Multiple introduction events and artificial long-distance dispersal of the exotic slug Ambigolimax valentianus in Japan

ABSTRACT

The three-band garden slug Ambigolimax valentianus, native to the Iberian Peninsula, is an exotic species distributed worldwide and was introduced to Japan into the 1950s. For control of this slug, it is necessary to elucidate its introduction sources and dispersal patterns since the introduction event occurred. However, knowledge about this slug in Japan remains poor. Thus, we attempted to estimate the origin and dispersal patterns of this slug using genetic approaches. We investigated the genetic diversity of the mitochondrial cytochrome c oxidase subunit I gene across 11 populations of A. valentianus in three prefectures in central Japan. Ten haplotypes were found in the Japanese populations, five of which were haplotypes found in foreign individuals. The same haplotypes were found in all three prefectures, whereas the average haplotype diversity was high across all populations. Significant genetic differentiation was detected among 22 of 55 population pairs, but there was no isolation by distance. These molecular results suggest that multiple introductions to Japan may have occurred in the past such that the founder effect in the early stage of introduction was diluted. Furthermore, long-distance dispersal of A. valentianus would have occurred after introduction into Japan because of human activities rather than natural dispersal.

KEYWORDS:

• Artificial dispersal
• gastropod
• genetic diversity
• introduction route
• mitochondrial DNA

Acknowledgments

The authors would like to thank Mr. Yuma Iwaoka, Ms. Mihoko Arikawa, Ms. Monami Endo, and Mr. Haruhiko Tada for assistance with the sampling. We also appreciate the constructive comments from Dr. Don Colgan (AMS) and two anonymous referees which have improved the manuscript. This work was partly supported by the Sasakawa Scientific Research Grant from The Japan Science Society.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Sasakawa Scientific Research Grant: [grant number 2018-5014].