Fish and other ectotherms living in warmer waters often grow faster as juveniles, mature earlier, but become smaller adults. Known as the temperature-size rule (TSR), this pattern is commonly attributed to higher metabolism in warmer waters, leaving fewer resources for growth. An alternative explanation focuses on growth and reproduction trade-offs across temperatures. We tested these hypotheses by measuring growth, maturation, metabolism and reproductive allocation from zebrafish populations kept at 26 and 30°C across six generations. Zebrafish growth and maturation followed TSR expectations but were not explained by baseline metabolic rate, which converged between temperature treatments after a few generations. Rather, we found that females at 30°C allocated more to reproduction, especially when maturing at the smallest sizes. We show that elevated temperatures do not necessarily increase baseline metabolism if sufficient acclimation is allowed and call for an urgent revision of modelling assumptions used to predict population and ecosystem responses to warming.
Copyright (2022) The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License, (https://creativecommons.org/licenses/by-nc/4.0/) which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Repository Status
Open
Socio-economic Objectives
Fisheries - wild caught not elsewhere classified; Assessment and management of terrestrial ecosystems