Showing papers on "Fluctuating asymmetry published in 2023"
TL;DR: This article showed that FA cannot be seen as a universal indicator of environmental stress and recommended that the use of FA as a stress index is discontinued until the scope of the developmental instability theory is clarified and its applicability limits are identified.
Abstract: The eco-evolutionary theory of developmental instability predicts that small, non-directional deviations from perfect symmetry in morphological traits (termed fluctuating asymmetry, FA) emerge when an individual is unable to buffer environmental or genetic stress during its development. Consequently, FA is widely used as an index of stress. The goal of the present study was to experimentally test a seemingly trivial prediction derived from the theory of developmental instability—and from previous observational studies—that significant growth retardation (which indicates stress) in plants is accompanied by an increase in FA of their leaves. We induced stress, evidenced by a significant decrease in biomass relative to control, in cucumber (Cucumis sativus), sweet pepper (Capsicum annuum), and common bean (Phaseolus vulgaris) by applying water solutions of copper and nickel to the soil in which plants were grown. Repeated blind measurements of plant leaves revealed that leaf FA did not differ between stressed and control plants. This finding, once again, demonstrated that FA cannot be seen as a universal indicator of environmental stress. We recommend that the use of FA as a stress index is discontinued until the scope of the developmental instability theory is clarified and its applicability limits are identified.
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TL;DR: In this article , the authors investigated the relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans and concluded that fluctuating asymmetry is a marker of developmental instability, developmental noise and phenotypic quality at population level.
Abstract: Random deviation from perfect symmetry of organisms is defined as fluctuating asymmetry. Fluctuating asymmetry is widely considered to be a marker of developmental instability, developmental noise and phenotypic quality at the population level. In this study, we investigated hypothesized relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans.
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TL;DR: In this article , a morphological study on the larvae of the cabbage butterfly Pieris brassicae, reared in conditions close to the natural environment, was performed and it was found that the regulatory mechanisms for limiting the effects of developmental disturbances, known to be effective under strictly controlled, very stable laboratory conditions, are also effective during growth under more natural environmental conditions.
Abstract: Simple Summary Size and shape are important features of most living beings, and the capacity of the organism to regulate size and shape during growth, containing the effects of developmental disturbances of different origins, is considered a key adaptation. Through a morphological study on the larvae of the cabbage butterfly Pieris brassicae, reared in conditions close to the natural environment, we found that the regulatory mechanisms for limiting the effects of developmental disturbances, known to be effective under strictly controlled, very stable laboratory conditions, are also effective during growth under more natural environmental conditions. This study may contribute to better characterization of these regulatory mechanisms and their combined effects in the developmental interactions between the organism and its environment. Abstract Size and shape are important determinants of fitness in most living beings. Accordingly, the capacity of the organism to regulate size and shape during growth, containing the effects of developmental disturbances of different origin, is considered a key feature of the developmental system. In a recent study, through a geometric morphometric analysis on a laboratory-reared sample of the lepidopteran Pieris brassicae, we found evidence of regulatory mechanisms able to restrain size and shape variation, including bilateral fluctuating asymmetry, during larval development. However, the efficacy of the regulatory mechanism under greater environmental variation remains to be explored. Here, based on a field-reared sample of the same species, by adopting identical measurements of size and shape variation, we found that the regulatory mechanisms for containing the effects of developmental disturbances during larval growth in P. brassicae are also effective under more natural environmental conditions. This study may contribute to better characterization of the mechanisms of developmental stability and canalization and their combined effects in the developmental interactions between the organism and its environment.
1 citations
TL;DR: Otolith features such as size and weight were analyzed in 656 fish specimens of Chelon labrosus, Chelon saliens and Mugil cephalus collected from the Köyceğiz Lagoon System, Aegean Sea, southwest Turkey as discussed by the authors .
Abstract: Otolith features such as size and weight were analysed in 656 fish specimens of Chelon auratus, Chelon labrosus, Chelon saliens and Mugil cephalus collected from the Köyceğiz Lagoon System, Aegean Sea, southwest Turkey. The aim was to calculate the asymmetry value of the otolith length (OL), otolith width (OW) and otolith weight (OWe). The asymmetry value of OL was greater than that of OW and OWe. The asymmetry value of the three otolith parameters increased with an increase in the fish's length. The probable cause of asymmetry in the otolith parameters investigated has been determined relative to the variability in growth prompted by ecological impact linked with the disparity in water temperature, salinity, depth and contaminants existing in the Köyceğiz Lagoon System.
