scholarly journals Contributions to the Knowledge of Sexual Dimorphism in Liolaemus darwinii (Squamata, Liolaemi-dae) in the Monte Desert of Argentina

Zoodiversity ◽  
2021 ◽  
Vol 55 (6) ◽  
pp. 479-484
Author(s):  
G. N. Castillo ◽  
C. J. Gonzalez-Rivas ◽  
J. C. Acosta
Keyword(s):  
Sexual Dimorphism ◽  
Wide Distribution ◽  
Cephalic Region ◽  
Sexual Differences ◽  
San Juan ◽  
Shape Variation ◽  
Monte Desert ◽  
Typical Species ◽  
Geometric Morphometry

The lizard Liolaemus darwinii (Liolaemidae) is a typical species with wide distribution in Monte environments of Argentina. The objective of this study is contribute to knowledge of sexual dimorphism in a population of L. darwinii (Bell, 1843). We evaluated sexual shape variation of the cephalic region through procustes analyses with geometric morphometry. We predict that the heads in males will have differences in shape with respect to females. The results showed significant sexual differences in shape, mainly in the region around the eyes. There were no significant differences in sizes. Geometric morphometry analyses are a useful tool for addressing sexual differences in Monte lizards. This constitutes the first study for the center-west of Argentina in San Juan province that implements these geometric morphometry analyses.

scholarly journals Sexual Dimorphism in the Multielemental Stoichiometric Phenotypes and Stoichiometric Niches of Spiders

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 484
Author(s):  
Łukasz Sobczyk ◽  
Michał Filipiak ◽  
Marcin Czarnoleski
Keyword(s):  
Sexual Dimorphism ◽  
Ecological Stoichiometry ◽  
C:N Ratio ◽  
Sexual Differences ◽  
Nutritional Limitation ◽  
Trade Offs ◽  
Hunting Mode

Nutritional limitations may shape populations and communities of organisms. This phenomenon is often studied by treating populations and communities as pools of homogenous individuals with average nutritional optima and experiencing average constraints and trade-offs that influence their fitness in a standardized way. However, populations and communities consist of individuals belonging to different sexes, each with specific nutritional demands and limitations. Taking this into account, we used the ecological stoichiometry framework to study sexual differences in the stoichiometric phenotypes, reflecting stoichiometric niches, of four spider taxa differing in the hunting mode. The species and sexes differed fundamentally in their elemental phenotypes, including elements beyond those most commonly studied (C, N and P). Both species and sexes were distinguished by the C:N ratio and concentrations of Cu, K and Zn. Species additionally differed in concentrations of Na, Mg and Mn. Phosphorous was not involved in this differentiation. Sexual dimorphism in spiders’ elemental phenotypes, related to differences in their stoichiometric niches, suggests different nutritional optima and differences in nutritional limitation experienced by different sexes and species. This may influence the structure and functioning of spider populations and communities.

A Geometric Morphometric Assessment of Hand Shape and Comparison to the 2D:4D Digit Ratio as a Marker of Sexual Dimorphism

2013 ◽  
Vol 16 (2) ◽  
pp. 590-600 ◽  
Author(s):  
Paul G. Sanfilippo ◽  
Alex W. Hewitt ◽  
Jenny A. Mountain ◽  
David A. Mackey
Keyword(s):  
Sexual Dimorphism ◽  
Geometric Morphometrics ◽  
Shape Analysis ◽  
Twin Studies ◽  
Analytical Techniques ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Hand Shape ◽  
Physical Traits ◽  
Biological Shape

Twin studies are extremely useful for investigating hypotheses of genetic influence on a range of behavioral and physical traits in humans. Studies of physical traits, however, are usually limited to size-related biological characteristics because it is inherently difficult to quantify the morphological counterpart – shape. In recent years, the development of geometry-preserving analytical techniques built upon multivariate statistical methodologies has produced a new discipline in biological shape analysis known as geometric morphometrics. In this study of hand shape analysis, we introduce the reader already familiar with the field of twin research to the potential utility of geometric morphometrics and demonstrate the cross-discipline applicability of methods. We also investigate and compare the efficacy of the 2D:4D ratio, a commonly used marker of sexual dimorphism, to the fully multivariate approach of shape analysis in discriminating between male and female sex. Studies of biological shape variation utilizing geometric morphometric techniques may be completed with software freely available on the Internet and time invested to master the small learning curve in concepts and theory.

