Fitzgerald-Dehoog Lindsay, Browning Jeremy, Allen Bengt J
Department of Biological Sciences, California State University, Long Beach, 1250 Bellflower Blvd, Long Beach, California 90840-3702, USA.
Biol Bull. 2012 Oct;223(2):205-16. doi: 10.1086/BBLv223n2p205.
In response to thermal stress, many rocky shore organisms exhibit characteristic physiological changes associated with increased tolerance to subsequent high temperatures. Although presumably adaptive, activation of the heat-shock response requires a significant energetic investment and therefore may impose a trade-off between survival and other life-history traits. We investigated the effects of chronic heat stress and variation in food availability on the relative allocation of resources to competing demographic parameters in the California mussel, Mytilus californianus. Our data support the idea that acclimatory responses to temperature stress can drive trade-offs among traits, as predicted by theory. Chronic heat stress invoked a cost to individuals, expressed as a reduction in shell growth or size-specific tissue mass in the field and laboratory, respectively. At the same time, prior thermal conditioning resulted in higher proportional survival after acute exposure to more extreme temperatures. Overall, mussels receiving less food exhibited poor condition and survival relative to individuals fed more, suggesting that individuals with limited access to resources are at greater risk because they are less able to mitigate potential costs of thermal stress through physiological mechanisms. Accurately forecasting the effects of climate change in rocky intertidal ecosystems will therefore require understanding not just how organisms respond to different temperature regimes, but also how variation in local resource availability modifies those responses.
作为对热应激的反应，许多岩岸生物会表现出特定的生理变化，这些变化与对随后高温的耐受性增强有关。尽管热休克反应可能具有适应性，但激活该反应需要大量的能量投入，因此可能会在生存和其他生活史特征之间形成权衡。我们研究了长期热应激和食物可利用性变化对加利福尼亚贻贝（Mytilus californianus）竞争人口统计学参数资源相对分配的影响。我们的数据支持了这样一种观点，即如理论所预测的，对温度胁迫的适应性反应会导致性状之间的权衡。长期热应激给个体带来了代价，分别表现为在野外和实验室中贝壳生长或特定大小组织质量的减少。与此同时，先前的热适应导致在急性暴露于更极端温度后有更高的比例存活率。总体而言，与喂食较多的个体相比，食物摄入较少的贻贝状况和存活率较差，这表明资源获取有限的个体面临更大风险，因为它们通过生理机制减轻热应激潜在代价的能力较弱。因此，要准确预测气候变化对岩岸潮间带生态系统的影响，不仅需要了解生物如何应对不同的温度状况，还需要了解当地资源可利用性的变化如何改变这些反应。
