Rapid phenotypic changes in Caenorhabditis elegans under uranium exposure Morgan Dutilleul • Laurie Lemaire • Denis Re ´ale • Catherine Lecomte • Simon Galas • Jean-Marc Bonzom Accepted: 4 June 2013 / Published online: 3 July 2013 Ó Springer Science+Business Media New York 2013 Abstract Pollutants can induce selection pressures on populations, and the effects may be concentration-depen- dant. The main ways to respond to the stress are acclimation (i.e. plastic changes) and adaptation (i.e. genetic changes). Acclimation provides a short-term response to environ- mental changes and adaptation can have longer-term impli- cations on the future of the population. One way of studying these responses is to conduct studies on the phenotypic changes occurring across generations in populations exper- imentally subjected to a selective factor (i.e. multigenera- tional test). To our knowledge, such studies have not been performed with uranium (U). Here, the phenotypic changes were explored across three generations in experimental Caenorhabditis elegans populations exposed to different U-concentrations. Significant negative effects of U were detected on survival, generation time, brood size, body length and body bend. At lower U-concentrations, the neg- ative effects were reduced in the second or the third gener- ation, indicating an improvement by acclimation. In contrast, at higher U-concentrations, the negative effects on brood size were amplified across generations. Consequently, under high U-concentrations acclimation may not be sufficient, and adaptation of individuals would be required, to permit the population to avoid extinction. The results highlight the need to consider changes across generations to enhance environ- mental risk assessment related to U pollution. Keywords Caenorhabditis elegans Á Chronic exposure Á Experimental evolution Á Phenotypic changes Á Uranium Introduction The demographical consequences of pollutants on popu- lations have largely been studied in ecotoxicology. How- ever, most of these studies have focused their attention on within-generation effects, whereas it is well known that pollutants acting on both survival and reproduction could also lead to evolutionary changes occurring across several generations (reviewed by Coutellec and Barata 2011). Long-term exposure to a pollutant can induce a local adaptation and improve resistance in populations exposed to heavy metal pollution (e.g. Shirley and Sibly 1999; Reed et al. 2003; Xie and Klerks 2003; Salice et al. 2010). Therefore, it is essential to consider multigenerational responses to highlight the evolutionary dynamics of a population affected by pollution. Populations can show three different types of response to a change in the environment: (i) within-individual phe- notypic plasticity (Scheiner 1993); (ii) cross-generation phenotypic plasticity (i.e. maternal effects; Mousseau and Fox 1998); and (iii) rapid genetic changes through selec- tion of different genotypes (i.e. local adaptation; Hendry and Gonzalez 2008). The first two types of response are generally both included in the term acclimation. When selection pressures are too strong, acclimation may not be M. Dutilleul (&) Á L. Lemaire Á C. Lecomte Á J.-M. Bonzom Laboratoire d’e ´cotoxicologie des radionucle ´ides, Institut de Radioprotection et de Su ˆrete ´ Nucle ´aire, Cadarache, Bat 190, BP3 13115 Saint-Paul-lez-Durance Cedex, France e-mail: morgan.dutilleul@hotmail.fr M. Dutilleul Á D. Re ´ale De ´partement des Sciences Biologiques, Canada Research Chair in Behavioural Ecology, Universite ´ du Que ´bec A ` Montre ´al, Montreal, Canada M. Dutilleul Á S. Galas Faculty of Pharmacy and Pharmaceutical Sciences, University of Montpellier 1, B.P. 14491, 34093 Montpellier Cedex 5, France 123 Ecotoxicology (2013) 22:862–868 DOI 10.1007/s10646-013-1090-9