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Fluctuating asymmetry, the non-directional deviation from bilateral symmetry resulting from developmental instability, can indicate early-life environmental stress. While fluctuating asymmetry can affect individual survival and reproductive success, its effect on fitness differs between species. Here, we analyzed up to 27 years of mark-recapture data from 894 RFID tagged individuals of three forest-living bat species in southern Germany to investigate the degree of fluctuating asymmetry in forearm length. In Bechstein's bats, Myotis bechsteinii, the species with the highest sample size, we furthermore investigated if fluctuating asymmetry has become more frequent over the study period, a time when juvenile bats have grown larger forearms in response to warmer summers. We also investigated whether fluctuating asymmetry affects individual lifespan and lifetime reproductive success in female Myotis bechsteinii. The degree of fluctuating asymmetry clearly exceeding the measurement error estimated on recaptured individuals was similar in all three species (1.8%). In female Myotis bechsteinii, the frequency of fluctuating asymmetry did not increase over the course of the study and even strong asymmetry had no effect on individual reproductive success and life expectancy. Our data suggest that fluctuating asymmetry is a poor predictor of fitness in the female Myotis bechsteinii studied, and is so far unaffected by the warming environment which is leading to larger individuals in our study population. [ABSTRACT FROM AUTHOR]

Habitats resulting from agricultural intensification harbour a wide array of stressors for resident organisms. Environmental stress during development can leave imprints on the phenotype that are useful as indicators of its impairment. Among them, fluctuating asymmetry (FA), considered the morphological manifestation of developmental instability (DI), may reflect the increment of developmental noise and the inefficiency of buffering mechanisms. Here, we evaluated for the first time the impact of intensive agriculture on the development of a viviparous reptile, the asp viper, Vipera aspis (Linnaeus 1758), by means of FA. To this end, we first quantified unsigned asymmetry indexes (uAI) of dorsal head shape captured by geometric morphometrics (GM) and of seven pholidotic traits in 127 and 482 individuals, respectively. Using linear models, we then tested for variation in uAI according to habitat type. Furthermore, we tested the effect of climatic variables with a potential influence on development, and thus, on FA. We performed analyses at the V. aspis zinnikeri subspecies range and at the population level, including three well‐sampled natural localities (NAT) and three sites of intensive agriculture (AGR). We found significantly higher FA levels in dorsal head shape in individuals from agricultural habitats than in those from natural habitats, which suggests that asp viper development is impaired by stressors resulting from agricultural intensification. Our results also point to a lower sensitivity of traditional morphological tools to capture the signal that intensive agriculture leaves on development and a lack of capacity of climatic factors in isolation to predict variation in the degree of asymmetry. In addition to encouraging the use of high‐precision methods, we hypothesize on the overall effect of different stressors linked to intensive agriculture as the real constraint. [ABSTRACT FROM AUTHOR]

The processes of developmental stability, canalization, and phenotypic plasticity have ecological and evolutionary significance, and been studied extensively, but mostly separately and thus the relationships between them are not straightforward. Our objective was to better integrate these processes in the context of temporally heterogeneous environments. We did this by investigating the effects of early experience with temporal heterogeneity in water availability on associations between developmental stability, canalization, and phenotypic plasticity. We subjected eight plant species to a first round of alternating inundation and drought vs. constantly moderate water treatments (heterogeneous experience) and a second round of water conditions (to test plasticity). We measured fluctuating asymmetry (FA) in leaf size, intra‐ and inter‐individual variation (CVintra and CVinter), and plasticity (PI) in traits and analyzed correlations between these variables across all species. Results showed little correlations between FA, CVintra and PI, several positive correlations between FA and CVinter in more stressful conditions, especially in as well as positive correlations between CVinter and PI initially and negative correlations between them later. These suggested the complexity of these relationships, which can depend on whether plasticity occurs. Greater inter‐individual variation will more likely cooperate with plasticity before or during plastic response, whereas higher canalization may reflect phenotypic convergence. Both higher FA and CVintra can reflect faster growth, while CVintra may also reflect plant growth stage, and the two mechanisms should cooperate in response to environmental challenges. The complexity of these relationships suggests plants deal with environmental variation in elaborate and integrative ways which can be affected by many factors. [ABSTRACT FROM AUTHOR]

Key message: Ash dieback causes alterations in leaf physiology and morphology, particularly affecting the specific leaf area, which can be used to discriminate between different degrees of damage. Since the introduction of the invasive fungal pathogen Hymenoscyphus fraxineus in Europe, the European common ash (Fraxinus excelsior L.) has been threatened by ash dieback. An infection leads, for example, to typical symptoms of dying shoots, but changes of leaf physiology and morphology are still largely unexplored. Therefore, five physiological and morphological traits, chlorophyll content, chlorophyll fluorescence, specific leaf area, leaf thickness, and fluctuating asymmetry, were investigated in four different study sites in southern Germany regarding possible changes due to ash dieback and their relationship to different degrees of damage. Both higher and lower levels of chlorophyll with increasing damage due to ash dieback were observed. Chlorophyll fluorescence and fluctuating asymmetry proved to be less suitable indicators of damage. Leaf thickness showed the tendency (however not significant) of an increase in more severely damaged trees. The specific leaf area was identified as a suitable indicator of the damage severity, with significant smaller values in less healthy trees. Therefore, ash dieback can also result in notable alterations in leaf physiology and morphology. [ABSTRACT FROM AUTHOR]

WingAnalogy is a computer tool for automated insect wing morphology and asymmetry analysis. It facilitates project management, enabling users to import pairs of wing images obtained from individual insects, such as left and right, fore- and hindwings. WingAnalogy employs image processing and computer vision to segment wing structures and extract cell boundaries, and junctions. It quantifies essential metrics encompassing cell and wing characteristics, including area, length, width, circularity, and centroid positions. It enables users to scale and superimpose wing images utilizing Particle Swarm Optimization (PSO). WingAnalogy computes regression, Normalized Root Mean Square Error (NRMSE), various cell-based parameters, and distances between cell centroids and junctions. The software generates informative visualizations, aiding researchers in comprehending and interpreting asymmetry patterns. WingAnalogy allows for dividing wings into up to five distinct wing cell sets, facilitating localized comparisons. The software excels in report generation, providing detailed asymmetry measurements in PDF, CSV, and TXT formats. [ABSTRACT FROM AUTHOR]

Simple Summary: Long-term exposure to low concentrations of insecticides can cause several adverse effects, both on target insects and on other organisms. Low doses can also generate tolerance in surviving offspring. One simple method to detect the consequences of long-term exposure to residual toxins is to measure deviations from ideal body symmetry. Fluctuating asymmetry (FA) is evidence that insects were stressed during development. This study aimed to verify FA in the wing veins of Drosophila suzukii, a fruit pest controlled by the insecticide acetamiprid. To determine whether low doses of insecticide in the diet induce the asymmetry effect, multigenerational insect breeding was carried out on media supplemented with different concentrations of two insecticides. Nicotine was used as a positive control. Even in the first generation, low doses reduced fertility and caused vein asymmetry. This effect persisted in subsequent generations, indicating a lack of tolerance that led to complete insect death after 10 generations. D. suzukii proved extremely sensitive to acetamiprid, and FA is a good index of this sensitivity. Long-term exposure to low concentrations of toxic substances can cause several adverse consequences ranging from molecular to morphological. Sublethal doses may also lead to increased tolerance in the offspring of surviving individuals. One of the consequences of such stress is deviations from the ideal body symmetry during development, reflected by increased levels of fluctuating asymmetry (FA). This research aimed to verify FA in the wing veins of insects belonging to the Drosophilidae family—Drosophila suzukii, a fruit pest controlled by the insecticide acetamiprid, a neonicotinoid. To determine whether FA varied depending on insecticides present in the diet, multigenerational cultures of D. suzukii were carried out on media supplemented with different concentrations (below the LC50) of two insecticides. Nicotine was used as a positive control. Fecundity decreased, the number of insects decreased, and breeding did not continue beyond the tenth generation. However, the FA level at different concentrations was similar, and high FA values were observed even at lower acetamiprid concentrations. We did not see significant changes in FA levels in subsequent generations. D. suzukii proved extremely sensitive to acetamiprid, and FA is a good index of this sensitivity. [ABSTRACT FROM AUTHOR]

