Analysing morphological variation of appendages and labrum in 10 species of Heterocypris Claus, 1893 (Podocopida : Cyprididae) with additional description of Heterocypris exigua

2018 ◽  
Vol 32 (6) ◽  
pp. 1448
Author(s):  
Tamara Karan-Žnidaršič ◽  
Vukica Vujić ◽  
Ángel Baltanás
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Relative Length ◽  
Interspecific Variation ◽  
Canonical Variate ◽  
Shape Variation ◽  
Males And Females ◽  
New Perspective ◽  
Relative Measurements ◽  
Post Hoc

Natural selection can lead to speciation, but its effects depend on amount of morphological variation within populations. In Ostracoda, the appendages enclosed within the calcified carapace are less influenced by environmental conditions in comparison with carapace valves. Here, we explored morphological variation of appendages and labrum in cosmopolitan genus Heterocypris, investigating the species occurring in Europe. With the aim to overcome taxonomical problems, both traditional and geometric morphometrics were applied. The relative lengths were analysed by one-way ANOVA and post-hoc tests to determine interspecific variation and sexual dimorphism. Significant traits were further analysed by Canonical Variate Analysis separately for males and females as segment width/length ratios and relative length of claws and setae ratios. Landmark-based geometric morphometrics were applied to analyse shape variation of the labrum and traits of the maxillular palp. From this, a new perspective on morphological variation within this genus emerged. Relative measurements of the second segment of the maxillular palp, and relative lengths of the natatory setae were found to be the characters that contribute most to discrimination among Heterocypris species. The most important discriminant traits in females are the relative lengths of the G2 and G1 claws. Heterocypris exigua is additionally described, as all findings demonstrated that this is the most distinctive species, the most similar to H. gevgelica. In conclusion, we found that in comparison with maxillular palp and other analysed characters, labrum traits showed as more reliable and deserve more attention in descriptions of new species.

How unique is unique? Quantifying geometric differences in stripe patterns of Cape mountain zebra, Equus zebra zebra (Perissodactyla: Equidae)

2020 ◽  
Author(s):  
Nicolas D Prinsloo ◽  
Martin Postma ◽  
P J Nico de Bruyn
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Individual Animal ◽  
Shape Variation ◽  
Model Species ◽  
Degree Of Branching ◽  
Pattern Similarity ◽  
Surface Models ◽  
Coat Pattern ◽  
Study Population

Abstract Quantified coat pattern dissimilarity provides a visible surface for individual animal traceability to populations. We determined the feasibility in quantifying uniqueness of stripe patterns of Cape mountain zebra (CMZ; Equus zebra zebra) using geometric morphometrics. We photogrammetrically created dense surface models of CMZ (N = 56). Stripe edges were landmarked, superimposed and compared for shape variation across replicates and the population. Significant allometry in stripe patterns prompted allometric correction to remove increased curvature of stripes at the rump, belly and back with larger adult individuals, to facilitate equilibrated comparison between individuals. Re-landmarked replicates showed lower dissimilarity (Di) than non-replicates (Dp), representing minimal landmarking error. Individuals were 78.07 ± 1.79% unique (U=1−DiDp×100%) relative to the study population. Size, the number of torso stripes and degree of branching in four rear torso stripes described the most shape variation (36.79%) but a significant portion could only be distinguished with geometric morphometrics (41.82%). This is the first known use of geometric morphometrics to quantify coat pattern uniqueness, using a model species to provide baseline individual morphological variation. Measures of coat pattern similarity have a place in phenotypic monitoring and identification.

Intraspecific variation in wing shape of Poecilobothrus regalis (Meigen, 1824) (Diptera, Dolichopodidae)

2016 ◽  
Vol 4 (16) ◽  
pp. 1
Author(s):  
Mariya A. Chursina ◽  
Oleg P. Negrobov
Keyword(s):  
Geometric Morphometrics ◽  
Flow Velocity ◽  
Intraspecific Variability ◽  
Wing Shape ◽  
Canonical Variate ◽  
Wind Flow ◽  
Allometric Relationships ◽  
Shape Variation ◽  
Average Temperature ◽  
Average Wind

A study of 186 specimens of Poecilobothrus regalis was conducted in order to examine intraspecific variability of wing shape. The wing shape variation was analyzed using geometric morphometrics analyses. Significant differences in the structure of wing were found both between sexes and between populations. Differences between sexes were observed in the structure of the medium portion of wing. The first extracted canonical variate of geographic variation showed a moderately linear association with latitude and average temperature of February and March. The second canonical variate was correlated with longitude and values of average wind flow velocity. Allometric relationships were weak both between populations and sexes.

scholarly journals Sources of Intraspecific Morphological Variation in Vipera seoanei: Allometry, Sex, and Colour Phenotype

