ddRAD of Porcellio spinicornis
In the Prairie Provinces of Canada (Alberta, Saskatchewan and Manitoba), all sowbugs (terrestrial isopods) (Isopoda: Oniscidea) are non-native, but little is known of their origins and subsequent movements. We investigated the population structure of the sowbug Porcellio spinicornis Say in Alberta using genomic markers (ddRADseq) and mitochondrial COI barcodes. Populations of P. spinicornis in Edmonton, Calgary, and southeastern Alberta are genetically dissimilar and likely originated from at least three separate introduction events. Edmonton populations display genetic homogeneity consistent with anecdotal reports that sowbugs in Alberta arrived recently. Evidence for greenhouses as initial introduction sites was inconclusive, with at least one 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 from native populations in Europe.