The aviation sector is believed to be responsible for considerable environmental damage attributed to emission of a large number and amount of pollutants. Airports are often surrounded by forest fragments and humid areas that attract birds of prey and hence may potentially serve as useful bioindicators. The aim of the present study was to examine genotoxic potential in raptors exposed to airport pollution using the micronucleus (MN) test and morphological changes as evidenced by bilateral symmetry. This investigation was conducted at Salgado Filho International Airport of Porto Alegre – RS as well as in private and zoological breeding grounds. The presence of metals was measured in the blood cells of the collected birds. Seventeen birds (Caracara (Polyborus) plancus) were used in this study 11 from exposed and 6 from non-exposed group. The nuclear alterations clearly indicate that organisms exposed to airport pollution exhibited a significantly higher frequency of genetic damage compared to non-exposed birds. Further, manganese and chromium were detected exclusively in the blood of the exposed group. In contrast, the analysis of bilateral symmetry did not detect any significant morphologic differences between the two groups. Therefore, data indicate that blood genotoxic stress occurs in birds of prey living in civil aviation areas as evidenced by MN frequency increase and presence of manganese and chromium. [ABSTRACT FROM AUTHOR]

Abstract WingAnalogy is a computer tool for automated insect wing morphology and asymmetry analysis. It facilitates project management, enabling users to import pairs of wing images obtained from individual insects, such as left and right, fore- and hindwings. WingAnalogy employs image processing and computer vision to segment wing structures and extract cell boundaries, and junctions. It quantifies essential metrics encompassing cell and wing characteristics, including area, length, width, circularity, and centroid positions. It enables users to scale and superimpose wing images utilizing Particle Swarm Optimization (PSO). WingAnalogy computes regression, Normalized Root Mean Square Error (NRMSE), various cell-based parameters, and distances between cell centroids and junctions. The software generates informative visualizations, aiding researchers in comprehending and interpreting asymmetry patterns. WingAnalogy allows for dividing wings into up to five distinct wing cell sets, facilitating localized comparisons. The software excels in report generation, providing detailed asymmetry measurements in PDF, CSV, and TXT formats.

Although evaluating developmental stress is challenging, it is critical to understanding phenotypic adaptation and differentials in morbidity and mortality related to spatiotemporal variation in environmental and cultural factors. This paper presents a new, reproducible, and reliable geometric morphometric (GM) protocol through which stress‐induced deviations to symmetry, known as fluctuating asymmetry (FA), can be robustly quantified. A case study, in which maternally mediated early‐life stress in human skeletal remains is explored through first permanent molar (M1) FA, illustrates the method's effectiveness and wide‐ranging potential to revolutionise the investigation of themes such as stress intensity, developmental processes, and buffering mechanisms in past populations. [ABSTRACT FROM AUTHOR]

The environmental transformations associated with cities are expected to affect organisms at the demographic, phenotypic, and evolutionary level, often negatively. The prompt detection of stressed populations before their viability is compromised is essential to understand species' responses to novel conditions and to integrate urbanization with biodiversity preservation. The presumably stressful conditions of urban environments are expected to affect organisms' developmental pathways, resulting in a reduction of the efficacy of developmental stability and canalization processes, which can be observed as increased Fluctuating Asymmetry (FA) and Phenotypic Variance (PV), respectively. Here, we investigated whether patterns of phenotypic variation of urban populations of a fully terrestrial salamander, Salamandra salamandra bernardezi, are affected by urban settings compared to surrounding native forest populations. We sampled populations within and around the city of Oviedo (northern Spain) and used geometric morphometrics to compare morphological differentiation, head shape deviance from the allometric slope, PV, and FA. We also compared morphological patterns with neutral genetic and structure patterns. We observed increased levels of differentiation among urban populations and in PV within certain of them, yet no differences in allometric deviance and FA were detected between habitats, and no morphological measures were found to be correlated with genetic traits. Our results do not support a clear negative impact of urban conditions over salamander populations, but rather suggest that other ecological and evolutionary local processes influence morphological variation in this urban system. [ABSTRACT FROM AUTHOR]

In the work, the relationship (FA) of the leaves of the hanging birch Betula pendula Roth with atmospheric pollution, climatic indicators and soil characteristics was determined. We analyzed data obtained from 10 sites located in the main geographical directions from the city of Ukhta (Komi Republic, Russia). FA was based on 5 morphological parameters (n=100). In the soil, we determined the pH (water and salt extracts), the content of organic matter and mobile forms of metals. Information on air pollution and climate parameters was obtained from open sources. We established high FA of B. pendula at all sites (0.064-0.076). It was shown that this is not related to the geographical location of the birch growing area. There was no excess of standards of pollutants in the air and soil at the sites. Correlation analysis showed that FA increases in response to a decrease in the proportion of organic matter in the soil and an increase in soil acidity (r is -0.49 and -0.42, respectively). Also, the increase in FA is associated with the content of mobile forms of Pb, Mn, Cu (r is 0.6, 0.36, 0.35, respectively). We found no effect of the content of mobile Zn, Fe, Cd in the soil on the FA level of the leaves. Thus, it is shown that soil characteristics affect the asymmetry of the bioindicator plant, including within environmental regulations. This fact should be taken into account when interpreting the results of the assessment of the ecological state of the territories.

Morphological plasticity may be induced by altering host plants and commonly it is sex‐specific in phytophagous insects. It is hypothesized that stress in insects caused by a host shift leads to morphological changes and developmental destabilization, which may be identified by fluctuating asymmetry. We performed reciprocal transplant experiments in eight replicated populations of the seed beetle Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae, Bruchinae) adapted to common bean (Phaseolus vulgaris L., Fabaceae) as its ancestral host and chickpea (Cicer arietinum L., Fabaceae) as a suboptimal host. Using methods of geometric morphometrics we assessed the effects of the short‐ and long‐term host shift on size and shape variation of beetles of both sexes. We also tested the hypothesis that fluctuating asymmetry is lower when the beetles develop within seeds of the ancestral host. Our results showed that females respond more plastically related to their body size and shape of the abdomen, particularly during a short‐term host shift, suggesting that females have a greater importance in maintaining the population on a new host. The level of fluctuating asymmetry is lowest in males that have evolved for generations on bean indicating that they have the most canalized development, so we suggested that symmetry in A. obtectus is maintained by sexual selection. Even if the beetles are adapted to a suboptimal host over many generations, they stabilize their development after returning to the ancestral host. Our work indicates that host shifts may change morphological aspects of the beetles in a sex‐specific manner and consequently influence their developmental trajectories. [ABSTRACT FROM AUTHOR]

