The role of thermal tolerance in determining elevational distributions of four arthropod taxa in mountain ranges of southern Asia

Abstract

Understanding the role of thermal tolerances in determining species distributions is important for assessing species responses to climate change. Two hypotheses linking physiology with species distributions have been put forward—the climatic variability hypothesis and the climatic extreme hypothesis. The climatic variability hypothesis predicts the selection of individuals with broad thermal tolerance in more variable climatic conditions and the climatic extreme hypothesis predicts the selection of individuals with extreme thermal tolerance values under extreme climatic conditions. However, no study has tested the predictions of these hypotheses simultaneously for several taxonomic groups along elevational gradients. Here, we related experimentally measured critical thermal maxima, critical thermal minima and thermal tolerance breadths for 15,187 individuals belonging to 116 species of ants, beetles, grasshoppers, and spiders from mountain ranges in central and northern Pakistan to the limits and breadths of their geographic and temperature range. Across all species and taxonomic groups, we found strong relationships between thermal traits and elevational distributions both in terms of geography and temperature. The relationships were robust when repeating the analyses for ants, grasshoppers, and spiders but not for beetles. These results indicate a strong role of physiology in determining elevational distributions of arthropods in Southern Asia. Overall, we found strong support for the climatic variability hypothesis and the climatic extreme hypothesis. A close association between species' distributional limits and their thermal tolerances suggest that in case of a failure to adapt or acclimate to novel climatic conditions, species may be under pressure to track their preferred climatic conditions, potentially facing serious consequences under current and future climate change.

Aerobic metabolic scope mapping of an invasive fish species with global warming

“…Nevertheless, the extent to which the relationship between temperature and aerobic scope affects the distribution and climate change sensitivity of ectotherms is currently debated ( Clark et al , 2013 ; Farrell, 2013 ; Pörtner and Giomi, 2013 ; Jutfelt et al , 2018 ). Some authors suggest that the relationship between temperature and aerobic scope is not always a good predictor of temperature performance ( Clark et al , 2013 ; Norin et al , 2014 ; Jutfelt et al , 2018 ), whereas others argue that this relationship may be a good predictor of performance at the extremes but not at temperature optima ( Verberk et al , 2016 ; MacMillan, 2019 ; Khaliq et al , 2023 ).…”