scholarly journals Sexual Dimorphism of the First Rib: A Comparative Approach Using Metric and Geometric Morphometric Analyses

2017 ◽  
Vol 62 (5) ◽  
pp. 1251-1258 ◽  
Author(s):  
Jeffrey James Lynch ◽  
Peter Cross ◽  
Vivienne Heaton
Keyword(s):  
Sexual Dimorphism ◽  
Comparative Approach ◽  
Geometric Morphometric ◽  
First Rib ◽  
Morphometric Analyses

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 hominin first rib discovered at the Sterkfontein Caves, South Africa

2016 ◽  
Vol Volume 112 (Number 5/6) ◽  
Author(s):  
Gaokgatlhee Tawan ◽  
Daniel García-Martínez ◽  
Jennifer Eyre ◽  
Markus Bastir ◽  
Lee Berger ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Fossil Record ◽  
Three Dimensional ◽  
Great Apes ◽  
Small Individual ◽  
Geometric Morphometric ◽  
First Rib ◽  
Morphometric Analyses ◽  
Fossil Hominin

Abstract First ribs – the first or most superior ribs in the thorax – are rare in the hominin fossil record, and when found, have the potential to provide information regarding the upper thorax shape of extinct hominins. Here, we describe a partial first rib from Member 4 of the Sterkfontein Caves, South Africa. The rib shaft is broken away, so only the head and neck are preserved. The rib is small, falling closest to small-bodied Australopithecus first ribs (AL 288-1 and MH1). Given that it was recovered near the StW 318 femur excavation, which also represents a small individual, we suggest that the two may be associated. Three-dimensional geometric morphometric analyses were used to quantify the rib fragment morphology and compare it to extant hominoid and other fossil hominin ribs. While only the proximal end is preserved, our analyses show that South African Australopithecus share derived features of the proximal first rib more closely resembling A. afarensis and later hominins than great apes.

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 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.

Intersexual and intrasexual selection for neck musculature in men: Attractiveness, dominance, and actual fighting success

2021 ◽  
Author(s):  
Neil Robert Caton ◽  
David M. G. Lewis
Keyword(s):  
Sexual Dimorphism ◽  
Evolutionary Biology ◽  
Theoretical Work ◽  
Human Anatomy ◽  
Geometric Morphometric ◽  
World Region ◽  
Sexual Characteristics ◽  
Neck Strength ◽  
Neck Musculature ◽  
Secondary Sexual

Countless organisms are equipped with physiological armor that reduce damage from opponents. Because humans have sustained a long evolutionary history of hand-to-hand combat, selection would have been placed on morphological structures which reduce rotational acceleration to the head and increase the likelihood of victory. Grounded in over 60 years of sports performance theory and recent theoretical work in evolutionary biology, geometric morphometric analyses revealed that larger neck musculature in professional combatants (N = 715) was associated with greater real-world fighting success, after for adjusting for allometry (Study 1). Because sexual dimorphism emerges from selection on morphological structures that improve men’s fighting success, we then discovered that the human neck is the most sexually dimorphic feature of human anatomy when compared to 91 other anatomical features (N = 6,068; Study 2). This male-biased sexual dimorphism held after controlling for these 91 allometric measurements, and held across every world region (Africa, Asia, Europe, Oceania, and North, Central, and South America). Because human psychological systems consequently evolved to attend to men’s secondary sexual characteristics, we discovered that men (N = 564 stimuli) with larger neck musculature (Study 3: geometric morphometrics; Study 4: physiological neck strength; Study 5: photorealistic stimuli) are rated (N = 772 raters) as stronger, more masculine, and higher in fighting ability and short-term attractiveness, after accounting for allometry. Combined, our research introduced a new secondary sexual characteristic to the biological, anthropological, and psychological sciences: the human neck.

scholarly journals New Geometric Morphometric Insights in Digital Taphonomy: Analyses into the Sexual Dimorphism of Felids through Their Tooth Pits

2021 ◽  
Vol 11 (17) ◽  
pp. 7848
Author(s):  
Darío Herranz-Rodrigo ◽  
Silvia J. Tardáguila-Giacomozzi ◽  
Lloyd A. Courtenay ◽  
Juan-José Rodríguez-Alba ◽  
Antonio Garrucho ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Geometric Morphometrics ◽  
Applied Statistics ◽  
Panthera Tigris ◽  
Panthera Pardus ◽  
Geometric Morphometric ◽  
Male And Female ◽  
New Horizons ◽  
Carnivore Species ◽  
Felid Species

Recent studies using geometric morphometrics for taphonomy have yielded interesting results, opening new horizons of research in both archaeological and paleontological sites. Here we present the analysis of tooth pits left by male and female individuals of two different carnivore species (Panthera tigris and Panthera pardus) in order to see if sexual dimorphism influences the morphology of tooth pit marks. In the process, 3D-scanning and applied statistics were used. Based on samples derived from two individuals of different sexes, the present results indicate sexual dimorphism in these felid species to not be a conditioning factor of tooth pit morphology.

scholarly journals Morphological diversity in tenrecs (Afrosoricida, Tenrecidae): comparing tenrec skull diversity to their closest relatives

2015 ◽  
Author(s):  
Sive Finlay ◽  
Natalie Cooper
Keyword(s):  
Quantitative Analysis ◽  
Quantitative Methods ◽  
Morphological Diversity ◽  
Lateral View ◽  
Ecological Niches ◽  
Diverse Group ◽  
Geometric Morphometric ◽  
Skull Shape ◽  
Morphometric Analyses ◽  
The Family

Morphological diversity is often studied qualitatively. However, to truly understand the evolution of exceptional diversity, it is important to take a quantitative approach instead of relying on subjective, qualitative assessments. Here, we present a quantitative analysis of morphological diversity in a Family of small mammals, the tenrecs (Afrosoricida, Tenrecidae). Tenrecs are often cited as an example of an exceptionally morphologically diverse group. However, this assumption has not been tested quantitatively. We use geometric morphometric analyses of skull shape to test whether tenrecs are more morphologically diverse than their closest relatives, the golden moles (Afrosoricida, Chrysochloridae). Tenrecs occupy a wider range of ecological niches than golden moles so we predict that they will be more morphologically diverse. Contrary to our expectations, We find that tenrec skulls are only more morphologically diverse than golden moles when measured in lateral view. Furthermore, similarities among the species-rich Microgale tenrec Genus appear to mask higher morphological diversity in the rest of the Family. These results reveal new insights into the morphological diversity of tenrecs and highlight the importance of using quantitative methods to test qualitative assumptions about patterns of morphological diversity.

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