Application of genetic structure analysis to explore the cause of
variation in radionuclide contamination among Asian black bear
populations in Fukushima
Abstract
1. After the Fukushima Daiichi Nuclear Power Plant accident in 2011,
radionuclides have been detected in the tissues of wild animals. It was
found that some individuals had higher radiocesium activity
concentrations than others, despite being captured in the same area. One
of the reasons for this disparity was attributed to migration from areas
where radiocesium contamination level was different. 2. We identified
the genetic population of Asian black bears using two genetic markers,
such as mtDNA D-loop haplotype and SNPs by MIG-seq analysis. Then, we
assessed migration between populations and variation in the radiocesium
activity concentrations in the muscle tissue of distinct populations. 3.
The SNPs analysis identified clearer two populations (SP1 and SP2) than
the mtDNA analysis. Population distribution inferred based on SNPs was
affected by geographic features and land use. 4. The radiocesium
activity concentrations in muscle tissues in SP2 were higher than those
in SP1. The radiocesium activity concentrations in muscle tissue were
positively correlated with radiocesium contamination levels at the
capture site. Since the radiocesium contamination levels at the capture
sites of SP2 were higher than those of SP1, it was inferred that the
levels of radiocesium contamination in each population would show a
similar pattern. 5. Migration occurred between the genetic populations
and migration rate differed between the genetic populations, with the
rate of individuals migrating from SP2 to SP1 being smaller than that
from SP1 to SP2. Therefore, it was suggested migration was responsible
for some individuals having relatively higher radiocesium activity
concentrations in muscle tissue, despite being captured in the same
area. 6. This study is the first report that showed the genetic
structure of Asian black bear in Fukushima Prefecture in fine scale, the
migration rate between the populations, and the effect of migration on
the variation of radiocesium activity concentration.