Data from: Prenatal exposure to predation affects predator recognition learning via lateralization plasticity

Prey with cerebral lateralization often shows a bias in escape direction and asymmetrical use of eyes for scanning. Such asymmetries are likely to cause ecological disadvantages when, for example, predators attack from the side in which the prey is more susceptible. However, lateralized individuals are diffuse in many species and, paradoxically, their frequency increases via developmental plasticity in environments with high-predation risk. Using wood frog tadpoles, Lithobates sylvaticus, we tested the hypothesis that cerebral lateralization enhances predator recognition learning and thus overcomes the costs of behavioral asymmetries in high predation risk environments. In the first experiment, we found tadpoles exposed to risk as embryos developed more intense lateralization in a rotational test compared to predator-naive controls. Risk exposure led to the more frequent development of clockwise swimming preference. In the second experiment, we found that tadpoles exhibiting no behavioral lateralization and tadpoles with marked clockwise swimming preference learned to recognize the novel predator odor, with the latter showing a better performance as predicted. Tadpoles with anticlockwise swimming preference did not learn to associate the predator with risk. Exposure to a high-risk environment during early ontogeny appears to favor the development of either a lateralization phenotype with refined predator recognition learning skills, or, to a lesser extent, a lateralization phenotype with poor predator recognition learning skills. Such individuals likely cope with predation using mechanisms other than learning.

具备大脑偏侧化（cerebral lateralization）的猎物通常存在逃逸方向偏好，且在环境扫描过程中表现出不对称的用眼行为。此类不对称性往往会带来生态劣势，例如当捕食者从猎物更易受攻击的一侧发起袭击时。但许多物种中大脑偏侧化的个体仍广泛分布，且矛盾的是，在高捕食风险环境中，这类个体的占比会通过发育可塑性（developmental plasticity）升高。本研究以林蛙蝌蚪（wood frog tadpoles，Lithobates sylvaticus）为实验材料，验证了"大脑偏侧化可提升捕食者识别学习能力，从而在高捕食风险环境中抵消行为不对称性带来的适应性代价"这一假说。在第一项实验中，相较于未接触过捕食者的对照组，胚胎期暴露于风险环境的蝌蚪在旋转测试中表现出更显著的偏侧化特征，且更易形成顺时针游泳偏好。第二项实验结果显示，无行为偏侧化的蝌蚪与具有明显顺时针游泳偏好的蝌蚪均能学会识别新型捕食者气味，且后者的学习表现如预期般更优；而具有逆时针游泳偏好的蝌蚪则无法建立捕食者与风险之间的关联。早期个体发育阶段暴露于高风险环境，似乎会促进两类偏侧化表型的形成：一类具备更精细的捕食者识别学习能力，另一类的学习能力相对较弱（占比更低）。这类个体大概率通过非学习的其他机制应对捕食压力。