Radiation-mediated supply of genetic variation outweighs the effects of selection and drift in Chernobyl Daphnia populations
AffiliationUniversity of Stirling; Ukrainian HydroMeteorological Intstitute; University of Chester
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AbstractPopulations experiencing varying levels of ionizing radiation provide an excellent opportunity to study the fundamental drivers of evolution. Radiation can cause mutations and thus supply genetic variation; it can also selectively remove individuals that are unable to cope with the physiological stresses associated with radiation exposure, or non-selectively cull swathes of the population, reducing genetic variation. Since the nuclear power plant explosion in 1986, the Chernobyl area has experienced a spatially heterogeneous exposure to varying levels of ionizing radiation. We sampled Daphnia pulex (a freshwater crustacean) from lakes across the Chernobyl area, genotyped them at ten microsatellite loci and also calculated the current radiation dose rates. We then investigated whether the pattern of genetic diversity was positively associated with radiation dose rates, consistent with radiation-mediated supply of de novo mutations, or negatively associated with radiation dose rates, as would be expected with strong radiation-mediated selection. We found that measures of genetic diversity, including expected heterozygosity and mean allelic richness (an unbiased indicator of diversity), were significantly higher in lakes that experienced the highest radiation dose rates. This suggests that mutation outweighs selection as the key evolutionary force in populations exposed to high radiation dose rates. We also found significant but weak population structure, indicative of low genetic drift and clear evidence for isolation-by-distance between populations. This further suggests that gene flow between nearby populations is eroding population structure and that mutational input in high radiation lakes could, ultimately, supply genetic variation to lower radiation sites.
CitationGoodman, J., Brand, J., Laptev, G., & Auld, S. K. (2022). Radiation‐mediated supply of genetic variation outweighs the effects of selection and drift in Chernobyl Daphnia populations. Journal of Evolutionary Biology, 35(3), 413-422. https://doi.org/10.1111/jeb.13983
JournalJournal of Evolutionary Biology
Description© 2022 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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