malaysia

Sexual Dimorphism in Body Size and Shape of Beal's Eyed Turtle (Sacalia bealei)

Abstract We studied the sexual dimorphism in body size and shape of Beal's eyed turtle, Sacalia bealei, by measuring 15 morphological characteristics of 68 adult individuals (40 females, 28 males) collected from Fujian Province, China. Females were slightly larger than males in carapace length with a sexual dimorphism index of 0.09. This translated into greater absolute values of females for all the traits we measured except for tail length, preanal tail length, and analia to supracaudal junction length. Comparisons between the sexes of size-corrected morphological traits indicated that females exhibited a longer plastron and higher carapace relative to carapace length, thereby providing a larger internal volume. Females also exhibited relatively wider heads. In males, the plastron was smaller and more indented than in females and the openings between the plastron and the carapace were also more developed. Overall, females were larger in size and displayed a more voluminous shell than did males while male...

Sexual dimorphism, bite force and diet in the diamondback terrapin

AbstractSexual dimorphism in head size and shape has been documented in many animals and is often thought to be related to the consumption of different prey in males and females thus reducing competition between the two sexes. However, for this to be true, the difference in head size and shape should be associated with a difference in performance allowing one sex to exploit different prey resources. In many durophagous turtle species, females are bigger than males and have bigger heads for a given size. Here, we test whether the observed dimorphism in head size and shape in the durophagous Malaclemys terrapin is reflected in differences in bite force. Furthermore, we measure the forces needed to crush different prey items in order to evaluate whether the observed bite force dimorphism allows access to different dietary resources in females. Finally, we compare head size and shape and bite force between the durophagous M. terrapin and a generalist (Trachemys scripta). Our results show that females of M. terrapin have higher bite forces than males in line with their bigger heads relative to their body size. Moreover, the higher bite forces in females allow them to eat larger as well as different types of snails resulting in differences in diet. Finally, our results show that both sexes of M. terrapin have bigger heads and bite forces for their body size compared to the generalist T. scripta, even as juveniles. Moreover, M. terrapin bite harder even when taking into account differences in head size, suggesting intrinsic differences in the jaw musculature in durophagous species.

3D analysis of sexual dimorphism in size, shape and breathing kinematics of human lungs.

Sexual dimorphism in the human respiratory system has been previously reported at the skeletal (cranial and thoracic) level, but also at the pulmonary level. Regarding lungs, foregoing studies have yielded sex-related differences in pulmonary size as well as lung shape details, but different methodological approaches have led to discrepant results on differences in respiratory patterns between males and females. The purpose of this study is to analyse sexual dimorphism in human lungs during forced respiration using 3D geometric morphometrics. Eighty computed tomographies (19 males and 21 females) were taken in maximal forced inspiration (FI) and expiration (FE), and 415 (semi)landmarks were digitized on 80 virtual lung models for the 3D quantification of pulmonary size, shape and kinematic differences. We found that males showed larger lungs than females (P < 0.05), and significantly greater size and shape differences between FI and FE. Morphologically, males have pyramidal lung geometry, with greater lower lung width when comparing with the apices, in contrast to the prismatic lung shape and similar widths at upper and lower lungs of females. Multivariate regression analyses confirmed the effect of sex on lung size (36.26%; P < 0.05) and on lung shape (7.23%; P < 0.05), and yielded two kinematic vectors with a small but statistically significant angle between them (13.22°; P < 0.05) that confirms sex-related differences in the respiratory patterns. Our 3D approach shows sexual dimorphism in human lungs likely due to a greater diaphragmatic action in males and a predominant intercostal muscle action in females during breathing. These size and shape differences would lead to different respiratory patterns between sexes, whose physiological implications need to be studied in future research.

Development of secondary sexual characters and their relationship to ontogeny and seasonal reproductive period in Hyphessobrycon igneus (Ostariophysi: Characiformes).

Sexual dimorphism in size, anal-fin shape and coloration of Hyphessobrycon igneus, Characidae, were examined. Males were more frequent at larger body sizes, confirming body size as a sexually dimorphic trait. Anal-fin shape and the colour of all fins were the same for females and juveniles, differing only in adult males. Likewise, only adult males had bony hooks on fin rays; larger and more sexually mature males had the most numerous and developed hooks and hooks were most developed in degree and number during peak reproductive periods. Fin hooks regressed in number and developmental degree after the reproductive period, but restarted development with the beginning of the new reproductive period without completely disappearing. Results show that bony hooks have a development and regression cycle related to reproductive seasonality.