One method of crop protection is the application of a widely used group of pesticides—pyrethroids. As xenobiotics, sub-lethal doses of insecticides cause stress in pests, resulting in a change in the shape and size of their organs or bodies. The stress caused by pesticides may lead to acute destabilization of development, but also to transgenerational canalization through the process of genetic assimilation. Fluctuating asymmetry (FA), small random deviations between the right and left sides of bilaterally symmetrical traits, is an outcome of developmental instability and is a measurable indicator of phenotypic response to stress. We exposed four populations of the seed beetle Acanthoscelides obtectus to sub-lethal doses of cypermethrin for ten generations in a laboratory evolution experiment. Using geometric morphometrics, we analyzed size and shape changes and the level of fluctuating asymmetry in untreated beetles and in samples from the fifth and tenth generation. Exposure over ten generations led to an increase in the body size of the beetles, shortening of their pronotum and elongation of their thorax and abdomen. After ten generations of exposure to cypermethrin, FA levels decreased, indicating a canalization of development. This study provides new insights into the phenotypic markers of environmental pollution from agricultural activities. [ABSTRACT FROM AUTHOR]

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This study aimed to conduct a detailed statistical shape analysis of the thorax across various dog breeds, focusing on the identification and characterization of shape variations and asymmetrical features. For this purpose, 3D images of 39 thoracic samples were collected from various regions across Türkiye, ensuring a diverse representation of breeds and populations. In the analysis, 136 specific anatomical landmarks were meticulously identified and marked from a lateral view of the thorax for each sample. The study revealed that the first principal component explained 28.89% of the total variation in directional asymmetry, suggesting consistent size or shape differences on one side of the thorax. Additionally, it was found that the first principal component explained 27.82% of the total variation in fluctuating facet asymmetry occurs if one region is consistently greater or has a different shape compared to the opposite and indicates underlying genetic or functional differences. This study highlights the usefulness of geometric morphometric analysis in distinguishing thoracic shape differences among various dog breeds, providing insights into their morphological diversity. Moreover, the findings underscore the potential of geometric morphometric analysis for taxonomic purposes, enabling more precise classification and understanding of breed-specific characteristics. This approach can aid in identifying subtle morphological variations that may be linked to breed history, function, or environmental adaptation. [ABSTRACT FROM AUTHOR]

The ossa coxae are the bones that connect the hindlimbs to the axial skeleton. The right and left os coxae join at the median plane to form the pelvis. In this study, variations in pelvis shape and the asymmetric structure of the pelvis were investigated across different classes of dogs. To achieve this, computed tomography images of the pelvis were obtained from 35 dogs, and 3D modelling of the pelvis was created. Subsequently, 45 landmarks were identified on these models. As a result of the Principal Component Analysis, the shape variation was observed in the pelvic canal and crista iliaca. Directional asymmetry between Principal Component 1 and Principal Component 2 accounted for 33.84% of the total variation, while fluctuating asymmetry contributed 23.66%. Canonical variate analysis revealed that canonical variate (CV) 1 explained 56.56% of the total variation between groups, with CV 2 explained 28.98%. Male dogs exhibited greater pelvic variation than females. Procrustes ANOVA indicated that the greatest proportion of shape variation corresponds to the effect of differences among individuals. While directional asymmetry was statistically significant, fluctuating asymmetry was not. Male dogs displayed more pronounced pelvic shape asymmetry, typically towards the right. Gundogs had a narrower pelvic canal and a wide crista iliaca, whereas terriers had a wider pelvic canal and smaller crista iliaca in shape. Geometric morphometry enables statistical analysis and the derivation of average shapes from samples, making it a vital tool in veterinary anatomy. This study provides insights into pelvic geometric morphometry across different classes of dogs. [ABSTRACT FROM AUTHOR]

Non-genetic variation is the phenotypic variation induced by the differential expression of a genotype in response to varying environmental cues and is broadly categorized into two types: phenotypic plasticity and developmental noise. These aspects of variation have been suggested to play an important role in adaptive evolution. However, the mechanisms by which these two types of non-genetic variations influence the evolutionary process are currently poorly understood. Using a machine-learning-based phenotyping tool, we independently quantified phenotypic plasticity and developmental noise in the wing morphological traits of the fruit fly Drosophila simulans. Utilizing a rearing experiment, we demonstrated plastic responses in both wing size and shape as well as non-zero heritability of both phenotypic plasticity and developmental noise, which suggests that adaptive phenotypic plasticity can evolve via genetic accommodation in the wing morphology of D. simulans. We found a positive correlation between phenotypic plasticity and developmental noise, while the correlation between the plastic response to three kinds of environmental factors that were examined (nutrient condition, temperature, and light–dark cycle) was poor. These results suggest that phenotypic plasticity and developmental noise contribute to evolvability in a similar manner, however, the mechanisms that underlie the correspondence between these two types of variation remain to be elucidated. [ABSTRACT FROM AUTHOR]

Stress experienced during development in organisms with bilateral structures could result in developmental instability, which is expressed as subtle non‐directional deviations from perfect symmetry, known as fluctuating asymmetry (FA). As such, FA has been proposed, and extensively used, as a trait indicating stress for many organisms with bilateral structures and many types of stress. However, while this concept may apply to animals, the evidence for plants' main vegetative structures, that is, leaves, remains equivocal, and a comprehensive synthesis on this topic is still missing.We designed observational field and controlled greenhouse studies, combining different growth and leaf forms across multiple stress gradients, comprising 21 species and 80 populations. We measured FA as the difference between the left and right area of the leaf, an approach that accommodates diverse leaf forms. We used high‐precision, blind, single‐person measurements and tested for other forms of symmetry and the effect of leaf size. We further complemented our study with a systematic literature review of FA in plant leaves, compiling 51 studies comprising 72 species, 23 stress types and 131 unique entries (species × stress type).We consistently found no effect of stress on leaf FA in any of the studied species in both our field and experimental gradients. In the systematic literature review, only 39% of the unique entries showed the expected increase in FA with stress, 53% showed no effect, 9% showed an opposite trend of a decrease in FA with stress and 1% showed a unimodal relationship. Importantly, only 40% of all entries fulfilled the crucial step of controlling for a high‐precision measurement, and of these 49% reported the expected increase in FA with stress.Both the results of our observational and experimental approaches and the systematic literature review failed to support a clear relationship between stress and FA in plant leaves. These results clearly show that FA in plant leaves cannot be used as a reliable trait indicating stress during development. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

ABSTRACT The processes of developmental stability, canalization, and phenotypic plasticity have ecological and evolutionary significance, and been studied extensively, but mostly separately and thus the relationships between them are not straightforward. Our objective was to better integrate these processes in the context of temporally heterogeneous environments. We did this by investigating the effects of early experience with temporal heterogeneity in water availability on associations between developmental stability, canalization, and phenotypic plasticity. We subjected eight plant species to a first round of alternating inundation and drought vs. constantly moderate water treatments (heterogeneous experience) and a second round of water conditions (to test plasticity). We measured fluctuating asymmetry (FA) in leaf size, intra‐ and inter‐individual variation (CVintra and CVinter), and plasticity (PI) in traits and analyzed correlations between these variables across all species. Results showed little correlations between FA, CVintra and PI, several positive correlations between FA and CVinter in more stressful conditions, especially in as well as positive correlations between CVinter and PI initially and negative correlations between them later. These suggested the complexity of these relationships, which can depend on whether plasticity occurs. Greater inter‐individual variation will more likely cooperate with plasticity before or during plastic response, whereas higher canalization may reflect phenotypic convergence. Both higher FA and CVintra can reflect faster growth, while CVintra may also reflect plant growth stage, and the two mechanisms should cooperate in response to environmental challenges. The complexity of these relationships suggests plants deal with environmental variation in elaborate and integrative ways which can be affected by many factors.

