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 <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.

No abstract

No abstract

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

In recent years, there has been a growing interest in the problem of asymmetry of bilateral traits in plants. Three types of bilateral asymmetry are found in the leaf blade, of interest to ecologists and evolutionists. A brief review of the methods used in testing bilateral asymmetry and developmental stability discusses their role in the development of homeostasis and ontogenesis. Intra-and interspecific differences are considered on the example of woody plants under the influence of factors influencing the expression of bilaterally symmetry. The influence of stress on the manifestation of asymmetric traits is considered. Apparently, the climate and topography of the area play a more important role, determining the plastic and fluctuating variability. The relationship of plasticity, evolutionary canalization, and development stability is considered on the example of woody and cultivated plants. Plasticity and fluctuation variability are in a relationship coordinated by climatic conditions, primarily lighting and temperature. This, in turn, determines the mechanisms of gene regulatory networks. Thus, phenogenetics, which studies the patterns and mechanisms of gene expression and ontogenesis, is based on the data from field botanical studies of plant shape and asymmetry. Epigenetic and population studies of phenotypic variations play a role in standardizing and finding suitable plant species and varieties.