Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Organismal and Evolutionary Biology Research Programme, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland.
J Exp Biol. 2020 Dec 11;223(Pt 23):jeb229195. doi: 10.1242/jeb.229195.
Global warming is predicted to increase both acute and prolonged thermal challenges for aquatic ectotherms. Severe short- and medium-term thermal stress over hours to days may cause mortality, while longer sub-lethal thermal challenges may cause performance declines. The inter-relationship between the responses to short, medium and longer thermal challenges is unresolved. We asked if the same individuals are tolerant to both rapid and slow warming challenges, a question that has so far received little attention. Additionally, we investigated the possibility of a thermal syndrome where individuals in a population are distributed along a warm-type to cold-type axis. We tested whether different thermal traits correlate across individuals by acclimating 200 juvenile zebrafish () to sub- or supra-optimal temperatures for growth (22 and 34°C) for 40 days and measuring growth and thermal tolerance at two different warming rates. We found that tolerance to rapid warming correlated with tolerance to slow warming in the 22°C treatment. However, individual tolerance to neither rapid nor slow warming correlated with growth at the supra-optimal temperature. We thus find some support for a syndrome-like organisation of thermal traits, but the lack of connection between tolerance and growth performance indicates a restricted generality of a thermal syndrome. The results suggest that tolerance to rapid warming may share underlying physiological mechanisms with tolerance to slower heating, and indicate that the relevance of acute critical thermal tolerance extends beyond the rapid ramping rates used to measure them.
全球变暖预计会增加水生变温动物的急性和长期热应激。数小时到数天的严重短期和中期热应激可能导致死亡，而较长时间的亚致死热应激可能导致性能下降。短期、中期和长期热应激反应之间的相互关系尚未解决。我们想知道同一个体是否能够耐受快速和缓慢的升温挑战，这个问题到目前为止还没有得到太多关注。此外，我们还研究了热综合征的可能性，即种群中的个体沿暖型到冷型轴分布。我们通过将 200 条幼年斑马鱼（）在 22 和 34°C 下适应 40 天来测试不同的热特征是否在个体间相关，这两种温度分别是生长的亚最佳和最佳温度，并在两种不同的升温速率下测量生长和热耐受性。我们发现，在 22°C 处理中，快速升温的耐受性与缓慢升温的耐受性相关。然而，个体对快速和缓慢升温的耐受性都与最佳温度下的生长无关。因此，我们发现热特征的综合征样组织有一定的支持，但对快速和缓慢升温的耐受性与生长性能之间缺乏联系表明热综合征的一般性受到限制。研究结果表明，对快速升温的耐受性可能与对较慢升温的耐受性具有相同的生理机制，并表明急性临界热耐受性的相关性超出了用于测量它们的快速升温速率。