Флуктуирующая асимметрия (ФА) – это мера онтогенетического шума, указывающая на отклонение в механизмах гомеостаза. Связана ли интегральная величина ФА с коррелированностью этого показателя в нескольких признаках? Предложена регрессионная модель интегрального индекса ФА листовой пластины липы мелколистной (Tilia cordata Mill), включавшая следующие факторы:а) коэффициент корреляции величин мерных признаков листовой пластины;б) коэффициент вариации размеров этих признаков;в) коэффициент корреляции ФА признаков.Наибольшим частным коэффициентом регрессии обладала вариация признаков (b=0,52; p=0,001). Коэффициент корреляции ФА обладал меньшей значимостью (b=0,37; p=0,01). Фактор корреляции признаков не показал статистического значимого влияние на величину ФА. Метод опорных векторов подтвердил результаты регрессионного анализа и показал наибольшее прогнозированное значение ФА при средних значениях вариации признаков и высокой коррелированности признаков по индексу ФА.

Recreational load affects the quality of the environment, which is confirmed by the change of fluctuating asymmetry of silver birch leaves. The deviation level of the environmental quality is minimal when the quality is normal. However, when the environmental quality level is declining it leads to decrease in stability and state of biome, which is observed by the sign of the magnitude of changes as the integral indicator of developmental stability. The purpose of the research was to study fluctuating asymmetry of leaves of silver birch ( Betula pendula Roth) in the green zone of Astana. The objects of research were 19-year-old artificial plantings of silver birch, some of which underwent intercropping practice simultaneously on the same field 7 years after planting. The planting site was conventionally divided into high and low latitudes due to the vertical elevation change in a landscape. All the studied forest plantings to some degree exhibited a weakening state. The condition of the trees is gradually declining, which constitutes 66.971.2 points on replanted plots and 72.372.4 points - on non-replanted trial plots in 2022. Prior to the creation of a recreational zone in transplanted crops at a high latitude, an initial stage of deviation from the conventional norm was observed. After the forest crop improvements were implemented, fluctuating leaf asymmetry indicator reached its highest magnitude in 2022 in all the studied crops, except for transplanted crops at a low latitude, which had a 3rd-4th score for all the years of observation. So far, in these forest plantings, the quality of the environment has not reached a critical level, but they also display a strong anthropogenic impact, because of compression of topsoil due to the settling of unorganized paths. Therefore, it is necessary to take silvicultural and other measures to increase sustainability and improve condition and state of artificial forest plantings. It is imperative to carry out plants trimming and utilize soil amendments, organize a regulated road and footpath network, and strengthen control over travelers.

Sheep (Ovis aries) play an important role in the economy of Turkey and the Balkan Peninsula due to their use in farming. As a domesticated species, sheep's morphometric and morphological diversity is likely determined by selective breeding practices rather than geographic distribution. This study aimed to analyse four different sheep breed skulls and reveal skull asymmetry using geometric morphometric methods. For this purpose, 2D images of 52 sheep skulls from different breeds were analysed from the dorsal view of the skull, using 28 landmarks. In the comparison of sheep skulls from the dorsal view, the first principal components for directional asymmetry (DA) and fluctuating asymmetry (FA) were 32.98% and 39.62% of the total variation, respectively. Sharri and Ivesi (Awassi) sheep breeds had the broadest distribution of skull shapes among the breeds, while Lara e Polisit was the most conservative breed. DA was used as a measure of biomechanical constraints, and FA was used as an indicator of environmental stress. Consistent with DA, both differences in centroid size and shape between breeds were statistically significant. No differences between males and females related to asymmetry were revealed. Ivesi sheep revealed the highest fluctuating asymmetry. Geometric morphometric methods proved to be a useful tool for distinguishing differences in the shape of the skull of different sheep breeds and also can be useful for taxonomic purposes. [ABSTRACT FROM AUTHOR]

Dogs are animals with strong bite force. This strong bite mechanism has led to significant changes in the skeletal system such as fossa masseterica. It can be thought that one side is used more than the other side in chewing and is related to the preference of using the same side's hand, eye and foot. In the study, directional asymmetry and fluctuating asymmetry, which occurs as a result of chewing asymmetry, were examined on the first molar teeth and the fossa masseterica in 85 dog mandibles including a wide diversity of morphotypes. The association of high PC1 values for directional asymmetry with a pronounced cranial index, as evident in breeds like Pekingese, Pomeranian and Bulldog, indicates a potential evolutionary or selective breeding trend favouring brachycephaly. On the contrary, guardian breeds like the German shepherd and Bernese mountain dog, which typically require strong jaws for their roles, showcased reduced PC1 values, which might be related to their functional morphology. Similarly, the PCA results for the first molar teeth shape variations also highlighted the influence of cranial shape, with boxer dogs displaying notably higher PC1 values. The fluctuating asymmetrical distributions provided valuable insights into individualistic variations. Interestingly, no specific breed distribution trend was observed for these asymmetries, indicating a more individual‐based variation rather than breed‐based. It is essential to note that while these results provide valuable insights, further studies are required to understand the underlying causes better. Factors like genetic variations, developmental processes, dietary habits and external environmental factors could play pivotal roles in these observed morphological differences. [ABSTRACT FROM AUTHOR]

Structural asymmetries of brain regions associated with lateralised functions have been extensively studied. However, there are fewer morphometric analyses of asymmetries of the gyri and sulci of the entire cortex. The current study assessed cortical asymmetries in a sample of healthy adults (N = 175) from an admixed population from South America. Grey matter volume and surface area of 66 gyri and sulci were quantified on T1 magnetic resonance images. The departure from zero of the differences between left and right hemispheres (L‐R), a measure of directional asymmetry (DA), the variance of L‐R, and an index of fluctuating asymmetry (FA) were evaluated for each region. Significant departures from perfect symmetry were found for most cortical gyri and sulci. Regions showed leftward asymmetry at the population level in the frontal lobe and superior lateral parts of the parietal lobe. Rightward asymmetry was found in the inferior parietal, occipital, frontopolar, and orbital regions, and the cingulate (anterior, middle, and posterior–ventral). Despite this general pattern, several sulci showed the opposite DA compared to the neighbouring gyri, which remarks the need to consider the neurobiological differences in gyral and sulcal development in the study of structural asymmetries. The results also confirm the absence of DA in most parts of the inferior frontal gyrus and the precentral region. This study contributes with data on populations underrepresented in the databases used in neurosciences. Among its findings, there is agreement with previous results obtained in populations of different ancestry and some discrepancies in the middle frontal and medial parietal regions. A significant DA not reported previously was found for the volume of long and short insular gyri and the central sulcus of the insula, frontomarginal, transverse frontopolar, paracentral, and middle and posterior parts of the cingulate gyrus and sulcus, gyrus rectus, occipital pole, and olfactory sulcus, as well as for the volume and area of the transverse collateral sulcus and suborbital sulcus. Also, several parcels displayed significant variability in the left–right differences, which can be partially attributable to developmental instability, a source of FA. Moreover, a few gyri and sulci displayed ideal FA with non‐significant departures from perfect symmetry, such as subcentral and posterior cingulate gyri and sulci, inferior frontal and fusiform gyri, and the calcarine, transverse collateral, precentral, and orbital sulci. Overall, these results show that asymmetries are ubiquitous in the cerebral cortex. [ABSTRACT FROM AUTHOR]