Sexual dimorphism and ontogenetic changes of Amazonian pit vipers (Bothrops atrox)

Sexual dimorphism of body size (SSD) is widespread in snakes and has been the subject of numerous studies, but few have examined sexual shape dimorphism (SShD). The present study explores sexual size and shape dimorphism in the Amazonian pit viper Bothrops atrox. We combine linear and geometric morphometrics to describe differences in body size and head shape between the sexes and how these differences are generated throughout ontogeny. Our study shows that B. atrox is sexually dimorphic, with females being larger than males, except for tail length. Females also have relatively larger heads, differing not only in size but also in shape. Our results reveal that both size and shape of the head vary significantly from neonates to adults. Head shape changes in B. atrox are associated with allometry and follow similar trends in both sexes: neonates have a relatively shorter and more robust head and shorter snout, while adults show a wider and flattened head. Although our results indicate that allometry is an important factor in determining sexual shape dimorphism, additional studies on diet and performance may be necessary to understand the ecological implications of such differences.

What do &lt;i&gt;Anolis&lt;/i&gt; eat?: evaluation of sexual dimorphism and geographic variation in the diet of &lt;i&gt;Anolis ventrimaculatus&lt;/i&gt; (Squamata: dactyloidae) in Colombia

Anolis lizards exhibit high morphological diversity, partially related to variation in structural resource use, that probably influences foraging behavior and prey selection of individuals and species. Anoles are largely insectivorous: most species are generalists/opportunists and few are specialists. Dietary differences between sexes and among individuals from different populations have been observed in several species. Sexual size dimorphism, spatial niche divergence between sexes and species, competition and food availability are some of the factors responsible for these differences. We characterized the diet of Anolis ventrimaculatus (Squamata: Dactyloidae), a species with sexual size and shape dimorphism, widely distributed in highland Colombian environments. Stomach and proximal intestinal content of preserved adults were analyzed. Prey items were classified to order and, when possible, to family. A. ventrimaculatus eats variable preys (mostly Hymenoptera, Coleoptera, and insect larvae) and is classified as a generalist/opportunist. Vegetal debris, shed skin, and stones presumably were ingested incidentally. Diets of males and females are similar. Sexual dimorphism and geographic variation in the diet were minimal. Males and females exhibited differences in total number and percentage of use of frequently consumed prey (Orthoptera and Hymenoptera), and these differences varied among localities. Total prey numbers consumed by females also varied among localities, whereas consumption of Coleoptera and Orthoptera varied in both sexes. Differences in prey size could explain the variation in prey number between sexes, with males probably ingesting larger items. Variation in prey availability (most likely attributable to differences in structural microhabitat use), sample sizes and dates of collecting events could explain minor geographic variation in some aspects of the foraging ecology in this species.

Phylogenomics reveals habitat-associated body shape divergence in Oryzias woworae species group (Teleostei: Adrianichthyidae)

The Oryzias woworae species group, composed of O. asinua, O. wolasi, and O. woworae, is widely distributed in southeastern Sulawesi, an island in the Indo-Australian Archipelago. Deep-elongated body shape divergence is evident among these three species to the extent that it is used as a species-diagnostic character. These fishes inhabit a variety of habitats, ranging from upper streams to ponds, suggesting that the body shape divergence among the three species may reflect adaptation to local environments. First, our geometric morphometrics among eight local populations of this species group revealed that the three species cannot be separated by body shape and that riverine populations had more elongated bodies and longer caudal parts than lacustrine populations. Second, their phylogenetic relationships did not support the presence of three species; phylogenies using mitochondrial DNA and genomic data obtained from RNA-Seq revealed that the eight populations could not be sorted into three different clades representing three described species. Third, phylogenetic corrections of body shape variations and ancestral state reconstruction of body shapes demonstrated that body shape divergence between riverine and lacustrine populations persisted even if the phylogenies were considered and that body shape evolved rapidly irrespective of phylogeny. Sexual dimorphism in body shape was also evident, but the degree of dimorphism did not significantly differ between riverine and lacustrine populations after phylogenetic corrections, suggesting that sexual selection may not substantially contribute to geographical variations in body shape. Overall, these results indicate that the deep-elongated body shape divergence of the O. woworae species group evolved locally in response to habitat environments, such as water currents, and that a thorough taxonomic reexamination of the O. woworae species group may be necessary.

An analysis of beak shape variation in two ages of domestic turkeys (Meleagris gallopavo) using landmark-based geometric morphometrics.

