scholarly journals Geometric morphometrics in herpetology: modern tools for enhancing the study of morphological variation in amphibians and reptiles

2011 ◽  
Author(s):  
Antigoni Kaliontzopoulou
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation

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.

scholarly journals Morphological assessment raises the possibility of cryptic species within the Luristan newt, Neurergus kaiseri (Amphibia: Salamandridae)

2019 ◽  
pp. 237-244
Author(s):  
Mansoureh Malekian
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Conservation Planning ◽  
Body Shape ◽  
Genetic Data ◽  
Species Level ◽  
Inadequate Knowledge ◽  
Morphological Distinction ◽  
Conservation Of Biodiversity ◽  
Morphological Assessment

One of the main challenges in the conservation of biodiversity is to overcome inadequate knowledge about species and their intra-specific diversity. In the present study, we attempted to assess morphological distinction of the two previously identified genetic clades within the Luristan newt (Neurergus kaiseri, Schmidt 1952) endemic to Iran, which is essential for its conservation planning. Signals of the morphological variation in N. kaiseri were evaluated using landmark-based geometric morphometrics of body shape and characters of osteological structures. Morphological approaches revealed consistent groupings within the species, confirming the presence of two distinct lineages (previously named as the northern and southern clades). The morphological and genetic data provide evidence for the possible co-existence of two species in N. kaiseri and we recommend assigning the newly recognised forms to the species level.

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.

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.

scholarly journals Wing morphometrics reveals the migration patterns of Africanized honey bees in Northeast Brazil

Sociobiology ◽  
2018 ◽  
Vol 65 (4) ◽  
pp. 679
Author(s):  
Caroline Julio Moretti ◽  
Claudineia Pereira Costa ◽  
Tiago Maurício Francoy
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Honey Bees ◽  
Rainy Season ◽  
Dry Season ◽  
Dispersion Pattern ◽  
Northeast Brazil ◽  
Africanized Honey Bees ◽  
Wing Morphometrics ◽  
Semi Arid

Climatic differences can directly affect the population structure of organisms. The Northeastern Brazilian covers an area of about 1.5 million square kilometres, in which the semi-arid part corresponds to approximately 60%. It is probably the most vulnerable region to climatic variations in Brazil. Here, we investigated the variability of Africanized honey bees in different localities from Northeast Brazil during the dry season and the influence of drought periods in morphological variation among populations. Analyses were carried out with data collected by traditional and geometric morphometrics of bees sampled during the dry season and showed a subtle morphological variation in agreement to the climatic pattern. Furthermore, once we added samples collected during the rainy season, we observed a change in its pattern, with a very different result from the same population sampled during drought periods. The geometric morphometrics results emphasized that samples collected during the rainy season in Mossoró would be more similar to bees from humid coastal areas. These results probably reflect the probable dispersion pattern of these bees between humid coastal and semi-arid areas.

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 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 Morphological variation of the caudal fossa of domestic cat skulls assessed with CT and geometric morphometrics analysis

2017 ◽  
Vol 20 (8) ◽  
pp. 752-758 ◽  
Author(s):  
Caroline R Gordon ◽  
Thomas W Marchant ◽  
Joanna Lodzinska ◽  
Jeffrey J Schoenebeck ◽  
Tobias Schwarz
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Three Dimensional ◽  
Internal Surface ◽  
Foramen Magnum ◽  
Domestic Cat ◽  
Bone Morphology ◽  
Normal Range ◽  
Advanced Imaging ◽  
Wide Range

Objectives This study aimed to investigate differences and demonstrate a normal range of morphological variation of the caudal fossa of the cranium of domestic cats. Methods CT scans of 32 domestic cat heads of 11 breeds were included. Isosurfaces from skulls were characterised through three-dimensional geometric morphometrics using geographical landmarks placed on the internal surface of the caudal fossa and foramen magnum. Raw data was transformed with a Procrustes fit and coordinate covariance was analysed by principal components to establish breed- and sex-level differences. Skulls were also classified according to the number of concavities along the mid-sagittal vermiform impression. Differences were investigated between breed groups and sex, and correlation was sought with age. Results Analyses revealed size-independent differences in occipital bone morphology across breeds and sex; however, no clustering was evident. Most variability was observed at the exoccipital bones, ventral portion of the supraoccipital bone, dorsum sellae of the basisphenoid and the osseous tentorium cerebelli. No statistically significant differences were identified via two-sample t-tests between breed groups or sexes. No statistically significant correlation using Spearman rho correlation coefficient was identified with age. Conclusions and relevance The feline caudal fossa displays a wide range of intra- and inter-breed variation, not linked to age or sex. Concavities along the vermiform impression have not previously been described. As advanced imaging modalities are becoming more frequently used for domestic felids, an established range of normality is important for discriminating pathological changes from anatomical variances.

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.

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