Experimental winter warming modifies thermal performance and primes acorn ants for warm weather. (July 2017)

• Record Type: Journal Article
• Authors: MacLean, Heidi J.; Penick, Clint A.; Dunn, Robert R.; Diamond, Sarah E.
• Is Part Of: Journal of insect physiology. Volume 100(2017:May)
• Page Start: 77
• Page End: 81
• Publication Date: 2017-07
• Subjects: Climate change -- Experimental climate warming -- Running speed -- Ants -- Phenotypic plasticity; Insects -- Physiology -- Periodicals; Insectes -- Physiologie -- Périodiques; Insects -- Physiology; Periodicals; 571.157
• DOI: 10.1016/j.jinsphys.2017.05.010
• Languages: English
• ISSNs: 0022-1910

Abstract

Graphical abstract: Highlights: Most measures of performance under climate change are limited to the growing season. Using winter warming treatments (+3 & 5 °C) we quantify performance in acorn ants. We see little cost or no benefit of warmer winters for colder test temperatures. However the winter warming treatment increased running speed at high temperatures. Thus warmer winters prime organisms for spring activity. Abstract: The frequency of warm winter days is increasing under global climate change, but how organisms respond to warmer winters is not well understood. Most studies focus on growing season responses to warming. Locomotor performance is often highly sensitive to temperature, and can determine fitness outcomes through a variety of mechanisms including resource acquisition and predator escape. As a consequence, locomotor performance, and its impacts on fitness, may be strongly affected by winter warming in winter-active species. Here we use the acorn ant, Temnothorax curvispinosus, to explore how thermal performance (temperature-driven plasticity) in running speed is influenced by experimental winter warming of 3–5 °C above ambient in a field setting. We used running speed as a measure of performance as it is a common locomotor trait that influences acquisition of nest sites and food in acorn ants. Experimental winter warming significantly altered thermal performance for running speed at high (26 and 36 °C) but not low test temperatures (6 and 16 °C). Although we saw little differentiation in thermal performance at cooler test temperatures, we saw a marked increase in running speed at the hotter test temperatures for ants that experienced warmer winters compared with those that experienced cooler winters. Our results provide evidence that overwintering temperatures can substantially influence organismal performance, and suggest that we cannot ignore overwintering effects when forecasting organismal responses to environmental changes in temperature.