Parain Elodie C, Gravel Dominique, Rohr Rudolf P, Bersier Louis-Félix, Gray Sarah M
Department of Biology - Ecology and EvolutionUniversity of Fribourg Chemin du Musée 101700 Fribourg Switzerland; Department of Ecology and Evolutionary Ecology Yale University 165 Prospect Street New Haven Connecticut 06520.
Département de Biologie, Chimie et Géographie Université du Québec à Rimouski 300 Allée des Ursulines Rimouski Quebec G5L 3A1 Canada; Département de Biologie - Ecologie Terrestre Université de Sherbrooke 2500, boulevard de l'Université Sherbrooke Quebec J1K 2R1 Canada.
Ecol Evol. 2016 Jun 21;6(14):4885-97. doi: 10.1002/ece3.2236. eCollection 2016 Jul.
Understanding how trophic levels respond to changes in abiotic and biotic conditions is key for predicting how food webs will react to environmental perturbations. Different trophic levels may respond disproportionately to change, with lower levels more likely to react faster, as they typically consist of smaller-bodied species with higher reproductive rates. This response could cause a mismatch between trophic levels, in which predators and prey will respond differently to changing abiotic or biotic conditions. This mismatch between trophic levels could result in altered top-down and bottom-up control and changes in interaction strength. To determine the possibility of a mismatch, we conducted a reciprocal-transplant experiment involving Sarracenia purpurea food webs consisting of bacterial communities as prey and a subset of six morphologically similar protozoans as predators. We used a factorial design with four temperatures, four bacteria and protozoan biogeographic origins, replicated four times. This design allowed us to determine how predator and prey dynamics were altered by abiotic (temperature) conditions and biotic (predators paired with prey from either their local or non-local biogeographic origin) conditions. We found that prey reached higher densities in warmer temperature regardless of their temperature of origin. Conversely, predators achieved higher densities in the temperature condition and with the prey from their origin. These results confirm that predators perform better in abiotic and biotic conditions of their origin while their prey do not. This mismatch between trophic levels may be especially significant under climate change, potentially disrupting ecosystem functioning by disproportionately affecting top-down and bottom-up control.
了解营养级如何响应非生物和生物条件的变化是预测食物网将如何应对环境扰动的关键。不同的营养级对变化的响应可能不成比例，较低营养级更可能反应更快，因为它们通常由体型较小、繁殖率较高的物种组成。这种响应可能导致营养级之间的不匹配，即捕食者和猎物对不断变化的非生物或生物条件的反应不同。营养级之间的这种不匹配可能导致自上而下和自下而上的控制改变以及相互作用强度的变化。为了确定不匹配的可能性，我们进行了一项相互移植实验，涉及由细菌群落作为猎物和六种形态相似的原生动物子集作为捕食者组成的紫瓶子草食物网。我们采用了析因设计，有四个温度、四种细菌和原生动物的生物地理起源，重复四次。这种设计使我们能够确定捕食者和猎物的动态如何受到非生物（温度）条件和生物（捕食者与来自其本地或非本地生物地理起源的猎物配对）条件的影响。我们发现，无论猎物的起源温度如何，在较温暖的温度下它们的密度都更高。相反，捕食者在其起源的温度条件下以及与来自其起源的猎物一起时密度更高。这些结果证实，捕食者在其起源的非生物和生物条件下表现更好，而它们的猎物则不然。在气候变化下，营养级之间的这种不匹配可能特别显著，可能通过不成比例地影响自上而下和自下而上的控制来扰乱生态系统功能。
