Phenotypic plasticity of the invasive apple snail, Pomacea canaliculata, in China: a morphological differentiation analysis

Pomacea canaliculata is listed among the world's 100 worst invasive species, for threatening rice production and wetland biodiversity. We compared morphological and genetic characteristics of the 14 P. canaliculata geographic populations in mainland China to explore morphological differentiation in relation to geographical isolation and climate effects. The results showed that the average shell height, standing height and body width of P. canaliculata samples were 29.39, 18.52 and 19.91 mm. Morphological characteristics were significantly different among the P. canaliculata geographic populations. The changes in morphological characteristics fitted a linear model. Geometric measurement showed a significant difference in centroid size among the 14 populations. Canonical variates analysis revealed three distinct clusters and that four geographic populations were independent in shell shape variation. Mahalanobis distances showed significant relationships among all populations except Pingtang vs. Zhangzhou. The cumulative contribution of PC1, PC2 and PC3 in principal component analysis reached 80%. The overall identification accuracy was 97%. However, only 3.9% of pairwise Coefficient of Difference values exceeded 1.28. The difference in morphological traits did not conform to the isolation-by-distance model. The P. canaliculata phenotype was closely related to local climatic factors. In summary, the adaptation of Chinese P. canaliculata populations is ongoing.