2020 ◽  
Author(s):  
Nahla Lucchini ◽  
Antigoni Kaliontzopoulou ◽  
Guillermo Aguado Val ◽  
Fernando Martínez-Freiría
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Morphological Variability ◽  
Tail Length ◽  
Shape Variation ◽  
Body Proportions ◽  
Head Shape ◽  
Relative Contribution ◽  
Colour Morphs ◽  
Intraspecific Morphological Variation

AbstractSnakes frequently exhibit ontogenetic and sexual variation in head dimensions, as well as the occurrence of distinct colour morphotypes which might be fitness-related. In this study, we used linear biometry and geometric morphometrics to investigate intraspecific morphological variation related to allometry and sexual dimorphism in Vipera seoanei, a species that exhibits five colour morphotypes, potentially subjected to distinct ecological pressures. We measured body size (SVL), tail length and head dimensions in 391 specimens, and examined variation in biometric traits with respect to allometry, sex and colour morph. In addition, we analysed head shape variation by recording the position of 29 landmarks in 123 specimens and establishing a low-error protocol for implementing geometric morphometrics to European vipers. All head dimensions exhibited significant allometry, while sexual differences occurred for SVL, relative tail length and snout height. After considering size effects, we found significant differences in body proportions between the sexes and across colour morphs, which suggests an important influence of lowland and montane habitats in shaping morphological variation. By contrast, head shape did not exhibit significant variation across sexes or colour morphs. Instead it was mainly associated to allometric variation, where the supraocular and the rear regions of the head were the areas that varied the most throughout growth and across individuals. Overall, this study provides a thorough description of morphological variability in Vipera seoanei and highlights the relevance of combining different tools (i.e. linear and geometric morphometrics) and analyses to evaluate the relative contribution of different factors in shaping intraspecific variation.

scholarly journals Disentangling biological variability and taphonomy: shape analysis of the limb long bones of the sauropodomorph dinosaur Plateosaurus

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9359
Author(s):  
Rémi Lefebvre ◽  
Ronan Allain ◽  
Alexandra Houssaye ◽  
Raphaël Cornette
Keyword(s):  
Geometric Morphometrics ◽  
Shape Analysis ◽  
Morphological Variation ◽  
Long Bones ◽  
Biological Variability ◽  
Shape Variation ◽  
Genus Level ◽  
Taxonomic History ◽  
Quantitative Basis ◽  
The Impact

Sauropodomorph dinosaurs constitute a well-studied clade of dinosaurs, notably because of the acquisition of gigantism within this group. The genus Plateosaurus is one of the best-known sauropodomorphs, with numerous remains from various localities. Its tumultuous taxonomic history suggests the relevance of addressing its intrageneric shape variability, mixed with taphonomic modifications of the original bone shape. Here we investigate quantitatively the morphological variation of Plateosaurus occurring at the genus level by studying the shape variation of a sample of limb long bones. By means of 3D geometric morphometrics, the analysis of the uncorrelated variation permits separation of the variation estimated as obviously taphonomically influenced from the more biologically plausible variation. Beyond the dominant taphonomic signal, our approach permits interpretation of the most biologically plausible features, even on anatomical parts influenced by taphonomic deformations. Those features are thus found on a quantitative basis from the variation of samples containing fossil specimens, by taking the impact of taphonomy into account, which is paramount in order to avoid making biologically ambiguous interpretations.

scholarly journals Identification of the species of the Cheilosia variabilis group (Diptera, Syrphidae) from the Balkan Peninsula using wing geometric morphometrics, with the revision of status of C. melanopa redi Vujić, 1996

2009 ◽  
Vol 78 (3) ◽  
pp. 129-140 ◽  
Author(s):  
Lj. Francuski ◽  
A. Vujić ◽  
A. Kovačević ◽  
J. Ludoški ◽  
V. Milankov
Keyword(s):  
Geometric Morphometrics ◽  
Balkan Peninsula ◽  
Wing Shape ◽  
Canonical Variate ◽  
Species Boundaries ◽  
Wing Size ◽  
Mahalanobis Distances ◽  
Males And Females ◽  
Wing Geometric Morphometrics ◽  
Shape And Size

The present study investigates phenotypic differentiation patterns among four species of the Cheilosia variabilis group (Diptera, Syrphidae) using a landmark-based geometric morphometric approach. Herein, wing geometric morphometrics established species boundaries that confirm C. melanopa and C. redi stat. nov. as evolutionarily independent entities or separate species within the previously described C. melanopa species. Seventeen samples of C. lasiopa, C. variabilis, C. melanopa and C. redi from 11 localities on the Balkan Peninsula were analysed. Based on wing shape and size, both species boundaries and intraspecific divergent units were delineated indicating the possible presence of evolutionarily independent units within the analysed taxa. 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 99.7% and 100% individuals of males and females, respectively. Considerable wing size variation was detected among males and females of conspecific populations of C. melanopa and males of C. variabilis. Contrary to partial discrimination based on the male wing shape among conspecific populations of C. redi and C. variabilis, clear separation of conspecific populations of C. melanopa (for both sexes) and females of C. redi and C. variabilis was observed. The UPGMA cluster analysis based on squared Mahalanobis distances revealed a close similarity between C. melanopa and C. redi, whereas C. lasiopa was the most divergent species. Results presented in this study utilize wing shape and size as new taxonomic characters in delimitating the closely related species and populations of the Cheilosia variabilis group.

