Role of climatic variability in shaping intraspecific variation of thermal tolerance in Mediterranean water beetles

• We tested the climatic variability hypothesis (CVH) and trade-off hypothesis in populations of three water beetles with similar annual mean temperature but contrasting thermal variability (continental vs. coastal population). • In two of the species, thermal ranges were wider in the continenta l (more variable) than the coastal (more stable) population, at the cost of losing plasticity of the upper thermal limit. • Overall, our results support the role of local adaptation to thermal variability and trade-offs between basal tolerance and physiological plasticity in shaping thermal tolera nce in aquatic ectotherms. AbstractThe climatic variability hypothesis (CVH) predicts that organisms in more thermally variable environments have wider thermal breadths and higher thermal plasticity than those from more stable environments. However, due to evolutionary trade-offs, taxa with greater absolute thermal limits may have little plasticity of such limits (trade-off hypothesis). The CVH assumes that climatic variability is the ultimate driver of thermal tolerance variation across latitudinal and altitudinal gradients, but average temperature also varies along such gradients. We explored intraspecific variation of thermal tolerance in three typical Mediterranean saline water beetles (families Hydrophilidae and Dytiscidae). For each species, we compared two populations where the species coexist, with similar annual mean temperature but contrasting thermal variability (continental...
Source: Insect Science - Category: Biology Authors: Tags: ORIGINAL ARTICLE Source Type: research