Measuring behavioral thermal tolerance to address hot topics in ecology, evolution, and conservation

Author(s)

Camacho, Agustin ^[1] ; Rusch, Travis ^[2] ; Ray, Graham ^[2] ; Telemeco, Rory S. ^{[3, 4]} ; Rodrigues, Miguel Trefaut ^[1] ; Angilletta, Michael J. ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Biociencias, Dept Zool, Sao Paulo - Brazil

^[2] Arizona State Univ, Sch Life Sci, Tempe, AZ 85287 - USA

^[3] Univ Washington, Dept Biol, Seattle, WA 98195 - USA

^[4] Univ Calif Fresno, Dept Biol, Fresno, CA 93740 - USA

• Document type: Journal article
• Source: Journal of Thermal Biology; v. 73, p. 71-79, APR 2018.
• Web of Science Citations: 7

Abstract

Understanding the impacts of anthropogenic climate change requires knowing how animals avoid heat stress, and the consequences of failing to do so. Animals primarily use behavior to avoid overheating, but biologists' means for measuring and interpreting behavioral signs of stress require more development. Herein, we develop the measurement of behavioral thermal tolerance using four species of lizards. First, we adapt the voluntary thermal maximum concept (VTM) to facilitate its measurement, interpretation, and comparison across species. Second, we evaluate the sensitivity of the VTM to diverse measurement options (warming rate, time of day, etc) across four species with highly different life histories. Finally, we clarify the interpretation of VTM in two ways. First, we show the effects of exposure to the VIM on panting behavior, mass loss, and locomotor function loss of two species. Second, we compared the VIM with the preferred body temperatures (PBT) and critical thermal maximum (CTMAX) intraspecifically. We found that the VTM can be consistently estimated through different methods and methodological options, only very slow warming rates affected its estimates in one species. Exposure to the VIM caused panting between 5 and 50 min and induced exceptionally high mass loss rates. Loss of locomotion function started after 205 min. Further, the VTM did not show intraspecific correlations with the PBT and CTMAX. Our study suggests the VTM is a robust and flexible measure of thermal tolerance and highlights the need for multispecies evaluations of thermal indices. The lack of correlation between the VIM, the PBT and CTMAX suggests the VIM may evolve relatively free between the other parameters. We make reccommendations for understanding and using the VIM in studies of ecology, evolution, and conservation. (AU)

• FAPESP's process: 12/15754-8 - Ecogeographical consequences of evolution of the snake-like morphotype in squamates
• Grantee: Agustín Camacho Guerrero
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/50297-0 - Dimensions US-BIOTA São Paulo: a multidisciplinary framework for biodiversity prediction in the Brazilian Atlantic forest hotspot
• Grantee: Cristina Yumi Miyaki
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 15/01300-3 - Use of voluntary maximum temperatures for linking thermal physiology and species geographic range size
• Grantee: Agustín Camacho Guerrero
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor