Qianqian Yang1, Suwen Liu1, Chao He1, Robert H Cowie2, Xiaoping Yu1, Kenneth A Hayes2,3. 1. Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, China. 2. Pacific Biosciences Research Center, University of Hawaii, Honolulu, HI, USA. 3. Bernice Pauahi Bishop Museum, Honolulu, HI, USA.
Abstract
BACKGROUND: Due to the similarities of overall shell morphology among apple snail species and considerable variability within species, substantial taxonomic confusion has plagued the accurate identification of Pomacea species. Many invasive apple snails have been mistakenly identified as P. canaliculata since their introduction to Asia around 1980. In 2008, three other introduced species in addition to P. canaliculata were recognized. In 2013, a fifth, previously unrecognized lineage was reported from China, indicating that despite the taxonomic clarity brought by previous work, continued surveys and taxonomic research are necessary to prevent additional introductions and continued spread, as well as to develop effective management strategies. RESULTS: Phylogenetic analysis of mitochondrial COI sequences confirmed the presence of a widespread unidentified Pomacea lineage in China. All sequences from samples of this newly documented lineage were recovered in a monophyletic clade delineated from closely related species; however, different DNA barcoding methods yielded inconsistent species boundaries. Additionally, nuclear EF1α sequences indicated incomplete lineage sorting or recent hybridization of the unidentified lineage with the other two established species. CONCLUSION: Barcoding is a valuable tool for species discovery, and a powerful approach for delineating introduced species. However, determining the identity of the newly discovered invasive lineage in China will require an integrated taxonomic approach incorporating individuals from the native range, and examination of natural history collections at museums around the world. To manage and prevent additional spread of already established species, and to stop the introduction of new taxa, continued monitoring and rigorous taxonomic assessments must be undertaken.
BACKGROUND: Due to the similarities of overall shell morphology among apple snail species and considerable variability within species, substantial taxonomic confusion has plagued the accurate identification of Pomacea species. Many invasive apple snails have been mistakenly identified as P. canaliculata since their introduction to Asia around 1980. In 2008, three other introduced species in addition to P. canaliculata were recognized. In 2013, a fifth, previously unrecognized lineage was reported from China, indicating that despite the taxonomic clarity brought by previous work, continued surveys and taxonomic research are necessary to prevent additional introductions and continued spread, as well as to develop effective management strategies. RESULTS: Phylogenetic analysis of mitochondrial COI sequences confirmed the presence of a widespread unidentified Pomacea lineage in China. All sequences from samples of this newly documented lineage were recovered in a monophyletic clade delineated from closely related species; however, different DNA barcoding methods yielded inconsistent species boundaries. Additionally, nuclear EF1α sequences indicated incomplete lineage sorting or recent hybridization of the unidentified lineage with the other two established species. CONCLUSION: Barcoding is a valuable tool for species discovery, and a powerful approach for delineating introduced species. However, determining the identity of the newly discovered invasive lineage in China will require an integrated taxonomic approach incorporating individuals from the native range, and examination of natural history collections at museums around the world. To manage and prevent additional spread of already established species, and to stop the introduction of new taxa, continued monitoring and rigorous taxonomic assessments must be undertaken.