Not Too Warm, Not Too Cold: Thermal Treatments to Slightly Warmer or Colder Conditions from Mother’s Origin Can Enhance Performance of Montane Butterfly Larvae

Abstract

Climate change alters organismal performance via shifts in temperature. However, we know little about the relative fitness impacts of climate variability and how cold-adapted ectotherms mediate these effects. Here, we advance the field of climate change biology by directly testing for species performance, considering the effects of different thermal environments at the first developmental stage of larvae. We conducted our experiments in climatic chambers (2019–2020) using five cold-adapted butterflies of the genus Erebia (Erebia aethiops, Erebia cassioides, Erebia manto, Erebia tyndarus, Erebia nivalis). Larvae were reared indoors and were treated with higher and lower temperatures than those of their mothers’ origins. Overall, we found evidence of better performance at warmer temperatures and a decreased performance at lower temperatures, and larvae were able to tolerate small temperature changes from mother’s origin. Warmer conditions, however, were unfavorable for E. nivalis, indicative of its limited elevational range and its poor ability to mediate a variety of thermal conditions. Further, larvae generally performed poorly where there was a large difference in thermal regimen from that of their maternal origin. Future efforts should include additional life history stages and focus on a more mechanistic understanding of species thermal tolerance. Such studies could increase the realism of predicted responses to climate change and could account for asynchronous changes in species development, which will alter community composition and ecosystem functioning.

Living on the edge—Genomic and ecological delineation of cryptic lineages in the high‐elevation specialist Erebia nivalis

“…Given the negative scenarios for other, similarly isolated Erebia species (e.g., Romo et al, 2023; Sistri et al, 2022), the loss of at least some E. nivalis mountaintop populations over the next decades seems likely. E. nivalis shows little ability to tolerate thermal shifts at the larval stage (Zografou et al, 2022) and, like other Alpine Erebia species, is considered freeze‐avoidant due to its overwintering under snow (Vrba et al, 2012). Abiotic changes in mountainous environments have already been documented in terms of loss of snow cover (Huss et al, 2017; Rumpf et al, 2022), which may especially impact Swiss E. nivalis , given the higher snow water equivalent in its abiotic environment (Figure 6 and Tables S12 and S13).…”

“…Furthermore, the niches of Erebia are often narrow and conserved to their local optima and tend to become narrower with increasingly specialised living conditions (Klečková et al, 2023). The larval performance of several Erebia is similarly reduced when thermal conditions shift too far from their usual range, though some species seem to perform better under warmer conditions (Zografou et al, 2022). An exception to the study above was Erebia nivalis (Lorkovic & De Lesse, 1954), which primarily occurs at elevations above 2100 m a.s.l.…”

“…(Kudrna et al, 2015) only in the Swiss and Austrian Alps (with a few populations in adjoining Italy). This species shows little capacity to tolerate different temperature conditions (Zografou et al, 2022). In addition, E. nivalis is one of the few Erebia species known to have a 2-year generation time, thus likely requiring overwintering under snow for two consecutive winters, which indicates that this species could be especially vulnerable to temperature changes that affect snow cover (Gratton et al, 2016;Sonderegger, 2005).…”