Directional and fluctuating asymmetry in the black-winged damselfly Calopteryx maculata (Beauvois) (Odonata: Calopterygidae)

2000 ◽  
Vol 78 (10) ◽  
pp. 1740-1748 ◽  
Author(s):  
Jason Pither ◽  
Philip D Taylor
Keyword(s):  
Measurement Error ◽  
Fluctuating Asymmetry ◽  
Directional Asymmetry ◽  
Sample Group ◽  
Literature Evidence ◽  
Calopteryx Maculata

Directional asymmetry (DA) has received considerably less attention than fluctuating asymmetry (FA) in the literature. Evidence for DA, however, is building among insect taxa. We examined asymmetries in two wing traits within both sexes of the damselfly Calopteryx maculata (Beauvois) (Odonata: Calopterygidae) sampled from three sites in southeastern Ontario. After accounting for measurement error, we show that proximal segments within right fore and hind wings are consistently longer than those in the left in all but one sample group. Full wing lengths, however, exhibited FA rather than DA. Mean asymmetry values for both traits (segment and length) occurred in the direction of right-wingedness significantly more often than expected by chance. Patterns of asymmetry were generally consistent among the sexes and sites, although males tended to exhibit more pronounced DA. We suggest that the wings of C. maculata may undergo compensatory development, so that full lengths are more bilaterally symmetrical than their component parts.

scholarly journals Asimetría cráneo-mandibular de Artibeus lituratus (Chiroptera, Phyllostomidae) en Colombia

2014 ◽  
Vol 20 (1) ◽  
pp. 141 ◽  
Author(s):  
Camilo López-Aguirre ◽  
Jairo Pérez-Torres
Keyword(s):  
Measurement Error ◽  
Fluctuating Asymmetry ◽  
Morphological Plasticity ◽  
Wide Distribution ◽  
Functional Similarity ◽  
High Abundance ◽  
Directional Asymmetry ◽  
Functional Importance ◽  
Mandibular Asymmetry ◽  
Artibeus Lituratus

Analyzing asymmetry in species associated with disturbed environments enables the evaluation of the morphological plasticity of generalistic species and the different evolutionary responses of sexes or populations to environmental or genetic stress. This report is a study of the cranial and mandibular asymmetry of Colombian Artibeus lituratus. This species has a wide distribution and high abundance, but its morphological plasticity remains uncertain. We characterized its presence, fluctuating asymmetry, directional asymmetry and antisymmetry by measuring 11 craneometric traits in 146 adults from different localities. Fluctuating asymmetry was present in all traits; directional asymmetry and antisymmetry in three; and no measurement error in any trait. Females showed more fluctuating asymmetry in the splachnocranium and males in the neurocranium. Traits with functional importance while biting had lower levels of asymmetry and higher similarity. Traits with antisymmetry did not show association while traits with directional asymmetry showed mandibular association. We discuss the relation between the presence of cranial and mandibular asymmetry, with the functional similarity of different traits.

scholarly journals Fluctuating Asymmetry and Developmental Instability, a Guide to Best Practice

Symmetry ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 9
Author(s):  
John H. Graham
Keyword(s):  
Measurement Error ◽  
Best Practices ◽  
Environmental Stress ◽  
Fluctuating Asymmetry ◽  
Best Practice ◽  
Developmental Instability ◽  
The Past ◽  
Size Scaling ◽  
Research Designs

Best practices in studies of developmental instability, as measured by fluctuating asymmetry, have developed over the past 60 years. Unfortunately, they are haphazardly applied in many of the papers submitted for review. Most often, research designs suffer from lack of randomization, inadequate replication, poor attention to size scaling, lack of attention to measurement error, and unrecognized mixtures of additive and multiplicative errors. Here, I summarize a set of best practices, especially in studies that examine the effects of environmental stress on fluctuating asymmetry.

scholarly journals Towards More Realistic Leaf Shapes in Functional-Structural Plant Models

Symmetry ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 278 ◽  
Author(s):  
Dominik Schmidt ◽  
Katrin Kahlen
Keyword(s):  
Fluctuating Asymmetry ◽  
Leaf Shape ◽  
Three Dimensional ◽  
Directional Asymmetry ◽  
The Novel ◽  
Shape Model ◽  
Plant Model ◽  
Virtual Plant ◽  
Perfect Symmetry

Fluctuating asymmetry in plant leaves is a widely used measure in geometric morphometrics for assessing random deviations from perfect symmetry. In this study, we considered the concept of fluctuating asymmetry to improve the prototype leaf shape of the functional-structural plant model L-Cucumber. The overall objective was to provide a realistic geometric representation of the leaves for the light sensitive plant reactions in the virtual plant model. Based on three-dimensional data from several hundred in situ digitized cucumber leaves comparisons of model leaves and measurements were conducted. Robust Bayesian comparison of groups was used to assess statistical differences between leaf halves while respecting fluctuating asymmetries. Results indicated almost no directional asymmetry in leaves comparing different distances from the prototype while detecting systematic deviations shared by both halves. This information was successfully included in an improved leaf prototype and implemented in the virtual plant model L-Cucumber. Comparative virtual plant simulations revealed a slight improvement in plant internode development against experimental data using the novel leaf shape. Further studies can now focus on analyses of stress on the 3D-deformation of the leaf and the development of a dynamic leaf shape model.