TL;DR: In this paper , the authors considered the relationship between hand grip strength and body symmetry in healthy young individuals and concluded that fluctuating asymmetry is not a reliable indicator to predict an individual's physical fitness and developmental quality.
Abstract: Some research in the field of anthropology provides some evidence that high hand grip strength and a symmetrical body are reliable indicators of health and fitness. In this study, we consider the relationship between these two indicators in healthy young individuals. In the study, 185 university students (87 males and 97 females) were examined. In addition to the weight and height of the students, eight bilateral traits were measured with an accuracy of 0.01 mm to evaluate their bodily symmetry, and their hand grip strength was determined with a hand dynamometer by applying the Southampton protocol. The composite fluctuating asymmetry formula was used to standardize the bodily symmetries of individuals. Analyzes show that women have a more symmetrical body structure and lower hand grip strength scores than men. When the effect of weight and body mass index was controlled, no correlation was observed between composite fluctuating asymmetry and hand grip strength in both sexes. As conclusion, although hand grip strength and body symmetry are accepted as reliable indicators of health and fitness, it is seen that there is no significant relationship between the two indicators in both sexes in our study. In addition, our findings support the view that fluctuating asymmetry is not a reliable indicator to predict an individual's physical fitness and developmental quality.
TL;DR: In this paper , the authors calculate and assess the asymmetry of two goatfish species, M. flavolineatus and P. forsskali, collected from Hurghada fishing harbour, Egypt.
Abstract: Abstract The current study aims to calculate and assess the asymmetry of the two goatfish species, Yellowstripe goatfish Mulloidichthys flavolineatus (Lacepède 1801) and Red Sea goatfish, Parupeneus forsskali (Fourmanoir & Guézé 1976) collected from Hurghada fishing harbour, Egypt. The asymmetry valuation for M. flavolineatus and P. forsskali is imperative to demonstrate the impact of asymmetry on the larvae settlement in this vital fishing ground. Asymmetry was calculated for the saccular otolith (Sagittae) biometry, namely length, width, and mass. The results showed that the otolith height had a lower asymmetry value than the otolith length for the two goatfish species inspected. No relationship between the asymmetry value of otolith length and width and total fish length was observed. Both goatfish species’ calculated otolith mass asymmetry was higher than that of many teleost fish species.
TL;DR: In this paper , the bilateral asymmetry was analyzed on 259 fish specimens comprising six Barbus species collected in June-August 2010 from rivers in western Anatolia, and the results showed that the ten morphological traits chosen for this study exhibit variable levels of bilateral asymmetric in the six B. pergamonensis species.
Abstract: The bilateral asymmetry was analysed on 259 fish specimens comprising six Barbus species collected in June-August 2010 from rivers in western Anatolia. The goals of this study are: (1) to check for the levels of bilateral asymmetry amid the ten morphological features of the six Barbus species and (2) to compare the levels of this asymmetry among the ten localities in western Anatolia. The possibility of applied investigations using bilateral asymmetry and fishes as an indicator of the health of the freshwater systems was also conducted. Statistical analyses have shown that the ten morphological traits chosen for this study exhibit variable levels of bilateral asymmetry in the six Barbus species collected from the ten localities studied. The asymmetry value was highest for snout length and lowest for the prepectoral fin length observed in B. pergamonensis. An increasing tendency in asymmetry levels was exhibited for each of the ten morphological traits in the fish length groups selected for each Barbus species assessed. The result of the individuals being right-handed or left-handed has shown that specific morphological characteristics are either dextral or sinistral or showed no bilateral asymmetry in different Barbus species studied.
TL;DR: In this article , the authors used climbing perch (Anabas testudieneus) to assess the FA in the diameter of the eye because of low-level cadmium exposure.
Abstract: Biomonitoring using fish has been a popular method of assessing the toxic effects of cadmium concentrations of cadmium in water bodies and has led to bioaccumulation in fish contributing to various morphological alterations. Among the known effects of these alterations is developmental instability via fluctuating asymmetry (FA). The utilization of FA data is a simple yet effec-tive method to evaluate the toxic effects of cadmium on the stability of development. This study used climbing perch (Anabas testudieneus) to assess the FA in the diameter of the eye because of low-level cadmium exposure. The left and right sides of the traits were measured once every four weeks for 16 weeks. The average measurements from both sides of the traits were used to calculate the FA value. Results found that the highest mean FA for the diameter of the eye was obtained in the highest treatment group, 0.015 mg/L. The results also indicate that increasing concentrations of cadmium exposure had a statistically significant effect on the FA of eye diameter. There was also a statistically significant interaction between the duration of exposure and treatment groups in FA of the diameter of the eye. The results from the study indicate that prolonged exposure to sub-lethal concentrations of cadmium can cause significant effects on the normal development of eyes in Anabas testudineus. This study can add to the body of research regarding fluctuating asymmetry as a tool to study developmental toxicants and assess other bilateral organs.
