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1,104 results for “morphological variations”
Figure 5 from: Wang C, Wang H, Kuang X, Guo G (2021) Life stages and morphological variations of Limnocythere inopinata (Crustacea, Ostracoda) from Lake Jiang-Co (northern Tibet): a bioculture experiment. ZooKeys 1011: 25-40. https://doi.org/10.3897/zookeys.1011.56065
Figure 5 Appendage morphology of L. inopinata, adult female A antennule B antenna C mandible D maxilla E first thoracopod F second thoracopod G third thoracopod H uropodal rami.
Figure 3 from: Wang C, Wang H, Kuang X, Guo G (2021) Life stages and morphological variations of Limnocythere inopinata (Crustacea, Ostracoda) from Lake Jiang-Co (northern Tibet): a bioculture experiment. ZooKeys 1011: 25-40. https://doi.org/10.3897/zookeys.1011.56065
Figure 3 A Locations of Lake Jiang-Co and Lake Dali B scatter plot with mean value of KL of L. inopinata populations from A-8 stage to adult in Lake Jiang-Co and Lake Dali (Zhai et al. 2015). The rounded dot and triangle represent the growth ratio between adjacent instars C comparison between KL of L. inopinata populations from A-8 stage to adult in Lake Jiang-Co and Lake Dali (Zhai et al. 2015). The grey dotted lines suggest a growth ratio of 1.26, the value predicted by Brooks' rule.
Figure 2 from: Wang C, Wang H, Kuang X, Guo G (2021) Life stages and morphological variations of Limnocythere inopinata (Crustacea, Ostracoda) from Lake Jiang-Co (northern Tibet): a bioculture experiment. ZooKeys 1011: 25-40. https://doi.org/10.3897/zookeys.1011.56065
Figure 2 A Length versus height of left valves and microscope photographs of L. inopinata from A-8 stage to adult B Plot demonstrating the growth ratio elements KL and KH of L. inopinata from A-8 stage to adult. KL = Lm+1 / Lm, KH = Hm+1 / Hm, where KL and KH are growth ratios of mean length and height, Lm and Hm are respectively mean length and height at stage m, and Lm+1 and Hm+1 are respectively mean length and height at stage m+1. The black line suggests a growth ratio of 1.26, the value predicted by Brooks' rule. All individuals are from the indoor bioculture laboratory.
Figure 2 from: Sousa FB, Milanin T, Morandini AC, Espinoza LL, Flores-Gonzales A, Gomes AL.S, Matoso DA, Mathews PD (2021) Molecular diagnostic based on 18S rDNA and supplemental taxonomic data of the cnidarian coelozoic Ceratomyxa (Cnidaria, Myxosporea) and comments on the intraspecific morphological variation. Zoosystematics and Evolution 97(2): 307-314. https://doi.org/10.3897/zse.97.64769
Figure 2 Transmission electron microscopy images of Ceratomyxa amazonensis isolated of Symphysodon discus from the Unini River, Amazonas State, Brazil. a. Myxospore showing two sub-spherical polar capsules and sporoplasm (sp) occupying most of the myxospore volume; b. Detail of the apical suture (black arrow) and sporoplasmosomes (arrowheads); c. Detail of lateral suture (black arrow); d. Polar capsule displaying still uncoiled internal polar tubule (black arrow). Scale bars: 2 µm (a); 1 µm (c); 500 nm (b, d).
Figure 1 from: Sousa FB, Milanin T, Morandini AC, Espinoza LL, Flores-Gonzales A, Gomes AL.S, Matoso DA, Mathews PD (2021) Molecular diagnostic based on 18S rDNA and supplemental taxonomic data of the cnidarian coelozoic Ceratomyxa (Cnidaria, Myxosporea) and comments on the intraspecific morphological variation. Zoosystematics and Evolution 97(2): 307-314. https://doi.org/10.3897/zse.97.64769
Figure 1 Light photomicrographs of Ceratomyxa amazonensis plasmodia. a, b. Slightly elongated plasmodia showing mature myxospores (white asterisks) and few early sporogonic stages (arrows); c. Spherical plasmodium with two slightly crescent-shaped mature myxospores (ms) and containing early sporogonic stages (arrows); d. Differential interference contrast microscopy snapshot of a slightly crescent-shaped mature myxospore. Scale bars: 10 µm.