Fluctuating Asymmetry and Measurement Error

1995 ◽  
Vol 44 (1) ◽  
pp. 97-101 ◽  
Author(s):  
Juha Merilä ◽  
Mats Björklund
Keyword(s):  
Measurement Error ◽  
Fluctuating Asymmetry

scholarly journals No Directional Scapular Asymmetry among Tamarines of the Genus Saguinus (Primates: Callitrichidae)

2020 ◽  
pp. 7-13
Author(s):  
P. M. Parés- Casanova ◽  
J. F. Vélez- García
Keyword(s):  
Fluctuating Asymmetry ◽  
Lateral Surface ◽  
The Other ◽  
Directional Asymmetry ◽  
Geometric Morphometric ◽  
Terrestrial Locomotion ◽  
Developmental Variation ◽  
Morphometric Methods ◽  
Perfect Symmetry ◽  
Left Scapula

Bilateral asymmetry is defined as a deviation of a whole organism or a part of it from a perfect symmetry, and different categories can be recognized. One is the fluctuating asymmetry, defined as the random developmental variation of a trait (or character) that is expected to be perfectly symmetrical on average, and the other one is directional asymmetry, which occurs when one of the sides shows stronger morphological structures or marks than the other. The aim of this study was to determine the kind of scapula asymmetry in Saguinus scapulae. On lateral surface of each right and left scapula, a set of 5 landmarks and 3 curves with semi-landmarks along the margins, on a sample of 16 pairs from different Saguinus species, were considered. Asymmetries (fluctuating and directional) on size and shape of the scapulae were analysed by means of geometric morphometric methods. Directional asymmetry was not detected, demonstrating no side scapular shape bias. The absence of significant directional asymmetry may indicate a similar contralateral pattern of employment of the shoulder, at least for one-arm vertical suspension, as it needs stronger forces than those for terrestrial locomotion and thus would cause more asymmetry in case side loadings were different. To our knowledge, this is the first investigation on the symmetrical/asymmetrical nature of scapulae in Saguinus. Our findings increase knowledge and understanding of humeral joint and arboreal locomotion in primates.

scholarly journals Developmental instability in wild Nigerian olive baboons (Papio anubis)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11832
Author(s):  
Kara C. Hoover ◽  
Emily Gelipter ◽  
Volker Sommer ◽  
Kris Kovarovic
Keyword(s):  
Life History ◽  
Fluctuating Asymmetry ◽  
Developmental Instability ◽  
Asymmetry Index ◽  
Permanent Dentition ◽  
Developmental Trajectory ◽  
Directional Asymmetry ◽  
Papio Anubis ◽  
Life History Stages ◽  
Males And Females

Background Developmental instability in archaeological samples can be detected through analysis of skeletal and dental remains. During life, disruptions to biological internal homeostasis that occur during growth and development redirect bodily resources to returning to homeostasis and away from normal processes such as symmetrical development. Because dental enamel does not remodel in life, any deviations from normal development are left behind. Even subtle disturbances to developmental trajectory may be detected in asymmetrical development of traits, specifically a random variation in sides termed fluctuating asymmetry. Human dental fluctuating asymmetry studies are common, but here we investigate the permanent dentition of a non-human primate Papio anubis, for potential fluctuating asymmetry relative to sex, weaning, and reproductive maturity. The sample stems from an outlier population that lives in the wettest and most humid habitat of any studied baboon group. Methods The skulls of adult baboons were collected after their natural death in Gashaka Gumti National Park, Nigeria. The permanent dentition of antimeric teeth (paired) were measured for maximum length and breadth using standard methods. The metrics were analyzed to assess the presence of fluctuating asymmetry in adult permanent mandibular and maxillary dentition. Measurement error and other forms of asymmetry (antisymmetry, directional asymmetry) were considered and dental measures expressing true fluctuating asymmetry were used to address three research questions. Results Males exhibit greater fluctuating asymmetry than females, suggesting that males experience greater overall instability during the developmental period. While weaning is not more stressful than other life history stages for males and females (using the first molar fluctuating asymmetry index as a proxy compared to other teeth), it is more stressful for females than males. The onset of reproduction is also not more stressful than other life history stages for males and females (using the third molar fluctuating asymmetry index as a proxy compared to other teeth), but it is more stressful for males than females. We explore possible explanations for these findings in the discussion.

scholarly journals Morphometric Analyses of (Hidden) Directional Asymmetry in Leaf Blades

2018 ◽  
Vol 2 (4) ◽  
Author(s):  
Sergey Gennadevich Baranov
Keyword(s):  
Fluctuating Asymmetry ◽  
Leaf Blade ◽  
Permutation Test ◽  
Principal Component ◽  
Bilateral Symmetry ◽  
Procrustes Analysis ◽  
Directional Asymmetry ◽  
Asymmetry Factor ◽  
Shape Deviation ◽  
Data Set

