Assessing Geographic Conchological Variations of the Different Banding Patterns in the Invasive Giant African Land Snail Achatina fulica From the Philippines

Abstract

 Abstract—Population of the invasive giant African snail Achatina fulica in the Philippines show conspicuous shell variations, which involve banding pattern, colour, size, and shape. Generally, shell shape and colour of land snails have been related to environmental factors. Therefore, the objective of this study is to determine and assess shape variations across population of geographically isolated shells with different banding patterns. Morphological analysis was performed on a total of 1309 matured shells from 15 different geographical locations across the Philippine island. Relative warp analysis revealed variation shell shape which could be slender-shaped or round-shaped. A variation in spire-whorl length coupled with aperture size was also observed. Canonical variance analysis scatter plot presented overlapping of populations from different geographical locations. Though there were no directly observable differences on the consensus shape superimposition of each geographically isolated population, results of multivariate analysis, Kruskal-Wallis test, and cluster analysis showed significant relationship of shell morphology of different banding patterns to geographical locations. However, the scattered distribution and short distance variation suggested a higher intrapopulation variation rather than interpopulation. Phenotypic plasticity, common in land snails, could be another explication for the observed intrapopulation conchological variations and that differentiation could also be due to multitude reactions to endogenous and exogenous factors.