Morphological diversity of wild rabbit populations: implications for archaeology and palaeontology

2019 ◽  
Vol 128 (1) ◽  
pp. 211-224 ◽  
Author(s):  
Maxime Pelletier
Keyword(s):  
Sexual Dimorphism ◽  
Western Europe ◽  
Geographical Location ◽  
Morphological Diversity ◽  
Population Level ◽  
European Rabbit ◽  
Wild Rabbit ◽  
Shape Variation ◽  
Hunting Behaviour ◽  
Behavioural Aspects

Abstract Morphometric characteristics of the European rabbit (Oryctolagus cuniculus) are regularly used in archaeological and palaeontological studies to explore aspects of prehistoric human hunting behaviour, to reconstruct past environments or to define new species. However, the variability of these characteristics is still both poorly understood and under-documented due to a lack of population-level data that are essential for reliably interpreting the fossil record of this species. Here we address the morphometric diversity of wild rabbits in seven current populations from south-western Europe. Size variations in different skeletal parts were analysed to explore the potential impact of sexual dimorphism. A geometric morphometric analysis of the third lower premolar (p3) – a tooth commonly used to distinguish leporid species – was used to evaluate the relative effects of size, phylogeny, geographical location and climate on shape variation. The results show a negligible impact of sexual dimorphism, contradicting previous studies. We also demonstrate geography and climate to be the main factors driving variation in p3 shape, potentially calling into question criteria typically used to identify rabbit species. These results are valuable not only for palaeobiologists studying the taxonomy and the evolutionary history of the leporid family but also for archaeologists interested in the socio-economic and behavioural aspects of Palaeolithic human groups.

scholarly journals Character state variation within Dendrothrips (Thysanoptera: Thripidae) with a revision of the species from China

Zootaxa ◽  
2019 ◽  
Vol 4590 (2) ◽  
pp. 231
Author(s):  
ZHAOHONG WANG ◽  
LAURENCE A. MOUND ◽  
XIAOLI TONG
Keyword(s):  
Sexual Dimorphism ◽  
Fore Wing ◽  
Host Plants ◽  
Wide Distribution ◽  
Wing Surface ◽  
Character State ◽  
State Variation ◽  
Species Groups

Character state variation among species within Dendrothrips Uzel is discussed, with seven species-groups suggested based on sculpture of body and fore wing surface. Sexual dimorphism in pronotal sculpture and posteroangular setae is described in D. magnoliae. The major host plants of several species are indicated, and the wide distribution across Asia of some species emphasised. Species of Dendrothrips from China are reviewed, D. octosparsus sp. n. is described from Oleaceae, and a key presented to the ten species from China. Two species previously known only from Japan, D. magnoliae Kudô and D. latimaculatus Nonaka & Okajima, are newly recorded from China along with the first description of their males. The male of D. homalii Zhang & Tong is described and illustrated. The record from China of D. mendax Bhatti is considered a misidentification of D. latimaculatus. D. schmiae Kudô is synonymized with D. minowai Priesner.

Re-discovery of Haemoproteus kopki (De Mello, 1916) in two geckoes from the Afghan border of Pakistan

Parasitology ◽  
1982 ◽  
Vol 84 (3) ◽  
pp. 527-536 ◽  
Author(s):  
Sam R. Telford
Keyword(s):  
Sexual Dimorphism ◽  
Chronic Infection ◽  
Sand Dune ◽  
Acute Infection ◽  
Sexual Differences ◽  
Mixed Infections ◽  
Initial Infection ◽  
Intimate Association ◽  
Large Round ◽  
Comparable Size

SummaryHaemoproteus kopki (De Mello, 1916) is reported from the geckoes Teratoscincus scincus and T. microlepis collected in three localities on the Afghan border of Pakistan. A detailed description of H. kopki is provided in correlation with the courses of an initial, acute infection and a relapsed, chronic infection. Haemoproteus kopki is characterized by large round or oval gametocytes which show sexual dimorphism in distribution of pigment: macrogametocytes show pigment dispersed in dark granules throughout the cytoplasm, while pigment in microgametocytes is aggregated into large, round golden masses within vacuoles in one, or rarely two foci. Other sexual differences exist in gametocyte dimensions. Gametocytes produced in the relapse infection grew much more slowly than did those of the initial infection, and never attained a comparable size despite being observed for twice the length of time. Despite a maximum parasitaemia of 53·8% in the initial infection, increased erythropoiesis did not occur. No asexual stages were found in tissues examined. The presence of mixed infections of H. kopki, Leishmania sp. and microfilariae in a harsh sand dune habitat with presumably limited dipteran fauna suggests their having a common vector in intimate association with the burrows inhabited by the geckoes.

scholarly journals Sexual dimorphism and morphometric analysis of Filopaludina martensi martensi (Gastropoda: Viviparidae)

2021 ◽  
Vol 31 (2) ◽  
pp. 87-92
Author(s):  
Weerachon Sawangproh ◽  
Chetsada Phaenark ◽  
Supatra Chunchob ◽  
Paiphan Paejaroen
Keyword(s):  
Sexual Dimorphism ◽  
Morphometric Analysis ◽  
Sexual Differences ◽  
Morphometric Analyses ◽  
Different Characteristics

