Chemosensory assessment of local predation threats in aquatic vertebrates

被捕食的动物经常面临发现和避免捕食者的相互冲突的要求，以及一系列其他与健康有关的行为活动，包括觅食、交配和领土防御。对威胁敏感的捕食者回避假说预测，能够与感知到的威胁程度成正比地调整反捕食者反应强度的猎物应该更好地装备来平衡这些权衡。这类模型假设猎物可以可靠地评估局部捕食风险，但令人惊讶的是，人们对猎物如何感知风险或影响这些权衡的因素知之甚少。我实验室最近的研究集中在使用化学感官线索作为一些捕食性鱼类风险的可靠指标，以及这些线索如何在对威胁敏感的决策中发挥作用。在一系列实验室和实地研究中，我将研究猎物如何整合多种信息源(即化学感官和视觉线索)，以及资源竞争、群体规模和栖息地复杂性等环境因素如何影响对威胁敏感的决策。我还将研究在短期(几天或几周)、长期(整个生长季)或进化(多代)持续时间范围内的时间尺度上，捕食风险的变异性在形成对威胁敏感的权衡中所起的作用。威胁敏感度模型预测，个体应该能够改变自己的行为，以补偿与躲避捕食者相关的成本，尽管这在自然条件下基本上仍未得到测试。我将进行长期的实地研究来调查这一假说。最后，最近的大量研究表明，人为污染物，如酸降水，削弱了被捕食者对当地捕食风险进行化学评估的能力。目前尚不清楚猎物是否能够通过改变它们的行为模式或增加它们对其他非化学输入的依赖来弥补化学感觉输入的损失。通过提高我们对猎物如何以对威胁敏感的方式评估和应对当地捕食威胁的理解，我们希望提高环境评估和管理计划以及渔业种群增加努力的生态有效性。

Prey animals are often faced with the conflicting demands of the detection and avoidance of predators and a suite of other fitness related behavioural activities, including foraging, mating and territorial defence. The threat-sensitive predator avoidance hypothesis predicts that prey capable of adjusting the intensity of the antipredator response proportional to the degree of perceived threat should be better equipped to balance these trade-offs. Such models assume that prey can reliably assess local predation risk, yet surprisingly little is known about how prey perceive risk or about the factors that shape these trade-offs. Recent studies in my laboratory have focused on the use chemosensory cues as reliable indicators of risk for a number of prey fishes and how these cues function in threat-sensitive decision-making. In a series of laboratory and field studies, I will examine how prey integrate multiple information sources (i.e., chemosensory and visual cues) and how environmental factors such as resource competition, group size and habitat complexity influence threat-sensitive decisions. I will also examine the role of variability in predation risk over time scales ranging over short-term (days or weeks), long-term (entire growing seasons) or evolutionary (multigenerational) durations plays in the shaping of threat-sensitive trade-offs. Threat-sensitivity models predict that individuals should be able to alter their behaviour in order to compensate for the costs associated with predator avoidance, though this remains largely untested under natural conditions. I will conduct long-term field studies to investigate this hypothesis. Finally, a great deal of recent research demonstrates that anthropogenic pollutants, such as acid precipitation, impair the ability of prey fishes to chemically assess local predation risks. It remains unknown if prey can compensate for the loss of chemosensory inputs by either altering their behaviour patterns or increasing their reliance on other, non-chemical inputs. By improving our understanding of how prey assess and respond to local predation threats in a threat-sensitive fashion, we hope to enhance the ecological validity of environmental assessment and management programs and fisheries stock enhancement efforts.