Estimating the benefits of plasticity in ectotherm heat tolerance under natural thermal variability

• Published in: Functional ecology Vol. 31; no. 8; pp. 1529 - 1539
• Main Authors: Gunderson, Alex R., Dillon, Michael E., Stillman, Jonathon H.
• Format: Journal Article
• Language: English
• Published: London Wiley 01.08.2017; Wiley Subscription Services, Inc
• Subjects: Acclimation; Acclimatization; amphibian; Amphibians; Animal physiological ecology; arthropod; Arthropods; Climate change; Compensation; Heat; Heat tolerance; Overheating; Plastic properties; Plasticity; reptile; Reptiles; Temperature effects; temperature variability; Terrestrial environments
• ISSN: 0269-8463; 1365-2435
• DOI: 10.1111/1365-2435.12874

Summary Plasticity is a near‐ubiquitous feature of the thermal physiology of ectothermic organisms. Understanding the significance of plasticity in evolutionary and ecological contexts requires determining whether observed plasticity is beneficial, and, if so, to what extent plasticity can compensate for environmental change (i.e. is plasticity ‘complete’ or ‘incomplete’). Using site‐specific daily temperature records spanning several decades, we test the ‘beneficial acclimation hypothesis’ by calculating the number of days predicted to exceed the heat tolerance limits of 103 terrestrial ectotherm populations when incorporating observed taxon‐specific plasticity and when plasticity is ignored. We find that heat tolerance plasticity can reduce the predicted number of overheating events, although the effects are clade specific with plasticity providing greater benefits to amphibians than to reptiles or arthropods. Despite these benefits, heat tolerance plasticity is incomplete; as temperatures rise, plasticity cannot prevent an increase in the risk of overheating. Specifically, we find that a one degree increase in mean maximum temperature leads to approximately one additional day of predicted overheating during the warmest months of the year, on average. We conducted a broad‐scale analysis of the degree to which plasticity in heat tolerance reduces the probability that ectotherms experience temperatures beyond their physiological heat limits. Our results indicate that plasticity in heat tolerance benefits ectotherms, but, consistent with previous studies, those benefits are inadequate to provide complete compensation for global climate change. Lay Summary