TL;DR: In this article , the authors found that areal asymmetry is low-moderately heritable and correlates phenotypically and genetically in specific regions, indicating coordinated development of asymmetries partly through genes.
Abstract: Cortical asymmetry is a ubiquitous feature of brain organization that is subtly altered in some neurodevelopmental disorders, yet we lack knowledge of how its development proceeds across life in health. Achieving consensus on the precise cortical asymmetries in humans is necessary to uncover the developmental timing of asymmetry and extent to which it arises through genetic and later influences in childhood. Here, we delineate population-level asymmetry in cortical thickness and surface area vertex-wise in 7 datasets and chart asymmetry trajectories longitudinally across life (4-89 years; observations = 3937; 70% longitudinal). We find replicable asymmetry interrelationships, heritability maps, and test asymmetry associations in large-scale data. Cortical asymmetry was robust across datasets. Whereas areal asymmetry is predominantly stable across life, thickness asymmetry grows in childhood and peaks in early adulthood. Areal asymmetry is low-moderately heritable (max h2SNP ~19%) and correlates phenotypically and genetically in specific regions, indicating coordinated development of asymmetries partly through genes. In contrast, thickness asymmetry is globally interrelated across the cortex in a pattern suggesting highly left-lateralized individuals tend towards left-lateralization also in population-level right-asymmetric regions (and vice versa), and exhibits low or absent heritability. We find less areal asymmetry in the most consistently lateralized region in humans associates with subtly lower cognitive ability, and confirm small handedness and sex effects. Results suggest areal asymmetry is developmentally stable and arises early in life through genetic but mainly subject-specific stochastic effects, whereas childhood developmental growth shapes thickness asymmetry and may lead to directional variability of global thickness lateralization in the population.
TL;DR: In this paper , the recruitment expectations of young mice born in woodlots in relation to food availability were analyzed through an index of developmental stability that combined values of fluctuating asymmetry (FA) for six traits of the lower mandibles.
Abstract: Generalist mice are key species for the long-term dynamics of fragmented forests due to their dual role as seed dispersers or predators of the dominant trees. Wood mice, Apodemus sylvaticus, usually act as a net predator in woodlots due to higher winter densities and earlier winter reproduction than in forests. Here we analyze the recruitment expectations of young mice born in woodlots in relation to food availability through an index of developmental stability that combined values of fluctuating asymmetry (FA) for six traits of the lower mandibles. FA was measured in young and adult mice caught at the end of the winter in control woodlots, food-supplemented woodlots and in a nearby large forest. Despite low sample sizes (n = 9 for young and n = 74 for adults), FA in young mice born in control woodlots were significantly higher than in those from food-supplemented woodlots and the forest and in all adults. Food limitation in woodlots was thus associated with increased developmental instability of young mice, but it had no effect on adults. Instability likely reduced the survival prospects of young mice through increased mortality, and this should be compensated by yearly recolonization of woodlots by adults from the agricultural matrix in autumn and winter. Future work analyzing mechanisms suggested here but using non-lethal methods will be important to clarify the impacts of FA on the population dynamics of wood mice.
TL;DR: In this paper , the authors studied the variations in testes size asymmetry among 116 anuran species associated with natural and sexual selection to test the packaging hypothesis and compensation hypothesis, and found that the positive correlation between testes sizes and livers mass followed the prediction of the package hypothesis, while the postcopulatory sperm competition and the degree of testes asymmetry was positively related.
