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Responses of terrestrial polar arthropods to high and increasing temperatures

Citation

Bahrndorff, Simon et al. (2021), Responses of terrestrial polar arthropods to high and increasing temperatures, Dryad, Dataset, https://doi.org/10.5061/dryad.cc2fqz65q

Abstract

Terrestrial arthropods in the Arctic and Antarctic are exposed to extreme and variable temperatures, and climate change is predicted to be especially pronounced in these regions. Available studies on insect ecophysiology typically focus on the ability of species to tolerate the extreme low temperatures that can occur in these regions, whereas studies investigating species’ plasticity and the importance of evolutionary adaptation to periodically high and increasing temperatures are limited. Here, we provide an overview of current knowledge on thermal adaptation to high temperatures of terrestrial arthropods in Arctic and Antarctic regions. Firstly, we summarize the literature on heat tolerance for terrestrial arthropods in these regions, and discuss variation in heat tolerance across species, habitats and polar regions. Secondly, we discuss the potential for species to cope with increasing and more variable temperatures through thermal plasticity and evolutionary adaptation. Thirdly, we summarize our current knowledge of the underlying physiological adjustments to heat stress in arthropods from these regions. It is clear that very little data are available on the heat tolerance of arthropods in polar regions, but that large variation in arthropod thermal tolerance exists across polar regions, habitats and species. Further, the species investigated show unique physiological adjustments to heat stress in, for example, being able to respond quickly to increasing or extreme temperatures. To understand the consequences of climate change on terrestrial arthropods in polar regions, we suggest that more studies on the ability of species to cope with stressful high and variable temperatures are needed.

Methods

Upper thermal tolerance limits (CTmax) were measured on nine species collected at two locations in Narsarsuaq, Greenland. The individuals used for thermal assays were collected in the field using species-specific catch methods (Table S1). Adults of unknown age and gender were tested. To measure CTmax, a dynamic ramping assay was used. Field-caught individuals were placed in 15 ml plastic vials with screw caps with a droplet of 2% agar to prevent desiccation during exposure. The vials were mounted to a rack and lowered into a water bath with a temperature of 25°C. Subsequently, the temperature was increased by 0.2 ± 0.01 °C min-1 using an immersion circulator (Polyscience MX Immersion Circulator model: MX-CA12E). Individuals in each vial were continuously stimulated with a flashlight and tapping on the screw cap with a rod until reaching a temperature at which movement ceased (heat coma). The temperature of heat coma was recorded for each individual. Individuals were stored in 70% ethanol after the thermal assay for later identification. Species were identified based on morphological features using a species identification key by Böcher et al. (2015).

Funding

Carlsbergfondet, Award: CF17-0415

Natur og Univers, Detict Frie Forskningsråd, Award: DFF-8021-00014B