scholarly journals Geometric morphometrics of nested symmetries: Hierarchical INTER- AND INTRA-INDIVIDUAL VARIATION IN BIOLOGICAL SHAPES

2018 ◽  
Author(s):  
Yoland Savriama ◽  
Sylvain Gerber
Keyword(s):  
Individual Variation ◽  
Biological Object ◽  
Sea Urchins ◽  
Rotational Symmetry ◽  
Large Body ◽  
Bilateral Symmetry ◽  
Morphological Integration ◽  
Full Symmetry ◽  
Masticatory Apparatus ◽  
Complex Organ

AbstractSymmetry is a pervasive feature of organismal shape and the focus of a large body of research in Biology. Here, we consider complex patterns of symmetry where a phenotype exhibits a hierarchically structured combination of symmetries. We extend the Procrustes ANOVA for the analysis of nested symmetries and the decomposition of the overall morphological variation into components of symmetry (among-individual variation) and asymmetry (directional and fluctuating asymmetry). We illustrate its use with the Aristotle’s lantern, the masticatory apparatus of ‘regular’ sea urchins, a complex organ displaying bilateral symmetry nested within five-fold rotational symmetry. Our results highlight the importance of characterising the full symmetry of a structure with nested symmetries. Higher order rotational symmetry appears strongly constrained and developmentally stable compared to lower level bilateral symmetry. This contrast between higher and lower levels of asymmetry is discussed in relation to the spatial pattern of the lantern morphogenesis. This extended framework is applicable to any biological object exhibiting nested symmetries, regardless of their type (e.g., bilateral, rotational, translational). Such cases are extremely widespread in animals and plants, from arthropod segmentation to angiosperm inflorescence and corolla shape. The method therefore widens the research scope on developmental instability, canalization, developmental modularity and morphological integration.

Inferring Developmental Modularity from Morphological Integration: Analysis of Individual Variation and Asymmetry in Bumblebee Wings

2001 ◽  
Vol 157 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Christian Peter Klingenberg ◽  
Alexander V. Badyaev ◽  
Susanna M. Sowry ◽  
Nathan J. Beckwith
Keyword(s):  
Individual Variation ◽  
Morphological Integration ◽  
Integration Analysis

scholarly journals Radial symmetry molding skull roundness: a human fetal MR study

2021 ◽  
Author(s):  
Graziano Serrao ◽  
Emanuele La Corte ◽  
Fabio Triulzi ◽  
Salvatore Longoni ◽  
Federica Ruggiero ◽  
...  
Keyword(s):  
Rotational Symmetry ◽  
Radial Symmetry ◽  
Morphological Integration ◽  
Complex Data ◽  
Skull Development ◽  
Complex Development ◽  
Dimensional Parameters ◽  
Fetal Mr ◽  
Craniofacial Complex ◽  
Modeling Growth

Abstract The aim of this study consists in evaluating the morphological integration and molding shape of the human fetal craniofacial complex development on MR sagittal images. The sella point has been used as a reference point to build eleven dimensional parameters encompassing the craniofacial complex. Data and measurements obtained were statistically analyzed by PCA. The designed rays were significantly correlated, normally distributed and characterized by linearity over the overall fetal development. These findings showed that the craniofacial units are clustering together, whereas craniobasal and craniopharyngeal traits are spread. The data analysis supported the efficacy of specific morphological traits to evaluate differences emerging during the modeling growth processes. Skull modeling seems to be characterized by a rotational symmetry around the sella as inertial point. We firstly present the intriguing hypothesis through which the skull development grows along a dihedral angle symmetry made of a both rotational and reflection vector.

scholarly journals From spiral cleavage to bilateral symmetry: The developmental cell lineage of the annelid brain

2018 ◽  
Author(s):  
Pavel Vopalensky ◽  
Maria Antonietta Tosches ◽  
Kaia Achim ◽  
Mette Handberg-Thorsager ◽  
Detlev Arendt
Keyword(s):  
Nervous System ◽  
Marine Invertebrates ◽  
Rotational Symmetry ◽  
Cell Lineage ◽  
Bilateral Symmetry ◽  
Cell Types ◽  
Spiral Cleavage ◽  
Larval Brain ◽  
Larval Stages ◽  
Extensive Cell

