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

Abstract

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.

Developmental stability, canalization and phenotypic plasticity in annual herbaceous species under different biotic and abiotic conditions

“…Both developmental stability and canalization emerge as by-products of regulatory complexity and redundancy in developmental systems and share overlapping developmental bases (Siegal & Bergman 2002). We also found FA was more likely to have positive correlations with RDPIs in all the three experiments, consistent with others (Baranov et al 2019;Gómez-Robles et al 2013;Leung et al 2017;Tonsor et al 2013). Although LF-CV or IN-CV had more negative correlations with both FA and RDPI s in EXP I, but IN-CV had more positive ones with them in EXP II.…”

“…More positive than negative correlations among FA, CV and RDPI s with higher densities and infertile soil suggested environmental stresses might have uncovered the cryptic variations at both phenotypic and genetic levels (Nijhout & Reed 2014;Snell-Rood et al 2015), leading to higher FA, greater phenotypic variations and stronger ability to avoid passive phenotypic responses to environmental stresses. And environmental factors may play a coordinated role in promoting the cooperation between plasticity, canalization and stability (Baranov et al 2019), which should be bene cial for dealing with stresses. Elgart et al (2015) showed how stress mediates tuning of developmental robustness and plasticity: when the stress is mild enough, plastic changes in some processes may prevent drastic changes in more robust traits; when the stress is su ciently severe, this buffering may no longer be able to prevent such overt changes, leading to phenotypic variability subjected to selection that might assist survival at the population level.…”

Environmental Factors Affecting the Expression of Bilateral-Symmetrical Traits in Plants

“…Genetic assimilation is the subsequent genetic fixing of the new trait in the population. Some recent experimental and theoretical works have established a quantitative basis for these classic concepts of Waddington [36].…”

Spatial Variability of Small-leaved Linden (Tilia cordata Mill.) Leaf Blade

“…Plastic variability (PI) of the size of morphological characters is often associated with asymmetry. If there is such a correlation, then the increase in FA is explained by an increase in the size of characters, but not by deviation in developmental stability [19].…”