Standard metabolic rate variation among New Zealand Orthoptera.

Standard metabolic rates (SMR) of ectotherms reflect the energetic cost of self-maintenance and thus provide important information about life-history strategies of organisms. We examined variation in SMR among fifteen species of New Zealand orthopteran. These species represent a heterogeneous group with a wide geographic distribution, differing morphologies and life histories. Gathering original data on morphological and physiological traits of individual species is a first step towards understanding existing variability. Individual metabolic rates of ectotherms are one of the first traits to respond to climate change. Baseline SMR datasets are valuable for modeling current species distributions and their responses to a changing climate. At higher latitudes, the average environmental temperature decreases. The pattern that cold-adapted ectotherms display higher SMR at colder temperatures and greater thermal sensitivity to compensate for lower temperatures and the shorter growing and reproductive seasons is predicted from the metabolic cold adaptation (MCA) hypothesis. We predict higher SMR for the orthopteran species found at higher latitudes. We further compared the index of thermal sensitivity Q