AbstractThe spiral cleavage pattern is characteristic for Spiralia (Lophotrochozoa), a large assembly of marine invertebrates. In most cases, spiral cleavage produces freely swimming, trochophora-type larvae with a simple nervous system that controls ciliary locomotion. These larvae acquire bilateral symmetry, as manifested for example in the larval brain. The transition from the rotational symmetry of spiral cleavage into the bilateral adult body has not yet been understood. Here, we present the developmental cell lineage of the brain of the annelid Platynereis dumerilii from the zygote until the mid-trochophore stage (~30 hpf), in combination with a gene expression atlas for several embryonic and larval stages. Comparison of multiple embryos reveals a highly stereotypical development and an invariant cell lineage of the differentiated cell types. In addition, we observe a fundamental subdivision of the larval brain into a highly proliferative dorsolateral region and an early differentiating ventromedial region that gives rise to the apical nervous system. The transition from rotational to bilateral symmetry progresses gradually from the lateral to the central regions. Strikingly, the spiral-to-bilateral transition does not involve extensive cell migration. Rather, corresponding cells in different spiral quadrants acquire highly divergent identities in line with their bilateral position.

Exemplification and Characterization Moves in the Classroom Teaching of Geometry Concepts

1980 ◽  
Vol 11 (1) ◽  
pp. 10-21
Author(s):  
Randall I. Charle
Keyword(s):  
Preservice Teachers ◽  
Small Groups ◽  
Rotational Symmetry ◽  
Bilateral Symmetry ◽  
Concept Acquisition ◽  
Classroom Teaching ◽  
Second Grade ◽  
Second Grade Students ◽  
Trained Teachers

The purposes of this study were to determine whether teachers can be trained to use exemplification (E) and characterization (C) moves and whether the use of these moves facilitates concept acquisition. Each of 18 preservice teachers (9 trained, 9 control) taught two 20-minute lessons on geometry concepts to small groups of second-grade students. Significant differences favoring the trained teachers were found for the number of E and C moves. Mean student posttest scores for the trained teachers were significantly greater than scores for the control teachers. The number of nonexamples used for teaching bilateral symmetry and the number of examples used for teaching rotational symmetry accounted for a significant amount of the variance in posttest scores.

scholarly journals Modularity and cranial integration across ontogenetic stages in Martino’s vole, Dinaromys bogdanovi

2016 ◽  
Vol 85 (3) ◽  
pp. 275-289 ◽  
Author(s):  
Tina Klenovšek ◽  
Vida Jojić
Keyword(s):  
Individual Variation ◽  
Covariance Structure ◽  
Morphological Integration ◽  
Postnatal Ontogeny ◽  
Shape Variation ◽  
Western Balkans ◽  
Ontogenetic Changes ◽  
Southeastern Part ◽  
Cranial Development ◽  
Ontogenetic Stages

We explored modularity and morphological integration of the ventral cranium during postnatal ontogeny in Martino’s vole (Dinaromys bogdanovi). Two closely related phylogenetic groups, originating from the Central and Southeastern part of the species range in the western Balkans, were considered. As expected, both phylogroups had similar patterns of ontogenetic changes in cranial size and shape variation, modularity and integration. At the level of within individual variation, the hypothesis that the viscerocranial and neurocranial regions are separate modules was rejected, indicating that the hypothesized modules are not developmental, but rather functional. At the level of among individual variation, the viscerocranium and the neurocranium could not be recognized as separate modules at the juvenile stage. The strength of association between the hypothesized modules becomes lower with age which finally results in a clear 2-module organization of the ventral cranium at the adult stage. On the other hand, patterns of morphological integration for the cranium as a whole, the viscerocranium and the neurocranium stay consistent across ontogenetic stages. The developmental mechanism producing integration of the cranium as a whole, as well as integration of the neurocranium, varies throughout postnatal ontogeny. In contrast, we detected the ontogenetic stability of the mechanism responsible for covariation of viscerocranial traits which could provide ongoing flexibility of the viscerocranial covariance structure for high functional demands during lifetime. Findings from our study most likely support the idea of the ‘palimpsest-like’ model of covariance structure. Moreover, similarity or dissimilarity in the patterns of within and among individual variation in different sets of analyzed traits and comparisons across ontogenetic stages demonstrate how studies on small mammals other than mice can give new insights into postnatal cranial development.