scholarly journals Sources of intraspecific morphological variation in Vipera seoanei: allometry, sex, and colour phenotype

2020 ◽  
Vol 42 (1) ◽  
pp. 1-16
Author(s):  
Nahla Lucchini ◽  
Antigoni Kaliontzopoulou ◽  
Guillermo Aguado Val ◽  
Fernando Martínez-Freiría
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Morphological Variability ◽  
Tail Length ◽  
Shape Variation ◽  
Body Proportions ◽  
Head Shape ◽  
Relative Contribution ◽  
Colour Morphs ◽  
Intraspecific Morphological Variation

Abstract Snakes frequently exhibit ontogenetic and sexual variation in head dimensions, as well as the occurrence of distinct colour morphotypes which might be fitness-related. In this study, we used linear biometry and geometric morphometrics to investigate intraspecific morphological variation related to allometry and sexual dimorphism in Vipera seoanei, a species that exhibits five colour morphotypes, potentially subjected to distinct ecological pressures. We measured body size (SVL), tail length and head dimensions in 391 specimens, and examined variation in biometric traits with respect to allometry, sex and colour morph. In addition, we analysed head shape variation by recording the position of 29 landmarks in 123 specimens and establishing a low-error protocol for implementing geometric morphometrics to European vipers. All head dimensions exhibited significant allometry, while sexual differences occurred for SVL, relative tail length and snout height. After considering size effects, we found significant differences in body proportions between the sexes and across colour morphs, which suggests an important influence of lowland and montane habitats in shaping morphological variation. By contrast, head shape did not exhibit significant variation across sexes or colour morphs. Instead it was mainly associated to allometric variation, where the supraocular and the rear regions of the head were the areas that varied the most throughout growth and across individuals. Overall, this study provides a thorough description of morphological variability in Vipera seoanei and highlights the relevance of combining different tools (i.e. linear and geometric morphometrics) and analyses to evaluate the relative contribution of different factors in shaping intraspecific variation.

scholarly journals Morphological variation under domestication: how variable are chickens?

2018 ◽  
Vol 5 (8) ◽  
pp. 180993 ◽  
Author(s):  
Madlen Stange ◽  
Daniel Núñez-León ◽  
Marcelo R. Sánchez-Villagra ◽  
Per Jensen ◽  
Laura A. B. Wilson
Keyword(s):  
Neural Crest ◽  
Geometric Morphometrics ◽  
Multivariate Statistics ◽  
Morphological Variation ◽  
Three Dimensional ◽  
Cranial Vault ◽  
Shape Variation ◽  
Skull Morphology ◽  
Variable Part ◽  
Brain Shape

The process of domestication has long fascinated evolutionary biologists, yielding insights into the rapidity with which selection can alter behaviour and morphology. Previous studies on dogs, cattle and pigeons have demonstrated that domesticated forms show greater magnitudes of morphological variation than their wild ancestors. Here, we quantify variation in skull morphology, modularity and integration in chickens and compare those to the wild fowl using three-dimensional geometric morphometrics and multivariate statistics. Similar to other domesticated species, chickens exhibit a greater magnitude of variation in shape compared with their ancestors. The most variable part of the chicken skull is the cranial vault, being formed by dermal and neural crest-derived bones, its form possibly related to brain shape variation in chickens, especially in crested breeds. Neural crest-derived portions of the skull exhibit a higher amount of variation. Further, we find that the chicken skull is strongly integrated, confirming previous studies in birds, in contrast to the presence of modularity and decreased integration in mammals.

scholarly journals Automated morphological phenotyping using learned shape descriptors and functional maps: A novel approach to geometric morphometrics

2021 ◽  
Author(s):  
Oshane Odane Thomas ◽  
Hongyu Shen ◽  
Ryan R Rauum ◽  
William EH Harcourt-Smith ◽  
John David Polk ◽  
...  
Keyword(s):  
Geometric Morphometrics ◽  
Shape Analysis ◽  
Morphological Variation ◽  
Shape Space ◽  
Functional Domain ◽  
Shape Variation ◽  
Computationally Efficient ◽  
Observer Bias ◽  
Shape Spaces ◽  
Novel Approach

