Intra- and Inter-Population Variability in the Golden Apple Snail Pomacea canaliculata

The Golden Apple Snail (GAS), Pomacea canaliculata Lamarck is considered as one of the most destructive pest of the rice agricultural system in the Philippines. Populations of this gastropod pests are exposed to varying management approaches, and hence, to different selective pressures. Thus, this study was conducted to determine inter- and intra-populational differentiation of golden apple snails in six populations collected from Agusan del Norte, Philippines. This was based on shape analysis of the spires. A total of 199 points were used to summarize the shapes of the spires from digital images of the top of the shell and seventeen landmark points in dorsal and aperture area of the shell. The landmark and outline data including the linear distances were analyzed to evaluate the variation in the shell shape. Using the CORIANDIS software, association among multivariate traits was shown. Also direct visualization of congruence of multivariate traits can be observed by looking their distance matrices with their compromises that were projected in compromise space and by looking their squared distances. Results of the analysis showed significant variation among the different male and female populations of GAS. One-way ANOVA statistical analysis was also used in linear measurements of the shell, where the female shells show more significant differentiation than the males.