Contribution à l'étude de la ptérylose chez Perisoreus canadensis (Linnaeus), (Aves : Corvidae)

1971 ◽  
Vol 49 (2) ◽  
pp. 147-158
Author(s):  
Henri Ouellet
Keyword(s):  
Sexual Dimorphism ◽  
Individual Variation ◽  
Narrow Band ◽  
Bilateral Symmetry ◽  
Cold Climate ◽  
The Other ◽  
Winter Temperatures ◽  
Perisoreus Canadensis ◽  
Posterior Element ◽  
Very High

The pterylosis of the Corvidae is generally not well known. The purpose of the present study is to describe the pterylography of the gray jay (Perisoreus canadensis). A French terminology is proposed for the various elements of the feather tracts and for the apteria. Down is present on the apteria of the winter individuals examined. The circles of feathers around the eyes are considered as feather tracts rather than elements of the other head feather tracts. There is no median fissure in the dorsal saddle, and the posterior element of the dorsal feather tract is attached to the saddle by a narrow band of feathers. There are 20 remiges; the 10th secondary is reduced in size and difficult to identify on study skins. The arrangement, shape, and orientation of the wing coverts are discussed. There are 12 rectrices, 6 on each side, but there are only 10 upper-tail coverts; a pair of filoplumes corresponds to each of them. Twelve (12) greater under tail coverts were found. A description of the natal down is provided. Individual variation in the pterylosis of the gray jay is slight, and there appears to be no sexual dimorphism; similarly, the bilateral symmetry is very high, perhaps perfect. Finally, it is suggested that the presence of down on the apteria in winter may be an adaptation to the low winter temperatures in the range of the species, and to breeding early in cold climate.

scholarly journals Modularity and intra-floral integration in metameric organisms: plants are more than the sum of their parts

2014 ◽  
Vol 369 (1649) ◽  
pp. 20130253 ◽  
Author(s):  
Pamela K. Diggle
Keyword(s):  
Individual Variation ◽  
Morphological Integration ◽  
Phenotypic Integration ◽  
Pollinator Attraction ◽  
Functional Feature ◽  
Form And Function ◽  
Multiple Organs ◽  
Independent Functions ◽  
Pollen Receipt ◽  
Architectural Effects

Within-individual variation in virtually every conceivable morphological and functional feature of reiterated structures is a pervasive feature of plant phenotypes. In particular, architectural effects, regular, repeatable patterns of intra-individual variation in form and function that are associated with position are nearly ubiquitous. Yet, flowers also are predicted to be highly integrated. For animal-pollinated plants, the coordination of multiple organs within each flower is required to achieve the complex functions of pollinator attraction and orientation, pollen donation and pollen receipt. To the extent that pollinators may select for multiple independent functions, phenotypic integration within flowers may also be modular. That is, subsets of floral structures may be integrated but vary independently of other subsets of structures that are themselves integrated. How can phenotypic integration and modularity be understood within the context of architectural effects? This essay reviews recent research on patterns of floral integration and modularity and explores the potential for spatial and temporal changes in the selective environment of individual flowers to result in positional variation in patterns of morphological integration.

scholarly journals The Emergence of the Bilateral Symmetry in Animals: A Review and a New Hypothesis

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 261
Author(s):  
Søren Toxvaerd
Keyword(s):  
Rotational Symmetry ◽  
Bilateral Symmetry ◽  
Enzymatic Reactions ◽  
Undifferentiated Cell ◽  
Biological Cells ◽  
Biological Organism ◽  
New Hypothesis ◽  
Biological Organisms

Most biological organisms exhibit different kinds of symmetry; an Animal (Metazoa), which is our Darwinist ancestor, has bilateral symmetry, and many plants exhibit rotational symmetry. It raises some questions: I. How can the evolution from an undifferentiated cell without bilateral symmetry to a complex biological organism with symmetry, which is based on asymmetric DNA and enzymes, lead to the bilateral symmetry? II. Is this evolution to an organism with bilateral symmetry obtained by other factors than DNA and enzymatic reactions? The existing literature about the evolution of the bilateral symmetry has been reviewed, and a new hypothesis has been formulated based on these reviews. The hypothesis is that the morphogenesis of biosystems is connected with the metabolism and that the oscillating kinetics in the Glycolysis have played a role in the polarity of the biological cells and in the establishment of the bilateral symmetry in Animals.

Sign in / Sign up

Export Citation Format

Share Document