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690 results for “Geometric morphometrics”
Data from: Evolutionary covariation in geometric morphometric data: analyzing integration, modularity, and allometry in a phylogenetic context
Quantifying integration and modularity of evolutionary changes in morphometric traits is crucial for understanding how organismal shapes evolve. For this purpose, comparative studies are necessary, which need to take into account the phylogenetic structure of interspecific data. This study applies several of the standard tools of geometric morphometrics, which mostly have been used in intraspecific studies, in the new context of analyzing integration and modularity based on comparative data. Morphometric methods such as principal component analysis, multivariate regression, partial least squares and modularity tests can be applied to phylogenetically independent contrasts of shape data. We illustrate this approach in an analysis of cranial evolution in 160 species from all orders of birds. Mapping the shape information onto the phylogeny indicates that there is a significant phylogenetic signal in skull shape. Multivariate regression of independent contrasts of shape on independent contrasts of size reveals clear evolutionary allometry. Regardless of whether or not a correction for allometry is used, evolutionary integration between the face and braincase is strong, and tests reject the hypothesis that the face and braincase are separate evolutionary modules. These analyses can easily be applied to other taxa and can be combined with other morphometric tools to address a wide range of questions about evolutionary patterns and processes.
Data from: Using geometric morphometric visualizations of directional selection gradients to investigate morphological differentiation
Researchers studying extant and extinct taxa are often interested in identifying the evolutionary processes that have lead to the morphological differences among the taxa. Ideally, one could distinguish the influences of neutral evolutionary processes (genetic drift, mutation) from natural selection, and in situations for which selection is implicated, identify the targets of selection. The directional selection gradient is an effective tool for investigating evolutionary process, because it can relate form (size and shape) differences between taxa to the variation and covariation found within taxa. However, although most modern morphometric analyses use the tools of geometric morphometrics (GM) to analyze landmark data, to date, selection gradients have mainly been calculated from linear measurements. To address this methodological gap, here we present a GM approach for visualizing and comparing between-taxon selection gradients with each other, associated difference vectors, and "selection" gradients from neutral simulations. To exemplify our approach, we use a dataset of 347 three-dimensional landmarks and semilandmarks recorded on the crania of 260 primate specimens (112 humans, 67 common chimpanzees, 36 bonobos, 45 gorillas). Results on this example dataset show how incorporating geometric information can provide important insights into the evolution of the human braincase, and serve to demonstrate the utility of our approach for understanding morphological evolution.
Data from: Geometric morphometrics reveal altered corpus callosum shape in pyridoxine-dependent epilepsy
Objective: To evaluate the features and maturational changes in overall callosal shape in patients with pyridoxine-dependent epilepsy (PDE). Methods: Measurements were conducted through landmark based geometric morphometrics applied on cerebral MRIs of PDE patients and age-matched control subjects. The outline of the corpus callosum was manually traced in the midsagittal plane. 300 semi-landmarks along the outline were collected and underwent statistical generalized Procrustes analysis. An allometric regression was applied to evaluate the callosal shape due to growth over time. Results: 38 patients with PDE and 38 age- and sex-matched control subjects were included. Mean age at the time of the MRI in the patient group was 9.3 years (median 6.3 years, range 0.01- 48 years). Significant differences (p<0.01) in the mean callosal shape between patients and controls were found. The allometric regression model revealed significant shape variations (p<0.01) between the two study groups across the developmental course after controlling for the effect of callosal size on shape. This latter effect turned out to be significant as well (p<0.001). Conclusions: Patients with PDE show an altered callosal shape and variations in callosal ontogeny which are likely secondary to the underlying genetic defect with abnormal function of antiquitin, the product of the ALDH7A1 gene.
Data from: Crowdsourced geometric morphometrics enable rapid large-scale collection and analysis of phenotypic data
1. Advances in genomics and informatics have enabled the production of large phylogenetic trees. However, the ability to collect large phenotypic datasets has not kept pace. 2. Here, we present a method to quickly and accurately gather morphometric data using crowdsourced image-based landmarking. 3. We find that crowdsourced workers perform similarly to experienced morphologists on the same digitization tasks. We also demonstrate the speed and accuracy of our method on seven families of ray-finned fishes (Actinopterygii). 4. Crowdsourcing will enable the collection of morphological data across vast radiations of organisms, and can facilitate richer inference on the macroevolutionary processes that shape phenotypic diversity across the tree of life.
