Last update: : Tuesday 23 February 2016, by
Par : Dr. Anders Pape MØLLER , Orsay (Univ. Paris Sud)
Date : vendredi 18 mars 2016 à 13h
Lieu : Amphithéâtre Marguerite Perey, bâtiment 01
The accidents at the nuclear reactors at Chernobyl and Fukushima are the most extensive according to the official IAEA classification. I will provide a brief overview of my research on organisms during the last 25 years. Numerous organisms have shown an ability to survive and reproduce under low dose radiation arising from natural background radiation or from nuclear accidents. Recently, a number of publications have claimed that there is evidence of adaptation to radiation. If we define adaptation as micro-evolutionary change towards a local or global fitness optimum due to selection, we can evaluate the outcome of these studies. We were able to locate 14 such estimates of adaptation that we subsequently evaluated. Most studies were based on common garden experiments with small sample sizes of typically two or three sampling locations. Most results showed effects of methylation or gene expression, which does not suffice for concluding that this is an adaptation. We only found one single experimental study showing improved resistance to radiation in two strains of bacteria from contaminated sites when compared to bacteria from an uncontaminated control population or a highly contaminated population. Finally, we judged the studies with respect to evidence of radiation hormesis (superior fitness at low levels of radiation compared to controls and high levels of radiation), but found no clear evidence. We conclude that rigorous experiments based on extensive sampling from multiple sites are required for drawing any firm conclusions.
Keywords: adaptation; Chernobyl; hormesis; methylation; micro-evolution; proteomics; pseudo-replication.
Anders Pape Møller
Laboratoire d’Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F-91405 Orsay Cedex, France