Data from: Among-character rate variation distributions in phylogenetic analysis of discrete morphological characters
Likelihood-based methods are commonplace in phylogenetic systematics. Although much effort has been directed toward likelihood-based models for molecular data, comparatively less work has addressed models for discrete morphological character data. Among-character rate variation may confound phylogenetic analysis, but there have been few analyses of the magnitude and distribution of rate heterogeneity among discrete morphological characters. Using seventy-six data sets covering a range of plants, invertebrate, and vertebrate animals, we used a modified version of MrBayes to test equal, gamma-distributed and lognormally-distributed models of among-character rate variation, integrating across phylogenetic uncertainty using Bayesian model selection. We found that in approximately 80% of data sets, unequal-rates models outperformed equal-rates models, especially among larger data sets. Moreover, although most data sets were equivocal, more data sets favored the lognormal rate distribution relative to the gamma rate distribution, lending some support for more complex character correlations than in molecular data. Parsimony estimation of the underlying rate distributions in several data sets suggests that the lognormal distribution is preferred when there are many slowly evolving characters and fewer quickly evolving characters. The commonly adopted four rate category discrete approximation used for molecular data was found to be sufficient to approximate a gamma rate distribution with discrete characters. However, among the two data sets tested that favored a lognormal rate distribution, the continuous distribution was better approximated with at least eight discrete rate categories. Although the effect of rate model on the estimation of topology was difficult to assess across all data sets, it appeared relatively minor between the unequal-rates models for the one data set examined carefully. As in molecular analyses, we argue that researchers should test and adopt the most appropriate model of rate variation for the data set in question. As discrete characters are increasingly used in more sophisticated likelihood-based phylogenetic analyses, it is important that these studies be built on the most appropriate and carefully selected underlying models of evolution.
Data from: Rate of evolutionary change in cranial morphology of the marsupial genus Monodelphis is constrained by the availability of additive genetic variation
We tested the hypothesis that the rate of marsupial cranial evolution is dependent on the distribution of genetic variation in multivariate space. To do so, we carried out a genetic analysis of cranial morphological variation in laboratory strains of Monodelphis domestica and used estimates of genetic covariation to analyze the morphological diversification of the Monodelphis brevicaudata species group. We found that within-species genetic variation is concentrated in only a few axes of the morphospace and that this strong genetic covariation influenced the rate of morphological diversification of the brevicaudata group, with between-species divergence occurring fastest when occurring along the genetic line of least resistance. Accounting for the geometric distribution of genetic variation also increased our ability to detect the selective regimen underlying species diversification, with several instances of selection only being detected when genetic covariances were taken into account. Therefore, this work directly links patterns of genetic covariation among traits to macroevolutionary patterns of morphological divergence. Our findings also suggest that the limited distribution of Monodelphis species in morphospace is the result of a complex interplay between the limited dimensionality of available genetic variation and strong stabilizing selection along two major axes of genetic variation.
Data from: Early evolutionary differentiation of morphological variation in the mandible of South American caviomorph rodents (Rodentia, Caviomorpha)
Caviomorphs are a clade of South American rodents recorded at least since the early Oligocene (>31.5 Ma) that exhibit ample eco-morphological variation. It has been proposed that phylogenetic structure is more important than ecological factors for understanding mandibular shape variation in this clade. This was interpreted as a result of the long-standing evolutionary history of caviomorphs and the early divergence of major lineages. In this work we test this hypothesis through analysis of morphological variation in the mandible of living and extinct species, and compare this information with that obtained through comparative phylogenetic analyses. Our results support the hypothesis of early origin of mandibular variation; moreover, they suggest conservation of early differentiated morphologies, which could indicate the existence of constrained evolutionary diversification.
Data from: Does morphological variation buffer against extinction? A test using veneroid bivalves from the Plio-Pleistocene of Florida
Although morphological variation is known to influence the evolutionary fates of species, the relationship between morphological variation and survivorship in the face of extinction-inducing perturbations is poorly understood. Here, we investigate this relationship for veneroid bivalves in association with the Plio-Pleistocene extinction in Florida. Fourteen pairs of related species were selected for analysis, with each pair including one species that survived the Plio-Pleistocene extinction and another that became extinct during the interval. Morphological landmark data were acquired for more than 1500 museum specimens, representing 19 localities that encompass four well-known Plio-Pleistocene units in the study region. Procrustes superimposition was applied to each sample, and overall multivariate variation was calculated as the mean squared partial Procrustes distance between specimens and their mean form. Morphological variation was calculated at three geographic scales for each species, and differences in variation between survivors and victims were examined within each species pair. Results indicate that species surviving the Plio-Pleistocene extinction were significantly more variable morphologically than victims. Greater morphological variation may promote survivorship by directly enhancing species adaptations to changing conditions or by permitting the occupation of a larger geographic range. Alternatively, high morphological variation and survivorship may both be mediated by a third variable, such as large geographic range.
Data from: QTL and quantitative genetic analysis of beak morphology reveals patterns of standing genetic variation in an Estrildid finch
The intra- and interspecific diversity of avian beak morphologies is one of the most compelling examples for the power of natural selection acting on a morphological trait. The development and diversification of the beak has also become a textbook example for evolutionary developmental biology, and variation in expression levels of several genes is known to causally affect beak shape. However, until now no genomic polymorphisms have been identified that are related to beak morphology in birds. QTL mapping does reveal the location of causal polymorphisms, albeit with poor spatial resolution. Here we estimate heritability and genetic correlations for beak length, depth and width and perform a QTL linkage analysis for these traits based on 1,404 informative single nucleotide polymorphisms genotyped in a four generation pedigree of 992 captive zebra finches (Taeniopygia guttata). Beak size, relative to body size, was sexually dimorphic (larger in males). Heritability estimates ranged from 0.47 for beak length to 0.74 for beak width. QTL mapping revealed four to five regions of significant or suggestive genome-wide linkage for each of the three beak dimensions (nine different regions in total). Eight out of eleven genes known to influence beak morphology are located in these nine peak regions. Five QTL do not cover known candidates demonstrating that yet unknown genes or regulatory elements may influence beak morphology in the zebra finch.
