Fluctuating Asymmetry Values Research Articles

Environmental factors influencing expression of bilateral symmetrical traits

Fluctuating asymmetry (FA) is a kind of asymmetry used to assess the stability of development, as the body’s ability to regulate its development on the phylogenetic level. Phenotypic plasticity helps plants to overcome negative effects of temperature variability, and allow to adjusting traits to adverse conditions. The aim of the study is to evaluate the level of plasticity and fluctuating asymmetry in leaf blade under influence of environmental factors. The leaf blades from urban population linden, Tilia spp. located in Moscow region, Russia were used. Fluctuating asymmetry was measured as FA = L – R / (L + R) in absolute value (L and R – left and right value of bilaterally symmetrical metric trait. Plastic variability was measured as PL = 1 – x/X (x and X – smallest and largest value of trait size). When some traits of a leaf blade had a high plasticity, other ones exposed instability of development with an increased FA value. The correlation PL - FA was changeable. In one site correlation r was – 0.69 (p<0.05; 2014; high temperature in May, up to 60% higher norm). The cold and humid vegetative season in 2017 revealed an increase in the plastic dimensions of leaf blades of the broad-leaved linden (Tilia platyphyllos Scop.) with increasing plastic variability of bilateral traits. We attribute results to the phenotypic deviation caused by low temperatures. The predominance of one type of variability was compensating by the weakness of other type variability most likely due to genetic epistasis.

Conjugacy of two types of phenotypic variability of small-leaved linden

The properties of five bilaterally symmetrical features of the leaf blades of the small-leaved linden (Tilia cordata Mill.) in four populations of the Moscow Region in 2014–2017 were studied. The angle trait was excluded, because it possessed the property of directional asymmetry. Instead, a new linear trait was used: the distance between the base of the second vein of the first order and the base of the first vein of the second order on the first vein of the first order. The population difference in fluctuating asymmetry (FA) was found only in the first two traits (leaf width and distance between the bases of the first vein of the first order and the second vein of the second order). The largest value of FA was in the urban environment, the smallest was in the rural areas. A weak negative correlation was obtained between the magnitude of linear characteristics and the value of FA, as well as a weak positive correlation relationship between the values of FA in five traits. The first trait had the highest fluctuation variability, and the second one had the highest plastic variability. The regression dependence of the fluctuation variability on the plastic variability (b1 = 0.25, p &lt;0.05) and the dependence of these two types of variability on the interaction of the factors “year” and “site of sampling” were revealed. Thus, the conclusion was made about the conjugacy of two types of variability: fluctuation and plastic. According to the authors, asynchronous growth, competition for light in conditions of high solar activity in 2014–2016 compared to the abnormal wet summer of 2017 led to an increase in FA due to destabilization of mechanisms of growth and regulation of gene expression, which contributed to a decrease in the stability of development. The increase in FA and the decrease in the developmental stability in urban ambient in 2016 could be due to: a)an intensive flow of vehicles in spring and summer, b) a high level of groundwater in this part of the city and c) increased hydrolytic acidity of the soil.

Fluctuating asymmetry of two crustacean species on fourteen sandy beaches of Rio de Janeiro State

Sandy beaches are the most frequented coastal environments in the world, and they consequently suffer different types of impacts due to the rapid urban occupation and demographic growth in coastal regions, which generate stressful conditions for the resident species and reduce the environmental quality of the beaches for resident species. Crustaceans can be used as reliable bioindicators of human stress, and the amphipod Atlantorchestoidea brasiliensis and the decapod Emerita brasiliensis are highlighted. One tool for evaluating the environmental quality and the instability of individual development is fluctuating asymmetry (FA), which measures small, random deviations from a perfect bilateral symmetry. To evaluate the environmental quality of the beaches, some indices have been developed in recent years; among the most used are the conservation, recreation and urbanization indices, which offer easy-to-use metric for decision makers. This study aimed to quantify and compare the levels of FA in the populations of A. brasiliensis and E. brasiliensis on 14 beaches in Rio de Janeiro State with different levels of urbanization and conservation. For each species, two individual indices and two composite indices of asymmetry were calculated and tested in four bilateral traits. The urbanization, recreation and conservation indices were used to assess environmental quality of the sandy beaches. The results of the present study indicate a complex spatial distribution of FA in relation to the indices of the environmental quality of the beaches. The beaches that obtained the highest values in the conservation index obtained the lowest values of FA for both species. The beaches located in the Metropolitan region, specifically in the city of Rio de Janeiro, generally presented the highest levels of FA for both species. These species are susceptible to different forms of impacts due to their distinct characteristics in feeding behavior, development mode and beach zone occurrence. A. brasiliensis is more susceptible to direct impacts on the beach, such as recreational activities, while E. brasiliensis is more sensitive to impacts on water (contamination and physicochemical changes). Our results indicate that fluctuating asymmetry can be used as a good tool to evaluate impacts on sandy beaches, but additional studies should be conducted to improve the understanding of the spatial distribution of FA on sandy beaches.