The semicircular canals of the inner ear are involved in balance and velocity control. Being crucial to ensure efficient mobility, their morphology exhibits an evolutionary conservatism attributed to stabilizing selection. Release of selection in slow‐moving animals has been argued to lead to morphological divergence and increased inter‐individual variation. In its natural habitat, the house mouse Mus musculus moves in a tridimensional space where efficient balance is required. In contrast, laboratory mice in standard cages are severely restricted in their ability to move, which possibly reduces selection on the inner ear morphology. This effect was tested by comparing four groups of mice: several populations of wild mice trapped in commensal habitats in France; their second‐generation laboratory offspring, to assess plastic effects related to breeding conditions; a standard laboratory strain (Swiss) that evolved for many generations in a regime of mobility reduction; and hybrids between wild offspring and Swiss mice. The morphology of the semicircular canals was quantified using a set of 3D landmarks and semi‐landmarks analyzed using geometric morphometric protocols. Levels of inter‐population, inter‐individual (disparity) and intra‐individual (asymmetry) variation were compared. All wild mice shared a similar inner ear morphology, in contrast to the important divergence of the Swiss strain. The release of selection in the laboratory strain obviously allowed for an important and rapid drift in the otherwise conserved structure. Shared traits between the inner ear of the lab strain and domestic pigs suggested a common response to mobility reduction in captivity. The lab‐bred offspring of wild mice also differed from their wild relatives, suggesting plastic response related to maternal locomotory behavior, since inner ear morphology matures before birth in mammals. The signature observed in lab‐bred wild mice and the lab strain was however not congruent, suggesting that plasticity did not participate to the divergence of the laboratory strain. However, contrary to the expectation, wild mice displayed slightly higher levels of inter‐individual variation than laboratory mice, possibly due to the higher levels of genetic variance within and among wild populations compared to the lab strain. Differences in fluctuating asymmetry levels were detected, with the laboratory strain occasionally displaying higher asymmetry scores than its wild relatives. This suggests that there may indeed be a release of selection and/or a decrease in developmental stability in the laboratory strain. [ABSTRACT FROM AUTHOR]

Dragonflies and damselflies are excellent bioindicators of the quality of both aquatic and terrestrial ecosystems. In our study, we assessed the usefulness of metric and meristic morphological traits as environmentally friendly and cost‐effective indicators of the integrative ecological quality of watercourses. Our study species of choice was the damselfly banded demoiselle, Calopteryx splendens (Harris) (Odonata: Calopterygidae). Adult C. splendens specimens were collected at three study sites along the trophic gradient of the Tisza River in Hungary and Ukraine. Body and abdomen length, head width, and distances between wing landmarks were assessed as metric traits, and the number of wing cells as meristic traits. The concentration of chlorophyll‐a was used to classify the three study sites into having a low, intermediate, and high trophic condition based on earlier studies. Significant differences were found along the trophic gradient based on the measured metric and meristic traits. Especially, insects from the site with the highest trophic condition had the largest body length, head width, and distances between wing landmarks, as well as the highest number of cells in the fore wings. There were also differences between males and females, but we did not find differences in fluctuating asymmetry (FA), i.e., differences between the left and the right wings. These results indicated that the morphological traits of adult banded demoiselles could be indicative of the environmental quality of a watercourse. [ABSTRACT FROM AUTHOR]

This article is dedicated to studying the influence of ash element distribution in the tissues of woody plants" foliar organs on the fluctuating asymmetry of leaf blades in industrial areas. The research goal is a comprehensive study of the trends in the relationship between ash content and fluctuation of morphometric parameters of leaf blades under conditions of increased anthropogenic impact, using Pavlodar as an example. The research hypothesis states that the increase in ash element content in the tissues of leaf blades is directly proportional to significant variations in morphometric parameters within the sample and serves as an indicator of environmental pollution. The research objects are leaves of Populus balsamifera, Betula pendula, Acer negundo. According to the location of industrial emission sources, they were divided into three zones: northern, eastern, and central. The leaves were collected at the end of the 2023 growing season, with subsequent measurements of the length and width of the leaf blade and calculation of the standard deviation. The significance of differences between samples was assessed based on the results of variance analysis. Ash content determination was carried out by the dry ashing method of leaves in a muffle furnace. It was found that the maximum concentration of ash elements is characteristic of Populus balsamifera and Acer negundo, with the highest degree of atmospheric air pollution identified for the Alumina Plant, consistent with the significant results of the range of variation in morphometric indicators within the sample. An increase in mineral accumulation in leaf blades from southeast to northwest within the central and eastern industrial zones (excluding the Alumina plant) was noted. The obtained results confirm a direct proportional relationship between significant fluctuations in morphometric parameters as ash content increases, which can be used as an indicative method of anthropogenic pollution in industrial regions. [ABSTRACT FROM AUTHOR]

The fluctuating asymmetry of seven characteristics is studied in five samples of the Sakhalin redfin Pseudaspius sachalinensis (Nikolskii, 1889). A comparison of these samples with each other shows that the ratio of the variances of fluctuating asymmetry between characteristics corresponds in a majority of samples to the variance of the average values for these samples. The uniqueness of the sample from Bolshoi Chibisan Lake is indicated by the smallest number of agreements with other samples and the largest sum of variances for all characteristics. Clusterization of samples of the Sakhalin redfins in terms of variances of the fluctuating asymmetry of all characteristics shows a division into two clusters: one includes samples from the Tym, Tumnin, Susuya, and Protochnaya rivers; and the other cluster includes a sample from the Bolshoi Chibisan Lake. For most indicators of fluctuating asymmetry, the Sakhalin redfin differs significantly from two other redfin species living in the same water bodies, this may indicate either species specificity or the influence of environmental factors at the initial stages of individual development of fish in the spawning sites. [ABSTRACT FROM AUTHOR]

Hyper‐allometry, whereby an anatomical unit increases in size at a faster rate than other structures of the same organism, is considered to be an important feature of many sexually selected structures, with large 'high‐quality' animals carrying a feature that is proportionally larger than smaller, 'low‐quality' animals. When these structures are bilaterally symmetrical, it has been suggested that the degree of fluctuating asymmetry (deviation from perfect symmetry) acts as an indicator of the quality of the bearer. Bovids are useful models for testing sexual selection hypotheses due to their large horns and variety of reproductive systems. Here we use male and female specimens of the southern African blue wildebeest (Connochaetes taurinus) to assess the levels of allometry and fluctuating asymmetry in morphological features of the horns and skull. Males were found to be significantly larger than females for overall horn size, horn length and horn circumference and the horns were found to be isometric in both sexes. Directional asymmetry was found for horn length and horn circumference with the right being longer than the left side. These findings suggest that in C. taurinus the horns follow predicted patterns of variation for sexually selected traits, but that here fluctuating asymmetry may not be as important in sexual selection as previously suggested. Additionally, females did not differ greatly from males in variation and asymmetry and allometry, indicating their horns could be under sexual selection as a result of male choice, or that like males, they also engage in intraspecific combat as well. [ABSTRACT FROM AUTHOR]

