2017年, 第42卷, 第1期　
刊出日期：2017-01-24

  

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  Geometric morphometrics: Current and future in China

  Ming Bai

  动物分类学报. 2017, 42(1): 1-3. https://doi.org/10.11865/zs.201701

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  Although there were many ancient Chinese mathematicians contributed a lot on geometry, Geometric morphometrics (GM) in modern concept was not firstly proposed by Chinese. The super capability of geometric morphometrics in scientific computing and problem solving has gained a lot of attentions in the world. Until early of 21 centuries, geometric morphometrics was introduced into China. Since then, GM was rapidly applied in many research fields. However, it is a pity that GM is still not well-known in China as many works are published out of China. Thus, the special issue "Geometric morphometrics: Current shape and future directions" is organized. The present issue presents a series of contributions in this scientific field. In future, there will be many considerable new developing fields on GM needed to pay more attentions, for instances, 3D geometric morphometrics, 4D analysis, visualization of amber, new machine developing, new software developing, automatic identification system, etc. Once these technical bottle-necks on 3D data collecting and merging geometric morphometric data from multiple characters could be solved, the automatic identification system and other fields based on Big Data would come true.
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  Morphometrics: History, development methods and prospects

  Norman MacLeod

  动物分类学报. 2017, 42(1): 4-33. https://doi.org/10.11865/zs.201702

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  Morphometrics has been pursued by graphical and computational means since the European Renaissance, drawing on core geometric principles first discovered in China and Classical Greece. Through the late 1800s, two distinct approaches to such analyses were pursued: a deformationist approach, epitomized by D’Arcy Thompson’s graphical trans-formation grids and the statistical approach popularized by Francis Galton, Karl Pearson, and Julian Huxley in which Cartesian spaces were employed to summarize patterns of variation in size and/or shape variables. Unification of these approaches was an oft-stated goal throughout the 20th century, but proved elusive until the mid-1980s when David Kendall, Fred Bookstein, and Colin Goodall proposed a radically new way of understanding form — as the locations of configurations of landmarks on the surfaces of a nested series of hyperdimensional manifolds. Once this new mathematics of form was understood development of basic concepts, procedures, graphical tools, and statistical tests followed quickly such that the core of the long-hoped for synthesis took less than a decade to achieve. The result — geometric morphometrics — continues to develop into an ever-more extensive toolkit that can be used by researchers to describe and understand a wide range of problems involving the characterization of morphological similarities and differences in all of their many and varied contexts. In particular, the new approaches involving the direct analysis of image pixels and new tools such as machine learning and artificial intelligence are set to reinvigorate (and possibly to revolutionize) the field once again.
Original Paper
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  A web based tool to merge geometric morphometric data from multiple characters

  Ming Bai, Jing Li, Wencheng Wang, Rolf G. Beutel, Benjamin Wipfler, Wangang Liu, Sha Li, Mengna Zhang, Yuanyuan Lu, Xingke Yang

  动物分类学报. 2017, 42(1): 34-45. https://doi.org/10.11865/zs.201703

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  Geometric morphometrics (GM) is an important method of shape analysis and increasingly used in a wide range of scientific disciplines. Presently, a single character comparison system of geometric morphometric data is used in almost all empirical studies, and this approach is sufficient for many scientific problems. However, the estimation of overall similarity among taxa or objects based on multiple characters is crucial in a variety of contexts (e.g. (semi-)automated identification, phenetic relationships, tracing of character evolution, phylogenetic reconstruction). Here we propose a new web-based tool for merging several geometric morphometrics data files from multiple characters into a single data file. Using this approach information from multiple characters can be compared in combination and an overall similarity estimate can be obtained in a convenient and geometrically rigorous manner. To illustrate our method, we provide an example analysis of 25 dung beetle species with seven Procrustes superimposed landmark data files representing the morphological variation of body features: the epipharynx, right mandible, pronotum, elytra, hindwing, and the metendosternite in dorsal and lateral view. All seven files were merged into a single one containing information on 649 landmark locations. The possible applications of such merged data files in different fields of science are discussed.
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  The maximum likelihood identification method applied to insect morphometric data

  Jean-Pierre Dujardin, Sebastien Dujardin, Dramane Kaba, Soledad Santillán-Guayasamin, Anita G. Villacís, Sitha Piyaselakul, Suchada Sumruayphol, Yudthana Samung, Ronald Morales Vargas