Can the use of landmarks improve the suitability of fluctuating asymmetry in plant leaves as an indicator of stress?

Fluctuating asymmetry (FA), defined as the random deviations from symmetry in morphological traits, has repeatedly been suggested as a handy indicator of genetic and environmental stress experienced by organisms during their development. However, the value of FA for applied ecological and environmental research is now questioned by a growing number of studies that have found no increases in FA under stress. We used geometric morphometrics to test the hypothesis that FA measures based on naturally defined landmarks are better suited for detection of deviations from leaf symmetry than are traditional measures of FA. We compared two sets of mountain birch (Betula pubescens ssp. czerepanovii) leaves, obtained from trees growing in industrially polluted natural populations and from experimentally stressed seedlings, by examining three measures of FA: 1) a traditional distance-based measure calculated from the width of the left and right halves of a leaf at the middle of the lamina (FAwidth), 2) a distance-based measure reflecting differences in vein length calculated from three landmarks (FAveins), and 3) a multivariate FA measure describing asymmetry in leaf shape based on five landmarks (FAshape). These three FA measures were poorly (albeit positively) correlated with each other. The two distance-based measures reflected different parts of the multivariate measure FAshape, which had the highest sensitivity for detection of deviations from leaf symmetry. FAshape was also the only FA measure that weakly confirmed the expected increase in FA under experimental stress, and particularly under stress caused by application of heavy metals. However, very high levels of within-individual variation in asymmetry remain to be explained, and even FAshape did not show the expected effects of industrial pollution on leaf symmetry. We conclude that FA in birch leaves cannot be regarded as a reliable indicator of environmental stress, even when quantified using modern methods.

Fluctuating Asymmetry as a Bioindicator of Environmental Stress Caused by Pollution in a Pioneer Plant Species.

Fluctuating asymmetry (FA) is a widely used tool to detect developmental instability and plants under stressful conditions are expected to exhibit increased values of asymmetry, as well as higher levels of herbivory. This study evaluated whether dust from roads can cause major deviations in the axis of symmetry of leaves of the pioneer plant species Cecropia pachystachya Trécul (Urticaceae). It was also investigated whether plants exposed to dust have greater nitrogen content and higher levels of herbivory levels. Ten leaves of 20 individuals of C. pachystachya were collected on two roads with different levels of dust deposition and a control area. FA was calculated as the size-scaled difference between the right (RW) and left (LW) leaf widths and leaf area removed was determined by the ratio between leaf area removed and total leaf area. C. pachystachya plants in areas under strong influence of dust pollution exhibited the highest FA values (0.279 cm), whereas plants in the control area exhibited the lowest. A positive relationship between levels of leaf area removed by insects and a gradient of dust pollution was also observed. Differences in foliar nitrogen concentration among sampling areas indicated differences in leaf quality and influenced herbivory levels of Cecropia. This study indicated that FA can be used as an indicator of developmental instability of plants and those individuals under the impact of road dust and pollution might be more susceptible to insect attack.

Fluctuating Dental Arch Asymmetry in Different Malocclusion Groups.

