Garcia-Robledo Carlos, Charlotten-Silva Mariela, Cruz Christopher, Kuprewicz Erin K
Department of Ecology & Evolutionary Biology, University of Connecticut, 75 North Eagleville Rd., Unit 3043, Storrs, CT 06269, USA.
Department of Biology, University of Puerto Rico at Ponce, PO Box 7183, Ponce, PR 00732, USA; Research Experience for Undergraduates NSF LSAMP-OTS. Organization for Tropical Studies (OTS), Duke University, Box 90633, Durham, NC 27708, USA.
J Therm Biol. 2018 Oct;77:7-13. doi: 10.1016/j.jtherbio.2018.07.018. Epub 2018 Jul 23.
Determining responses of organisms to changing temperatures is a research priority, as global warming threatens populations and ecosystems worldwide. Upper thermal limits are frequently measured as the critical thermal maximum (CT), a quick bioassay where organisms are exposed to increasing temperatures until individuals are not able to perform basic motor activities such as walking or flying. A more informative approach to understand organism responses to global warming is to evaluate how vital rates, such as growth or survival, change with temperatures. The main objectives of this study are: (1) to determine if factors affecting insect vital rates such as diet quality, developmental temperatures or acclimation also affect CT and (2) to determine if vital rates of different life stages (i.e., insect larvae or adults) display different responses to temperature changes. If different life stages have particular thermal requirements, this may indicate different susceptibility to global warming. This study focuses on Cephaloleia belti (Coleoptera: Chrysomelidae), a tropical insect currently expanding its diet to an exotic host plant. We determined how high and low-quality diets (i.e., native vs novel host), as well as exposure temperatures affect CT of adult beetles. We also estimated larval and adult survival when feeding on high and low quality host plants, when exposed to temperatures typical of the elevational distribution of this species, or when exposed to projected temperatures in 100 years. We did not detect an effect of diet quality or acclimation on CT. However, larvae and adults had different thermal requirements. CT is not affected by previous diet or acclimation as an adult. We propose that to understand processes involved in the adaptation and persistence of ectotherm populations in a warming world, studies must explore responses beyond CT, and focus on the response of vital rates to changing temperatures.
确定生物体对温度变化的反应是一项研究重点，因为全球变暖威胁着世界各地的种群和生态系统。热上限通常被测量为临界热最大值（CT），这是一种快速生物测定法，将生物体暴露于不断升高的温度下，直到个体无法进行诸如行走或飞行等基本运动活动。一种更具信息量的理解生物体对全球变暖反应的方法是评估诸如生长或存活等生命率如何随温度变化。本研究的主要目标是：（1）确定影响昆虫生命率的因素，如饮食质量、发育温度或驯化是否也会影响CT，以及（2）确定不同生命阶段（即昆虫幼虫或成虫）的生命率对温度变化是否表现出不同的反应。如果不同生命阶段有特定的热需求，这可能表明对全球变暖的易感性不同。本研究聚焦于贝利头叶甲（鞘翅目：叶甲科），一种目前正在将其食性扩展到外来寄主植物的热带昆虫。我们确定了高质量和低质量饮食（即本地寄主与新寄主）以及暴露温度如何影响成年甲虫的CT。我们还估计了在以高质量和低质量寄主植物为食时、暴露于该物种海拔分布典型温度时或暴露于100年后预测温度时幼虫和成虫的存活率。我们未检测到饮食质量或驯化对CT有影响。然而，幼虫和成虫有不同的热需求。CT不受成虫之前的饮食或驯化影响。我们提出，为了理解变温动物种群在变暖世界中的适应和持续存在所涉及的过程，研究必须探索CT之外的反应，并关注生命率对温度变化的反应。
