Extreme Insolation: Climatic Variation Shapes the Evolution of Thermal Tolerance at Multiple Scales.

Extreme Insolation: Climatic Variation Shapes the Evolution of Thermal Tolerance at Multiple Scales. Am Nat. 2018 Sep;192(3):347-359 Authors: Baudier KM, D'Amelio CL, Malhotra R, O'Connor MP, O'Donnell S Abstract The climatic variability hypothesis (CVH) is a cornerstone of thermal ecology, predicting the evolution of wider organismal thermal tolerance ranges in more thermally variable environments. Thermal tolerance ranges depend on both upper and lower tolerance limits (critical thermal maxima [[Formula: see text]] and critical thermal minima [[Formula: see text]]), which may show different responses to environmental gradients. To delineate the relative effects of mean and extreme temperatures on thermal tolerances, we conducted a within-latitude comparative test of CVH predictions for army ants (Dorylinae) at multiple scales: across elevations, in seasonal versus aseasonal forests, and in subterranean versus surface microhabitats. Consistent with the CVH, thermally buffered subterranean species had narrower thermal tolerance ranges. Both [Formula: see text] and [Formula: see text] decreased with elevation for subterranean species. In contrast, aboveground species (those exposed to insolation) showed a decrease in [Formula: see text] but no change in [Formula: see text] across elevations. Furthermore, greater seasonal temperature variation in dry forests correlated with increased [Formula: see text] but not [Formula: see text]. The...
Source: The American Naturalist - Category: Biology Authors: Tags: Am Nat Source Type: research