scholarly journals Jurassic scorpionflies (Mecoptera) with swollen first metatarsal segments suggesting sexual dimorphism

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yan-jie Zhang ◽  
Peter J. M. Shih ◽  
Jun-you Wang ◽  
Maria E. McNamara ◽  
Chungkun Shih ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Middle Jurassic ◽  
Sexually Dimorphic ◽  
Geometric Morphometric ◽  
First Metatarsal ◽  
Phylogenetic Studies ◽  
Morphometric Analyses ◽  
New Findings ◽  
Mating Opportunities ◽  
Species Specific

Abstract Background Sexual dimorphism is widespread in insects. The certain specialized structures may be used as weapons in male–male combats or as ornaments to enhance mating opportunities. Results We report striking swollen first tarsal segments in two families, four genera and six species of scorpionflies from the Middle Jurassic Yanliao Biota of Northeastern China. Swollen tarsal segments are restricted to male specimens and to hind leg tarsi. The geometric morphometric analyses reveal that the degree of swelling within the orthophlebiid species possessing swollen first metatarsal segments is species-specific, which can be used as a diagnostic character for taxonomic and phylogenetic studies. Conclusions The new findings indicate that swollen first metatarsal segments are relatively common in the family Orthophlebiidae during the Middle Jurassic. The tarsal swellings are considered to be sexually dimorphic, potentially associated with sexually display by males and/or camouflage of a “nuptial gift” in the mating process.

Sexual dimorphism in the carapace shape and length of the freshwater palaemonid shrimp Macrobrachium potiuna (Müller, 1880) (Decapoda: Caridea: Palaemonidae): geometric and traditional morphometric approaches

2017 ◽  
Vol 67 (2) ◽  
pp. 93-103 ◽  
Author(s):  
Madson Silveira de Melo ◽  
Setuko Masunari
Keyword(s):  
Body Weight ◽  
Sexual Dimorphism ◽  
Behavioral Differences ◽  
Geometric Morphometric ◽  
Freshwater Shrimps ◽  
Morphometric Analyses ◽  
Males And Females ◽  
Morphological Differences ◽  
Three Rivers ◽  
Coastal Basin

Sexual dimorphism is characterized by morphological, physiological, or behavioral differences between males and females. The genus Macrobrachium is a diverse group of freshwater shrimps distributed throughout tropical and subtropical regions. They have a great intra- and interspecific morphological variation, with some species showing sexual dimorphism. We investigated the sexual dimorphism of the size and shape of the carapace and body weight of Macrobrachium potiuna (Müller, 1880) in three populations of the State of Paraná through traditional and geometric morphometric techniques. The populations were sampled from three rivers: the Pombas River, Coastal Basin, the Piraquara River, First Plateau, and the Guabiroba River, Second Plateau. Morphometric analyses indicated that male shrimps showed differences in carapace length and body weight: the higher the distance from the sea, the smaller and lighter the shrimps. Carapace shape also differed significantly between the sexes in all three populations, with males having a less robust carapace, but a more elongated rostrum than females. The morphological differences between the genders seem to reflect the reproductive roles of males and females in this environment.

scholarly journals A cross-cultural study of sex-typicality and averageness: Correlation between frontal and lateral measures of human faces

2017 ◽  
Author(s):  
Dariusz P. Danel ◽  
Jaroslava Varella Valentova ◽  
Oscar R. Sánchez ◽  
Juan D. Leongómez ◽  
Marco A. C. Varella ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Cultural Study ◽  
Cross Cultural ◽  
Sexually Dimorphic ◽  
Geometric Morphometric ◽  
Lateral Projection ◽  
Cross Cultural Study ◽  
Mutual Relations ◽  
Human Faces ◽  
Published Research