ObjectiveTo compare the degree of dental arch fluctuating asymmetry (FA) among patients with Class I, II, and III malocclusions.Subjects and methodsThe sample comprised randomly selected plaster casts of 131 patients: 39 Class I (19 males and 20 females), 57 Class II (23 males and 34 females), and 35 Class III (20 males and 15 females). Dental models were scanned and digitized using ATOS II SO. The measurements of the teeth and dental arches were taken using the ATOS viewer version 6.A.2 software. Six arch widths and five arch depths were measured. The FA was assessed as a composite index of total weighted asymmetry (TWA). The analysis of variance was used to determine whether there were any statistically significant differences between the groups.ResultsComposite TWA measures of fluctuating asymmetry for dental arch variables were the highest in Class III, and lowest in Class I malocclusion. Males displayed a higher degree of asymmetry than females. The asymmetry degree was higher in the mandibular dental arches than in the maxillary dental arches in all malocclusion groups.ConclusionThe TWA values were low but they differed significantly between the groups of malocclusion. Class III malocclusion displayed higher FA values than Class I and Class II malocclusion. Higher FA of dental arches in Angle’s Class III can be considered an indicator of increased developmental instability in this malocclusion due to high levels of genetic and environmental stress during the period of early development.

Tri-Trophic Impacts of Bt-Transgenic Maize on Parasitoid Size and Fluctuating Asymmetry in Native vs. Novel Host-Parasitoid Interactions in East Africa.

Environmental stress can affect trait size and cause an increase in the fluctuating asymmetry (FA) of bilateral morphological traits in many animals. For insect parasitoids, feeding of hosts on transgenic maize, expressing a Bacillus thuringiensis toxin gene is a potential environmental stressor. We compared the size of antennae, forewings, and tibia, as well as their FA values, in two parasitoids developed on two East African host species feeding on non-transgenic vs. transgenic maize. The two lepidopteran stem-borer hosts were the native Sesamia calamistis Hampson (Lepidoptera: Noctuidae) and a recent invader, Chilo partellus Swinhoe (Lepidoptera: Crambidae). The two braconid parasitoids were the native, gregarious larval endoparasitoid Cotesia sesamiae and the recently introduced Cotesia flavipes. Both parasitoids attacked both hosts, creating evolutionarily old vs. novel interactions. Transient feeding of hosts on transgenic maize had various effects on FA, depending on trait as well as the host and parasitoid species. These effects were usually stronger in evolutionarily novel host–parasitoid associations than in the older, native ones. These parameters have capacity to more sensitively indicate the effects of potential stressors and merit further consideration.

Screening of the state of urban ecosystem with the use of bioindication method (on the example of Kazan city)

The urban environment is a complex of natural, natural-anthropogenic and socioeconomic factors that exert a large and diverse impact on urban residents. In addition to traditional environmental monitoring, we propose to use a new bioindication method based on the evaluation of morphological changes in the leaves of Betula pendula Roth by fluctuating asymmetry (FA) to assess the quality of recreational areas. Such screening for the purpose of assessing of the environment state is very informative, since the bioindication assessment is an integral characteristic of the quality of the environment which is under the influence of all the abundance of chemical, physical and other factors. The two-sided symmetry of a leaf was calculated on the sites in the middle of the park zone, on the border of the park and on a roadside strip. The results of the study showed a connection between the FA values and the distance to the highway, and also revealed the absence of significant differences in FA indicators at the surveyed sites, which may indicate insufficient sizes of recreational areas and their insufficient potential to contribute to improving the quality of the environment.

Experience of applying plant and animal fluctuating asymmetry in assessment of environmental quality in terrestrial ecosystems: Results of 20-year studies of wildlife and anthropogenically transformed territories

