Evolution and mechanisms of thermal performance – answers through artificial selection in zebrafish
Abstract Climate change is warming waters globally. Ectothermic animals, such as fish, have the same body temperature as the surrounding water and are therefore thought to be particularly sensitive to warming. To predict climate change impacts on fish populations, we must first know how fish are affected and how rapidly evolution may help mitigate some of those impacts.   Some of the most central questions regarding thermal acclimation and adaptation of ectothermic animals remain unresolved: 1. Which mechanisms limit upper thermal tolerance?  2. How rapid is evolution of thermal performance? 3. Which physiological mechanisms limit thermal performance? 4. Which genetic changes are most important for climate change adaptation?  5. Do laboratory experiments predict thermal adaptation in the wild?   By addressing these important questions, this project will substantially move the field of thermal biology forward. We will gain knowledge needed to understand and predict climate change impacts, insights that may help focusing conservation efforts. The proposed project will address these great challenges by using two artificial selection experiments on wild zebrafish (Danio rerio). The first selection experiment on upper acute thermal tolerance has recently been completed, and the adapted zebrafish lines will be used in the current proposal for physiological and genetic analyses. The second and larger selection experiment on thermal performance will be conducted during the first three years of the proposed project, and those adapted zebrafish lines will be used to identify the physiological and genetic changes that adaptation required. Additionally, unique natural warm-adapted stickleback (Gasterosteus aculeatus) populations from geothermally heated lakes on Iceland will be used to validate the project’s findings on zebrafish.