The Brazilian Atlantic Forest has undergone significant transformation, resulting in habitat loss and the endangerment of many species of mammals and other vertebrates. In this study, the presence of fluctuating asymmetry of four anatomical structures of the arboreal rodent Rhipidomys mastacalis was evaluated using geometric morphometrics. The study focused on adult specimens collected in a mosaic of vegetation composed of forested vegetation, occupancy mosaics in forested areas, and cocoa plantations. The results showed significant values of fluctuating asymmetries in all structures and in all areas. The skulls and scapulae showed the highest values of asymmetry in forested vegetation and cocoa plantations, while the mandibles showed the greatest values in forested vegetation, and the pelvis in occupancy mosaics and cocoa plantations. These findings are consistent with previous studies that have evaluated developmental stability in mammals and suggest that high asymmetry values indicate an effect on different phases of ontogeny, which can harm the survival of a species in future generations. Overall, this study provides important insights into the impacts of habitat fragmentation on Rhipidomys mastacalis and highlights the need for conservation efforts to preserve the integrity of the Brazilian Atlantic Forest and its diverse range of wildlife. [ABSTRACT FROM AUTHOR]

In a study of patterns of language laterality in left- and right-handers, Woodhead et al. (Woodhead ZVJ, Thompson PA, Karlsson EM, Bishop DVM. 2021 R. Soc. Open Sci. 8, 200696. (doi:10.1098/rsos.200696)) noted that several tasks showed no bias to the left hemisphere in left-handed individuals. This might appear to suggest that these functions were mediated by the two hemispheres working together equally—what can be termed ‘hemispheric equipoise’. Here, I consider an alternative possibility that individuals show lateral bias on these tasks, but the bias can occur to either the left or right—a form of fluctuating asymmetry. Further analysis of the distributions of data from individuals in Woodhead et al. is compared with simulated data. The pattern of results suggests that the impression of hemispheric equipoise may be an artefact of reliance on group data: even though the group mean does not differ from zero, a high proportion of individuals are biased to the left or right.

Long-term exposure to low concentrations of toxic substances can cause several adverse consequences ranging from molecular to morphological. Sublethal doses may also lead to increased tolerance in the offspring of surviving individuals. One of the consequences of such stress is deviations from the ideal body symmetry during development, reflected by increased levels of fluctuating asymmetry (FA). This research aimed to verify FA in the wing veins of insects belonging to the Drosophilidae family—Drosophila suzukii, a fruit pest controlled by the insecticide acetamiprid, a neonicotinoid. To determine whether FA varied depending on insecticides present in the diet, multigenerational cultures of D. suzukii were carried out on media supplemented with different concentrations (below the LC50) of two insecticides. Nicotine was used as a positive control. Fecundity decreased, the number of insects decreased, and breeding did not continue beyond the tenth generation. However, the FA level at different concentrations was similar, and high FA values were observed even at lower acetamiprid concentrations. We did not see significant changes in FA levels in subsequent generations. D. suzukii proved extremely sensitive to acetamiprid, and FA is a good index of this sensitivity.

During development, cells are subject to stochastic fluctuations in their positions (i.e. cell-level noise) that can potentially lead to morphological noise (i.e. stochastic differences between morphologies that are expected to be equal, e.g. the right and left sides of bilateral organisms). In this study, we explore new and existing hypotheses on buffering mechanisms against cell-level noise. Many of these hypotheses focus on how the boundaries between territories of gene expression remain regular and well defined, despite cell-level noise and division. We study these hypotheses and how irregular territory boundaries lead to morphological noise. To determine the consistency of the different hypotheses, we use a general computational model of development: EmbryoMaker. EmbryoMakercan implement arbitrary gene networks regulating basic cell behaviors (contraction, adhesion, etc.), signaling and tissue biomechanics. We found that buffering mechanisms based on the orientation of cell divisions cannot lead to regular boundaries but that other buffering mechanisms can (homotypic adhesion, planar contraction, non-dividing boundaries, constant signaling and majority rule hypotheses). We also explore the effects of the shape and size of the territories on morphological noise. [ABSTRACT FROM AUTHOR]

We have tested the hypotheses that the satyrs Aphantopus hyperantus and Coenonympha arcania accumulate metals in higher concentrations near the Middle Ural Copper Smelter than in the background area and that metal accumulation in the body of adult individuals is negatively correlated with the wing length but positively correlated with the fluctuating asymmetry of the wing length. We measured the length of the forewing and individual concentrations of Zn, Cu, Pb, and Cd in the body of adults captured at different distances from the copper smelter (Revda city, Russia). The metal content reaches very high levels, with Zn concentrations being higher than Cu and Pb concentrations by an order of magnitude and Cd concentration by two orders of magnitude. In both species, metal accumulation is higher in males than in females. Maximum concentrations of Zn, Cu, and Cd have been recorded near the smelter. The wing length either did not differ between the sites or was higher near the smelter. The statistically significant negative relationship between Cu concentrations and the wing length has been recorded only for females of one of the species (A. hyperantus). In both species, the fluctuating asymmetry of the wing length did not differ between samples from different sites and did not depend on metal concentrations at the individual level. [ABSTRACT FROM AUTHOR]

Dermatoglyphic patterns are permanently established and matured before the 24th week of gestation. Their frequencies and localization might be a good indicator of developmental instability in individuals with an altered neurodevelopment and show potential as biomarkers of autism spectrum disorder (ASD). In this study, fingerprint pattern counts and fluctuating asymmetry in the distribution of patterns are compared between 67 boys diagnosed with ASD (aged 5.11 ± 2.51 years) and 83 control boys (aged 8.58 ± 3.14 years). Boys with ASD had a higher rate of discordance in their fingerprint patterns (p =.0026), showing more often bilateral differences in the occurrence of certain patterns. A chi‐square test revealed that the difference in pattern frequencies between boys with ASD and the control group is the most significant in frequencies of whorls, tented arches, and ulnar loops. Boys with ASD have significantly fewer ulnar loops, significantly more whorls, and tented arches in the right hand. The achieved results are in favor of the suggestion that prenatal influences, which play a role in the development of bilateral differences in fingerprint patterns up to the 24th week of gestation, may be a potential cause of an altered neurodevelopment in ASD individuals. [ABSTRACT FROM AUTHOR]

One method of crop protection is the application of a widely used group of pesticides—pyrethroids. As xenobiotics, sub-lethal doses of insecticides cause stress in pests, resulting in a change in the shape and size of their organs or bodies. The stress caused by pesticides may lead to acute destabilization of development, but also to transgenerational canalization through the process of genetic assimilation. Fluctuating asymmetry (FA), small random deviations between the right and left sides of bilaterally symmetrical traits, is an outcome of developmental instability and is a measurable indicator of phenotypic response to stress. We exposed four populations of the seed beetle Acanthoscelides obtectus to sub-lethal doses of cypermethrin for ten generations in a laboratory evolution experiment. Using geometric morphometrics, we analyzed size and shape changes and the level of fluctuating asymmetry in untreated beetles and in samples from the fifth and tenth generation. Exposure over ten generations led to an increase in the body size of the beetles, shortening of their pronotum and elongation of their thorax and abdomen. After ten generations of exposure to cypermethrin, FA levels decreased, indicating a canalization of development. This study provides new insights into the phenotypic markers of environmental pollution from agricultural activities.