  动物分类学报. 2017, 42(1): 46-58. https://doi.org/10.11865/zs.201704

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  To distinguish species or populations using morphometric data is generally processed through multivariate analyses, in particular the discriminant analysis. We explored another approach based on the maximum likelihood method. Simple statistics based on the assumption of normal distribution at a single variable allows to compute the chance of observing a particular data (or sample) in a given reference group. When data are described by more than one variable, the maximum likelihood (MLi) approach allows to combine these chances to find the best fit for the data. Such approach assumes independence between variables. The assumptions of normal distribution of variables and independence between them are frequently not met in morphometrics, but improvements may be obtained after some mathematical transformations. Provided there is strict anatomical correspondence of variables between unknown and reference data, the MLi classification produces consistent classification. We explored this approach using various input data, and compared validated classification scores with the ones obtained after the Mahalanobis distance-based classification. The simplicity of the method, its fast computation, performance and versatility, make it an interesting complement to other classification techniques.
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  Shell geometric morphometrics in Biomphalaria glabrata (Mollusca: Planorbidae) uninfected and infected with Schistosoma mansoni

  Cesar Parra, Jonathan Liria

  动物分类学报. 2017, 42(1): 59-64. https://doi.org/10.11865/zs.201705

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  Freshwater planorbid mollusks belonging to the genus Biomphalaria act as intermediate hosts for Schistosoma mansoni, the etiological agent of human intestinal schistosomiasis, in the Neotropical Region. Identification of Biomphalaria spp. are carried out based on morphological characters, and the Schistosoma infection are determined by the presence of cercariae (verified through microscope preparation and mounting). Recently, the geometric morphometrics has proven to be a useful tool for determining shape differences in disease vectors arthropods. Due to this, we used geometric morphometrics to determine Biomphalaria glabrata shell differences (shape and size) between uninfected and infected specimens. We digitalized 12 anatomical points over the shell left side (from umbilicus to the last whorl) by combining type I and II landmarks and sliding semilandmarks; the coordinates were aligned by generalized Procrustes analysis. Principal component analyses were implemented for examining main variation axes, and discriminant analysis for testing group membership significance. We found significant separation between infected and uninfected shell conformation. All specimens were 100% correctly classified. The main differences occur in the peristome. The Kruskal-Wallis test finds significant differences in shell isometric size among infected and uninfected specimens. These findings correspond to other studies of traditional morphometrics, that infected snails showed the reduction in shell size in contrast to those uninfected specimens.
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  Head geometric morphometrics of two Chagas disease vectors from Venezuela

  Ana María Oropeza, Carlos Arturo Perri Fernández, Jonathan Liria, Ana Soto-Vivas

  动物分类学报. 2017, 42(1): 65-70. https://doi.org/10.11865/zs.201706

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  Triatominae species are considered the main vectors of Chagas disease or American Trypanosomiasis. In Venezuela, the principal vectors are Rhodnius prolixus (St?l, 1959) and Triatoma maculata (Erichson, 1848), which are belonged to the tribe Rhodniini and Triatomini, respectively. The head conformation and size development of these species can reflect ontogenetic changes which contribute with the vectors biology studies, as well to support of instars determination. The goal of the paper is to the application of geometric morphometric techniques for describing head conformation and size of instars of these species. We photographed 140 heads in R. prolixus: First instar (I: 16), second instar (II: 17), third instar (III: 18), fourth instar (IV: 21), fifth instar (V: 21), adult female (F: 26) and adult males (M: 21); in T. maculata heads of 136 specimens were photographed, I: 20, II: 17, III: 26, IV: 15, V: 19, F: 20 and M: 19. Landmark coordinate (x, y) configurations were registered and aligned by Generalized Procrustes Analysis. Covariance Analyses were implemented with proportions of re-classified groups and MANOVA. Statistical analyses of variance found not significant differences in head isometric size (Kruskal–Wallis) among IV and V instars in both species. The a posteriori re-classification was almost perfect in R. prolixus (82%) and T. maculata (86%); the main head differences occurs in antenniferous tubercles, postocular and preocular. Our study using quantitative tools for describing the shape differences contributes to explain the morphology variability and development of Chagas disease vectors.
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  Impact of environmental factors on the body shape variation and sexual shape dimorphism in Carabus granulatus L. (Coleoptera: Carabidae)

  Raisa A. Sukhodolskaya, Anatoliy A. Saveliev

  动物分类学报. 2017, 42(1): 71-89. https://doi.org/10.11865/zs.201707

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  Despite plenty of data in insects shape variation, papers on environmental factors effect on such variation are scarce and in ground beetles are practically absent. The aim of this research was to: (i) model the effect of the region of habitation, urbanization and habitat vegetation into the shape variation in widespread carabid species; (ii) describe sexual shape dimorphism in studied species. Samples were pitfall trapped in different regions of its area in the spectrum of anthropogenic influence (cities, suburbs, natural biotopes). One thousand and one hundred sixty-eight specimens were analyzed for six morphometric traits and terminal points of those measurements were used as landmarks for Procrustes analysis. We used linear models to reveal which factor (region, urbanization or vegetation) and in what direction affected beetles shape. Results showed that males in C. granulatus had more convex elytra and head, and the more convex in apical-basal direction pronotum. In its area from the east to the west elytra flattened in medial-distal direction and pronotum flattened in apical-distal direction. In disturbed urban environment beetles pronotum became more convex in both sexes and males elytra became more convex too. In open habitats (meadows, lawns) beetles became more flattened.
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  Geometric morphometric analysis of Eysarcoris guttiger, E. annamita and E. ventralis (Hemiptera: Pentatomidae)

