author(s)
Jhun Joules M. Mahilum and Cesar G. Demayo

abstract
This study was conducted to describe the shell shape differences among intra- and inter-lake populations of P. canaliculata using the geometric morphometric analysis. The shell shape variation among all populations collected is common in the spire, shell body and apertural area morphology. It was found out that minimal sexual dimorphism was observed on the dorsal portion of the shell where male and female populations tend to group separately. While on the ventral portion, male and female populations grouped uniquely. Results have shown significant variations validated by showing the superimposition with the expansion maps among all populations which showed the occurrence of variation of the both dorsal and ventral portion of the shell. This is either caused by the organism’s phenotypic responses (plasticity) or particularly which act during ontogenetic development or directly affected by the environmental factors.