Sexual dimorphism is the condition where individuals of different sex in the same species exhibit different characteristics beyond the differences in their sexual organs. In this study, individuals of a viviparid species Filopaludina martensi from the Kwai Yai River in Kanchanaburi Province (Thailand) were examined for eight shell and operculum characteristics. Sexual differences were observed in size of shell and operculum, with females being larger than males. The results indicated that morphometric analyses are useful to detect subtle differences between sexes in this species.

scholarly journals Intraspecific Morphological Variation in Two Common Marine Fish Species from South Africa

2013 ◽  
Vol 6 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Eric Mattson ◽  
Mark C. Belk
Keyword(s):  
Sexual Dimorphism ◽  
Marine Fish ◽  
Fish Species ◽  
Morphological Variation ◽  
Environmental Gradients ◽  
Human Consumption ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Feeding Niche ◽  
Intraspecific Morphological Variation

Intraspecific morphological variation in fish is typically associated with sexual dimorphism, or one of three common environmental gradients: variation in intensity of predation, variation in water velocity, or variation in feeding niche. The preponderance of examples of environment-associated morphological variation within fish species has been documented in freshwater systems. It is not clear whether environment-associated intraspecific morphological variation is less common in marine fishes or whether there has just been a lack of investigation. We used geometric morphometric analysis to quantify shape variation in two species of South African marine fish commonly harvested for human consumption, Pterogymnus laniarius (panga), and Argyrosomus inodorus (silver kob). Neither species exhibited significant sexual dimorphism, but both species exhibited significant intraspecific morphological variation. This variation appears consistent with patterns expected from variation along the benthic-pelagic feeding niche continuum.

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.

scholarly journals The dynamic ontogenetic patterns of adaptive divergence and sexual dimorphism in Arctic charr

2021 ◽  
Author(s):  
Marina De la Cámara ◽  
Lieke Ponsioen ◽  
Quentin J.B. Horta-Lacueva ◽  
Kalina H Kapralova
Keyword(s):  
Sexual Dimorphism ◽  
Sexual Maturation ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Common Garden ◽  
Open Water ◽  
Adaptive Divergence ◽  
Shape Variation ◽  
Ontogenetic Trajectories ◽  
Main Driver

ABSTRACTArctic charr (Salvelinus alpinus) in lake Thingvallavatn (Iceland) is one of the most iconic examples of post-glacial adaptive divergence, resulting in four ecomorphs that diverge along the ecological benthic-limnetic axis (bottom lake versus open water feeders), and are distinct both phenotypically and genotypically. Here, we used geometric morphometrics tools on a common garden setup to determine the factors responsible for genetically based shape variation during the post-embryonic ontogeny of two morphs that represent the benthic-limnetic axis: the small benthic (SB) and the planktivorous (PL). This experiment uses pure crosses and F1 reciprocal hybrids between the two morphs, and includes the onset of sexual maturation, offering an excellent opportunity to explore the genetic component of adaptive divergence and the role of sexual dimorphism in this scenario. We found that growth is the main driver of shape variation across time and provided evidence of a genetically-controlled ontogenetic shift that gives rise to the limnetic morph. Additionally, our results indicate that the onset of sexual maturation triggers differences both in sex ontogenetic trajectories and in static shape variation at different time points, likely dissipating the canalisation for traits traditionally associated with benthic-limnetic adaptations.

Description of four new species from the Haploniscus unicornis Menzies, 1956 complex (Isopoda: Asellota: Haploniscidae)

Zootaxa ◽  
2010 ◽  
Vol 2536 (1) ◽  
pp. 1 ◽  
Author(s):  
WIEBKE BRÖKELAND
Keyword(s):  
Puerto Rico ◽  
New Species ◽  
Sexual Dimorphism ◽  
Deep Sea ◽  
Species Complex ◽  
Wide Distribution ◽  
Adult Males ◽  
Southwest Atlantic ◽  
Walvis Ridge ◽  
Iceland Basin

Based on the adult males the four species Haploniscus bihastatus n. sp., H. monoceros n. sp., H. machairis n. sp. and H. angolensis n. sp. are described from the deep sea of the Southeast Atlantic. These belong to a species complex, which also includes H. unicornis Menzies from the Puerto Rico Trench and H. aduncus Lincoln from the Iceland Basin and shares several characters with species from the genus Mastigoniscus Lincoln. While males of the species complex can be reasonably well distinguished by their habitus and pleopods 1 and 2, the discrimination of female specimens is hampered by the pronounced sexual dimorphism. The Haploniscus unicornis complex has a wide distribution in the Atlantic Ocean, but appears to be absent from basins south of the Walvis Ridge and also from the southwest Atlantic basins.

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