|Title||Dynamics of adaptation in experimental yeast populations exposed to gradual and abrupt change in heavy metal concentration|
|Author(s)||Gorter, F.A.; Aarts, M.M.G.; Zwaan, B.J.; Visser, Arjan de|
|Source||American Naturalist 187 (2016)1. - ISSN 0003-0147 - p. 110 - 119.|
Laboratory of Genetics
Groep KoornneefGroep Koornneef
|Publication type||Refereed Article in a scientific journal|
|Keyword(s)||Environmental change - Experimental evolution - Genotype-environment interaction - Heavy metals - Pleiotropy - Saccharomyces cerevisiae|
Directional environmental change is a ubiquitous phe-nomenon that may have profound effects on all living organisms. However, it is unclear how different rates of such change affect the dynamics and outcome of evolution. We studied this question using experimental evolution of heavy metal tolerance in the baker’s yeast Saccharomyces cerevisiae. To this end, we grew replicate lines of yeast for 500 generations in the presence of (1) a constant high concentration of cadmium, nickel, or zinc or (2) a gradually increas-ing concentration of these metals. We found that gradual environ-mental change leads to a delay in fitness increase compared with abrupt change but not necessarily to a different fitness of evolution-ary endpoints. For the nonessential metal cadmium, this delay is due to reduced fitness differences between genotypes at low metal con-centrations, consistent with directional selection to minimize intra-cellular concentrations of this metal. In contrast, for the essential metals nickel and zinc, different genotypes are selected at different concentrations, consistent with stabilizing selection to maintain con-stant intracellular concentrations of these metals. These findings in-dicate diverse fitness consequences of evolved tolerance mechanisms for essential and nonessential metals and imply that the rate of en-vironmental change and the nature of the stressor are crucial deter-minants of evolutionary dynamics.