Abstract: Simple Summary Testis asymmetry is particularly common in animals and it has been explained by two main hypotheses: the packaging hypothesis and compensation hypothesis. We studied the variations in testes size asymmetry among 116 anuran species associated with natural and sexual selection to test the two hypotheses. We found that the positive correlation between testes size asymmetry and livers mass followed the prediction of the packaging hypothesis, while the postcopulatory sperm competition (e.g., residual testes size) and the degree of testes asymmetry was positively related, supporting the positive role of sexual selection on testes size asymmetry. However, we did not find any effect of developmental stress on variation in testes size asymmetry among anurans, which was inconsistent with the compensation hypothesis. Abstract Directional asymmetry in testes size is commonly documented in vertebrates. The degree of testes size asymmetry has been confirmed to be associated with natural and sexual selection. However, the role of natural and sexual selection driving variations in testes size asymmetry among species of anurans are largely unknown. Here, we studied the patterns of variations in testes size asymmetry and the factors shaping its variations among 116 anuran species. The results indicated that the left size-biased testes in 110 species (94.83% of 116 species) is more common than the right size-biased testes in six species. For all studied species, the degree of testes size asymmetry was positively associated with relative livers and body fat mass, following the prediction of the packaging hypothesis. We also found that the postcopulatory sperm competition (e.g., residual testes size) was positively associated with the degree of testes asymmetry. However, environmental stress (e.g., high latitude, precipitation seasonality and temperature seasonality) did not promote more symmetrical testes for all species. Our findings suggest that both natural selection for larger livers in body space and sexual selection for rapid increase in testis mass for most species during the breeding season can play key roles in driving in testes size asymmetry across anuran species.
TL;DR: In this paper , a statistically significant relationship between the overall facial asymmetry and the number of children born was found, which was mediated by the age at first reproduction, however, the size of the effect was rather low.
Abstract: OBJECTIVES
The level of fluctuating asymmetry is suggested as a putative signal of developmental stability, thus according to this theoretical framework more symmetric individuals should be in better biological condition and have greater reproductive potential. Here we hypothesize that women with more symmetric faces have more successful reproduction.
METHODS
Data were collected from 164 postmenopausal Polish women. Facial photographs were taken and the overall facial asymmetry (OFA) was calculated. The associations between the OFA and reproductive parameters were analyzed using multiple regression models. Furthermore, the mediation analysis was conducted to test for the indirect effects of the OFA on reproductive success.
RESULTS
There was a statistically significant relationship between the OFA and the number of children born, which was mediated by the age at first reproduction (p = 0.03), however, the size of the effect was rather low. Women with more symmetric faces had an earlier age at first reproduction and, in consequence, a greater number of children.
DISCUSSION
As fluctuating asymmetry is suggested to be established in utero, these findings shed light on the possible life-long importance of developmental conditions in shaping women's reproductive potential and performance.
TL;DR: In this article , the authors investigated whether the degree of fluctuating asymmetry in fallow deer antlers was associated with breakage or with tactical investment in fighting and found no relationship between FA and contest tactics.
Abstract: The horns and antlers borne by the males of many species of ungulate are considered to be both badges of quality, and armaments for use during intraspecific combat. Underpinning arguments concerning their dual utility is the idea that these structures should be costly to produce in order that the signal value of the structure is maintained. In agreement with such theorising is the belief that fluctuating asymmetry (FA), small deviations from symmetry around a mean of zero, measures individual quality as it represents the ability of the individual to withstand stress. We investigated whether the antlers of fallow deer indicated something of the quality of the bearer by assessing whether the degree of antler FA was associated with breakage (i.e., badge of quality) or with tactical investment in fighting (i.e., armament). We show the anticipated relationship between FA and antler damage, however, there was no relationship between FA and contest tactics. The present study, therefore, shows partial support for the idea that the magnitude of fluctuating asymmetry expressed by weaponry is related to individual quality.
TL;DR: In this article , different morphological and ecological traits and indices of abiotic and biotic stressors (such as head size and shape, fluctuating asymmetry, body condition index, tail autotomy, and population abundance) were analyzed in alpine and subalpine populations of two lacertid species (Zootoca vivipara and Lacerta agilis) from Serbia and North Macedonia.
Abstract: Alpine habitats are exposed to increasing anthropogenic pressure and climate change. The negative impacts can lead to chronic stress that can affect the survival and reproductive success of individuals and even lead to population extinction. In this study, we analyse different morphological and ecological traits and indices of abiotic and biotic stressors (such as head size and shape, fluctuating asymmetry, body condition index, tail autotomy, and population abundance) in alpine and subalpine populations of two lacertid species (Zootoca vivipara and Lacerta agilis) from Serbia and North Macedonia. These lizards live under different conditions: allotopy/syntopy, different anthropogenic pressure, and different levels of habitat protection. We found differences between syntopic and allotopic populations in pileus size, body condition index (in both species), pileus shape, fluctuating asymmetry (in L. agilis), and abundance (in Z. vivipara). Differences between populations under anthropogenic pressure and populations without it were observed in pileus shape, body condition index (in both species), pileus size, fluctuating asymmetry, tail autotomy and abundance (in L. agilis). On the basis of our results, it is necessary to include other stress indicators in addition to fluctuating asymmetry to quickly observe and quantify the negative effects of threat factors and apply protective measures.
