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.

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.

scholarly journals The structure of the sedimentary complex of the Middle and South Caspian depressions (Azerbaijan sector)

2021 ◽  
Vol 43 (4) ◽  
pp. 199-216
Author(s):  
N.P. Yusubov ◽  
I.S. Guliyev
Keyword(s):  
Seismic Data ◽  
Oil And Gas ◽  
Sedimentary Cover ◽  
Clay Content ◽  
Geological Structure ◽  
Point Of View ◽  
South Caspian Basin ◽  
Origin And Evolution ◽  
Geological Interpretation ◽  
High Degree

The high degree of knowledge of the upper horizons of the sedimentary cover of the Middle and South Caspian depressions, given an insufficient increase in hydrocarbon reserves, leads to the need for a detailed approach to the search for oil and gas deposits in deep-seated sediments (over 6 km). During the geological interpretation of new highly informative seismic data, as well as data of deep drilling and petrological core studies, there were revealed obvious shortcomings in the concepts of the origin and evolution of the Middle and South Caspian depressions. These ideas misinterpret evolution, especially the South Caspian Basin, which is characterized by a number of unique features: very thick sedimentary cover (up to 22 km), extremely high sedimentation rate, low heat flow and reservoir temperatures, abnormally high pore and reservoir pressures, high clay content of the section, etc. The main purpose of the study was to elucidate the regional structure and features of the dissection of the sedimentary cover of the Middle and South Caspian depressions, the conditions of occurrence and distribution of facies and thicknesses of individual complexes of deposits. The paper analyzes the results of some previous studies of the geological structure of the Middle and South Caspian depressions based on the data of deep seismic sounding, seismological and gravimetric observations. We consider the main conclusions of these studies, about the geological structure of the sedimentary complex of the region’s, very outdated and subject to revision. The results of seismic stratigraphic analysis of seismic data allowed the authors to identify new data about the tectonic structure and express a completely different point of view regarding the structure of the sedimentary cover in the region. The work also touches on the issue associated with the tectonics of the region and the alleged subduction zone here.

Advanced Passive Thermal Management for LED Bulb Systems

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 001277-001293
Author(s):  
James Petroski
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Energy Savings ◽  
Cooling System ◽  
Point Of View ◽  
Hazardous Substances ◽  
Size And Shape ◽  
Lighting Systems ◽  
Liquid Cooling System ◽  
Forced Cooling

The movement to LED lighting systems worldwide is accelerating quickly as energy savings and reduction of hazardous substances (RoHS) increase in importance. Furthering this trend are government regulations, rebate programs and declining prices. The market drive today is to replace light bulbs of common outputs (60W, 75W and 100W) without resorting to Compact Fluorescent (CFL) bulbs containing mercury while maintaining the standard industry bulb size and shape referred to as A19 for fixture retrofitting. This A19 size and shape restriction causes a small heat sink which is only capable of dissipating heat for 60W equivalent LED bulbs with natural convection. 75W and 100W equivalent bulbs require larger sizes, some method of forced cooling, or some unusual liquid cooling system; generally none of these approaches are desirable for light bulbs from a consumer point of view. Thus, there is interest in developing natural convection cooled A19 light bulb designs for LEDs that cool far more effectively than today's current designs. Current A19 size heat sink designs typically have thermal resistances of 5–7 °C/W. A more efficient method of cooling can be created using a chimney-based design to lower system thermal resistances below 4 °C/W while meeting all other requirements for bulb system design. Numerical studies and test data are in good agreement for various orientations including methods for keeping the chimney partially active in horizontal orientations. Such chimney-based designs are capable of cooling 75W and 100W equivalent LED light bulbs in the limited volume constraints of A19-size devices.

The Cheilosia canicularis group (Diptera: Syrphidae): species delimitation and evolutionary relationships based on wing geometric morphometrics

Zootaxa ◽  
2008 ◽  
Vol 1825 (1) ◽  
pp. 40 ◽  
Author(s):  
JASMINA LUDOŠKI ◽  
LJUBINKA FRANCUSKI ◽  
ANTE VUJIĆ ◽  
VESNA MILANKOV
Keyword(s):  
Sequence Data ◽  
Balkan Peninsula ◽  
Wing Shape ◽  
Canonical Variate ◽  
Wing Size ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Mahalanobis Distances ◽  
Size And Shape ◽  
Upgma Cluster Analysis

A landmark-based geometric morphometric approach was used to assess differences in the size and shape of wing among/within three species of the Cheilosia canicularis group (Diptera: Syrphidae): C. canicularis, C. himantopus and C. orthotricha. Wing size and shape variation was observed from 25, 176 and 41 specimens of C. canicularis, C. himantopus and C. orthotricha, respectively, collected from six localities on the Balkan Peninsula. Significant differences in wing size were obtained among the analysed species and canonical variate analysis showed that wing shape was sufficiently different to allow the correct classification of 73% individuals of C. canicularis, 80% of C. orthotricha and 94% of C. himantopus, and clear delimitation of the species pairs C. canicularis/C. orthotricha and C. himantopus/C. orthotricha. In all analysed species, the consistent sex dimorphism in wing shape was observed indicating that female specimens had shorter and broader wings than males. The UPGMA cluster analysis based on squared Mahalanobis distances revealed close accordance with previously published phylogenetic relationships of these species indicated by allozyme and DNA sequence data analysis. Our results suggested that wing parameters contain useful information in quantification phenotypic variation and identification of species in this challenging group for taxonomy and systematics.

