Thermal Characterization of European Ant Communities Along Thermal Gradients and Its Implications for Community Resilience to Temperature Variability

Abstract

Ecologists are increasingly concerned about how climate change will affect biodiversity yet have mostly addressed the issue at the species level. Here, we present a novel framework that accounts for the full range and complementarity of thermal responses present in a community; it may help reveal how biological communities will respond to climatic (i.e., thermal) variability. First, we characterized the thermal niches of 147 ant species from 342 communities found along broad temperature gradients in western Europe. Within each community, species' mean thermal breadth and the difference among species' thermal optima (thermal complementarity) were considered to define community thermal niche breadth-our proxy for community thermal resilience. The greater the range of thermal responses and their complementarity within a community, the greater the likelihood that the community could cope with novel conditions. Second, we used simulations to calculate how robust community thermal resilience was to random species extinctions. Community resilience was considered to be robust when random species extinctions largely failed to constrict initial community thermal breadth. Our results indicate that community thermal resilience was negatively and positively correlated with mean temperature and temperature seasonality, respectively. The pattern was reversed for robustness. While species richness did not directly affect community resilience to thermal variability, it did have a strong indirect effect because it determined community resilience robustness. Consequently, communities in warm, aseasonal regions are the most vulnerable to temperature variability, despite their greater number of species and resultant greater resilience robustness.

Evidence for locally adaptive metabolic rates among ant populations along an elevational gradient

“…The gap between the temperature sensitivity of MR and activity levels also raises intriguing questions about the extent to which colony life may relax selection on worker‐level metabolic traits related to climate variability. On the one hand, thermal performance traits of workers shape ant ecology and distributions at local (Cerdá, Retana, & Cros, ; Kaspari et al, ; Talbot, ) and biogeographic scales (Arnan & Blüthgen, ; Arnan, Blüthgen, Molowny‐Horas, & Retana, ; Diamond et al, ). However, colony‐level performance is also governed by a capacity for thermoregulation (Baudier & O'Donnell, ) since colonies can use nest architecture to thermally manipulate larval development rates (Penick & Tschinkel, ) and shift colony growth rates (Penick, Diamond, Sanders, & Dunn, ).…”

Local and regional drivers of ant communities in forest-grassland ecotones in South Brazil: A taxonomic and phylogenetic approach

“…Closed-canopy habitats, such as forests, are typically shaded and cooler than open-canopy ecosystems (in our study, grasslands: mean 29.9°C with max 36.2°C; forests: mean 24.8°C with max 32.7°C), in addition to offering buffered microclimate conditions to the biota [81]. Thus, forests and grasslands may present ant species with different thermal niches [82], with forest ant communities more sensitive to the daily thermal oscillation in comparison to grassland species. Further studies should clarify this topic in detail with experiments and field observations.…”

Functional richness shows spatial scale dependency in Pheidole ant assemblages from Neotropical savannas

“…The concomitant warm and dry conditions in the northern Cerrado might restrict foraging times of tropical ants and increase temporal niche overlap (and thus competition). Such thermal constraints on ant species have been demonstrated even for temperate habitats, where thermal resilience of ant assemblages is reduced in warm and aseasonal regions (Arnan, Blüthgen, Molowny‐Horas, & Retana, ). Considering that tropical ant species are already close to their upper thermal tolerances (Diamond et al, ), it is likely that physiological limitations shape the outcome of the biotic interactions.…”

“…where thermal resilience of ant assemblages is reduced in warm and aseasonal regions (Arnan, Blüthgen, Molowny-Horas, & Retana, 2015). Considering that tropical ant species are already close to their upper thermal tolerances (Diamond et al, 2012), it is likely that physiological limitations shape the outcome of the biotic interactions.…”