The deviation from perfect bilateral symmetry is a phenomenon actively exploring in evolutionary and environmental studies. The bilateral variation presents on different ecosystem level. The methods applied vary depending on the task and the final goal of study. The present study demonstrates the statistically significant presence of components (traces) of directional asymmetry (DA), fluctuating asymmetry (FA) and antisymmetry (AS) in leaf blade of Betula pendula on low level of ecosystem such as tree and leaf blade. The Generalized Procrustes Analysis was applied for testing asymmetry of shape in all data set and subgroups. The category ‘population’ revealed no significant value of DA (factor ‘side’). In the levels ‘tree’ and ‘leaf blade’ the factor ‘side’ was statistically significant as well as fluctuating asymmetry (factor interaction ‘leaf × side’).The principal component analysis showed visually the difference in PC scores between antisymmetry matrices of the left and right halves of the leaf blade. Covariate analysis matrices demonstrated the shape deviation from strict symmetry. The metric traits showed directional asymmetry in t-test in the leaf blade and the low kurtosis values. Permutation test of kurtosis values in geometric morphometric approach showed deviation from normality that could verified as a weak presence AS traces. The discriminant analysis results showed that traces of DA differed at the subpopulation level, as three of 10 populations revealed not significant factor ‘side’. Descriptive statistics of the metric train showed a correspondence to the trace of directional asymmetry in the shape of leaf blade. Fluctuating asymmetry in its pure form, at three levels of ecosystem was met only in single population of ten that should be taken into account testing developmental stability of birch and possibly other woody plants.

scholarly journals Side Differences in the Skull of Sheep: An Assessment by Geometric Morphometrics

2020 ◽  
pp. 1-7
Author(s):  
P. M. Parés-Casanova ◽  
A. Tolić ◽  
R. Carnicero
Keyword(s):  
Fluctuating Asymmetry ◽  
Genetic Factors ◽  
Bilateral Symmetry ◽  
Directional Asymmetry ◽  
Two Dimensional ◽  
Geometric Morphometric ◽  
Dorsal Aspect ◽  
Morphometric Methods ◽  
Muscular Function ◽  
External Stimuli

Effects of perturbations during development can be due to environmental and/or genetic factors, resulting in increased developmental instability which in turn can be expressed as fluctuating asymmetry (FA), defined as the non-directional deviation (right-left differences) from bilateral symmetry. However, other asymmetry types can appear, such as and directional asymmetry (DA), characterized by a distribution skewed to one side (right or left) at the, which is originated as a response to external stimuli that affect differentially on both sides of the organism. In order to describe asymmetric patterns in the ovine skull, we studied 165 specimens from animals belonging to the sheep breed “Navarra” from North Spain, using geometric morphometric methods. On digital pictures, we analyzed two midline and 8 bilateral two-dimensional landmarks on skull dorsal aspect. Results showed that FA accounted for a reduced amount of total variation, while DA explained most of it. We suggest that the presence of side differences due to lateralized muscular function (mastication) is the most important factor in skull asymmetry. Obtained results should provide a basis for relating asymmetries to the mechanics of cranial skeletum in sheep.

scholarly journals Scutation asymmetries in red-footed tortoise Chelonoidis carbonaria Spix, 1824 (Testudines: Testudinidae)

2020 ◽  
Vol 60 ◽  
pp. e20206039
Author(s):  
Pere M. Parés-Casanova ◽  
Pinzón Brando ◽  
Daniel Caviedes ◽  
Arcesio Salamanca-Carreño
Keyword(s):  
Fluctuating Asymmetry ◽  
Environmental Conditions ◽  
Developmental Stability ◽  
Developmental Instability ◽  
Directional Asymmetry ◽  
Random Perturbations ◽  
Scale Cover ◽  
Potential Sources ◽  
Sources Of Variation ◽  
Preliminary Study

The ability of an individual to withstand random perturbations during its development is considered a good indicator of environmental and genetic stress. A common means of assessing developmental stability is through analysis of fluctuating asymmetry (FA) in bilateral traits. Tortoises, with their large, solid plastron, allow for measurement of body geometry. Their bilateral shell scutes are ideal candidates for asymmetries researches. With this issue in mind we assessed, as a preliminary study, levels of plastron scute asymmetry in a sample of 46 red-footed tortoise Chelonoidis carbonaria from Arauca, N Colombia. We found significative fluctuating asymmetry (FA) but no directional asymmetry, the former not increasing with carapace size and thus indicating that tortoise shells do not become increasingly asymmetrical with age, or in other words, signaling that FA is not being influenced by pholidosis (variability of scale cover mosaic according to the development of the scutes). Asymmetry in plastron shape, although not necessarily apparent at first glance, varied, with gender with males exhibiting higher levels of FA than females. Although we can not identify the potential sources of variation responsible for the observed patterns of developmental instability, we consider this detected form of asymmetry due to unfavorable environmental conditions.

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