The objective of this study was to assess beak shape variation in domestic turkeys (Meleagris gallopavo) and determine the effects of age, sex, and beak size on beak shape variation using geometric morphometrics. Dorsal and right lateral images were taken of 2442 turkeys at 6 and 18.5 weeks of age. Landmarks were digitized in tpsDig in three analyses of the dorsal upper mandible, lateral upper mandible, and lateral lower mandible shape of each turkey at both ages. The coordinate data were then subjected to a principal components analysis (PCA), multivariate regression, and a canonical variates analysis (CVA) with a Procrustes ANOVA in MorphoJ. For the dorsal images, three principal components (PCs) showed beak shape variation ranged from long, narrow, and pointed to short, wide, and blunt upper mandibles at both ages (6 weeks: 95.36%, 18.5 weeks: 92.21%). Three PCs showed the lateral upper mandible shape variation ranged from long, wide beaks with long, curved beak tips to short, narrow beaks with short, pointed beak tips at both ages (6 weeks: 94.91%, 18.5 weeks: 94.33%). Three PCs also explained 97.80% (6 weeks) and 97.11% (18.5 weeks) of the lateral lower mandible shape variation ranging from wide and round to narrow and thin lower mandibles with superior/inferior beak tip shifts. Beak size accounted for varying proportions of the beak shape variation (0.96–54.76%; P < 0.0001) in the three analyses of each age group. For all the analyses, the CVA showed sexual dimorphism in beak shape (P < 0.0001) with female upper mandibles appearing wider and blunter dorsally with long, curved beak tips laterally. Whereas male turkey upper mandibles had a narrow, pointed dorsal appearance and short, pointed beak tips laterally. Future applications of beak shape variability could have a genetic and welfare value by incorporating beak shape variation to select for specific turkey beak phenotypes as an alternative to beak treatment.

An ontogenetically stable sexual character in a montane agamid, Salea horsfieldii Gray, 1845 (Reptilia: Agamidae) from Nilgiris, India

ABSTRACTMany agamid lizards are known to show sexual dimorphism in body shape, colour and ornamentation or a combination of these traits. Adult males of Salea horsfieldii have a discontinuous dorsal crest at the nuchal region, which is a sexually dimorphic character. However, there is no information about the age or size at which this dimorphic ornamentation develops and if the species exhibits sexual shape dimorphism (SShD). The authors studied the morphology of S. horsfieldii and found that its ornamentation is an ontogenetically stable character present in all males, including juveniles. Seven morphological characters were measured to determine if they exhibited SShD at adult and juvenile stages. Analysis of covariance was used to identify differences in morphology between sexes. The results show that only adults exhibited SShD, but not juveniles. Adult males had larger head and foot lengths in comparison to females of the same size. Larger head length in adult males is a sexual fitness trait, which increases bite-force during intra-sexual combats. Although the presence of sexually dimorphic ornamentation right from the juvenile stage is rare in agamids, S. horsfieldii is an exception . The role of sexually dimorphic ornamentation at juvenile stages remains unknown and requires further investigation.

Cranial sexual dimorphism in the Kinda baboon (Papio hamadryas kindae).

The smallest extant member of genus Papio, the Kinda baboon exhibits low sexual dimorphism and a distinctive cranial shape. Ontogenetic scaling accounts for most cranial-shape differences within Papio, but studies have shown that the Kinda follows a separate ontogenetic trajectory. If so, its cranial-dimorphism pattern should differ from other subspecies. To evaluate this hypothesis, morphometric analysis was used to investigate cranial dimorphism in Papio. Three-dimensional landmarks were digitized on 434 adult crania representing six Papio subspecies. Size- and shape-dimorphism magnitudes were quantified using centroid size and Procrustes distances. Patterns of sex- and size-related variation were explored using MAN(C)OVA, multivariate regression, and form-space PCA. Canine dimorphism was investigated using dental metrics. Kinda size and shape dimorphism are significantly lower than in other Papio subspecies. The relative magnitude of Kinda shape dimorphism is similar to other southern baboons; Kinda canine dimorphism is unremarkable. MAN(C)OVA results support subspecies differences in cranial dimorphism and scaling. Allometric and dimorphism vectors differ significantly in some subspecies, and their vector-angle matrices are strongly correlated. The Kinda's allometric vector angles are divergent. Form-space PC3, summarizing size-independent dimorphism, separates the Kinda from other subspecies. The Kinda baboon exhibits significantly lower size and shape dimorphism than other baboons, but its relative dimorphism levels are unexceptional. The Kinda differs from other subspecies in patterns of allometry, size-related shape dimorphism, and residual shape dimorphism. Kinda facial shape is "masculinized" relative to size, especially in females, suggesting female sexual selection contributed to the evolution of Kinda dimorphism.