Data from: Cellular basis of morphological variation and temperature-related plasticity in Drosophila melanogaster strains with divergent wing shapes
Organ shape evolves through cross-generational changes in developmental patterns at cellular and/or tissue levels that ultimately alter tissue dimensions and final adult proportions. Here, we investigated the cellular basis of an artificially selected divergence in the outline shape of Drosophila melanogaster wings, by comparing flies with elongated or rounded wing shapes but with remarkably similar wing sizes. We also tested whether cellular plasticity in response to developmental temperature was altered by such selection. Results show that variation in cellular traits is associated with wing shape differences, and that cell number may play an important role in wing shape response to selection. Regarding the effects of developmental temperature, a size-related plastic response was observed, in that flies reared at 16 °C developed larger wings with larger and more numerous cells across all intervein regions relative to flies reared at 25 °C. Nevertheless, no conclusive indication of altered phenotypic plasticity was found between selection strains for any wing or cellular trait. We also described how cell area is distributed across different intervein regions. It follows that cell area tends to decrease along the anterior wing compartment and increase along the posterior one. Remarkably, such pattern was observed not only in the selected strains but also in the natural baseline population, suggesting that it might be canalized during development and was not altered by the intense program of artificial selection for divergent wing shapes.
FIGURE 3 in A survey of morphological variation in adult Meristogenys amoropalamus (Amphibia, Anura, Ranidae), with a description of a new cryptic species
FIGURE 3. Ova of Meristogenys amoropalamus (A) and M. dyscritus (B). Scale bar = 2 mm.
FIGURE 9 in A survey of morphological variation in adult Meristogenys amoropalamus (Amphibia, Anura, Ranidae), with a description of a new cryptic species
FIGURE 9. Sonograms of advertisement calls by Meristogenys dyscritus recorded at Liwagu.
FIGURE 5 in Problems with the taxonomy of Phytoptus tetratrichus Nalepa 1890 (Acari: Eriophyoidea) inhabiting Tilia spp.: Analysis based on morphological variation among individuals
FIGURE 5. Leaf damage caused by Phytoptus tetratrichus on Tilia americana.
FIGURE 2 in New records of Rhagoletis (Diptera: Tephritidae) in Colombia, with discussion on the morphological variations of some species
FIGURE 2. Dorsal view of mesonotum of Rhagoletis jamaicensis from Vélez, Santander.
FIGURE 4 in New records of Rhagoletis (Diptera: Tephritidae) in Colombia, with discussion on the morphological variations of some species
FIGURE 4. Dorsal view of mesonotum of Rhagoletis sp., psalida group from Bogotá, Cundinamarca.
FIGURES 10–12. S. sculptus male adult. 10, 11 in Intraspecific morphological variation of Scutovertex sculptus Michael (Acari: Oribatida: Scutoverticidae) and description of its juvenile stages
FIGURES 10–12. S. sculptus male adult. 10, 11, ventral view; 12. S. sculptus adult, anal region.
Figure 80 in A preliminary report on the World species of Bemisia Quaintance and Baker and its congeners (Hemiptera: Aleyrodidae) with a comparative analysis of morphological variation and its role in the recognition of species Raymond Gill
Figure 80. Bemisia afer complex, Madeira, Levada above Ribeiro Bonito, nr. Sao Jorge, 550 m, 01 Apr. 1996, ex. Chamaespartium sp.?, Leguminosae, Martin and Aguiar, colls., JHM #6583.
Figure 72 in A preliminary report on the World species of Bemisia Quaintance and Baker and its congeners (Hemiptera: Aleyrodidae) with a comparative analysis of morphological variation and its role in the recognition of species Raymond Gill
Figure 72. Bemisia lauracea Martin et al., Madeira, Seixal, 6-iii-1992, ex. Ocotea foetens, F. Aguiar, coll., #C125.
Figure 62 in A preliminary report on the World species of Bemisia Quaintance and Baker and its congeners (Hemiptera: Aleyrodidae) with a comparative analysis of morphological variation and its role in the recognition of species Raymond Gill
Figure 62. Bemisia afer complex, Canary Islands, Tenerife, Barranco, de las Moradas, at 7-900m, 18 May 1997, ex. Hypericum grandifolium, J. Martin, coll., JHM # 7041.
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Allen Brain Atlas
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International Brain Laboratory public data
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OpenNeuro
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