The value of fluctuating asymmetry (FA) of trees and small mammals is considered as an indicator of developmental instability. The urban territories with recreation zones, sites with increased radiation background, and the areas affected by mining facilities have been analyzed as anthropogenically transformed areas. The following tree and small mammalian species are the objects of the study: Siberian silver birch (Betula platyphylla), spreading birch (B. divaricata), dwarf birch (B. exilis), shrub alder (Duschekia fruticosa), basket willow (Salix viminalis), northern red-backed vole (Clethrionomys rutilus), tundra vole (Microtus oeconomus), Laxmann’s shrew (Sorex caecutiens), and tundra shrew (S. tundrensis). In total, 60000 leaves have been measured and 3500 rodent sculls have been examined. The issues of selection of bioindicator species and the factors distorting the results of environmental quality assessment according to developmental instability are discussed. A statistically significant increase in FA of plants is recorded in urban territories as compared with the wildlife biotopes. A positive correlation of FA value with transport load, concentration of heavy metals in soil, and atmospheric air pollution is observed. The proximity to a roadway and the state of road pavement influence the FA value. The main source of pollution in the administrative center (Yakutsk) is motor vehicles; correspondingly, large streets and crossroads with a high transport load are the most polluted sites. As for the industrial center (city of Mirnyi), pollution spreads from the areas affected by mining to the residential area. The main pollution source in a small administrative center (city of Aldan) is the federal highway. It is recommended to concurrently use the FA characteristics of plant and animals in the area affected by the mining industry. Characteristic of this industry is withdrawal of large areas of natural landscapes; typically, transformed plots alternate weakly affected plots. The specific features of the effects of diamond, gold, and coalmining industries, as well as oil and gas field development, are discussed, which should be taken into account in sampling for bioindication. The problem of bioindication in the areas completely devoid of soil and plant cover can be solved by biotesting via assessment of bunching onion seed germination rate and the rate of mitotic aberrations. An increase in the FA level in trees and small mammals is observed in the areas transformed by the mining industry displaying a chronically increased radiation background and oil-polluted as a result of technogenic accidents. The use of FA index makes it possible to estimate the environmental quality and to compare the state of territories located under different natural and climatic conditions and influenced by multicomponent anthropogenic impacts differing in their strength and genesis, which interferes with their comparison.

Fluctuating asymmetry of birch leaves did not increase with pollution and drought stress in a controlled experiment

Fluctuating asymmetry (FA), defined as small, non-directional deviations from perfect symmetry in morphological characters, is often recommended as a handy indicator of environmental stress. A reliance on observational data to provide empirical evidence for the effects of different stressors on FA, in combination with increasing attempts to use FA in environmental research, underscore the need for careful examination of the relationships between environmental stress and FA. We experimentally tested the hypotheses that (i) heavy metal and drought stress increase the leaf FA in plants, and that (ii) plants persisting in heavily polluted sites possess greater stress tolerance and therefore show smaller increases in leaf FA in response to heavy metals than do plants from unpolluted sites. We collected mountain birch, Betula pubescens subsp. czerepanovii, seeds from eight polluted and ten unpolluted sites and reared the seedlings in a sophisticated greenhouse (phytotron). We compared leaf FA between control seedlings, seedlings irrigated with water containing copper and nickel sulphates, and seedlings exposed to drought. Leaf FA showed no response to either heavy metals or drought, despite significant impacts of these treatments on seedling height, leaf size and photosynthetic efficiency. This FA result was independent of the level of pollution at the site of seed origin and consistent for FA values based on low and high accuracy measurements of leaf width, as well as for FA values based on measurements of the widths and areas of leaf halves. Our findings add to accumulating evidence regarding inconsistent relationships between FA and abiotic stress, thereby questioning the indicatory value of FA. We strongly recommend that the use of FA as an indicator of environmental stress be limited to study systems for which the existence of cause-and-effect relationship between the stressing impact and the changes in FA is confirmed by controlled, blinded experiments.

Socioeconomic Status Is Not Related with Facial Fluctuating Asymmetry: Evidence from Latin-American Populations.

The expression of facial asymmetries has been recurrently related with poverty and/or disadvantaged socioeconomic status. Departing from the developmental instability theory, previous approaches attempted to test the statistical relationship between the stress experienced by individuals grown in poor conditions and an increase in facial and corporal asymmetry. Here we aim to further evaluate such hypothesis on a large sample of admixed Latin Americans individuals by exploring if low socioeconomic status individuals tend to exhibit greater facial fluctuating asymmetry values. To do so, we implement Procrustes analysis of variance and Hierarchical Linear Modelling (HLM) to estimate potential associations between facial fluctuating asymmetry values and socioeconomic status. We report significant relationships between facial fluctuating asymmetry values and age, sex, and genetic ancestry, while socioeconomic status failed to exhibit any strong statistical relationship with facial asymmetry. These results are persistent after the effect of heterozygosity (a proxy for genetic ancestry) is controlled in the model. Our results indicate that, at least on the studied sample, there is no relationship between socioeconomic stress (as intended as low socioeconomic status) and facial asymmetries.

