Studying Tilia cordata Mill. intraspecific variation on the basis of leaf bilateral asymmetry

The aim of this study was to examine the manifestations of three types of bilateral asymmetry in three experimental Tilia cordata Mill. populations and, therefore, genotypic and phenotypic manifestations in the value of bilaterally symmetric traits at the population significance level. We studied three types of bilateral asymmetry in traits of T. cordata Mill. leaves for four years (2004-2007). Annually, we gathered 100 T. cordata Mill. leaves as close as possible in size from each of three experimental areas and measured their metric characteristic. Two populations were under industrial stress (proximity of a gas station and a highway or a chemical factory). The third population was in the mixed forest (Krutovsky conservation area). We determined three asymmetry types using A Palmer and K Strobek's methodological approach. Directional asymmetry as a genotypic population trait and fluctuating asymmetry as a phenotypic population trait were statistically significant and showed high value in one population near the chemical factory in 2004. Emission values served as an indirect evidence of the genotypic variety. We noted the highest amount of emissions in industrial stress area near the chemical factory, gasoline station and highway, whereas phenotypic variety in fluctuating asymmetry manifested itself only in population near the chemical factory. Genotypic traits clearly revealed on sites and showed a correlation between genotype and phenotype that was proved by the presence of statistically significant FA and DA. Conservation zone served as a control was not marked by an amount of emissions in patterns of distribution (R - L). Thus, directional asymmetry and fluctuating asymmetry can serve as bioindicative markers of anthropogenic stress in population of T. cordata Mill. For four years of study genotypic variety revealed itself in DA (first trait) in the same population and in the same year when the FA highest value was obtained on the fourth trait (chemical factory population). It makes us conclude that some transformation of leaf shape exists, which means genotypic and phenotypic effect under chemical factory pollution stress.

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