scholarly journals Variation in Chin and Mandibular Symphysis Size and Shape in Males and Females: A CT-Based Study

2020 ◽  
Vol 17 (12) ◽  
pp. 4249
Author(s):  
Tatiana Sella Tunis ◽  
Israel Hershkovitz ◽  
Hila May ◽  
Alexander Dan Vardimon ◽  
Rachel Sarig ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Anatomical Landmark ◽  
Anatomical Structure ◽  
Sexually Dimorphic ◽  
Selection Theory ◽  
Size And Shape ◽  
Size Index ◽  
Sexual Selection Theory ◽  
Males And Females ◽  
Anthropological Literature

The chin is a unique anatomical landmark of modern humans. Its size and shape play an important role from the esthetic perspective. However, disagreement exists in the dental and anthropological literature regarding the sex differences in chin and symphysis morphometrics. The “sexual selection” theory is presented as a possible reason for chin formation in our species; however, many other contradictory theories also exist. This study’s aims were therefore to determine how chin and symphysis size and shape vary with sex, and to discuss “sexual selection” theory as a reason for its formation. Head and neck computed tomography (CT) scans of 419 adults were utilized to measure chin and symphysis sizes and shapes. The chin and symphysis measures were compared between the sexes using an independent-samples t-test, a Mann–Whitney test, and the F-statistic. The chin width was significantly greater in males than in females (p < 0.001), whereas the chin height, area, and size index were significantly greater in females (p < 0.001). Symphysis measures did not differ significantly between the sexes. Size accounted for 2–14% of the chin variance and between 24–33% of the symphysis variance. Overall, the chin was found to be a more heterogeneous anatomical structure than the symphysis, as well as more sexually dimorphic.

Fourier analysis applied to Stephanomys (Rodentia, Muridae) molars: nonprogressive evolutionary pattern in a gradual lineage

Paleobiology ◽  
1996 ◽  
Vol 22 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Sabrina Renaud ◽  
Jacques Michaux ◽  
Jean-Jacques Jaeger ◽  
Jean-Christophe Auffray
Keyword(s):  
Fourier Coefficients ◽  
Size Variation ◽  
Evolutionary Pattern ◽  
Size And Shape ◽  
Mechanical Constraints ◽  
Phylogenetic Studies ◽  
Single Structure ◽  
Lower Molar ◽  
Shape Changes ◽  
Elliptic Fourier Transform

Size and shape are analyzed for Pliocene lineages of the rodent genus Stephanomys Schaub 1938. Previous phylogenetic studies were based mainly on size variation and descriptive comparisons, without any attempt to quantify shape changes. Hence, on the basis of regular size increase, Stephanomys has been considered a prime example of phyletic gradualism. In order to quantify morphological variation within the lineage, a method for analyzing complex outlines, the elliptic Fourier transform, was applied to tooth contour (upper and lower first molars). It was then possible to compare evolution in size, estimated by tooth area, as well as evolution of shape, represented by Fourier coefficients.While size seems to change gradually through time, morphology gives a rather discontinuous evolutionary pattern for both the upper and lower molar. Such a discrepancy between the evolution of size and shape of a single structure suggests that different genetic determinisms and mechanical constraints may act on size and shape. Hence it may be misleading to infer generalized evolutionary processes from either size or shape alone.

scholarly journals A revision of the genus Olivancillaria (Mollusca: Olividae) from the southwestern Atlantic

Zootaxa ◽  
2011 ◽  
Vol 2889 (1) ◽  
pp. 1 ◽  
Author(s):  
VALERIA TESO ◽  
GUIDO PASTORINO
Keyword(s):  
Geographic Distribution ◽  
Morphometric Analysis ◽  
Field Observations ◽  
Southwestern Atlantic ◽  
Sem Images ◽  
Geometric Morphometric ◽  
Size And Shape ◽  
Egg Capsules ◽  
Living Species ◽  
Geometric Morphometric Analysis

The genus Olivancillaria is revised and restricted to eight living species: O. deshayesiana, O. carcellesi, O. urceus, O. contortuplicata, O. orbignyi, O. teaguei, O. auricularia and O. vesica. The last two species were previously considered as subspecies. The name O. uretai is a junior synonym of O. orbignyi. The genus Olivancillaria is endemic to the southwestern Atlantic, ranging from Bahia state, Brazil (~12°S) to Chubut province (42°37’S), Argentina, intertidal to 70 m depth. It is a clear representative of the Argentine Malacological province. Redescriptions and re-illustration of types were done for each species. Shell ultrastructure, radulae, penes, siphon papillae and egg capsules are described and illustrated by SEM images. A geometric morphometric analysis was carried out to confirm shell variation on size and shape among species. The geographic distribution of each species is provided based on field observations as well as on museum records.

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.

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