Abstract Terrestrial isopods (Isopoda: Oniscidea), also known as sowbugs, are readily transported by human activity, with greenhouses considered common introduction sites. In the Prairie Provinces of Canada (Alberta, Saskatchewan, and Manitoba), all sowbugs are non-native, but little is known of their origins and subsequent movements. We investigated the population structure of the sowbug Porcellio spinicornis Say, 1818, in Alberta using genomic markers (ddRADseq) and mitochondrial COI barcodes to explore its dispersal history and assess the long-held hypothesis that greenhouses play an important role in sowbug introduction. We found that populations of P. spinicornis in Edmonton, Calgary, and southeastern Alberta are genetically dissimilar and likely originated from at least 3 separate introduction events. Edmonton populations display genetic homogeneity consistent with anecdotal reports that sowbugs in Alberta arrived recently. However, evidence for greenhouses as initial introduction sites was inconclusive, with at least 1 greenhouse population in Edmonton potentially originating from an adjacent outdoor site rather than serving as a source population itself. COI diversity in Alberta populations of P. spinicornis is low and consists entirely of haplotypes that are currently only reported from North America, suggesting that they may have originated from other North American populations rather than directly from the more COI-diverse native populations in Europe. Given the probable recentness of P. spinicornis introduction, sowbug populations in Alberta should be monitored for future range expansion outside of urban areas.
Stormer et al. (Sun,) studied this question.