TL;DR: In this article , the authors describe amounts of asymmetry in collegiate cross-country runners and compare different methods of calculating asymmetry between limbs, using independent t-tests to determine statistical differences in variables between legs.
TL;DR: In this article , measurements of otolith asymmetry between hatchery and natural origin Coho Salmon Oncorhynchus kisutch from three different river systems were compared to assess the overall differences in asymmetry when the calcium carbonate polymorph is accounted for.
Abstract: Many aspects of natural and hatchery origin salmonid genetics, physiology, behaviour, anatomy, and life histories have been compared due to concerns about what effects domestication and hatchery rearing conditions have on fitness. Genetic and environmental stressors associated with hatchery rearing could cause greater developmental instability, and therefore a higher degree of fluctuating asymmetry in various bilaterally paired characters, such as otoliths. However, to appropriately infer what effect developmental instability has on otolith asymmetry, otolith mineralogy must be accounted for. Vateritic otoliths differ substantially from aragonitic otoliths in terms of mass and shape and can artificially inflate any measurement of fluctuating asymmetry if not properly accounted for. In this study, measurements of otolith asymmetry between hatchery and natural origin Coho Salmon Oncorhynchus kisutch from three different river systems were compared to assess the overall differences in asymmetry when the calcium carbonate polymorph is accounted for. 59.3% of otoliths from hatchery origin O. kisutch were vateritic compared to 11.7% of otoliths from natural origin O. kisutch. Otolith mineralogy, rather than origin, was the most significant factor influencing differences in asymmetry for each shape metric. When only aragonitic otoliths were compared, there was no difference in absolute asymmetry between hatchery and natural origin O. kisutch. We recommend that other researchers assess otolith mineralogy when conducting studies regarding otolith morphometrics and otolith fluctuating asymmetry. This article is protected by copyright. All rights reserved.
TL;DR: In this article , facial asymmetry and facial disharmony have been found to have an influence on mate rejection by men in a study with self-declared heterosexual men who were asked to reject one of the faces as a potential mate for a longterm relationship.
Abstract: Investigations on mate choice in humans frequently report preferences, but there is little knowledge about what is important for rejection by a potential mate. The present study aims to verify if facial asymmetry and facial disharmony have an influence on mate rejection by men. We hypothesized that more asymmetric and disharmonious faces would be more rejected. For this purpose, photographs of women’s faces were presented in pairs by self-declared heterosexual men. It was requested they reject one of the faces as a potential mate for a long-term relationship. Women’s faces were also analyzed to measure facial asymmetry and facial disharmony. We used a linear mixed model to evaluate the effect of the cited metrics on each face’s number of rejections. We found that the female metrics influenced mate rejection only if associated with male age and income. The older participants rejected female partners with asymmetric faces. We suggest that aging makes men more demanding in mate choices, at least considering facial asymmetry. We concluded that rejection could be a key variable in mate choice studies, but further research is needed to clarify its effects.
TL;DR: In this article , three methods were used to determine the fluctuating asymmetry (FA) of leaf blades and the developmental stability of smallleaved linden (Tilia cordata Mill): the normalizing difference method, the sample normalization method, and the two-factor analysis method (FA10).
Abstract: Three methods were used to determine the fluctuating asymmetry (FA) of leaf blades and the developmental stability of smallleaved linden (Tilia cordata Mill): the normalizing difference method, the sample normalization method, and the two-factor analysis method (FA10). The collection of leaf blades took place along the latitudinal zonality gradient from north to south in five cities from Murmansk (68°58′ N) to Mozhaisk (55°30′ N), including the cities of Apatity, Petrozavodsk and Saint Petersburg. In all analyses, the highest FA value was obtained in the population of Petrozavodsk, the lowest in the population of Mozhaisk. In other cities, the FA indices differed, except for the populations in Apatity and Petrozavodsk with FA10 indices, respectively, 0.02 (p=0.02) and 0.03 (p=0.01). In the northernmost population (Murmansk), no decrease in developmental stability was noted. The stability of the development of Tilia cordata was more strongly influenced by the climatic and geographical conditions of the area and the technogenic state of the environment than by the geographic latitude. The authors note that a non-parametric sample distribution is advisable to use the two-factor analysis of variance, since normality difference and normalization lead to a non-equivalent deviation of the results. Bonferroni’s adjustments for measurement error were convenient for accurately distributing FA values at significance level.
TL;DR: This paper analyzed the relationship between fluctuating asymmetry (FA) and the mean values of character measurements in a set of morphological traits and proposed a two-dimensional complex to demonstrate the uniformly negative slopes of standardized FA vs. mean value regressions.