The expansion of urban areas leads to a decrease in natural habitats, resulting some species to live in urban environments. Novel environmental factors might influence their size, body condition and development stability. The environmentally induced developmental instability can be indicated by fluctuating symmetry, which means random deviations from perfect symmetry in bilaterally symmetric creatures.Our research aimed to explore the impact of various urbanization factors on snake populations within urban habitats. To achieve this, we examined how dice snake (Natrix tessellata) populations differ in their asymmetry, body condition and size in a lake characterized by highly modified lakeside habitats, intensive urban land use, and severe human disturbance. The average size, body condition and two asymmetry indices were determined for 25 dice snake populations around Lake Balaton in Hungary. The impacts of the urban environment were characterized by land use and local variables, and the risk of road kill was also estimated.Populations living in areas with a more intensive road network or near a main road showed more asymmetric traits. It is conceivable that pollutants from vehicle traffic lead to developmental disorders that manifest themselves in more asymmetric individuals. In addition, the body condition of snakes was negatively correlated with the area of the harbours, possibly due to the intensive boat traffic and human disturbance. Finally, populations living in more urbanized areas had larger body sizes meaning that despite its negative effects through pollution, anthropized areas can provide a suitable habitat for dice snakes.While urban artificial surroundings can function as suitable habitats, our results confirm that urban environmental factors have negative effects on dice snakes. Our findings indicate that the density of road networks and the proximity of roads have adverse effects on the developmental stability of urban snakes. This underscores the need to implement conservation actions to mitigate the negative effects of roads on biodiversity.

Coastal lagoons are key 'transitional' aquatic environments for biodiversity conservation. Ecological indicators are useful tools for the management of water resources in the European Union. Among different biological communities, fish are a very sensitive tool to assess environmental integrity. Indeed, their parasites can be used as complementary indicators of habitat quality. Yet there is still a deep lack of information on ecological assessment using fish (along with their parasites) for coastal lagoons, particularly for the Iberian Peninsula.The aim of the present study was to assess the use of fish morphology and their parasite communities as ecological indicators of anthropogenic impact within the Mar Menor coastal lagoon (SE Spain), a Mediterranean area of special conservation concern for European/Iberian biodiversity.Fish samples (black‐striped pipefish Syngnathus abaster and marbled goby Pomatoschistus marmoratus) were collected in August 2022 from the Littoral (high level of nutrient enrichment) and Barrier habitats. Physical status (both external and internal indices), asymmetry (level of developmental instability), parasite load, diversity and life‐cycle complexity were compared between habitat types.Body condition and mainly the health assessment index were better in the Barrier habitat. Except for pectoral fins in pipefish, the fluctuating asymmetry was statistically greater in the Littoral habitat (i.e. with eutrophication leading to poorer fish development). The parasite load was higher in the Littoral habitat for both host fish species. However, the diversity and life‐cycle complexity of parasite communities were statistically lower in the Barrier habitat (a structurally simpler environment) only for gobies.This study demonstrates an elevated potential for certain fish morphological and parasitological traits to be considered as good ecological indicators of environmental health. This could help environmental managers and policy makers to design effective monitoring programmes to detect impacts within valuable areas for conservation, such as the Mar Menor coastal lagoon. [ABSTRACT FROM AUTHOR]

Aim: The centre–periphery hypothesis (CPH) sustains that peripheral populations are subjected to harsher environmental conditions, which reduces demographic performance manifested, among others, by lower abundance, higher inbreeding and higher developmental instability. However, range centrality/peripherality is not necessarily a good proxy for environmental suitability since geographical distributions are often irregular in shape, barriers may limit dispersal towards suitable areas, and ancestral range shifts may have occurred unevenly in each direction. We evaluated predictions of the CPH for populations of the Neotropical lizard Notomabuya frenata by modelling the effects of environmental suitability and geographical centrality/peripherality upon demographic performance. Location: Brazilian Cerrado. Taxon: Notomabuya frenata (Squamata, Scincidae). Methods: We used populational values of body size, body mass, body condition, tail autotomy and fluctuating asymmetry (FA; a proxy of developmental instability) to estimate demographic performance. Then, we built correlative models to estimate environmental suitability for each sampled population. Finally, we used hierarchical Bayesian models based on a combination of stochastic partial differential equations and integrated nested Laplace approximations to model the relationships between demographic performance and predictor variables (geographical centrality/peripherality and environmental suitability) and make predictions across the geographical distribution of N. frenata. Results: Generalized boosting produced the best environmental suitability models. The total suitability area spanned more than 4 million km2 in cis‐Andean South America. All scalation counts presented some degree of asymmetry. Only three response variables—all related to FA—responded significantly to predictor changes. Contrary to the predictions of the CPH, one scalation count presented higher asymmetry closer to the range center and another in more suitable environments. Peripherality did not significantly influence any of the response variables. Main Conclusions: Populations may respond differently to geographical centrality/peripherality and environmental suitability, as these characteristics do not necessarily coincide. Studies testing the CPH should ideally incorporate these different predictors of demographic performance. [ABSTRACT FROM AUTHOR]

Elaborate avian feather ornaments have proven to be enigmatic because their function is often unclear, even though they are used in courtship and social displays. Male and female Whiskered Auklets Aethia pygmaea display on their faces four elaborate feather ornaments that serve both courtship and mechanosensory functions: three bilateral pairs of white facial plume tracts (superorbital, suborbital and auricular) and a slender black forehead crest, each consisting of several filoplumes. We studied left–right symmetry in the three antenna‐like bilateral white head plumes of 721 wild‐caught marked individuals (162 of known sex, 94 of known age that were 1–16 years old) during 1992–2009. Auricular and suborbital plumes were slightly more asymmetric in subadults (1‐year‐olds) than in adults (≥ 2 years old) but the opposite was true for superorbital plumes. Ornament asymmetries were not sexually dimorphic, nor were they significantly related to individual body condition, body size or age, except that superorbital plume asymmetry decreased significantly with tarsus length. Relative asymmetry (scaled for ornament size) of all three ornaments was negatively correlated with plume size, as predicted by some sexual selection models, but variation in asymmetries was large and differences between left (L) and right (R) sides in most birds were probably too small to be detected visually. Marginal mean absolute asymmetries (|L–R|) of super‐ and suborbital plumes were correlated with ocean climate during the preceding year when the birds would have been moulting, suggesting that fluctuating asymmetry at the population level might be a useful index of environmental stress in this seabird. The spectacular bilaterally expressed facial plumes displayed by Whiskered Auklets provide an interesting test case for questions about asymmetry in sexually and naturally selected traits. [ABSTRACT FROM AUTHOR]

The class Polyplacophora (chitons) represents a dorsoventrally flattened mollusk group that has an oval-shaped body covered with eight overlapping sclerites providing bilateral symmetry. Chitons show abnormalities (teratologies) that are characterized by symmetry deviations between the right and left sides of their bodies. As these deviations do not result in damage that affects vital functions, chitons are able to reach adult stages. In this study, we quantify the asymmetric condition of the species Chiton articulatus using a landmark-based geometric morphometric approach to assess variation in shape and bilateral symmetry. A geometric configuration of 22 landmarks and 50 semi-landmarks was created to evaluate shape variation in abnormal and deformed specimens compared to normal Chiton articulatus specimens. Vectors of change in the body shape configurations of chitons indicate that the greatest change occurs in the anterior part of the body, with less change in the middle and posterior parts. This gives chitons a widened appearance and provides anatomic compensation to restore the bilateral symmetry of the body scleritome. The diverse abnormalities and deformities had little impact on shape variations and confirmed that the coalescence condition is an intermediate step between a normal condition and the abnormal conditions of hypomerism or hypermerism. The low levels of fluctuating asymmetry expressed in C. articulatus indicate that despite living in areas of high stress, such as the rocky intertidal coast, this species maintains stability in its development and shape. Our results can serve as a model for studying bilateral symmetry deviation in polyplacophorans. [ABSTRACT FROM AUTHOR]

