Upper thermal tolerance and oxygen limitation in terrestrial arthropods
Date
2004
Authors
Klok C.J.
Sinclair B.J.
Chown S.L.
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Abstract
The hypothesis of oxygen limitation of thermal tolerance proposes that critical temperatures are set by a transition to anaerobic metabolism, and that upper and lower tolerances are therefore coupled. Moreover, this hypothesis has been dubbed a unifying general principle and extended from marine to terrestrial ectotherms. By contrast, in insects the upper and lower limits are decoupled, suggesting that the oxygen limitation hypothesis might not be as general as proposed. However, no direct tests of this hypothesis or its predictions have been undertaken in terrestrial species. We use a terrestrial isopod (Armadillidium vulgare) and a tenebrionid beetle (Gonocephalum simplex) to test the prediction that thermal tolerance should vary with oxygen partial pressure. Whilst in the isopod critical thermal maximum declined with declining oxygen concentration, this was not the case in the beetle. Efficient oxygen delivery via a tracheal system makes oxygen limitation of thermal tolerance, at a whole organism level, unlikely in insects. By contrast, oxygen limitation of thermal tolerances is expected to apply to species, like the isopod, in which the circulatory system contributes significantly to oxygen delivery. Because insects dominate terrestrial systems, oxygen limitation of thermal tolerance cannot be considered pervasive in this habitat, although it is a characteristic of marine species.
Description
Keywords
carbon dioxide, oxygen, adaptation, analysis of variance, animal, article, beetle, comparative study, environment, Isopoda, metabolism, motor activity, physiology, pressure, South Africa, species difference, temperature, Adaptation, Physiological, Analysis of Variance, Animals, Beetles, Carbon Dioxide, Environment, Isopoda, Motor Activity, Oxygen, Partial Pressure, South Africa, Species Specificity, Temperature, Animalia, Armadillidium, Armadillidium vulgare, Arthropoda, Coleoptera, Gonocephalum, Hexapoda, Isopoda
Citation
Journal of Experimental Biology
207
13
207
13