AbstractObjectivesFacial averageness and sexual dimorphism are extensively studied attractiveness markers, which are viewed as possible indicators of biological quality. Both are complex morphological traits and both can be easily assessed from frontal and lateral projection of a human face. Interestingly, examination of mutual relations between the frontal and lateral dimensions of these markers has so far received little attention in published research.MethodsIn our cross-cultural study, we used geometric morphometric data from male and female faces from Brazil, Cameroon, Colombia, and the Czech Republic, and analysed correlations between frontal and lateral measurements of averageness and degree of maleness/femaleness, i.e. individual variation in features that characterize sexual dimorphism. We also analysed whether the association between frontal and lateral measurements differs in men and women.ResultsIn general, our results showed a moderate correlation in sexually dimorphic features between lateral and frontal facial configuration in both sexes, while frontal and lateral facial averageness was moderately correlated only in women. This pattern was less consistent when individual populations were analysed separately.ConclusionsReferring to the multiple signalling theory, we propose that especially in women, lateral/frontal correlations support a hypothesis of redundancy of information provided by the frontal and lateral dimension of a given facial attractiveness marker. The absence of a significant correlation in male facial averageness suggests that frontal and lateral averageness may convey different information about an individual.

scholarly journals Sexual dimorphism of the mandibular conformational changes in aging human adults: A multislice computed tomographic study by geometric morphometrics

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0253564
Author(s):  
Leonor Costa Mendes ◽  
Julien Delrieu ◽  
Claudia Gillet ◽  
Norbert Telmon ◽  
Delphine Maret ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Conformational Changes ◽  
Sexually Dimorphic ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Computed Tomographic ◽  
Age Related ◽  
Human Adults ◽  
Geometric Morphometric Analysis ◽  
Shape Changes

The aging process has an impact on mandibular bone morphology and can therefore affect shape sexual dimorphism. Understanding the effect of senescence on mandibular shape changes is particularly important to correctly estimate the sex of an individual and predict age-related conformational modifications. The purpose of this study was to assess age-related changes in mandibular shape and sexual dimorphism. The study sample comprised 160 Multi Slice Computed Tomography examinations of individuals aged 40 to 79 years. Geometric morphometric analysis of fourteen osteometric landmarks was used to examine sexual dimorphism and patterns of mandibular shape variation with age. Results showed that mandibular sexual dimorphism of shape remained significant with aging. Conformational changes occurred between 50 and 70 years and were different for male and female individuals. Females presented earlier and more marked age-related shape changes than males. These observations suggest that mandibular senescence is a sexually dimorphic process since its onset, rate, and the areas subjected to conformational changes differ from male to female individuals. Senescence-related changes present substantial variability, and further investigation is required to determine precisely the age that marks their onset.

Zachvatkinibates (Acari: Oribatida: Mycobatidae) of North America, with descriptions of sexually dimorphic species

2005 ◽  
Vol 137 (6) ◽  
pp. 631-647 ◽  
Author(s):  
Valerie M. Behan-Pelletier ◽  
Barbara Eamer
Keyword(s):  
Sexual Dimorphism ◽  
North America ◽  
Forest Canopy ◽  
Oribatid Mite ◽  
Forest Litter ◽  
Sexually Dimorphic ◽  
Littoral Habitat ◽  
Dermal Glands ◽  
Three New Species ◽  
Species Specific

AbstractThe oribatid mite genus Zachvatkinibates, found in littoral, forest canopy, and forest litter habitats, includes some species showing distinct sexual dimorphism in the octotaxic system of dermal glands, and others lacking this dimorphism. Three new species in this genus are described on the basis of adults, each of which shows species-specific sexual dimorphism: Z. nortonisp. nov. and Z. schatzisp. nov. from beach debris in British Columbia, Canada, and Z. shaldybinaesp. nov. from the littoral in eastern and northeastern Canada. We discuss the association of sexual dimorphism with the littoral habitat of species in this genus and, more generally, the expression of sexually dimorphic porose areas in Ceratozetoidea. We revise the diagnosis for the genus Zachvatkinibates and present a revised key for adults of Zachvatkinibates species of North America north of Mexico.

