Instituto de Biología Molecular y Celular de Plantas (CSIC), Campus UPV, Avenida de los naranjos s/n, 46022 Valencia, Spain. sfelena@ibmcp.upv.es
Mutations are the ultimate fuel for evolution, but most mutations have a negative effect on fitness. It has been widely accepted that these deleterious fitness effects are, on average, magnified in stressful environments. Recent results suggest that the effects of deleterious mutations can, instead, sometimes be ameliorated in stressful environments.