Taylor’s Power Law for Leaf Bilateral Symmetry

Ping Wang,David A Ratkowsky,Xiao Xiao,Xiaojing Yu,Jialu Su,Peijian Shi,Lifang Zhang

doi:10.3390/f9080500

Ping Wang, David A Ratkowsky + Show 5 more

Open Access

https://doi.org/10.3390/f9080500

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Journal: Forests	Publication Date: Aug 16, 2018
Citations: 18	License type: CC BY 4.0

Affiliation: University of Tasmania, Nanjing Forestry University

Abstract

Leaf shape and symmetry is of interest because of the importance of leaves in photosynthesis. Recently, a novel method was proposed to measure the extent of bilateral symmetry in leaves in which a leaf was divided into left and right sides by a straight line through the leaf apex and base, and a number of equidistant strips were drawn perpendicular to the straight line to generate an equivalent number of differences in area between the left and right parts. These areal differences are the basis for a measure of leaf bilateral symmetry, which was then examined to see how well it follows Taylor’s power law (TPL) using three classes of plants, namely, 10 geographical populations of Parrotia subaequalis (H.T. Chang) R.M. Hao et H.T. Wei, 10 species of Bambusoideae, and 10 species of Rosaceae. The measure of bilateral symmetry followed TPL for a single species or for a class of closely related species. The estimate of the exponent of TPL for bamboo plants was significantly larger than for the dicotyledonous trees, but its goodness of fit was the best among the three classes of plants. The heterogeneity of light falling on branches and leaves due to above-ground architectural patterns is an important contributor to leaf asymmetry.

Highlights

The leaf is the most important organ of plant photosynthesis
The estimate based on the pooled data is 1.925 with 95% confidence intervals (CIs) (1.904, 1.946) (Figure 4), apparently larger than the estimates of the exponent of Taylor’s power law (TPL), which for most species range from 1.4 to 1.9, except for species 2, 4, and 5 whose estimates are significantly larger than the estimates of the remaining seven species (Figures 3b and 4)
These three species with large estimates of the exponent of TPL belong to the same genus Indocalamus

Summary

Introduction

The leaf is the most important organ of plant photosynthesis. The scaling relationship between leaf weight and leaf area (W = aAb , where W denotes leaf weight, A denotes leaf area, a and b are constants to be estimated) is of wide interest because the leaf dry mass per unit area (LMA = W/A = aAb −1 ) has been shown to be proportional to photosynthetic efficiency [1,2,3,4]. Leaf shape can affect the scaling relationship between leaf weight and leaf area [5], so that closely related species with a large variation in leaf shape, for example, Rosa, will have a very weak scaling relationship between leaf weight and leaf area for pooled data from those species. If the closely related species are similar in leaf shape, for example, bamboo plants, there can be a strong scaling relationship both for a single species and for pooled leaf weight and leaf area data from different species [6]. Previous studies on leaf shape paid much attention to leaf teeth and leaf anatomic structure, but largely neglected leaf bilateral symmetry [5,8]. Bilateral symmetry has attracted attention in biotic and abiotic areas, there are still few quantitative studies about leaf symmetry [9,10,11,12]

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