Regulation of thermal acclimation varies between generations of the short-lived mosquitofish (Gambusia holbrooki) that developed in different environmental conditions

1. Environmental variability and perturbations can influence population persistence. It is therefore important to understand whether and how animals can compensate for environmental variability, and thereby increase resilience of natural populations. Evolutionary theory predicts that in fluctuating environments selection should favour developmental modifiers that reduce phenotypic expression of genetic variation. The expected result is that phenotypes are buffered from environmental variation across generations. 2. Our aim was to determine whether phenotypes of mosquitofish (Gambusia holbrooki) remain stable across generations in which individuals were born into different thermal environments. We predicted that the spring generation (cool environment) would acclimate by increasing the concentration of regulatory transcription factor mRNA and activities of rate-limiting enzymes (hierarchical regulation) to compensate for the negative thermodynamic effects of lower temperatures on metabol...