Wing lengths of three Arctic butterfly species decrease as summers warm in Alaska

Abstract

Climate warming can cause arthropods to express plastic and/or evolved changes in morphology. Previous studies have demonstrated that body sizes of Arctic butterflies are influenced by the temperatures experienced as larvae. To investigate whether this was occurring among Alaskan butterflies, we analyzed temporal trends in the wing sizes of three Holarctic species, Colias hecla, Boloria chariclea and Boloria freija, using museum specimens collected in Arctic tundra regions of Alaska between 1971 and 1995. Wing length was compared to accumulated growing degree days (GDD) during both the spring of the year collected and the previous year's summer during the normal period of larval development. We used mixed‐effects models to test if spring and summer temperatures affected adult morphology. Results show that for every 1°C increase in average seasonal temperature, wingspans decreased between 0.7 and 5 mm, with B. freija the most strongly affected. Our results suggest that the morphological sensitivity of Arctic butterflies to warming is the outcome of interactions between life‐history traits and regional climate, with all species sensitive to warming the summer before the flight year as well as warming the spring of the flight year. Boloria freija, which overwinters as late instar larvae that do not feed before pupation the following spring, was particularly strongly affected by summer warming.

Unravelling arthropod movement in natural landscapes: small-scale effects of body size and weather conditions

“…Moreover, ambient temperatures and wind speeds can either augment or impede small-scale movement efficiency, depending on factors like wind direction and thermal thresholds. The looming influence of climate change introduces another layer of complexity, with expected potential changes in body sizes (Daly et al, 2024; Davies, 2019; Polidori et al, 2020) and wind patterns (Greene et al, 2010). This implies that changes in local weather conditions, associated with global warming, will not only influence population sizes by increasing stress on a local scale, but might also exert a direct impact on behaviours at boundaries, thereby propagating or constraining subsequent movements among habitat patches.…”

“…Our study provides a mechanistic behavioural perspective on movement at habitat boundaries, which can be integrated in predictive biodiversity models to better understand future metacommunity processes (Urban et al, 2016). This is particularly important given the impending effects of climate change, which are anticipated to alter body sizes (Daly et al, 2024; Davies, 2019; Polidori et al, 2020), temperatures and wind patterns (Greene et al, 2010). This suggests that global warming will not only impact population sizes by increasing stress on a local scale but that it may also directly influence behaviours at habitat boundaries.…”