Fluctuating asymmetry as an indicator of Ecological stress and Developmental instability of Neurothemis ramburii (Odonata: Libellulidae) in Iligan City, Philippines
By: Michelle M. Barbon, Jazzie D'Zeim Arreza, Sharon Rose M. Tabugo
Key Words: Asymmetry, Neurothemis ramburii, Odonata, Procrustes ANOVA, SAGE.
J. Bio. Env. Sci. 8(3), 142-152, March 2016.
Odonata species are often used for biomonitoring purposes are often influenced by environmental instability in diverse ways. The degree of developmental stability of individuals and populations is most often estimated by their level of fluctuating asymmetry (FA). FA refers to a slight number and nondirectional deviations from strict bilateral symmetry of biological objects that occur as a result of stochastic microscopic processes. In this study, analysis was done on eurytopic species Neurothemis ramburii. Specifically, it investigated the differences in fluctuating asymmetry (right and left wing) of three populations from different barangays (Dalipuga, Pugaan and Buruun) Iligan City, Mindanao, Philippines. It determined developmental stability via fluctuating symmetry and used FA as an indicator of stress. Analysis was based on Procrustes Method and makes comparison of FA indices of homologous points. Using landmark method for shape asymmetry, anatomical landmarks were used and analyzed using Symmetry and Asymmetry in Geometric Data (SAGE) program. Procrustes ANOVA and Principal Component Analysis (PCA) results showed considerable variation and significant evidence of FA for all populations with relatively high FA for more disturbed areas (Pugaan and Dalipuga). Significant FA may present inability of species to buffer against endogenous and exogenous stress in its developmental pathways hence, would mean developmental instability. Directional asymmetry (DA) was also significant in all populations. A significant FA and DA suggest that stress and variation could be a product of genotype-environment interaction. Awareness and understanding of adaptation and survival of Odonata species as biological indicators for wetland assessment is essential