2020/12/14 by Rachael Morgan, Mette H. Finnøen, Henrik Jensen +2 · 1 voice · 8 citations
Agricultural and Biological Sciences · Environmental Science · #Animal Behavior and Reproduction #Fish Ecology and Management Studies #Physiological and biochemical adaptations
paper · pdf · doi:10.1073/pnas.2011419117
openalex publication_date 2020/12/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
) to increase (Up-selected) or decrease (Down-selected) upper thermal tolerance over six generations. Selection to increase upper thermal tolerance was also performed on warm-acclimated fish to test whether plasticity in the form of inducible warm tolerance also evolved. Upper thermal tolerance responded to selection in the predicted directions. However, compared to the control lines, the response was stronger in the Down-selected than in the Up-selected lines in which evolution toward higher upper thermal tolerance was slow (0.04 ± 0.008 °C per generation). Furthermore, the scope for plasticity resulting from warm acclimation decreased in the Up-selected lines. These results suggest the existence of a hard limit in upper thermal tolerance. Considering the rate at which global temperatures are increasing, the observed rates of adaptation and the possible hard limit in upper thermal tolerance suggest a low potential for evolutionary rescue in tropical fish living at the edge of their thermal limits.