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42 results for “discrete characters”
Figure 17 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 17. Schematic drawing of the gnathochilarium and its components. A, Cambala annulata; B, Amastigogonus fossuliger; C, Chonecambala crassicauda; D, Bilingulus sinicus (Pericambalinae) [modified from Zhang & Li (1981)].
Figure 4 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 4. Results of strict consensus based on the discrete dataset for the matrices MPr (mentum + promentum; A) and eM (elongated mentum; B) with the values of branch support. The Bremer relative support is highlighted in yellow and symmetric resampling in green. Only values of support above 40 GC (group present/contradicted) are shown.
Figure 3 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 3. Results of strict consensus based on the discrete dataset for the matrices MPr (mentum + promentum) (k = 6, 224 trees, total fit = 18.55) and eM (elongated Mentum) (k = 6, 141 trees, total fit = 17.48).
Figure 16 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 16. Schematic drawing of the gnathochilarium and its components. A, Blaniulus dollfusi; B, Ommatoiulus sp.; C, Gymnostreptus subsericeus; D, Phallorthus colombianus.
Figure 8 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 8. Reconstruction of ancestral groundplans of the mentum based on concatenated analysis (discrete characters and landmarks) for the matrix eM. The red dots refer to the landmarks (1–7) of Cambalomma laeƲis and blue lines on the diagrammatic images the movements in each landmark from the ancestor node.
Figure 11 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 11. Morphological variation of the gnathochilarium assessed by the principal component analyses. A, PCA based on the mentum + promentum dataset; B, PCA based on the elongated mentum dataset; C, measurements of Pseudonannolene erikae. Abbreviations: PrL, promentum length; PrW, promentum width; MtW, mentum width; MtL, mentum length; SL, stipes length; LL, lamellae linguales length.
Figure 14 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 14. Morphological variation of the gnathochilarium. A, Epinannolene sp. (ICN); B, Cambalomma laeƲis (MCZ); C, Pseudonannolene typica (MSNG); D, Pseudonannolene erikae (IBSP); E, Holopodostreptus braueri (MNRJ); F, Phallorthus colombianus (FMNH). Images taken not to scale. Abbreviations: cd, cardo; in, inner palpus; ll, lamellae linguales; mt, mentum; ot, outer palpus; pm, promentum; ps, posmentum; st, stipes.
Figure 15 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 15. Morphological variation of the gnathochilarium. A, Amastigogonus fossuliger (NHMD); B, Dinocambala ingens (NHMD); C, Equestrigonus tasmaniensis (NHMD); D, Zinagon sp. (MCZ). Images taken not to scale. Abbreviations: cd, cardo; in, inner palpus; ll, lamellae linguales; mt, mentum; ot, outer palpus; pm, promentum; ps, posmentum; st, stipes.
Figure 12 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 12. Morphological variation of the gnathochilarium. A, Blaniulus dollfusi (Blaniulidae) (NHMD); B, Californiulus yosemitensis (Paeromopodidae) (NHMD); C, Gonoplectus ingenuus (NHMD); D, Prionopetalum frundsbergi (NHMD); E, Gymnostreptus subsericeus (IBSP); F, Chonecambala crassicauda (NHMD). Images taken not to scale. Abbreviations: cd, cardo; in, inner palpus; ll, lamellae linguales; mt, mentum; ot, outer palpus; pm, promentum; ps, posmentum; st, stipes.
Figure 10 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 10. Summary of the concatenated analyses of the matrices duplomentum as 'mentum + promentum' (MPr) (A), and duplomentum as 'elongated Mentum' (eM) (B). The colours refer to the clades and their respective ancestral groundplans of the mentum, each shown with landmarks 1-7.
Figure 6 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 6. Reconstruction of ancestral groundplans of the mentum based on concatenated analysis (discrete characters and landmarks) for the matrix MPr. The red dots refer to the landmarks of Pseudonannolene typica (1–7) and blue lines on the diagrammatic images the movements in each landmark from the ancestor node.
Data from: Journeys through discrete-character morphospace: synthesising phylogeny, tempo, and disparity
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Data from: Morphological disparity in theropod jaws: comparing discrete characters and geometric morphometrics
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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: Phylogenetic inference using discrete characters: performance of ordered and unordered parsimony and of three-item statements
The cladistic literature does not always specify the kind of multistate character treatment that is applied for an analysis. Characters can be treated either as unordered transformation series or as rooted [three-item analysis (3ia)] or unrooted state trees (ordered characters). We aimed to measure the impact of these character treatments on phylogenetic inference. Discrete characters can be represented either as rows or columns in matrices (e.g. for parsimony) or as hierarchies for 3ia. In the present study, we use simulated and empirical examples to assess the relative merits of each method considering both the character treatment and representation. We measure two parameters (resolving power and artefactual resolution) using a new tree comparison metric, ITRI (inter-tree retention index). Our results suggest that the hierarchical character representation not only results (with our simulation settings) in the greatest resolving power, but also in the highest artefactual resolution. Our empirical examples provide equivocal results. Parsimony unordered states yield less resolving power and more artefactual resolutions than parsimony ordered states, both with our simulated and empirical data. Relationships between three operational taxonomic units (OTUs), irrespective of their relationships with other OTUs, are called three-item statements (3is). We compare the intersection tree (which reconstructs a single tree from all of the common 3is of source trees) with the traditional strict consensus and show that the intersection tree retains more of the information contained in the source trees.
Figure 9 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 9. Continued (Fig. 8).
Figure 7 in Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches
Figure 7. Continued (Fig. 6).
Data from: Among-character rate variation distributions in phylogenetic analysis of discrete morphological characters
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Data from: Phylogenetic inference using discrete characters: performance of ordered and unordered parsimony and of three-item statements
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Data from: Estimating morphological diversity and tempo with discrete character-taxon matrices: implementation, challenges, progress, and future directions
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