Slimy invasion: Climatic niche and current and future biogeography of Arion slug invaders

Abstract

Aim: The current volume of global trade has led to an unprecedented rate of biological invasions, causing severe problems to native ecosystems. The knowledge of species introduction routes and areas suitable for establishment is therefore an important step in preventing future invasions. The situation can be further exacerbated by climate change, which might alter the amount of environmentally suitable areas for establishment of invasive species. Here, we focus on three Arion slug species recently introduced to North America and Australia with potentially significant impact—A. ater, A. rufus and A. vulgaris. Location: Worldwide. Results: We combined interception records, molecular analyses and species distribution modelling to assess their introduction history and to predict which regions are at highest risk of future invasions. We found extensive sharing of mitochondrial haplotypes among continents in all three species. In concordance with the genetic analyses, interception records suggest that slugs were introduced to the USA and Australia primarily from France, the Netherlands and the UK, but also from other locations in North America. The models predicted climatically suitable regions for the three Arion species in several areas across the globe for which management actions can be targeted. Main conclusions: While the amount of regions with climatic conditions that would be suitable for slug establishment is predicted to slightly decrease under future scenarios, new suitable areas will also emerge. We therefore recommend that prevention efforts to limit new introductions should continue in order to protect vulnerable native ecosystems.