scholarly journals Active pollination favours sexual dimorphism in floral scent

2013 ◽  
Vol 280 (1772) ◽  
pp. 20132280 ◽  
Author(s):  
Tomoko Okamoto ◽  
Atsushi Kawakita ◽  
Ryutaro Goto ◽  
Glenn P. Svensson ◽  
Makoto Kato
Keyword(s):  
Sexual Dimorphism ◽  
Floral Scent ◽  
Choice Test ◽  
Sexually Dimorphic ◽  
Pollen Transfer ◽  
Male And Female ◽  
Unisexual Flowers ◽  
Male Flowers ◽  
Species Specific ◽  
Female Flowers

Zoophilous flowers often transmit olfactory signals to attract pollinators. In plants with unisexual flowers, such signals are usually similar between the sexes because attraction of the same animal to both male and female flowers is essential for conspecific pollen transfer. Here, we present a remarkable example of sexual dimorphism in floral signal observed in reproductively highly specialized clades of the tribe Phyllantheae (Phyllanthaceae). These plants are pollinated by species-specific, seed-parasitic Epicephala moths (Gracillariidae) that actively collect pollen from male flowers and pollinate the female flowers in which they oviposit; by doing so, they ensure seeds for their offspring. We found that Epicephala -pollinated Phyllanthaceae plants consistently exhibit major qualitative differences in scent between male and female flowers, often involving compounds derived from different biosynthetic pathways. In a choice test, mated female Epicephala moths preferred the scent of male flowers over that of female flowers, suggesting that male floral scent elicits pollen-collecting behaviour. Epicephala pollination evolved multiple times in Phyllantheae, at least thrice accompanied by transition from sexual monomorphism to dimorphism in floral scent. This is the first example in which sexually dimorphic floral scent has evolved to signal an alternative reward provided by each sex, provoking the pollinator's legitimate altruistic behaviour.

scholarly journals Effects of taphonomic deformation on geometric morphometric analysis of fossils: a study using the dicynodont Diictodon feliceps (Therapsida, Anomodontia)

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9925
Author(s):  
Christian F. Kammerer ◽  
Michol Deutsch ◽  
Jacqueline K. Lungmus ◽  
Kenneth D. Angielczyk
Keyword(s):  
Sexual Dimorphism ◽  
Phylogenetic Signal ◽  
Principal Component ◽  
Biological Variation ◽  
Biological Information ◽  
Geometric Morphometric ◽  
Uniform Shear ◽  
Geological Processes ◽  
Morphometric Analyses ◽  
True Position

Taphonomic deformation, the distortion of fossils as a result of geological processes, poses problems for the use of geometric morphometrics in addressing paleobiological questions. Signal from biological variation, such as ontogenetic trends and sexual dimorphism, may be lost if variation from deformation is too high. Here, we investigate the effects of taphonomic deformation on geometric morphometric analyses of the abundant, well known Permian therapsid Diictodon feliceps. Distorted Diictodon crania can be categorized into seven typical styles of deformation: lateral compression, dorsoventral compression, anteroposterior compression, “saddle-shape” deformation (localized collapse at cranial mid-length), anterodorsal shear, anteroventral shear, and right/left shear. In simulated morphometric datasets incorporating known “biological” signals and subjected to uniform shear, deformation was typically the main source of variance but accurate “biological” information could be recovered in most cases. However, in empirical datasets, not only was deformation the dominant source of variance, but little structure associated with allometry and sexual dimorphism was apparent, suggesting that the more varied deformation styles suffered by actual fossils overprint biological variation. In a principal component analysis of all anomodont therapsids, deformed Diictodon specimens exhibit significant dispersion around the “true” position of this taxon in morphospace based on undistorted specimens. The overall variance associated with deformation for Anomodontia as a whole is minor, and the major axes of variation in the study sample show a strong phylogenetic signal instead. Although extremely problematic for studying variation in fossil taxa at lower taxonomic levels, the cumulative effects of deformation in this study are shown to be random, and inclusion of deformed specimens in higher-level analyses of morphological disparity are warranted. Mean morphologies of distorted specimens are found to approximate the morphology of undistorted specimens, so we recommend use of species-level means in higher-level analyses when possible.

