Versteeg Evan J, Fernandes Timothy, Guzzo Matthew M, Laberge Frédéric, Middel Trevor, Ridgway Mark, McMeans Bailey C
University of Toronto Mississauga Mississauga ON Canada.
Department of Integrative Biology University of Guelph Guelph ON Canada.
Ecol Evol. 2021 Sep 30;11(21):14950-14959. doi: 10.1002/ece3.8179. eCollection 2021 Nov.
Teleost fishes occupy a range of ecosystem, and habitat types subject to large seasonal fluctuations. Temperate fishes, in particular, survive large seasonal shifts in temperature, light availability, and access to certain habitats. Mobile species such as lake trout () can behaviorally respond to seasonal variation by shifting their habitat deeper and further offshore in response to warmer surface water temperatures during the summer. During cooler seasons, the use of more structurally complex nearshore zones by lake trout could increase cognitive demands and potentially result in a larger relative brain size during those periods. Yet, there is limited understanding of how such behavioral responses to a seasonally shifting environment might shape, or be shaped by, the nervous system.Here, we quantified variation in relative brain size and the size of five externally visible brain regions in lake trout, across six consecutive seasons in two different lakes. Acoustic telemetry data from one of our study lakes were collected during the study period from a different subset of individuals and used to infer relationships between brain size and seasonal behaviors (habitat use and movement rate).Our results indicated that lake trout relative brain size was larger in the fall and winter compared with the spring and summer in both lakes. Larger brains coincided with increased use of nearshore habitats and increased horizontal movement rates in the fall and winter based on acoustic telemetry. The telencephalon followed the same pattern as whole brain size, while the other brain regions (cerebellum, optic tectum, olfactory bulbs, and hypothalamus) were only smaller in the spring.These findings provide evidence that flexibility in brain size could underpin shifts in behavior, which could potentially subserve functions associated with differential habitat use during cold and warm seasons and allow fish to succeed in seasonally variable environments.
硬骨鱼栖息于一系列生态系统以及受季节性大幅波动影响的栖息地类型中。特别是温带鱼类，它们能在温度、光照可用性以及特定栖息地的获取等方面经历巨大的季节性变化中存活下来。像湖鳟（）这样的洄游物种可以通过行为来应对季节性变化，比如在夏季，随着表层水温升高，它们会向更深的水域和更远的近海转移栖息地。在较凉爽的季节里，湖鳟对结构更复杂的近岸区域的利用可能会增加认知需求，并有可能在这些时期导致相对脑容量更大。然而，对于这种对季节性变化环境的行为反应如何塑造神经系统，或者如何被神经系统塑造，我们的了解还很有限。在这里，我们对两个不同湖泊中连续六个季节的湖鳟相对脑容量以及五个外部可见脑区的大小变化进行了量化。在研究期间，我们从其中一个研究湖泊收集了声学遥测数据，这些数据来自不同的个体子集，并用于推断脑容量与季节性行为（栖息地利用和移动速度）之间的关系。我们的结果表明，在两个湖泊中，湖鳟的相对脑容量在秋季和冬季比春季和夏季更大。根据声学遥测，更大的脑容量与秋季和冬季对近岸栖息地的更多利用以及水平移动速度的增加相吻合。端脑与全脑大小遵循相同的模式，而其他脑区（小脑、视顶盖、嗅球和下丘脑）仅在春季较小。这些发现提供了证据，表明脑容量的灵活性可能是行为转变的基础，这可能潜在地有助于在寒冷和温暖季节与不同栖息地利用相关的功能，并使鱼类能够在季节性变化的环境中成功生存。
