Frazier M R, Woods H A, Harrison J F
Department of Biology, Arizona State University, Tempe, AZ 85287-1501, USA.
Physiol Biochem Zool. 2001 Sep-Oct;74(5):641-50. doi: 10.1086/322172.
Although higher temperatures strongly stimulate ectothermic metabolic rates, they only slightly increase oxygen diffusion rates and decrease oxygen solubility. Consequently, we predicted that insect gas exchange systems would have more difficulty meeting tissue oxygen demands at higher temperatures. In this study, Drosophila melanogaster were reared from egg to adult in hyperoxic (40%), hypoxic (10%), and normoxic (21%) conditions and in temperatures ranging from 15 degrees -31.5 degrees C to examine the interactive effect of temperature and oxygen on development. Hyperoxia generally increased mass and growth rate at higher rearing temperatures. At lower rearing temperatures, however, hyperoxia had a very small effect on mass, did not affect growth rate, and lengthened time to eclosion. Relative to normoxia, flies reared in hypoxic conditions were generally smaller (mass and thorax length), had longer eclosion times, slower growth rates, and reduced survival. At cooler temperatures, hypoxia had relatively modest or nonsignificant effects on development, while at higher temperatures, the effects of hypoxia were large. These results suggest that higher temperatures reduce oxygen delivery capacity relative to tissue oxygen needs, which may partially explain why ectotherms are smaller when development occurs at higher temperatures.
尽管较高温度会强烈刺激变温动物的代谢率，但它们只会略微提高氧气扩散速率并降低氧气溶解度。因此，我们预测昆虫的气体交换系统在较高温度下更难满足组织对氧气的需求。在本研究中，将黑腹果蝇在高氧（40%）、低氧（10%）和常氧（21%）条件下，以及在15摄氏度至31.5摄氏度的温度范围内从卵饲养至成虫，以研究温度和氧气对发育的交互作用。高氧通常会在较高饲养温度下增加体重和生长速率。然而，在较低饲养温度下，高氧对体重的影响非常小，不影响生长速率，且会延长羽化时间。相对于常氧，在低氧条件下饲养的果蝇通常体型较小（体重和胸长），羽化时间更长，生长速率较慢，且存活率降低。在较凉爽的温度下，低氧对发育的影响相对较小或不显著，而在较高温度下，低氧的影响则很大。这些结果表明，相对于组织对氧气的需求，较高温度会降低氧气输送能力，这可能部分解释了为什么变温动物在较高温度下发育时体型较小。
