Department of Biology, University of Central Arkansas, Conway, AR, 72035, USA.
Oecologia. 2022 Aug;199(4):757-768. doi: 10.1007/s00442-022-05185-w. Epub 2022 May 24.
The General Stress Paradigm (GSP) predicts that prey body compositions should shift under chronic predation as prey increase body carbon and decrease body nitrogen content through dietary changes, heightened metabolism, reduced dietary efficiency, and the breakdown of nitrogen rich tissues to make labile carbohydrates available. In our study, we explored how the elemental and macronutrient content along with the morphology of three abundant Ozark glade grasshopper species differed between glades with and without predatory collared lizard (Crotaphytus collaris) populations. Our results indicated that lichen grasshoppers (Trimerotropis saxatilis) increased body C:N ratios in response to predators. Scudder's short-wing grasshoppers (Melanoplus scudderi) increased both body %C and %protein content, while the handsome grasshoppers (Syrbula admirabilis) did not significantly respond to the presence of collared lizards. None of the three grasshopper species showed morphological responses to predation. We also found that elemental and macronutrient content of grasshoppers was not always significantly correlated and was not associated with the same environmental factors, indicating a need to incorporate both perspectives in future research and utilize more accurate macromolecular assays. Overall, we found support for some aspects of the GSP in field-active animals and add to the growing body of evidence that predator-induced changes in prey body composition are more complex than predicted by the original GSP.
一般应激范式（GSP）预测，随着猎物通过饮食变化、新陈代谢升高、降低饮食效率以及分解富含氮的组织以获得可用的不稳定碳水化合物来增加身体的碳含量和减少氮含量，其身体成分应该会在慢性捕食下发生变化。在我们的研究中，我们探讨了在有和没有掠食性环颈蜥蜴（Crotaphytus collaris）种群的林间空地中，三种丰富的欧扎克林间空地草蜢的元素和宏量营养素含量以及形态有何不同。我们的结果表明，地衣草蜢（Trimerotropis saxatilis）会因捕食者而增加身体的 C:N 比值。斯卡德短翅草蜢（Melanoplus scudderi）增加了身体的 C%和蛋白质含量，而英俊草蜢（Syrbula admirabilis）对环颈蜥蜴的存在没有明显反应。这三种草蜢物种都没有表现出对捕食的形态反应。我们还发现，草蜢的元素和宏量营养素含量并不总是显著相关，也与相同的环境因素无关，这表明未来的研究需要同时考虑这两个方面，并利用更准确的大分子分析。总的来说，我们在野外活动的动物中发现了对 GSP 某些方面的支持，并为越来越多的证据增加了支持，即猎物身体成分的捕食诱导变化比原始 GSP 预测的要复杂得多。
