Landmark-based geometric analysis in describing the shell of the freshwater gastropod Vivipara angularis (Gastropoda: Viviparidae) from Lake Dapao, Pualas, Lanao del Sur, Mindanao, Philippines

摘要

This study was conducted to describe the shell shapes of Vivipara angularis collected fromfour different locations in Lake Dapao, one of the deepest lakes in Mindanao, Philippines. Geometricmorphometric tools specifically relative warp (RW) and euclidean distance matrix analysis (EDMA) wereused to describe the shapes. Results showed there was no population differentiation in the snail as theshell shapes in all four populations were concentrated towards the means shape revealed by relativewarp analysis. A closer look at variations in shell shapes based on the results of EDMA revealed thatindividual variations were due to differences in selected interlandmark distances observed along thespire, body whorl and aperture of the shell. Observed variations in shell shapes can be argued to be dueto ecological factors, developmental differences and/or maybe environmentally induced.