Context – There is ample societal and scientific debate about the risks and the radioactive contamination on humans and natural ecosystems. In Chernobyl more than 30 years later, and despite some recent studies suggesting the recovery of natural populations in the area as well as footprints of adaptation to the chronic exposure to radiation, there is still no scientific consensus about the long-term effects on wildlife of the chronic exposure to the remaining low-dose radiation levels in the areas affected by the radioactive fallout.
Environmental pollutions can lead to intense selection for pollutant tolerance or population declines which can result in a decreased genetic diversity with potential detrimental effects on their evolutionary potential. But also, exposure to pollutants can lead to an increased mutation rate, which can partially offset the genetic diversity loss caused by population bottlenecks. Finally, polluted areas can also be ecological sinks, i.e. a low-quality habitat which leads to a demographic deficit (mortality>natality), and where the population may not persist without immigration sources.
To date we have begun to study the genetic diversity of 11 tree frog populations (Hyla orientalis) sampled in the radio-contaminated Chernobyl Exclusion Zone (CEZ), Ukraine, representing a total of 126 individuals. The level of heterozygosity based on 21 different microsatellites was equal to 0.1957 (+- 0.023) and was similar to other populations studied outside this area. However, the mitochondrial haplotype diversity, based on cytochrome b gene, displayed a value equal to 0.7895 (+- 0.0849) indicating a very high genetic diversity within the Chernobyl exclusion zone compared to other studies. Our first results clearly reject the assumption of a loss of genetic diversity in frog populations in the CEZ. However, it is premature to discriminate between an increased mutation rates due to ionizing radiation contaminations or the CEZ acting as an ecological sink. Answering this question will require analysis of new populations outside and all around CEZ.
We aim at producing research to improve our understanding of the effects of radiocontamination on wildlife, including the study of the effects of radiocontamination on physiological (stress hormones, oxidative stres…) and behavioural parameters on the tree frogs in the Fukushima and Chernobyl areas.
Objective – This project focuses on evaluating the impact of the chronic exposure to environmental doses of ionizing radiation in wildlife. Specifically, using tree frogs as a study model, we propose (1) to understand and quantify the genetic diversity of different populations of tree frogs (Hyla orientalis) living in differentially contaminated areas of the Chernobyl Exclusion Zone, (2) to analyse the signatures ionizing radiation exposure at the genomic, transcriptomic and proteomic levels in tree frogs, (3) to measure physiological and behavioural effects of frogs caught at night in the Chernobyl Exclusion Zone.
In this research project, the PhD candidate will focuses primarily on task (1). The specifics of the project will be determined jointly by the successful candidate, supervisors and collaborators (see below).
Collaborative research – The student will benefit from the collaboration and the expertise of several researchers to complete his/her PhD: in genetic diversity: A. Gilles (Uni. d’Aix-Marseille); in genomic and transcriptomic: O. Armant (IRSN); in proteomic: S. Frelon (IRSN); in physiology and behaviour: N. Mondy, T. Lengagne (Uni. Lyon 1), J-M Bonzom (IRSN), and G. Orizaola (Uni. Oviedo, Spain); in radioecology: K. Beaugelin, C. Adam-Guillermin, J-M Bonzom (IRSN); in field work: S. Gaschak (International Radioecology Laboratory, Ukraine), and J-M Bonzom.
Candidate profile – The candidates must hold a Master degree in a relevant field (e.g. Ecology, Molecular ecology, Ecophysiology, Ecotoxicology…). Key requirements include population genetic background. The ideal candidate is highly motivated, hardworking, creative, and has experience from fieldwork and laboratory work. Moreover, he/she will not be afraid to handle and dissect frogs. The student has to be able to work independently as well as a part of a team. The working language is French and/or English.
Additional informations – The PhD will start in October 2019 and is funded for three years in the Research laboratory on the effects of radionuclides on ecosystems (LECO) of the French Institute for Radioprotection and Nuclear Safety (IRSN) in Cadarache (located in the south of France: 30 minutes from Aix-en-Provence and Manosque; 1 hour from Marseille), in close collaboration with Dr. André Gilles, co-supervisor of this PhD (UMR Aix-Marseille University-IRSTEA, team Evolution Genome Environment). Possibility of furnished apartment close to LECO/IRSN-Cadarache laboratory (at approximately 500 m: http://www.habitat-pluriel.fr/residences/le-hameau).
Contact person – To apply or for any questions, please contact by email before April 12, 2019: [email protected]
Send a short motivation letter with a description of pertinent experience, a CV, the names and e-mail addresses of two or three academic/research references, and copies of certificates of academic qualifications (in French or in English).