Using ecophysiological traits to predict climatic and activity niches: lethal temperature and water loss inMediterranean ants

Abstract

Aim Unravelling the constraints acting on the distribution and abundance of species is a major goal in ecology. Climatic niche models have become an important but controversial tool for predicting the consequences of global warming for species distributions. However, to date, classical ecophysiological traits such as thermal tolerance and water loss have rarely been accounted for in species distribution models. Here we meet the challenge of linking ecophysiological measures with climatic niche descriptions at two different spatial scales across ant species in a comparative modelling framework. Location Western Europe. Methods Two ecophysiological traits (lethal temperature and water loss) were characterized for 17 sympatric Mediterranean ant species under controlled laboratory conditions. These data, along with two eco‐behavioural traits (timing of activity and habitat specialization) were then used in models examining the species climatic and activity niches, i.e. at the biogeographical and local scales. Climatic niches were built using species distribution maps, while activity niches were built using activity data gathered in the field. Results Physiological traits characterized in the laboratory (particularly lethal temperatures) explained 50% of the interspecific variation in climatic envelopes, especially the maximum temperatures experienced by species in their geographical ranges. Habitat specialization also made an important contribution; other traits such as water loss did not appear to be important. Physiological lethal temperatures also helped define activity niches at the local scale, especially in the case of behaviourally dominant species. Main conclusions Relatively simple physiological traits alone, especially thermal tolerance, combined with some behavioural and natural history traits, can be important predictors of species biogeographical climatic niches. Thermal constraints and behaviour may thus be promising directions for studies seeking to predict species distributions in the face of climatic change.

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

“…Furthermore, the fundamental thermal niches of species are shaped by species-specific physiological constraints; fundamental thermal niches only become realized thermal niches as a consequence of biotic interactions (e.g., competition) and demographic/dispersal constraints (see Meier et al, 2010 for an example). Interestingly, a previous study utilizing the subset of ant species examined here demonstrated that species physiological thermal tolerance and biogeographic climatic niches (i.e., realized climatic niches) were strongly correlated (Arnan and Blüthgen, 2015). Third, estimations of species thermal niche indices based on species records are obviously scale dependent; our species-specific thermal niche indices may therefore be biased.…”

“…It was assumed that the niches were well described by the mean and standard deviation of the thermal conditions in which the species occur. Species thermal niches often follow a Gaussian distribution (Huey and Kingsolver, 1993), which was also true of the niches of the subset of ant species used in this study (Arnan and Blüthgen, 2015). We calculated the following two species-level indices, which are illustrated in Figure 1A.…”

“…The second is that the robustness of community resilience to species extinctions should be the lowest in regions where community resilience is highest. Note that our approach is based on the analyses of species climate niches, which in ants are strongly predicted by thermal physiological constraints (Arnan and Blüthgen, 2015).…”

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

“…A third explanation for the ecological packing is that the morphological traits used here are weakly related to Pheidole ecological niches and, therefore, functional packing is unlikely. This alternative is however questionable given the strong evidence linking ant morphological traits with physiological (Arnan & Blüthgen, ; Arnan et al, ; Bishop et al, ), behavioral (Hurlbert, Ballantyne, & Powell, ; Medan & Josens, ), and life‐history traits (Weiser & Kaspari, ). Most likely, the similarities in morphological traits among Pheidole species do reflect similar ecological adaptations, which ultimately indicate that increased niche packing rather than niche displacement underlies the diversity pattern of Pheidole assemblages in Neotropical savannas.…”

Anthropogenic disturbance and rainfall variation threaten the stability of plant–ant interactions in the Brazilian Caatinga

“…Ant preferences for EFN-bearing plants depend on EFN nectar amount and composition Fiedler 2004a, b, Bixenman et al 2011), and nectar production is highly dependent on abiotic and biotic factors (Bixenman et al 2011, Alves-Silva andDel-Claro 2014). In addition, the physical conditions of microhabitats determine the spatial and temporal foraging patterns of ants (Fitzpatrick et al 2014, Arnan andBlüthgen 2015). Thus, in more environmentally unstable areas (probably the most disturbed and arid areas), shifts in ant foraging patterns and plant preferences may be more pronounced from year to year, thus increasing temporal instability in interaction networks.…”