Which are the most heat-tolerant animals? Insights from a Mediterranean lepismatid under thermal stress in the context of climate change

Measuring behavioural and physiological thermal limits is crucial to understanding how they interact with the environment under a climate change scenario. We experimentally assessed the effects of acclimation on sequentially measured voluntary (VTmax), critical (CTmax), and upper thermal limit (UTL) limits in the Mediterranean silverfish Sceletolepisma guadianicum. Individuals were acclimated for six days at either 25{degrees}C (n=32) or 35{degrees}C (n=29) and heated at [~]0.5{degrees}C min-1, and VTmax, CTmax, and lethal limits were recorded. S. guadianicum exhibited some of the highest thermal limits reported to date among terrestrial arthropods. VTmax showed limited (1.04 {degrees}C) but statistically detectable plasticity, increasing with high acclimation temperature and heating rate, whereas CTmax rate and lethal limits remained unchanged. We provide hypotheses explaining the co-ocurrence of exceptional heat tolerance levels together with their reduced plasticity in this and other extremely heat-tolerant species. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/690525v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1f5adaaorg.highwire.dtl.DTLVardef@5c95baorg.highwire.dtl.DTLVardef@6a1bddorg.highwire.dtl.DTLVardef@4b55aa_HPS_FORMAT_FIGEXP M_FIG C_FIG