Data from: Effects of different segmentation methods on geometric morphometric data collection from primate skulls
1. Increasing numbers of studies are analysing the shapes of objects using geometric morphometrics with tomographic data, which are often segmented and transformed to three-dimensional (3D) surface models before measurement. The present study aimed to evaluate the effects of different image segmentation methods on geometric morphometric data collection using computed tomography data collected from non-human primate skulls. 2. Three segmentation methods based on a visually-selected threshold, a half-maximum height protocol and a gradient and watershed algorithm were compared. For each method, the efficiency of surface reconstruction, the accuracy of landmark placement and the level of variation in shape and size compared with various levels of biological variation were evaluated. 3. The visual-based method inflated the surface in high-density anatomical regions, whereas the half-maximum height protocol resulted in large numbers of artificial holes and erosion. However, the gradient-based method overcame these issues and generated the most efficient surface model. The segmentation method used had a much smaller effect on shape and size variation than interspecific and inter-individual differences. However, this effect was statistically significant and not negligible when compared with intra-individual (fluctuating asymmetric) variation. 4. Although the gradient-based method is not widely used in geometric morphometric analyses, it may be one of the most appropriate options for reconstructing 3D surfaces. When evaluating small variations, such as fluctuating asymmetry, care should be taken around combining 3D data that were obtained using different segmentation methods.
FIGURE 9. Geometric morphometric shape change vectors for Principal Component 1 in Silversides of the genus Labidesthes (Atheriniformes: Atherinopsidae)
FIGURE 9. Geometric morphometric shape change vectors for Principal Component 1.
Functional and ecomorphological evolution of orbit shape in Mesozoic archosaurs is driven by body size and diet: Geometric morphometric data, 3D models (stl files), FEA models (Hypermesh, Abaqus files)
<p class="MsoNormal">The orbit is one of several skull openings in the archosauromorph skull. Intuitively, it could be assumed that orbit shape would closely approximate the shape and size of the eyeball resulting in a predominantly circular morphology. However, a quantification of orbit shape across Archosauromorpha using a geometric morphometric approach demonstrates a large morphological diversity despite the fact that the majority of species retained a circular orbit. This morphological diversity is nearly exclusively driven by large (skull length > 1000 mm) and carnivorous species in all studied archosauromorph groups, but particularly prominently in theropod dinosaurs. While circular orbit shapes are retained in most herbivores and smaller species, as well as in juveniles and early ontogenetic stages, large carnivores adopted elliptical and keyhole-shaped orbits. Biomechanical modeling using finite element analysis reveals that these morphologies are beneficial in mitigating and dissipating feeding-induced stresses without additional reinforcement of the bony structure of the skull.</p>
Supplementary material 6 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
PCA with Calomys terrer and C. expulsus : Data type: statistical data
Supplementary material 5 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Tests for normality, hornoscedasticity and homogeneity : Data type: statistical data
Supplementary material 4 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Protocol for testing error in the digitalization : Data type: statistical data
Supplementary material 3 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Specimens of the wear category class 2 : Data type: species data
Supplementary material 2 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Wear categories : Data type: measurement
Supplementary material 1 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Alisphenoid strut : Data type: multimedia
Supplementary material 3 from: Ren J, Bai M, Yang X-K, Zhang R-Z, Ge S-Q (2017) Geometric morphometrics analysis of the hind wing of leaf beetles: proximal and distal parts are separate modules. ZooKeys 685: 131-149. https://doi.org/10.3897/zookeys.685.13084
Coordinates data of landmarks. :
Figure 3 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Figure 3 - PCA showing the individual projections of Calomys sp., C. expulsus and C. tener in the two major axis (PC1 28.7%, PC2 12.3% of the variance). The wireframes illustrate shape differences between most different specimens: CE 09, CT 05, CT 02, and SP 11. Black circles: C. expulsus; Gray triangle: C. tener; Black square: Calomys sp. identified as C. expulsus; Gray square: Calomys sp. identified as C. tener; Gray triangle with black edge: specimen CT 02; Stars: mean shape for each species.