  Rongrong Li, Hufang Zhang, Shengcai Li, Ming Bai

  动物分类学报. 2017, 42(1): 90-101. https://doi.org/10.11865/zs.201708

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  The genus Eysarcoris can be easily distinguished from other genera through the two spots in the basal angle of the scutellum. Nevertheless, Eysarcoris species show complex variances. Geometric morphometric methods have been increasingly applied to distinguish species and to define the boundary of genera among insects. In the present study, geometric morphometric approach was firstly employed to evaluate the shape variation of three characters (fore wing, hind wing and pygophore) of E. guttiger, E. annamita and E. ventralis using E. aeneus as outgroup to ascertain whether this approach is a reliable method for the taxonomy of Eysarcoris. Analysis was conducted on the landmarks of the three characters of these species. Multivariate regression of procrustes coordinates against centroid size was conducted to test the presence of allometry. Principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis were utilized to describe variations in shapes among the studied species. For all of the three characters, though PCA analysis showed some overlap among species, p-values for procrustes distance and mahalanobis distance were all less than 0.0001. The distribution of the three studied species corresponds with their species status. This study demonstrates that the geometric morphometrics of both the fore wing and the hind wing might represent a possible tool for the identification of species within this genus.
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  The Woodcock’s head: Resolving a morphological oddity using geometric morphometrics

  Jesus Marugán-Lobón

  动物分类学报. 2017, 42(1): 102-107. https://doi.org/10.11865/zs.201709

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  The scope of shape analysis based on geometric morphometrics has evolved into underscoring complex patterns of multidimensional shape change with multivariate statistical modelling (e.g., allometry, morphological integration, etc.). Such breakthrough was made possible because the method relies on a consistent comparative reference system to compare shapes, the latter which is computed using the Cartesian coordinates of homologous landmarks. It has been shown elsewhere that traditional comparative reference systems based on anatomy, and oriented in stereotyped postures, such as the Frankfurt plane at rest, the Lateral Semicircular Canal when the animal is in alert, or the cranial floor when the animal is flying, are all inconsistent for anatomical comparisons. They vary too much and unpredictably across species. An extraordinary example of the problems that can arise in descriptive and comparative anatomy when using such reference systems is the traditional interpretation of the head of the Woodcock. Anywhere in literature it is written that the eyes of this gamebird are oriented backwards to protect itself from predators. Here, using geometric morphometrics it is demonstrated that the woodcock’s skull is highly transformed, yet following a normal trend among birds. In turn, using GM it is demonstrated that the collective wisdom about this oddity is simply the result of interpreting the anatomy of its skull using unreliable reference systems.
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  Multiple 2D approaches to human sexual dimorphism of the distal end of femur

  Sitha Piyaselakul, Bumpenporn Sanannam, Jean-Pierre Dujardin

  动物分类学报. 2017, 42(1): 108-122. https://doi.org/10.11865/zs.201710

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  Various studies on the difference of distal femoral condyles between genders have been reported recently in order to provide anatomic information for knee prosthesis design and surgical planning in total knee arthroplasty. They also had the objective to be used as a sex recognition character, as may be needed in forensic medicine. Except for a recent 3D approach on the distal femur, most of the studies used dimensional information or aspect ratio but not shape. Our 2D study aimed to determine the size and shape variation of femoral condyles in Thais, considering age, sex and sides. One hundred and twenty-four cadaveric femurs (male 84 legs and female 40 legs) were dissected. The specimens were photographed by digital camera and images were analyzed using three geometric techniques: (i) the landmark-based method (5 landmarks), (ii) with or without addition of 23 sliding semilandmark and (iii) the outline-based methods. From the resulting geometric coordinates, size and shape were extracted for comparisons between genders and sides. Between sides, directional asymmetry could be detected only for shape variation, and only when introducing curves in the analyses (either through the semilandmarks technique or through the outline-based one). Non-directional asymmetry, probably fluctuating asymmetry, was detected for size, as well as for shape, in both genders. Sex discrimination was performed for each geometric technique using two classification methods: the Mahalanobis distance classification and the Maximum likelihood classification. The latter provided much more satisfactory gender validated reclassification (87%) than shape (72%).