Large microsatellite shifts in wild boar after the Fukushima accident

Although nuclear power plant accidents have raised concerns about the genetic consequences of radiation exposure, no studies have successfully compared the DNA of wild animals before and after the accident in the same area around a nuclear power plant. Here, we investigated 12 microsatellites of Japanese wild boar in the Fukushima prefecture before and after the Fukushima Daiichi nuclear accident. A population structure analysis of the microsatellites revealed that wild boar of the 4 prefectures of North Kanto were divided into 5 populations before the nuclear accident. Yet, wild boar sampled after the nuclear accident did not belong to any of these 5 populations. The reason for this result was related to significant changes in the composition of microsatellites after the nuclear accident; on average, 90% of post-accident microsatellite alleles were newly emergent in Fukushima prefecture. In samples obtained before the nuclear accident, each microsatellite had either even or odd-length alleles. Yet, in samples obtained after the nuclear accident, most microsatellites had alleles of both even and odd lengths. Moreover, we examined haplotypes and their frequencies in the mitochondrial DNA control region, and found no significant differences before and after the nuclear accident in both Fukushima and Tochigi prefectures, and no haplotypes were distributed only in distant areas suggesting an influx of wild boar after the nuclear accident. This research suggested that the change in microsatellites was a result of microsatellite instability rather than a result of the migration of wild boar from other areas. This research provides important insights into the effects of a nuclear accident on mammals.