Cresencio C. Cabuga, Jr. 1,2*, Joylinber P. Tandingan 3, Medralyn B. Milloria 4 and Armi G. Torres 5
1 Department of General Education, College of Industrial Technology and Teacher Education, Caraga State University Cabadbaran Campus, Cabadbaran City 8605, Philippines
2 PhD Biology Program, Faculty of Advanced and International Studies, Davao Oriental State University, Mati City 8200, Philippines
3 Department of Environmental Science, College of Forestry and Environmental Science, Central Mindanao University, Maramag 8710, Philippines
4 Department of Education, Ampayon National High School, Barangay Ampayon, Butuan City 8600, Philippines
5 Environmental Science Program, School of Interdisciplinary Science, Mindanao State University-Iligan Institute of Technology, Andres Bonifacio Avenue, Iligan City 9200, Philippines
*(e-mail: cccabuga@csucc.edu.ph)
(Received: 3 April 2025; Accepted: 30 July 2025)
ABSTRACT
Morphometric techniques have been increasingly employed to detect body shifts and variations within biological communities as indicators of environmental stress. This study investigates shell shape variation of the Golden Apple Snail (Pomacea canaliculata) using geometric morphometric (GM) analysis to assess the presence, spatial distribution, and sex-based differences in shape variation in the second largest lake in (Mainit) in Mindanao, Philippines. One hundred eighty adult shells of uniform size were collected from three selected areas within the lake. Sampling was stratified by site, with 60 individuals collected from each location, ensuring an equal representation of males and females (n = 30 per sex per site). Using Relative Warp Analysis (RWA) to discriminate the shell shapes, the anatomical landmark points were employed in the Multivariate Analysis of Variance, Principal Component Analysis, and Canonical Variate Analysis. The highest levels of fluctuating asymmetry were observed in the northern portion of the lake, particularly in the abapertural (55.76%) and apertural (56.89%) shell regions, followed by the southern portion and the middle part, respectively. MANOVA and RWA confirmed significant morphological variation across sites and sexes, suggesting that environmental factors strongly influence shell development in different lake regions. Findings revealed a significant difference (p < 0.05) in shell shape across the sampling sites and between the sexes. Additionally, the Pearson correlation coefficient (r = −0.3156) and found that the water did not affect on the shell shape of the gastropods. Thus, the results showed that P. canaliculata shell shape varies in size and shape and indicates distinguishable morphology across varying ecological locations.
Key words : gastropods, landmarks, morphometrics, morphology, shell shape