Reproducibility of fluctuating asymmetry measurements in plants: Sources of variation and implications for study design

Fluctuating asymmetry (FA), i.e. small, non-directional deviations from perfect symmetry in morphological characters, increases under genetic and/or environmental stress. Ecological and evolutionary studies addressing FA became popular in past decades; however, their outcomes remain controversial. The discrepancies might be at least partly explained by inconsistent and non-standardised methodology. Our aim was to improve the methodology of these studies by identifying factors that affect the reproducibility of FA measurements in plant leaves. Six observers used a highly standardised measurement protocol to measure FA using the width, area and weight of the same set of leaves of 10 plant species that differed in leaf size, shape of the leaf margin and other leaf traits. On average, 24% of the total variation in the data was due to measurement error. Reproducibility of measurements varied with the shape of leaf margin, leaf size, the measured character and the experience of the observer. The lowest reproducibility of the width of leaf halves was found for simple leaves with serrate margins and the highest for simple leaves with entire margins and for compound pinnate leaves. The reproducibility was significantly lower for the weight of leaf halves than for either their width or area, especially for plants with small leaves. The reproducibility was also lower for measurements made by experienced observers than by naïve observers. The size of press-dried leaves decreased slightly but significantly relative to fresh leaves, but the FA of press-dried leaves adequately reflected the FA of fresh leaves. In contrast, preservation in 60% ethanol did not affect leaf size, but it decreased the width-based values of FA to 89.3% of the values measured from fresh leaves. We suggest that although reproducibility of leaf FA measurements depends upon many factors, the shape of the leaf margin is the most important source of variation. We recommend, whenever possible, choosing large-leaved plants with entire leaf margins as model objects for studies involving measurements of FA using the width of leaf halves. These measurements should be conducted with high accuracy from images of fresh or press-dried leaves.

The use of Procrustean analysis of variance in investigating the asymmetry of English oak sheet plates

Definition of the development stability is carried out by morphogeometric method with the use of Procrustean analysis by the value of fluctuating asymmetry (FA). Three populations of English oak (Quercus robur) in inundated oak forests of the Klyazma river have been studied. In the population being under the effect of anthropogenic stress (Vladimir city), the FA value is higher than that in Kovrovsky and Melenkovsky districts with less industrial and motor transportation load. Thus, the fluctuating asymmetry can serve as bioindication characteristic of the ecological state of English oak populations.

How reproducible are the measurements of leaf fluctuating asymmetry?

Fluctuating asymmetry (FA) represents small, non-directional deviations from perfect symmetry in morphological characters. FA is generally assumed to increase in response to stress; therefore, FA is frequently used in ecological studies as an index of environmental or genetic stress experienced by an organism. The values of FA are usually small, and therefore the reliable detection of FA requires precise measurements. The reproducibility of fluctuating asymmetry (FA) was explored by comparing the results of measurements of scanned images of 100 leaves of downy birch (Betula pubescens) conducted by 31 volunteer scientists experienced in studying plant FA. The median values of FA varied significantly among the participants, from 0.000 to 0.074, and the coefficients of variation in FA for individual leaves ranged from 25% to 179%. The overall reproducibility of the results among the participants was rather low (0.074). Variation in instruments and methods used by the participants had little effect on the reported FA values, but the reproducibility of the measurements increased by 30% following exclusion of data provided by seven participants who had modified the suggested protocol for leaf measurements. The scientists working with plant FA are advised to pay utmost attention to adequate and detailed description of their data acquisition protocols in their forthcoming publications, because all characteristics of instruments and methods need to be controlled to increase the quality and reproducibility of the data. Whenever possible, the images of all measured objects and the results of primary measurements should be published as electronic appendices to scientific papers.

