Genetic diversity and phylogeography of urban hedgehogs (Erinaceus europaeus) around Helsinki, Finland, revealed by mitochondrial DNA and microsatellite analyses

The European hedgehog (Erinaceus europaeus) is widely distributed in Europe, from Iberia and Italy to Scandinavia, and in New Zealand. They inhabit a wide range of environments, from natural habitats to urban areas. Finland is the northern edge of the current distribution area, which has expanded from Pleistocene refugia in Europe. Finnish hedgehogs are not only found in the suburbs, but also in urban areas such as the capital city, Helsinki. However, the phylogenetic relationships to other populations and the population structure were unknown for the urban hedgehogs in Helsinki. We reconstructed a molecular phylogeny and analyzed the population structure and genetic diversity from samples of 106 hedgehogs collected around Helsinki in 2017–2019, based on partial sequences of the mitochondrial control region and cytochrome b gene as well as 11 microsatellite loci. Our phylogenetic data indicate that the Helsinki population is closely related to the Estonian population. This means that at least part of the Helsinki population originates from Estonia, due to natural expansion from glacial refugia and anthropogenic introduction for vermin control, as shown in previous reports. The microsatellite data indicated that the Helsinki population is genetically homogeneous, with low genetic diversity. This may be due to the absence of effective geographic barriers to gene flow at present, but it is also possible that the subpopulations formed by migration are concealed by the genetic uniformity resulting from founder effect of natural expansion to the northward or artificial introduction. Further study is necessary to evaluate the effect of urban fragmentation in Helsinki.