Abstract: This study addresses the problem of concordance in fluctuating asymmetry (FA) across traits by analyzing the relationship between FAs and the mean values of character measurements in a set of morphological traits. Regression slopes vary in natural populations, thus, revealing discordance in FA across traits among these populations. Hence, commonly accepted techniques for measuring developmental instability with FA result in uncertainties. Here, I relate FA to mean as a two-dimensional complex to demonstrate the uniformly negative slopes of standardized FA vs. mean value regressions for sets of morphological traits from eighteen distinct natural marine and aquatic populations. Comprehensive analysis of the FA–mean complex cannot be recommended for wide use in assessing stress and fitness, but it offers promise to improve FA measuring methodologies and to better understand the nature of developmental instability.
21 Mar 2023
TL;DR: In this article , the authors compared the degree of back symmetry in two groups of subjects with and without pathologic facial asymmetry and assessed any possible associations between face and back asymmetry evaluated on three-dimensional surface faces and back scans.
Abstract: The aim was to compare the degree of back symmetry in two groups of subjects with and without pathologic facial asymmetry and to assess any possible associations between face and back asymmetry evaluated on three-dimensional surface face and back scans.The study design consisted of allocation of 70 subjects (35 females, 35 males) aged 6.4±0.5 years, according to the percentage of whole face symmetry assessed on three-dimensional (3D) facial scans into a 'symmetric' (symG; symmetry ≥70%) and 'asymmetric'(asymG; symmetry <70%). The 3D face and back scans were analysed using colour deviation maps and percentages of symmetry of the whole face and back surfaces as well as their three separate areas: forehead, maxillary and mandibular areas for the face and neck, upper and middle trunk areas for the back, were calculated. Non-parametric statistical tests were used for between-group comparisons (Mann-Whitney U test). Within each group, differences between each face or back area were tested with the Friedman test. Correlations between face and back symmetry were assessed with the Spearman rho coefficient.The symG exhibited a significantly higher symmetry in each facial area than the asymG. The mandibular area was the least symmetric area of the face within each group, with significantly smaller values than the maxillary area in the symG and significantly smaller values than the forehead and maxillary area in the asymG. The percentage of whole back symmetry did not significantly differ (p>0.05) between the symG ( 82.00% [67.4;88.00]) and asymG (74.3% [66.1;79.6]). The only significant between-group difference was observed for the symmetry of the upper trunk area (p=0.021), with lower symmetry values in the asymG. No significant associations were detected between face and back parameters.The percentages of symmetry in each facial area were significantly higher among subjects without pathologic facial asymmetry. The most asymmetric area of the face, regardless of the degree of whole face symmetry, was its mandibular area. No significant differences were detected within different back areas; however, subjects with asymmetric faces showed significantly smaller symmetry of their upper trunk area.
TL;DR: In this article , the authors assess the environmental impact of urbanization in three freshwater biotopes, using the levels of fluctuating asymmetry (FA) in 10 meristic morphological traits in the Marsh Frog (Pelophylax ridibundus).
Abstract: In this paper, we assess the environmental impact of urbanization in three freshwater biotopes, using the levels of fluctuating asymmetry (FA) in 10 meristic morphological traits in the Marsh Frog (Pelophylax ridibundus (Pallas, 1771)). Two of the studied biotopes are located in the boundaries of the city of Plovdiv (one in the central part, the other in a suburban residential area), and the third is located in the vicinity of the village of Orizare. Our working hypothesis is based on the assumption that urban and suburban sites are more severely affected by human activities than rural sites. However, according to our results, the population of P. ridibundus inhabiting Maritsa River in the central part of Plovdiv City, and that in the suburban zone, have found relatively good living conditions. Contrary to our expectations, the worst environmental conditions were observed in the rural zone, where anthropogenic stress related to intensive pastoral animal husbandry and crop farming was present. The absence of adult individuals in the rural site is also an indicator of unfavorable living conditions.
TL;DR: In this paper , the influence of population density on fluctuating asymmetry of the adult's ventral body was investigated. But contrary to the hypothesis that environmental stress caused by higher density would increase its level, the study showed that population density did not influence fluctuating abnormality of S. oryzae adults.
TL;DR: In this article , the authors investigated the sensitivity of a sexually dimorphic trait, forewing morphology, to an early life environmental stressor, and found that males were more sensitive to shape changes due to stress than females.