Confirmation bias in studies of fluctuating asymmetry

Fluctuating asymmetry (FA) represents small, non-directional deviations from perfect symmetry in morphological characters. FA is generally accepted to increase in response to stress; therefore, FA is frequently used in ecological studies as an index of stress experienced by an organism, in particular due to environmental pollution. We experimentally tested the hypothesis that the outcomes of studies based on FA measurements may have been influenced by confirmation bias, i.e. the tendency of humans to seek out evidence in a manner that confirms their hypotheses and beliefs. We collected 100 leaves of downy birch (Betula pubescens) from a single tree, grouped them haphazardly into ten samples, scanned every sample, and then asked each of 31 scientists (experienced in studying FA) to measure FA from the scanned images of all 100 leaves. Three groups of participants were provided with false information about the origin of each sample and about the hypothesis to be tested, and one group (control) was provided with true information. The participants who believed that the leaves originated from a heavily polluted site reported significantly higher values of FA when compared to the participants who believed that the leaves were collected from an unpolluted site. When the participants were told that half the samples originated from a polluted site and half from a clean site and were asked to attribute each sample to either of these sites based on leaf FA, the differences in FA between samples classified as ‘polluted’ and ‘unpolluted’ were much higher than the differences obtained from measurements of the same sets of samples made by the control group. We conclude that when scientists expected to find high FA in some samples, the results of their measurements confirmed their expectations. This effect, classified as confirmation bias, may considerably influence the outcomes of the research on FA. This confirmation bias can be avoided by using a blind method, where the person conducting measurements is not aware of the origin of samples being measured. We argue that the use of blind methods is critically important for any study addressing environmental or genetic impacts on FA.

Breast size and asymmetry during pregnancy in dependence of a fetus's sex.

Breast size and fluctuating asymmetry (FA) are related to women's biological condition, as size correlates positively with fecundity, whereas FA correlates negatively with biological quality. We tested if breast volume, FA, and their changes during pregnancy are related to a fetus's sex. Women with bigger, symmetrical breasts, with a greater increase in size during pregnancy, should be more likely to carry a more ecologically sensitive and energetically demanding male fetus. Ninety-three women participated in a 3-stage longitudinal study. 3D breast scans were performed in the first, second, and third trimester of pregnancy. As there was a small variation in pregnancy week at each research stage between the participants, the expected breast volume and FA values for the 12th, 22nd, and 32nd pregnancy week were calculated, basing on the obtained measurements. Those values were compared between mothers who carried a boy and mothers who carried a girl. Although women who carried a boy had somewhat larger breasts at each trimester than women who carried a girl, the difference was not significant. ANOVA for repeated measurements revealed a greater breast size increase in women carrying a boy (P = 0.039). FA decreased during pregnancy, but was not related to a fetus's sex. Pregnancy-induced breast volume increase is a better cue of a fetus's sex than breast asymmetry or breast size per se, i.e., the traits that are supposed to indicate a woman's biological condition. Women with a larger increase in breast size during pregnancy are more likely to carry to term a more ecologically vulnerable male fetus.

Fear and stress measurements in pure and hybrid red-legged partridges

The purposes of this study were to examine the duration of induced tonic immobility (a reliable fear indicator considered a passive anti-predator behavioural trait) and two stress indicators (heterophil to lymphocyte ratio, and fluctuating asymmetry of leg length, middle-toe length, and wing length) in females and males of the red-legged partridge, and to analyze the differences between pure and hybrid populations. A total of 132 birds (66 pure and 66 hybrid partridges; 48 females and 84 males) at 52 weeks of age were used. There was a significant difference between pure and hybrid birds in tonic immobility duration (P<0.005) and heterophil to lymphocyte ratio (P<0.02), the duration being longer and the ratio being higher in the pure group of birds. There was a significant difference between pure and hybrid birds in the relative fluctuating asymmetry of middle toe length (P<0.002) and the combined fluctuating asymmetry value of the three traits (P<0.03). There were no significant differences between sexes in any indicator of fear or stress. Thus, pure red-legged partridges were more fearful, stressed, and asymmetrical than hybrid partridges, having increased tonic immobility duration, heterophil to lymphocyte ratio, and relative fluctuating asymmetry. Results indicate that levels of fear and stress, e.g. tonic immobility duration, heterophil to lymphocyte ratio, and fluctuating asymmetry, are higher in the pure partridge, and that fear and stress indicators have been modified in hybrid partridges leading to more passive animals.