Figure 7 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Figure 7 - Pooled regression within the two species, between shape (dependent variable) and centroid size (independent variable). Black circles: C. expulsus; Gray triangle: C. tener; Black square: Calomys sp. identified as C. expulsus; Gray square: Calomys sp. identified as C. tener.
Figures 4-6 from: Boroni NL, Lobo LS, Romano PSR, Lessa G (2017) Taxonomic identification using geometric morphometric approach and limited data: an example using the upper molars of two sympatric species of Calomys (Cricetidae: Rodentia). Zoologia 34: 1-11. https://doi.org/10.3897/zoologia.34.e19864
Figures 4-6 Shape differences wireframes in PC1. Gray solid lines indicate C. tener (positive PC1 values) and black dotted lines indicate C. expulsus (negative PC1 values), see Fig. 3 for individual projections. (4) Differences between the mean shapes of C. tener and C. expulsus; (5) differences between the disparate shape of C. tener represented by CT 05 and C. expulsus represented by CE 09; (6) shape differences wireframes in PC2. Gray solid lines indicate the mean of shape of PC2 value and black dotted lines indicate specimen CT 02 (C. tener outlier).
Figure 4 from: Ren J, Bai M, Yang X-K, Zhang R-Z, Ge S-Q (2017) Geometric morphometrics analysis of the hind wing of leaf beetles: proximal and distal parts are separate modules. ZooKeys 685: 131-149. https://doi.org/10.3897/zookeys.685.13084
Figure 4 - Modularity test results. A The hypothesized partition: proximal part landmarks 1-6, 23, 24, and 26–36 and distal part landmarks 7–22, 25; different colour presents different modules B The partition with minimal covariance in all evaluated 104 partitions by RV coefficient C The partition with minimal covariance in all evaluated 106 partitions by RV coefficient.
Figure 2 from: Ren J, Bai M, Yang X-K, Zhang R-Z, Ge S-Q (2017) Geometric morphometrics analysis of the hind wing of leaf beetles: proximal and distal parts are separate modules. ZooKeys 685: 131-149. https://doi.org/10.3897/zookeys.685.13084
Figure 2 - PCA and CVA results. A Centroid size graph of hind wing landmarks (Procrustes fit) B PCA results, the shape changes associated with the first three PCs: the relative size of the apical area which could be considered the main feature (variance contribution ratio was 45.01%) to influence of the overall variance of the hind wing, the changes of cross vein cv in the middle area (variance contribution ratio was 12.39%), and relative size of the anal area size (variance contribution ratio was 10.56%) C CVA results, the axis of CV1 and CV2 presented the first two large shape variance of all variance; points with different colours indicated different subtribes' specimens; the ellipse is presented as an equal-frequency ellipse with a given probability level of 90%, which contains approximately 90% of the data points.
Figure 1 from: Ren J, Bai M, Yang X-K, Zhang R-Z, Ge S-Q (2017) Geometric morphometrics analysis of the hind wing of leaf beetles: proximal and distal parts are separate modules. ZooKeys 685: 131-149. https://doi.org/10.3897/zookeys.685.13084
Figure 1 - Leaf beetle hind wing (Chrysomela populi Linnaeus), with landmark locations (the dot with number), vein nomenclature and regional division. The nomenclature of the wing venation follows that of Kukalová-Peck & Lawrence (1993, 2004). Radial area: green, central area: blue, medial area: purple, anal area: yellow, apical (folding) area: red. Proximal part landmarks 1–6, 23, 24, and 26–36 mainly include radial, medial, and anal areas; distal part landmarks 7–22 and 25 include the central area, radial cell, and apical area. Abbreviations: Costa (C), Subcosta (Sc), Subcosta Anterior (ScA), Subcosta Posterior (ScP), Radius Anterior (RA), Radius Posterior (RP), Radial cross veins (r3, r4), Media Posterior (MP), Radio-medial cross veins (rp-mp1, rp-mp2), medial cross vein (cv), Cubitus Anterior (CuA), Medio-cubital Cross-vein or Arculus (mp-cua), Anal Anterior (AA), Anal posterior (AP). "+" indicates fused veins. The sub-number of veins reflects vein branches.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
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International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.