Adaptation to temperature stress and aerial exposure in congeneric species of intertidal porcelain crabs (genus Petrolisthes): correlation of physiology, biochemistry and morphology with vertical distribution
Adaptation to temperature stress and aerial exposure in congeneric species of intertidal porcelain crabs (genus Petrolisthes): correlation of physiology, biochemistry and morphology with vertical distribution
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发表时间：
1996-08
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通讯作者：
J. Stillman;G. Somero
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作者：
J. Stillman;G. Somero
我们研究了两种潮间带瓷蟹（属岩蟹），居住在离散的垂直区域的温度和空气暴露的生理和生化反应。在东北太平洋沿岸，P. cinctipes（Randall）出现在中到高潮带的岩石和贻贝床下，P. eriomerus（Stimpson）出现在低潮带的岩石下，潮下至80米。由于它们不同的垂直分布，这两个物种经历了非常不同的非生物胁迫水平。在每一个低潮期，花足拟步行虫（P. cinctipes）都能出现个体，但毛足拟步行虫（P. eriomerus）只在大潮最低潮时出现，大多数日子根本不出现。在中潮间带岩石下测得的温度高达31 °C，比在低潮间带岩石下测得的最高温度高15 °C。在25 °C的空气中，大型的花足拟步行虫能够保持比同样大小的毛足拟步行虫更高的呼吸速率。在小样本中，没有观察到呼吸反应的种间差异。对心率对温度的反应的研究表明，花足拟步行虫的阿耳忒弥斯转折温度（ABT，阿耳忒弥斯曲线斜率不连续的温度）比其同类高5 °C（31.5 °C对26.6 °C）。结果表明，在1.5 °C的低温下，花足裸腹蛛的心率完全恢复，而在2 °C或更低的低温下，绒头裸腹蛛的心率没有恢复。结果表明，花足马勃心率的ABT值与最高微生境温度非常接近，表明该物种的个体可能生活在或接近其热耐受极限。花足海鞘在羽化过程中能够维持好氧代谢，而绒头海鞘则转变为厌氧代谢。在25 °C下于空气中孵育5小时的P.eriomerus样本中发现全身乳酸盐的显著积累，但在类似处理的P.cinctipes中没有发现。环足马蜂在其行走腿的腹节上具有膜状结构，但在毛足马蜂中没有这种结构。为了验证腿膜的功能，我们测量了腿膜被遮蔽后的花足裸胸蛙的空气呼吸速率和乳酸积累。这些个体在30 °C时的空气呼吸速率显著低于对照蟹。在28 °C下，腿膜被遮蔽的蟹在5 h的浮出期间也积累了相当数量的乳酸，但对照蟹在相同条件下没有显示出积累。这些数据表明，腿膜作为呼吸结构的功能。研究结果表明，一套形态、生理和生化特征使花足海鞘比毛海鞘在潮间带生活得更高。
We examined physiological and biochemical responses to temperature and aerial exposure in two species of intertidal porcelain crabs (genus Petrolisthes) that inhabit discrete vertical zones. On the shores of the Northeastern Pacific, P. cinctipes (Randall) occurs under rocks and in mussel beds in the mid to high intertidal zone and P. eriomerus (Stimpson) occurs under rocks in the low intertidal zone and subtidally to 80 m. Because of their different vertical distributions, these two species experience very different levels of abiotic stress. Individuals of P. cinctipes can be emersed during every low tide, but P. eriomerus is only emersed during the lowest spring tides and on most days is not emersed at all. Temperatures measured underneath rocks in the mid intertidal zone were as high as 31 °C, 15 °C higher than maximal temperatures measured under rocks in the low intertidal zone. In air, at 25 °C, large specimens of P. cinctipes were able to maintain a higher respiration rate than similarly sized P. eriomerus. No interspecific differences in the respiratory response to emersion were seen in small specimens. Examination of the response of heart rate to temperature revealed that P. cinctipes has a 5 °C higher Arrhenius break temperature (ABT, the temperature at which there is a discontinuity in the slope of an Arrhenius plot) than its congener (31.5 °C versus 26.6 °C). The heart rate of P. cinctipes recovered fully after exposure to cold (1.5 °C), but the heart rate of P. eriomerus did not recover after exposure to 2 °C or cooler. The ABT of heart rate in P. cinctipes was very close to maximal microhabitat temperatures; thus, individuals of this species may be living at or near their thermal tolerance limits. P. cinctipes were able to maintain aerobic metabolism during emersion, whereas P. eriomerus shifted to anaerobic metabolism. A pronounced accumulation of whole-body lactate was found in specimens of P. eriomerus incubated in air at 25 °C over a 5 h period, but not in P. cinctipes similarly treated. P. cinctipes possesses a membranous structure on the ventral merus of each walking leg, but this structure is not found in P. eriomerus. To test the function of the leg membrane, we measured the aerial respiration rates and the lactate accumulation of P. cinctipes with their leg membranes obscured. These individuals had significantly lower aerial respiration rates at 30 °C than control crabs. Crabs with leg membranes obscured also accumulated a considerable amount of lactate during a 5 h period of emersion at 28 °C, but control crabs showed no accumulation under the same conditions. These data suggest that the leg membrane functions as a respiratory structure. The results of this study illustrate that a suite of morphological, physiological and biochemical features allows P. cinctipes to live higher in the intertidal region than P. eriomerus.