Reduced developmental stability in Tilia cordata leaves: effects of disturbed environment

Abstract

Background and Purpose: Developmental stability (DS) or homeostasis refers to the ability of an individual to produce a consistent phenotype in a given environment. Reduced DS can result from a wide variety of environmentally (or genetically) induced perturbations. The main aim of the presented paper is to highlight the importance of the differences in ability Tilia cordata leaves to buffer their development under contrasting environmental conditions and points to the concept that developmental stability is character specific. Materials and Methods: Three different techniques were performed in this study: fluctuation asymmetry (FA) and leaf size as integrative measures of environmental stress during leaf developmental processes and within-plant variance in leaf morphology, presented as coefficient of morphological variation (CV). The study tested the hypothesis that the population from a chronically polluted area would express greater developmental instability in leaf traits. Two bilateral, linear dimensions on each leaf leaf width (LW) and lobe length (LL) were analyzed. Results: The three different measures of developmental stability all showed a trend for T cordata leaves in the polluted area to be developmentally less stable than leaves from the reference area. Leaves in the reference area were significantly larger compared with those from the polluted site. Although leaves tend to be larger on the outside of a tree's crown, the pattern found here was the reverse. Both, outside and inside leaves from the polluted area had significantly higher FAs than leaves front the sante position sampled in the reference area for both traits. Within-tree variance assessed as CV showed that LL was a more variable measure than LW Moreover, the data suggest that LL is under more selective pressure to adapt to current environmental conditions than LW. Conclusions: Obtained data suggest that T cordata leaves may represent a reliable indicator for developmental stability evaluation studies based on an assay using a combination of end-points. Furthermore, my results highlighted the differences in ability of leaf morphometric characters to buffer their development under contrasting environmental conditions.