Abstract: Purpose In many Orthopteran species, including crickets, forewings exhibit substantial sexual dimorphism driven by sexual selection. In the cricket, Acheta domesticus, females are the "choosy" sex and males exhibit multiple sexual signals to attract and successfully mate. Male forewings have highly specialized structures critical for acoustic signaling and mating. In contrast, female forewings currently serve no known purpose in this flightless species. Forewings also differ morphologically with male forewings containing complex acoustic producing and resonating regions and females lacking any defined structures. Due to their importance to mating as well as their structural complexity, impacts of environmental stress that target cricket forewing development may therefore have more severe consequences in males than females. Here, we investigate the sensitivity of a sexually dimorphic trait, forewing morphology, to an early life environmental stressor. Materials and Methods: We applied ionizing radiation (0-27.8Gy) as a stressor as dose can be precisely applied as well as its relevance in both environmental contamination and use in the Sterile Insect Technique. Results: A canonical variate analysis indicated that wing shape was significantly altered in males at all doses; 0.58Gy, 2.3Gy, 4.6Gy, 16.2Gy, and 23.2Gy. In females, shape was significantly altered at 27.8Gy and 23.2Gy groups and to a lesser extent at 0.58Gy and 16.2Gy. Linear regression analysis of centroid size indicated a dose dependent decline in wing size in both sexes, with males exhibiting more decline. Fluctuating asymmetry, a measure of environmental sensitivity, revealed that males were more sensitive to shape changes due to stress than females. This difference in sensitivity is likely due to the complexity of male forewings. Conclusion: These results expand understanding of sex dimorphism in stress responses and sensitivity to ionizing radiation.
TL;DR: In this paper , the authors assessed the geographic variation in otoliths' shape and size and the effect of potential fluctuating asymmetry (FA) in the otolith size on the stock structure of Mullus barbatus collected from the Bizerte and Ghar El Melh lagoons located in northeastern Tunisia.
Abstract: This study aimed to assess the geographic variation in otoliths’ shape and size and the effect of potential fluctuating asymmetry (FA) in otolith size on the stock structure of Mullus barbatus collected from the Bizerte and Ghar El Melh lagoons located in northeastern Tunisia and to evaluate the relationship between the otolith mass asymmetry (OMA) and total length (TL). Analysis of the otolith shape showed a statistically significant intersexual shape difference, i.e. asymmetry, in the left and right and left-left and right-right otoliths between populations of the two lagoons. In addition, significant intersexual differences were detected in Lo, Wo, and Mo, as well as in FA, between the left and right otoliths among the two populations. Moreover, no statistically significant relationship (P > 0.05) was found between OMA and TL between and within the two populations. At the intrapopulation level, a significant intrasexual asymmetry was observed in the left and right, as well as on left-left and right-right sides, otoliths’ shape and size only within the Ghar El Melh lagoon. Discriminant function analysis of the otoliths’ contour shape confirmed the presence of two separate stocks representing the Bizerte and Ghar El Melh lagoons, which should be managed separately. This significant inter and intrapopulation asymmetry detected in otolith shape and size due to FA can be attributed to the instability of larval development caused either by environmental stress associated with variation in water temperature, salinity, feeding conditions and pollutants or due to poor living conditions of larvae resulting from unfavourable environments.
TL;DR: In this paper , the authors examined the directional asymmetry in the gonad length of 20 species of moray eels (Muraenidae) and two outgroup species with 2959 individuals and found that the degree of asymmetry varied among species and was not significantly related to taxonomic closeness.
Abstract: Directional asymmetry indicates a unidirectional deviation from perfect bilateral symmetry, which was rarely examined in the inner organs of the teleost (Teleostei) compared to external traits. This study examines the directional asymmetry in the gonad length of 20 species of moray eels (Muraenidae) and two outgroup species with 2959 individuals. We tested three hypotheses: (1) moray eel species did not exhibit directional asymmetry in the gonad length; (2) the directional asymmetry pattern was the same for all selected species; (3) the directional asymmetry was not related to the major habitat types, depth and size classes, and taxonomic closeness of the species. Moray eels were generally "right-gonadal", the right gonad length being constantly and significantly longer than the left one in all studied Muraenidae species. The degree of asymmetry varied among species and was not significantly related to taxonomic closeness. The habitat types, depth, and size classes had intermingled effects on observed asymmetry without a clear correspondence. The directional asymmetry in the gonad length is a unique and widely occurring phenomenon in the Family Muraenidae, which was likely a by-product in the evolutionary history without significant disadvantage in survival.
TL;DR: In this paper , the authors present a review of studies analyzing bilateral asymmetries in specific (in-water tests) and nonspecific (dry-land tests) swimming contexts and investigate the effects of interlimb asymmetry on swimming performance.
