Habitat selection behavior by aquatic and terrestrial animals is influenced by both abiotic (e.g., temperature) and biotic (e.g., threat from predators) environmental factors. In this study, the mechanisms underlying the variability in behavior of habitat selection of Daphnia under environmental stress were examined. Experiments were conducted using five Daphnia clones with different environmental preferences and, consequently, with a different width of the reaction norm. These clones also showed variation in their constitutive levels of stress-related heat shock proteins (HSP60, HSP70 and HSP90), but none of the tested stress factors had any direct effect on their expression. However, behavioral plasticity was significantly positively correlated with the constitutive level of HSP70. It is likely that animals with a high constitutive HSP70 level can cope better with sudden changes in environment conditions that they experience, e.g., during vertical migrations. In contrast, non-migrating animals with low HSP levels do not allocate energy to the synthesis of stress proteins and have a narrow range of behavioral plasticity.

水生和陆生动物的栖息地选择行为受非生物（例如温度）和生物（例如来自捕食者的威胁）环境因素的影响。在这项研究中，研究了水蚤在环境压力下栖息地选择行为变异性的机制。使用五个水蚤进行实验具有不同环境偏好的克隆，因此具有不同的反应规范宽度。这些克隆的应激相关热休克蛋白（HSP60、HSP70 和 HSP90）的组成水平也显示出变化，但没有一个测试的应激因素对其表达有任何直接影响。然而，行为可塑性与 HSP70 的组成水平显着正相关。具有高组成型 HSP70 水平的动物很可能能够更好地应对它们所经历的环境条件的突然变化，例如在垂直迁移期间。相比之下，具有低 HSP 水平的非迁移动物不会将能量分配给应激蛋白的合成，并且行为可塑性范围很窄。