Ionizing radiation affects the demography and the evolution of Caenorhabditis elegans populations

• Published in: Ecotoxicology and environmental safety 2023-01, Vol.249, p.114353, Article 114353
• Main Authors: Quevarec, Loïc, Réale, Denis, Dufourcq-Sekatcheff, Elizabeth, Armant, Olivier, Adam-Guillermin, Christelle, Bonzom, Jean-Marc
• Format: Article
• Language: English
• Subjects: Environmental safety; Environmental Sciences; Experimental evolution; Life history traits; Local adaptation; Population growth rate; Stressful environment
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2022.114353

Ionizing radiation can reduce survival, reproduction and affect development, and lead to the extinction of populations if their evolutionary response is insufficient. However, demographic and evolutionary studies on the effects of ionizing radiation are still scarce. Using an experimental evolution approach, we analyzed population growth rate and associated change in life history traits across generations in Caenorhabditis elegans populations exposed to 0, 1.4, and 50.0 mGy.h−1 of ionizing radiation (gamma external irradiation). We found a higher population growth rate in the 1.4 mGy.h−1 treatment and a lower in the 50.0 mGy.h−1 treatment compared to the control. Realized fecundity was lower in both 1.4 and 50.0 mGy.h−1 than control treatment. High irradiation levels decreased brood size from self-fertilized hermaphrodites, specifically early brood size. Finally, high irradiation levels decreased hatching success compared to the control condition. In reciprocal-transplant experiments, we found that life in low irradiation conditions led to the evolution of higher hatching success and late brood size. These changes could provide better tolerance against ionizing radiation, investing more in self-maintenance than in reproduction. These evolutionary changes were with some costs of adaptation. This study shows that ionizing radiation has both demographic and evolutionary consequences on populations. •Ionizing radiation had both demographic and evolutionary consequences on populations.•Multigenerational radiation exposure led to decreased reproduction and embryo survival.•Populations adapted to radiation through improved embryo survival and a slower life strategy.•Evolutionary changes in irradiated environments were accompanied by adaptive costs.