scholarly journals High rates of evolution preceded shifts to sex-biased gene expression in Leucadendron, the most sexually dimorphic angiosperms

2021 ◽  
Author(s):  
Mathias Scharmann ◽  
Anthony G Rebelo ◽  
John R Pannell
Keyword(s):  
Gene Expression ◽  
Sexual Dimorphism ◽  
Rapid Evolution ◽  
Sex Bias ◽  
Sexually Dimorphic ◽  
Expression Levels ◽  
Rates Of Evolution ◽  
Expression Evolution ◽  
Males And Females ◽  
Species Specific

AbstractThe males and females of many dioecious plants differ in morphological (Dawson and Geber 1999; Barrett and Hough 2013; Tonnabel et al. 2017), physiological (Juvany and Munné-Bosch 2015), life-history (Delph 1999), and defence traits (Cornelissen and Stiling 2005). Ultimately, such sexual dimorphism must largely be due to differential gene expression between the sexes (Ellegren and Parsch 2007), but little is known about how sex-biased genes are recruited and how their expression evolves over time. We measured gene expression in leaves of males and females of ten species sampled across the South African Cape genus Leucadendron, which shows repeated changes in sexual dimorphism and includes the most extreme differences between males and females in flowering plants (Midgley 2010; Barrett and Hough 2013; Tonnabel et al. 2014). Even in the most dimorphic species in our sample, fewer than 2% of genes showed sex-biased gene expression (SBGE) in vegetative tissue, with surprisingly little correspondence between SBGE and vegetative dimorphism across species. The identity of sex-biased genes in Leucadendron was highly species-specific, with a rapid turnover among species. In animals, sex-biased genes often evolve more quickly than unbiased genes in their sequences and expression levels (Ranz et al. 2003; Khaitovich et al. 2005; Ellegren and Parsch 2007; Voolstra et al. 2007; Harrison et al. 2015; Naqvi et al. 2019), consistent with hypotheses invoking rapid evolution due to sexual selection. Our phylogenetic analysis in Leucadendron, however, clearly indicates that sex-biased genes are recruited from a class of genes with ancestrally rapid rates of expression evolution, perhaps due to low evolutionary or pleiotropic constraints. Nevertheless, we also find evidence for adaptive evolution of expression levels once sex bias evolves. Thus, although the expression of sex-biased genes is ultimately responsive to selection, high rates of expression evolution might usually predate the evolution of sex bias.

scholarly journals Claw asymmetry in crabs: approaching an old issue from a new point of view

2019 ◽  
Author(s):  
Federica Spani ◽  
Massimiliano Scalici ◽  
Keith A Crandall ◽  
Paolo Piras
Keyword(s):  
Point Of View ◽  
Sexually Dimorphic ◽  
Crab Species ◽  
Geometric Morphometric ◽  
Origin And Evolution ◽  
Size And Shape ◽  
Phylogenetic Studies ◽  
Interspecific Comparisons ◽  
Claw Asymmetry ◽  
Ecological Convergence

Abstract Crabs are considered exceptional examples of antisymmetry resulting from the phenomenon of heterochely. Here we investigate morphometrically both the size and the shape of heterochely in 28 crab species, distributed unequally along a brachyuran phylogeny. We address the importance of investigating claw size and shape for interspecific comparisons by linking geometric morphometric outputs to phylogenetic data for 134 brachyuran species. New indices introduced as new sexual dimorphic characters of size and shape, namely heterometry (right chela size/left chela size) and heteromorphy (Procrustes distance between right and left chelae shape), revealed sexually dimorphic differences in diverse crab species. We demonstrate that both size and shape heterochely occur amongst the examined species, but there are no ecological correlations. Our study demonstrates that claw similarity between two or more species was due mainly to phylogenetic relatedness rather than ecological convergence, suggesting that claw morphological features could be useful morphological markers in phylogenetic studies. Although further investigation is needed, this study represents one of the first to thoroughly analyse the origin and evolution of heterochely within the Brachyura clade.

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