Sex‐specific shifts in morphology and colour pattern polymorphism during range expansion of an invasive lizard

AbstractAimHuman‐assisted range expansion of animals to new environments can lead to phenotypic shifts over ecological time‐scales. We investigated whether phenotypic changes are sex‐specific using an invasive lizard (Lampropholis delicata).LocationPacific region (Hawaiian Islands, Lord Howe Island, New Zealand, eastern Australia).MethodsUsing our knowledge of the introduction history of L. delicata, we examined museum specimens of individuals collected across the native and introduced range to determine whether shifts in morphology or colour pattern polymorphism had occurred during its range expansion, and if so, whether they differed between the sexes.ResultsSexual dimorphism in both size and shape was documented within the native range of the delicate skink. However, during range expansion, phenotypic shifts were observed in shape, but not size. In two of the three invasive populations, these phenotypic shifts were sex‐specific. In the Hawaiian Islands, changes in shape were driven by males, whereas in New Zealand it was due to shifts in females. Similarly, changes in the frequency of a colour pattern polymorphism, a mid‐lateral stripe shown to have sex‐specific impacts on fitness (positive in females, negative in males), occurred following colonization of the Hawaiian Islands and Lord Howe Island. In Hawaii, the incidence of the polymorphism increased over time in females, and decreased in males.Main conclusionsPhenotypic shifts during the range expansion of invasive species may be sex‐specific, and are potentially related to the degree of realized niche shift that has occurred between the source and introduced range.

Sexual dimorphism and sexual selection in cytheroidean ostracodes from the Late Cretaceous of the U.S. Coastal Plain

AbstractSexual dimorphism is common in many extant animals, but it is difficult to demonstrate in fossil species. Working with material from the Late Cretaceous of the U.S. Coastal Plain, we herein analyze sexual dimorphism in ostracodes from the superfamily Cytheroidea, a group whose extant members have males that are relatively more elongate than females. We digitized outlines of more than 6000 individual ostracode valves or carapaces, extracted size (area) and shape (length-to-height ratio) information, and used finite mixture models to assess hypotheses of sexual dimorphism. Male and female clusters can be discerned in nearly all populations with sufficient data, resulting in estimates of size and shape dimorphism for 142 populations across 106 species; an additional nine samples are interpreted to consist only of females. Dimorphism patterns varied across taxa, especially for body size: males range from 30% larger to 20% smaller than females. Magnitudes of sexual dimorphism are generally stable within species across time and space; we can demonstrate substantial evolutionary changes in dimorphism in only one species,Haplocytheridea renfroensis. Several lines of evidence indicate that patterns of sexual dimorphism in these ostracodes reflect male investment in reproduction, suggesting that this study system has the potential to capture variation in sexual selection through the fossil record.

The characteristic mid-shaft cross-sectional shape of the ulna in Jomon hunter-gatherers.

The Jomon people were hunter-gatherers who inhabited the Japanese archipelago between 10,000 BC and 300 BC. Here, we focus on the mid-shaft cross-sectional shape of the ulna in the Jomon population and compare it with modern Japanese people. Jomon specimens, including 32 males and 22 females, were excavated from shell mound sites in the Pacific and Seto inland coastal area of Honshu island in the Japanese archipelago dated to the Late-to-Final Jomon phase (between 2,000 BC and 300 BC). Mid-shaft ulna cross-sectional shapes were compared with modern Japanese specimens (25 males, 21 females) using standard linear measurements and elliptic Fourier analysis (EFA). Differences from both sides of this element were compared using predicted handedness. Linear measurements and EFA results show that ulna shape of both sexes within the Jomon population are relatively larger in the antero-posterior direction and have more developed posterior borders than modern Japanese males and females. No significant differences were observed between Jomon sexes based on the predicted dominant side, but differences were evident in the predicted nondominant side. At the same time, bilateral differences were recognized in Jomon females, because of a lower level of posterior border development in the predicted nondominant side compared to the dominant side. Shape differences between Jomon people and modern Japanese can be explained by variation in the habitual loading of the ulna. Sexual dimorphism in ulna shape within the Jomon population suggests division of labor differences.

Development and growth in skulls of three Otariidae species: a comparative morphometric study

We examined the skulls ofArctocephalus australis,Callorhinus ursinusandOtaria byroniawith the objectives of (1) estimating the development and growth rates and comparing these parameters among the species; (2) describing the development for each linear measure, for each species and sex; (3) determining which variables are best correlated with age; (4) determining age of physical maturity. We employed traditional and geometric morphometric techniques to study the skulls. InA. australisandC. ursinus, skulls of females mature at about 6 years of age, and those of males at about 8 years.Otaria byroniamatures later, at about 9 years. Using geometric morphometric data sets, the rate and constant of growth inA. australisdid not differ between the sexes.Callorhinus ursinusandO. byroniashowed rates significantly different between sexes concerning growth (and in the constant as well), but onlyO. byroniadiffered between sexes in both developmental model parameters (rates and constant). Comparisons between the growth and developmental models showed significant differences in slope and constant. In both treatments employed, a relationship between size and shape dimorphism could be inferred for the skulls of all three species. We conclude that rates or timing of growth and development evolves within a conserved spatiotemporal organization of morphogenesis.