Abstract

ALVES-SILVA, Estevão. The influence of Ditylenchus (Nematoda) galls and shade on the fluctuating asymmetry of Miconia fallax (Melastomataceae). Ecol. austral [online]. 2012, vol.22, n.1, pp.53-61. ISSN 1667-782X.

Fluctuating asymmetry (FA) can be defined as small, random deviations from bilateral symmetry in structures that are bilaterally symmetrical and can estimate a population's inability to buffer its growth against perturbations of environmental origins. Another important issue about FA is whether biotic factors may also induce stress in organisms. Therefore, in this study I aimed to investigate the influence of both the abiotic (light exposure) and biotic (Ditylenchus sp. galls) factors accounting for increased FA in Miconia fallax leaves. Galls are known as parasites and a major cause of leaf stress. Additionally, since M. fallax is a pioneer plant species, individuals in the shade were supposed to present high levels of FA relative to plants on the edges exposed to direct sunlight. Results showed no concomitant interaction between gall abundance, light exposure and FA. Separate analysis showed that plants in the shade presented the highest level of FA, almost 25% higher than plants on the edges, indicating that plants growing in places with little sunlight were in stressful condition. The presence of galls did not cause alterations in FA relative to leaves without galls. The lack of relationship between galls and leaf FA indicates that M. fallax can tolerate and buffer the presence of these leaf parasites, revealing the high homeostasis ability of this plant species against a biotic stress.

Keywords : Edge effect; Light exposure; Pioneer plant; Cerrado.

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