The methods of geometric morphometrics are commonly used to quantify morphology in a broad range of biological sciences. The application of these methods to large datasets is constrained by manual landmark placement limiting the number of landmarks and introducing observer bias. To move the field forward, we need to automate morphological phenotyping in ways that capture comprehensive representations of morphological variation with minimal observer bias. Here, we present Morphological Variation Quantifier (morphVQ), a shape analysis pipeline for quantifying, analyzing, and exploring shape variation in the functional domain. morphVQ uses descriptor learning to estimate the functional correspondence between whole triangular meshes in lieu of landmark configurations. With functional maps between pairs of specimens in a dataset we can analyze and explore shape variation. morphVQ uses Consistent ZoomOut refinement to improve these functional maps and produce a new representation of shape variation, area-based and conformal (angular) latent shape space differences (LSSDs). We compare this new representation of shape variation to shape variables obtained via manual digitization and auto3DGM, an existing approach to automated morphological phenotyping. We find that LSSDs compare favorably to modern 3DGM and auto3DGM while being more computationally efficient. By characterizing whole surfaces, our method incorporates more morphological detail in shape analysis. We can classify known biological groupings, such as Genus affiliation with comparable accuracy. The shape spaces produced by our method are similar to those produced by modern 3DGM and to auto3DGM, and distinctiveness functions derived from LSSDs show us how shape variation differs between groups. morphVQ can capture shape in an automated fashion while avoiding the limitations of manually digitized landmarks, and thus represents a novel and computationally efficient addition to the geometric morphometrics toolkit.

scholarly journals Application of the geometric morphometrics approach in the discrimination of morphological traits between brown trout lineages in the Danube Basin of Croatia

2021 ◽  
pp. 22
Author(s):  
Ivan Špelić ◽  
Andrea Rezić ◽  
Tamara Kanjuh ◽  
Ana Marić ◽  
Ivana Maguire ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Geometric Morphometrics ◽  
Brown Trout ◽  
Function Analysis ◽  
Phylogenetic Analyses ◽  
Canonical Variate ◽  
Shape Variation ◽  
Danube Basin ◽  
Body Depth ◽  
Significant Difference

Brown trout is a salmonid fish with a natural range extending throughout western Eurasia and North Africa. Due to its commercial value, it has also been introduced worldwide. In continental Croatia, introduced trout of the Atlantic lineage hybridizes with native trout of the Danubian lineage, threatening the native genetic diversity. The geometric morphometrics approach was used in this study to analyse changes in shape between native trout, introduced trout and their hybrids, classified a priori by molecular phylogenetic analyses. A total of 19 landmarks and semi-landmarks were used to capture the shape of 92 trout individuals belonging to two lineages and their hybrids. Canonical variate analysis and discriminant function analysis were used to analyse and describe shape variation. A significant difference was found between the shape of the Atlantic lineage trout and both Danubian lineage trout and hybrids, with the most prominent differences in body depth, head length and eye size. No statistically significant shape differences were observed between Danubian lineage trout and the hybrids. The observed significant differences in shape could be the result of genetic diversity or trout phenotypic plasticity. Further studies are needed to clarify the origin of this variation in shape.

The Effects of the sphragis on male and female genitalia in Acraea (Nymphalidae) butterflies

2020 ◽  
Vol 22 ◽  
Author(s):  
Shannon L Summers ◽  
Akito Y Kawahara ◽  
Ana P. S. Carvalho
Keyword(s):  
Interspecific Variation ◽  
Sperm Storage ◽  
Male Mating ◽  
Museum Collections ◽  
Storage Organ ◽  
Mating Plug ◽  
Males And Females ◽  
Comparison And Analysis ◽  
Imagej Software ◽  
Sexually Antagonistic Coevolution

Male mating plugs have been used in many species to prevent female re-mating and sperm competition. One of the most extreme examples of a mating plug is the sphragis, which is a large, complex and externalized plug found only in butterflies. This structure is found in many species in the genus Acraea (Nymphalidae) and provides an opportunity for investigation of the effects of the sphragis on the morphology of the genitalia, which is poorly understood. This study aims to understand morphological interspecific variation in the genitalia of Acraea butterflies. Using specimens from museum collections, abdomen dissections were conducted on 19 species of Acraea: 9 sphragis bearing and 10 non-sphragis bearing species. Genitalia imaging was performed for easier comparison and analysis and measurements of genitalia structures was done using ImageJ software. Some distinguishing morphological features in the females were found. The most obvious difference is the larger and more externalized copulatory opening in sphragis bearing species, with varying degrees of external projections. Females of the sphragis bearing species also tend to have a shorter ductus (the structure that connects the copulatory opening with the sperm storage organ) than those without the sphragis. These differences may be due to a sexually antagonistic coevolution between the males and females, where the females evolve larger and more difficult to plug copulatory openings and the males attempt to prevent re-mating with the sphragis.

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