The ecological context of bilateral symmetry of organ and organisms

Danilo M. Daloso

doi:10.4236/ns.2014.64022

Abstract

A particular phenotype is generated through numerous networks of interactions from within the cell to the whole ecosystem. The level of the environmental noise and the ability of a given genotype to render different phenotypes under different environmental conditions, called phenotypic plasticity, determine survival or death at individual and/or population level. It is important to highlight that non-lethal environmental changes are important for generating genetic variability and promoting biological adaptations. However, when the level of environmental noise starts to be stressed, the developmental stability (DS) of the organism can be perturbed. The DS has been analysed through the symmetry deviations in organs or organisms with bilateral structure. The symmetry deviations occur due to inability to contain disorders from environmental or endogenous conditions during its development. This deviation is called fluctuating asymmetry (FA) when is a non-directional deviation in the symmetry of a bilateral structure normally distributed in a population. Low FA has been associated with greater DS. The analysis of FA has often been used to measure the effects of environmental perturbations. In this review, I discuss the concept of plant stress and phenotypic plasticity connecting both to the generation of an asymmetry phenotype, highlighting the usefulness of FA as an indicator of the level of stress which the organism is subjected to. Further, although this review explores mainly the connection between FA and stress in plants, the ecological context of symmetry in animals and plant-insect interaction is also discussed. Finally, I provided some methodologies used to detect symmetry variations in organs or organisms with bilateral structure.

Highlights

Every ambient has a level of oscillations which can range from the optimal to the stress condition in a short time
The phenotype can be produced by the interaction of genotype and ambient in a different way under non-stress conditions (Figure 1— solid lines) or under stress conditions, which may have the generation of development instability (DI) and fluctuating asymmetry (FA) (Figure 1—dashed lines)
This review showed examples of FA in a small number of organisms, it’s important to highlight that this kind of analysis can be carried out in every organ or organism with bilateral structure

Summary

INTRODUCTION

Every ambient has a level of oscillations which can range from the optimal to the stress condition in a short time. Deviations from the perfect symmetry of organs or organisms with bilateral structure occur due to the inability of the organism to contain disorders from environment or endogenous conditions during its development. It reflects the inability of the organism to maintain precision development during ontogeny [6]. FA, an analysis of the symmetry normally distributed in a population (discussed below), has been often used to measure the effects of environmental perturbations in a wide range of organisms [2,8], since FA can indicate the level of stress which the individual and/or population are subjected to [9,10]

THE ECOLOGICAL CONTEXT OF THE SYMMETRY

Face Symmetry as a Trait for Sexual Selection in Mammals

Symmetry and Good Runners

Flower Symmetry Determine the Success of Pollination

CONNECTING STRESS TO PLANT ASYMMETRY

HOW TO MEASURE SYMMETRY DEVIATIONS?

Findings

CONCLUDING REMARKS