Taxonomic shortcuts lead to long delays in species discovery, delineation, and identification

Abstract

Invasive species threaten biodiversity, ecosystem functions, and human health around the world. Accurate and reliable species delineation and identification are prerequisites for any effort to control the introduction of new species and the spread of those already introduced. The advent of DNA assisted taxonomic tools has fueled the development of diverse and innovative approaches often touted as simple, inexpensive, and universally applicable for addressing impediments to rapid identification of non-native species. Ampullariidae (apple snails) are a family of freshwater snails with at least five species that have been introduced outside their native range and a prime example of how taxonomic uncertainty may hamper our understanding of invasion biology. Matsukura et al. (Appl Entomol Zool 43(4):535–540, 2008) and Cooke et al. (Conserv Genet Resour 4(3):591–593, 2012) developed species-specific PCR primers as rapid, simple, and inexpensive approaches to distinguishing among and identifying the most notorious and widespread invasive apple snails, Pomacea canaliculata and Pomacea maculata, and a third species in the aquarium trade, Pomacea diffusa. Neither approach was evaluated within the context of the overall genetic diversity of the target species, or with consideration for the species diversity within the family. To evaluate both shortcut approaches, the primers were tested for their utility in delineating and identifying the target species and other closely related taxa, including 24 apple snails representing 21 species. The results indicate that the primers are of limited taxonomic utility, and fail to consistently identify the target taxa, or congenerics. More importantly, use of these primers without additional data leads to misidentifications, potentially endangering native biodiversity and allowing novel introduced species to go undetected.