Mean-variance relationships of leaf bilateral asymmetry for 35 species of plants and their implications

Authors: GUO, XIALI - Chinese Academy Of Sciences; Reddy, Gadi V.P.; HE, JIAYAN - Shanghai University; LI, JINGYE - University Of Alberta; SHI, PEIJIAN - University Of Gottingen

Submitted to: Global Ecology and Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2020
Publication Date: 6/12/2020
Publication URL: https://handle.nal.usda.gov/10113/6983959
Citation: Guo, X., Reddy, G.V., He, J., Li, J., Shi, P. 2020. Mean-variance relationships of leaf bilateral asymmetry for 35 species of plants and their implications. Global Ecology and Conservation. 23:e01152. https://doi.org/10.1016/j.gecco.2020.e01152.
DOI: https://doi.org/10.1016/j.gecco.2020.e01152

Interpretive Summary: A plant’s leaves, providing the basis for carbon fixation, regulation of water and heat balance plays an important role in plant growth. Leaf morphological structure, including size and shape, is an important indicator of the photosynthetic capacity of plants, which results from long-term adaptation to the environment. Studying the morphological characteristics of leaves can contribute to our understanding of how leaves interact within a particular environment in the long growing season across eco-evolutionary dynamics. In this study, we examined the leaf bilateral asymmetry of 35 species from four families (Lauraceae, Magnoliaceae, and Bambusoideae/Poaceae) to test whether the mean-variance relationships for leaf bilateral asymmetry measured at the species and family levels. The results indicated that the numerical value of the Taylor’s power law exponent of for the Magnoliaceae species was the greatest among the studied four families, indicating that the Magnoliaceae plants may have a more irregular aboveground architecture for outlines (especially the clustering of branches) and exhibit a greater heterogeneity of light intercept for leaves. Thus, species with a larger deviation from a perfect bilateral symmetry have a more heterogeneous leaf shape, which is likely to reflect the influence of light heterogeneity for the leaves on different positions of leaf morphology.

Technical Abstract: Leaf bilateral asymmetry, an important indicator of leaves that tend to be affected by the above-ground architectural structure of plants and their environments (especially light), has been poorly studied. Taylor’s power law (TPL) describes a power-law relationship between the mean and variance of a non-negative random variable, and its exponent has been demonstrated to reflect the degree of eterogeneity of the spatial distribution of plants. In this study, we checked whether the mean-variance relationship of the absolute difference in area between the left and right sides of 11396 leaves from 35 species of plants within four families followed TPL. TPL was found to hold true for each species investigated here, and the estimated TPL exponents fell within a range of 1.5 to 2.0. At the family level, there were no any significant differences in the estimated exponents of TPL among the pooled data of Lauraceae, Oleaceae, and Bambusoideae, but those exponent values were significantly smaller than that of Magnoliaceae. We also pooled the data from the four families, and we found that there was a general rule for the mean-variance relationship for the bilateral asymmetry among the studied broad-leaved plants. Given the variety of leaf bilateral asymmetry among species, our results highlight the importance of plant aboveground architecture and the heterogeneity of leaves on different positions to a better understanding of leaf development mechanism and how it responds to the surrounding environment.