Abstract: The objectives of this review were to (a) map the studies analyzing bilateral asymmetries in specific (in-water tests) and nonspecific (dry-land tests) swimming contexts and (b) investigate the effects of interlimb asymmetries on swimming performance. Searches were systematically conducted on 4 databases. Of 768 studies examined, 60 were eligible for the final selection (https://osf.io/46gya). Twenty-eight studies analyzed asymmetries during in-water tests, with asymmetry values ranging from 2.7 to 60.0%, and most studies (n = 18) reported significant between-limb differences (p < 0.05). Asymmetries were also analyzed during dry-land tests in 24 studies, with asymmetry values ranging from 1.1 to 16.6%. Interestingly, most of these studies (n = 12) did not verify any significant between-limb differences (p > 0.05). Eight studies measured asymmetries in both contexts and reported asymmetry values from −24.1–17.4%, with 4 studies finding significant differences between body sides (p < 0.05). Seven of the 60 studies selected investigated the relationship between asymmetries and swimming performance, with 5 reporting no meaningful associations. In conclusion, significant asymmetries in swimming are more evident during in-water than during dry-land tests. In addition, the few studies investigating asymmetries' influence on swimming performance reported that asymmetries rarely impact swimming performance.
TL;DR: In this paper , the authors examined the spatial variation in otolith morphology (shape and asymmetry) and genetic composition of 395 wild-caught Gilthead seabream (Sparus aurata) specimens, collected from the Aegean and Ionian Seas (eastern Mediterranean) between 2014-2018.
Abstract: Reliable stock identification constitutes an integral component of effective fishery management. Current methods for the identification of putative stock units comprise the analysis of both phenotypic and genetic variability. The present study examined the spatial variation in otolith morphology (shape and asymmetry) and genetic composition of 395 wild-caught Gilthead seabream (Sparus aurata) specimens, collected from the Aegean and Ionian Seas (eastern Mediterranean) between 2014–2018. The degree of scale regeneration (SRD, % of regenerated scales) was used as an indicator to assess the potential presence of aquaculture escapees in the wild-caught samples. Otolith shape and asymmetry analyses showed a phenotypic discrimination between northwestern Aegean and Ionian Gilthead seabream populations. Genetic analyses of nine microsatellite markers revealed higher levels of genetic variation in the wild compared with samples obtained from aquaculture farms. Despite the absence of genetic structure among the wild-caught seabream populations, a low but statistically significant genetic differentiation was found between reared fish and fish collected in the field. The SRD was considered effective in detecting the presence of aquaculture escapees that may have escaped in either early or late rearing phases.
TL;DR: The transfer function and matrix evolution make it possible to have a rational interpretation regarding the existence of the ''global'' symmetry and the stability of any object be it natural or artificial, living or non-living as discussed by the authors .
TL;DR: In this paper , the authors examined the association between flight muscle development and morphological wing variation in T. infestans individuals, and found that the underdeveloped flight muscle was associated with a decrease in wing developmental stability, canalization and a morphological aspect of wings.
Abstract: Triatoma infestans, the primary vector of Chagas disease in southern South America, is reported as a dimorphic species for flight muscle development and presents a marked phenotypic plasticity in traits related to flight. In triatomines, studying the relationship between flight muscle development and wing variation is important, since it involves flight capacity and dispersion. Therefore, we examined the association between flight muscle dimorphism and morphological wing variation in T. infestans individuals. We hypothesized that if the underdeveloped flight muscle were associated with a decrease in wing developmental stability, canalization and morphological aspect of wings, and with a loss of wing modularity, then wing variation would be associated with flight muscle dimorphism. Wing size and shape were characterized using geometric morphometrics. Patterns of canalization, developmental instability, and modularity were inferred from fluctuating asymmetry analysis of wing shape. Morphological aspects of wings were estimated using maximum wing length and wing area. The results showed that there are differences in wing shape but not in wing size among groups. Canalization and developmental stability were positively associated in individuals with muscle development and negatively associated in individuals with underdeveloped flight muscles. The covariance structure of variation among individuals was different between groups but not for fluctuating asymmetry, both for females and males. Modularity hypothesis related to the wing subdivision into two parts, a stiff part and a membranous one, showed significant association for the variation among individuals and fluctuating asymmetry variation in females with flight muscles. Wing aspect showed that females with flight muscles exhibited more elongated and thinner wings than those without flight muscles. The results obtained in this study reveal an association between flight muscle development and forewing variation in T. infestans. Females with flight muscles have certain differential characteristics in their wings that would be related to an enhanced flight performance.