Fluctuating asymmetry in Pelophylax ridibundus (Amphibia: Ranidae) as a response to anthropogenic pollution in south Bulgaria

The aim of this study was to investigate the integral indicator for developmental stability, the fluctuating asymmetry (FA), in the marsh frog Pelophylax ridibundus populations that inhabit biotopes of different types (running rivers and still, dam lakes), when exposed to different types of anthropogenic pollution (domestic sewage pollution and heavy metal pollution) in south Bulgaria. A total of 920 P. ridibundus individuals were used for FA analyses over three years (2009-2011). Fluctuating asymmetry was defined by 10 morphological traits, using the index frequency of asymmetric manifestation of an individual (FAMI). In closed water basins, regardless of the nature of toxicants, the FA values in P. ridibundus populations were statistically lower than those in river populations. The FA values were constantly the highest under conditions of sustained anthropogenic pollution, with high concentrations of toxicants in rivers with domestic sewage pollution and heavy-metal pollution. The results provide better opportunities to use FA in P. ridibundus populations for bioindication and biomonitoring, and for parallel and independent analyses of the physicochemical assessment of the environmental condition.

Studies on fluctuating asymmetry (FA) for certain morphological traits in four species of the Drosophila bipectinata complex

Fluctuating asymmetry (FA) is defined as subtle deviations from perfect bilateral symmetry, evident in differences between the right and the left sides of any given trait. It is a pattern of variation between sides and measures developmental instability. Differences in the level of FA may be used for comparing developmental precision among closely related species and thus may give an idea whether developmental stability was affected during the divergence and separation of populations into distinct species. Keeping this in view, FA was studied in four species of the Drosophila bipectinata complex i.e. D. bipectinata, D. parabipectinata, D. malerkotliana and D. pseudoananassae. In females of all the four species, FA values did not vary significantly for any of the traits considered. However, in case of males, they varied significantly for Wing length (WL) and sex comb tooth number (SCTN). Also, while in females Composite fluctuating asymmetry (CFA) did not exhibit significant variation, in males it was found to vary significantly across the four species. However, Bonferroni t-tests did not reveal any consistent difference in FA levels between any two species. The magnitude of FA was found to differ significantly among traits and CFA values were found to be higher for males than females in all the four species. Therefore, it may be concluded that the level of FA shows trait specific variations and males are more prone to developmental perturbations. However, the FA levels are more or less similar in all the four species of this complex. Thus, developmental precision remains nearly same in all the four species of this complex irrespective of the degree of evolutionary divergence reached.

Evaluation of Environmental Conditions in Two Cities of East Siberia Using Bio-indication Methods (Fluctuating Asymmetry Value and Mutagenic Activity of Soils)

Bioindicational evaluation of environmental quality on the territory of Yakutsk and Mirny (East Siberia, Yakutia) has been performed. Fluctuating asymmetry (FA) value of leaves of the Japanese White Birch Betula platyphylla Sukacz. was examined and soil condition was assessed by occurrence of Mitosis Pathologies (MP) in germinating Japanese leek Allium fistulosum L. cultivated on samples of lawn soils. About 18,000 leaves and 37 soil samples (over 20,000 anaphase and telophase cells) was examined. In most samples from city territories statistically significant increase in FA and MP in comparison to unimpaired habitats was registered. Positive correlation between FA value and traffic load as well as total content of heavy metals in soil was found. On the territory of the administrative center (Yakutsk), motor transport was found to be the main source of the pollution. Consequently major streets, especially in the immediate vicinity of roadways, and crossroads with heavy traffic load suffer from pollution most. On the territory of the industrial center (Mirny) pollution spreads from technogenically impaired areas to the residential area. Developmental stability abnormalities and total mutagenic background indicate deterioration of environmental conditions as a consequence of combined impact of negative factors arising from anthropogenically transformed environment.