Fluctuating asymmetry (FA) is hypothesized to be a useful predictor of population canalization, especially for organisms at risk from environmental change.Identification of traits that meet statistical criteria as FA measures remains a challenge.Here, a laboratory experiment subjected immature butterflies (Vanessa cardui) to diet and temperature conditions of varying stress levels. Variation in dietary macronutrient ratio (protein: carbohydrate) and rearing temperature (optimal: 25°C; elevated: 32°C) was introduced as stressors. Temperature and nutrition are key variables influencing ectotherm growth and fitness and so are likely to be important stressors that influence FA.Individuals subjected to stressful conditions were predicted to show elevated FA of three wing size traits, as well as increased mortality and decreased adult body size.Trait FA did not vary across treatments. Instead, treatment levels impacted viability: The combined incidence of pupal death and expression of significant wing malformations increased in treatment levels designated as stressful. Variation in adult dry mass also reflected predicted stress levels. Results suggest that individuals predicted to display increased FA either died or displayed gross developmental aberrations.This experiment illustrates important constraints on the investigation of FA, including selection of appropriate traits and identification of appropriate levels of stressors to avoid elevated mortality. The latter concern brings into question the utility of FA as an indicator of stress in vulnerable, natural populations, where stress levels cannot be controlled, and mortality and fitness effects are often not quantifiable.

As natural disasters become more frequent due to climate change, understanding the biological impact of these ecological catastrophes on wild populations becomes increasingly pertinent. Fluctuating asymmetry (FA), or random deviations from bilateral symmetry, is reflective of developmental instability and has long been positively associated with increases in environmental stress. This study investigates craniofacial FA in a population of free‐ranging rhesus macaques (Macaca mulatta) that has experienced multiple Category 3 hurricanes since the colony's inception on Cayo Santiago, including 275 individuals from ages 9 months to 31 years (F = 154; M = 121). Using geometric morphometrics to quantify FA and a linear mixed‐effect model for analysis, we found that sex, age, and decade of birth did not influence the amount of FA in the individuals included in the study, but the developmental stage at which individuals experienced these catastrophic events greatly impacted the amount of FA exhibited (p =.001). Individuals that experienced these hurricanes during fetal life exhibited greater FA than any other post‐natal developmental period. These results indicate that natural disasters can be associated with developmental disruption that results in long‐term effects if occurring during the prenatal period, possibly due to increases in maternal stress‐related hormones. [ABSTRACT FROM AUTHOR]

The ability to detect and avoid predators has been suggested as one of the main drivers for behavioral lateralization. This is supported by studies reporting that animals from high‐predation environments are more lateralized than those from low‐predation environments. Some studies, however, have shown no effect of predator regime on lateralization. Lateralized behavior can also be driven by phenotypic asymmetry, where the more attractive side of the body is preferentially displayed during male–female interaction and courtship. The importance of fluctuating asymmetry for mate choice has been highly debated for a number of reasons. Here, we revisited the concepts of predator‐induced behavioral lateralization and phenotypic asymmetry using wild Trinidadian guppies Poecilia reticulata from three different stream systems. Using fish collected from both high‐ and low‐predation environments, we quantified behavioral lateralization in terms of directional turning bias, measured right–left body color asymmetry, and investigated whether a male side‐showing preference was present in male–female interaction trials. We found that guppies were, at best, moderately lateralized on average (across all populations), without any general effect of predator regime. There were some slight stream‐dependent side biases in color asymmetry, but this did not translate into a side‐showing preference in any of the populations in the interaction trials. Some significant observed effects align with previously published results, but these were dependent on stream‐origin and were not repeated across different experiments, complicating interpretation. We conclude that when investigating the effects of predation regime in general, and such effects on behavioral lateralization or fluctuating asymmetry in particular, attention must be focused toward several factors such as experimental assay used and population origin, and broad generalizations from results stemming from experiments including only one population should be avoided. [ABSTRACT FROM AUTHOR]

Habitat fragmentation and ecosystem changes have the potential to affect animal populations in different ways. To effectively monitor these changes, biomonitoring tools have been developed and applied to detect changes in population structure and/or individual traits that reflect such changes. Fluctuating asymmetry (FA) represents random deviations from perfect symmetry in bilateral traits from perfect symmetry in response to genetic and/or environmental stresses. In this study, we evaluated the use of FA as a tool to monitor stress caused by forest fragmentation and edge formation, using the tropical butterfly M. helenor (Nymphalidae) as a model species. We collected adult butterflies from three fragments of Atlantic Forest in Brazil encompassing both edge and interior habitats. Four wing traits (wing length, wing width, ocelli area, and ocelli diameter) were evaluated. Butterflies captured at edge sites exhibited higher FA values for wing length and wing width compared to those captured at interior sites, whereas traits related to ocelli did not show differences between the two habitat types. Our results suggest that the differences in abiotic and biotic conditions between forest interior and edges can act as a source of stress, impacting the symmetry of flight-related traits. On the other hand, as ocelli are crucial for butterfly camouflage and counter-predator strategies, our results indicate that this trait may be more conserved. By employing FA, we identified trait-specific responses to habitat fragmentation, thus suggesting its potential as a biomarker for environmental stress that can be used in butterflies to monitor habitat quality and change. [ABSTRACT FROM AUTHOR]

The reasons for distortion of the results of assessment of fluctuating asymmetry of woody plants are examined by the example of the silver birch Betula pendula Roth. The results of assessment of the fluctuating asymmetry by researchers with different skill levels in using this method are presented; it is shown that, for researchers without any experience in using this method, it is typical to overestimate the results by up to 50%, while training provides similar results. When assessing the environmental health by the magnitude of fluctuating asymmetry, it is necessary to comply with the method requirements for material collection and processing; noncompliance can lead to problems with the interpretation of the results. [ABSTRACT FROM AUTHOR]

The temporal variation of the degree of fluctuating asymmetry of the characters of skull morphology, as a measure of the developmental stability, is evaluated in the common shrew (Sorexaraneus L., 1758) in Central Siberia. Four-year cycles in this population under conditions of climatic stability in the past century were accompanied by significant changes in the level of developmental stability, suggesting a negative impact under a high density. Population fluctuations under the conditions of climatic instability in this century commonly occur without essential changes in the developmental stability, which can be related to both the impact of oscillations in the environmental conditions and an increase in the carrying capacity of the habitat due to the increase in temperature. Deterioration of developmental stability takes place occasionally in the case of an adverse overpopulation impact in the year of peak population abundance that is beyond the certain threshold level, which has increased due to climate change. The results indicate the importance of simultaneous monitoring of population abundance and developmental stability to provide information on possible mechanisms of changes in the population dynamics that occur due to climate change. [ABSTRACT FROM AUTHOR]