Chappell Mark A, Bailey Nathan W, Redak Richard A, Antolin Michael, Zuk Marlene
Department of Biology, University of California, Riverside, California 92521, USA.
Physiol Biochem Zool. 2009 Sep-Oct;82(5):405-18. doi: 10.1086/603632.
Mormon crickets, large flightless katydids from western North America, occur in two forms that differ dramatically in population density and daily movement distances. The low-density form is small and cryptic and moves <1 m/d, while the high-density form is large and dark colored and travels up to 1-2 km/d in migratory bands. We determined daytime body temperatures and measured resting metabolic rate (RMR) and maximal aerobic metabolic rate (MMR) in forced exercise across a 10 degrees - 40 degrees C temperature range. Field body temperatures were 15 degrees - 20 degrees C in the morning and 25 degrees - 35 degrees C during most of the day, and they never exceeded 40.6 degrees C in either form. Mass-adjusted RMR and MMR were positively correlated across temperatures (significantly in some comparisons), indicating repeatability. Similarly, RMR was always positively and sometimes significantly correlated with MMR, suggesting a functional linkage between minimal and maximal aerobic performance. Factorial aerobic scopes (MMR/RMR) were highest at 10 degrees C and declined at higher temperatures, but absolute scope (MMR - RMR) was highest between 30 degrees and 40 degrees C. Given the ca. 1,000-fold contrast in daily movement distances, we expected higher MMR and aerobic scope in the migratory high-density form. However, there were no differences between forms in RMR, MMR, aerobic scope, or ventilation patterns. The forms were also similar in metabolic response to temperature (Q(10)) and in the mass scaling of metabolic rate. The absence of metabolic divergence among low- and high-density forms shows that large differences in locomotor behavior may not require concomitant changes in aerobic physiology.
摩门螽斯是北美洲西部大型的不会飞的螽斯，有两种形态，其种群密度和每日移动距离差异极大。低密度形态体型小且不易被发现，每天移动距离小于1米，而高密度形态体型大且颜色深，在迁徙群体中每天能行进1 - 2千米。我们测定了10摄氏度至40摄氏度温度范围内的白天体温，并测量了静息代谢率（RMR）以及强制运动中的最大有氧代谢率（MMR）。野外体温在早晨为15摄氏度至20摄氏度，白天大部分时间为25摄氏度至35摄氏度，两种形态的体温都从未超过40.6摄氏度。经体重调整后的RMR和MMR在不同温度下呈正相关（在某些比较中显著），表明具有重复性。同样，RMR总是与MMR呈正相关，有时显著相关，这表明最低和最高有氧表现之间存在功能联系。有氧能力系数（MMR/RMR）在10摄氏度时最高，在较高温度下下降，但绝对能力（MMR - RMR）在30摄氏度至40摄氏度之间最高。鉴于每日移动距离有大约1000倍的差异，我们预计迁徙的高密度形态具有更高的MMR和有氧能力。然而，两种形态在RMR、MMR、有氧能力或通气模式方面没有差异。两种形态在代谢对温度的反应（Q10）以及代谢率的体重标度方面也相似。低密度和高密度形态之间不存在代谢差异表明，运动行为的巨大差异可能并不需要有氧生理的相应变化。
