Hacettepe University, Department of Biology, Ankara 06800, Turkey.
School of Biological Sciences, Monash University, Victoria 3800, Australia.
J Insect Physiol. 2021 Apr;130:104209. doi: 10.1016/j.jinsphys.2021.104209. Epub 2021 Feb 18.
Critical thermal limits are one of the most important sources of information on the possible impacts of climate change on soil microarthropods. The extent of plasticity of tolerance limits can provide valuable insights about the likely responses of ectotherms to environmental change. Although many studies have investigated various aspects of the acclimatory response of thermal limits to temperature changes in arthropods, the number of studies focusing on the temporal dynamics of this plastic response is relatively small. Collembola, one of the key microarthropods groups in almost all soil ecosystems around the world, have been the focus of several thermal acclimation studies. Yet the time course of acclimation and its reversal have not been widely studied in this group. Here we investigated the time course of acclimation of critical thermal maxima (CT) and minima (CT) of two springtail species. We exposed a Cryptopygus species from temperate southern Australia to high and low temperature conditions and Mucrosomia caeca from Sub-Antarctic Macquarie Island to high temperature conditions. Upper thermal limits in both species were found to be highly constrained, as CT did not show substantial response to high and low temperature acclimation both in the Cryptopygus species and M. caeca, whereas CT showed significant responses to high and low temperature conditions. The acclimation begins to stabilize in approximately seven days in all treatments except for the acclimation of CT under high temperature conditions, where the pattern of change suggests that this acclimation might take longer to be completed. Although reversal of this acclimation also begins to stabilize under 7 days, re-acclimation was relatively slow as we did not observe a very clear settling point in 2 of the 3 re-acclimation treatments. The observed limits on the plasticity of CT indicate that both of these species may be very limited in their ability to respond plastically to short-term rapid changes in temperature (i.e temperature extremes).
临界热极限是了解气候变化对土壤微型节肢动物可能影响的最重要信息来源之一。耐受极限可塑性的程度可以为变温动物对环境变化的可能反应提供有价值的见解。虽然许多研究已经调查了节肢动物对温度变化的热极限适应反应的各个方面，但关注这种可塑性反应的时间动态的研究数量相对较少。弹尾目，即全球几乎所有土壤生态系统中的关键微型节肢动物群之一，已经成为了几个热驯化研究的焦点。然而，在这个群体中，适应的时间过程及其逆转尚未得到广泛研究。在这里，我们研究了两种跳虫物种的临界热最大值（CTmax）和最小值（CTmin）的适应时间过程。我们将来自澳大利亚南部温带的 Cryptopygus 物种暴露于高温和低温条件下，将来自南极洲麦夸里岛的 Mucrosomia caeca 暴露于高温条件下。发现两种物种的上热极限都受到高度限制，因为 CTmax 在 Cryptopygus 物种和 M. caeca 中都没有对高温和低温适应产生显著反应，而 CTmin 对高温和低温条件都有显著反应。除了高温条件下的 CTmax 适应之外，所有处理中的适应都在大约七天内开始稳定，而在高温条件下的 CTmax 适应中，变化模式表明这种适应可能需要更长的时间才能完成。尽管在 7 天内，这种适应的逆转也开始稳定，但再适应相对较慢，因为我们在 3 种再适应处理中的 2 种中没有观察到非常明确的稳定点。观察到的 CTmax 可塑性限制表明，这两个物种可能在对短期快速温度变化（即极端温度）做出可塑性反应方面非常有限。
