Asymmetry in the shape of the carapace of Scylla serrata (Forsskal, 1755) collected from Lingayen Gulf in Luzon, Philippines

摘要

The nature of organisms is influenced by the conditions of the environment. The shape changes occurring in the body of organisms could be attributed to its response to environmental perturbations. This study was therefore conducted to describe the changes in carapace shape in both sexes of S. serrata collected from different areas in the Lingayen Gulf using geometric morphometrics as a tool. Variations particularly the level of symmetry of its carapace shape, Symmetry and Asymmetry in Geometric Data (SAGE) software was used to analyze a total of 58 landmarks to obtain the biological shape information of 130 crab individuals. Procrustes ANOVA was employed to assess intra-population variability, directional and fluctuating asymmetry within sexes. Results showed sexual dimorphism in the carapace. Individual and directional asymmetry was also observed within sexes. However, fluctuating asymmetry was also detected in the anterolateral teeth, posterolateral margin and posterior border of the carapace indicating observed asymmetry that maybe attributed to both genetic and the interplay of genotype x environmental interaction suggesting that FA existence can be due to developmental instability as a consequence of the effect of the ecological health of the Lingayen Gulf.