Neuroendocrine control of seasonal phenotypic plasticity in birds

大多数生物表现出季节性变化，以应对可预测的环境变化。季节性繁殖的鸣禽表现出极大的可塑性。鸟类会根据季节调整社会行为、繁殖和迁徙。他们在大脑、生殖生理和其他系统中表现出高度的可塑性。一只鸟的健康主要取决于它在行为和生理上适当地适应季节变化的能力。我的研究项目的一个中心主题是鸟类如何利用环境线索来调节生理、神经生物学和行为的季节变化。未来5年我研究的主要目标是探索大脑和行为的季节性变化的环境生理学。本程序的主要假设包括***1。季节性重述个体发生：调节大脑发育的细胞机制诱导季节性神经可塑性***2。雄性激素、雌性激素和非甾体激素对季节性神经发生和其他形式的季节性大脑可塑性的影响是不同的，它们的作用在不同的季节会有所不同。作为运动综合症的一部分，睾丸激素调节、迁移行为和分散在个体之间是相关的。4 .由光周期同步的内源性时钟控制迁徙的时间，而性腺雄激素加速和同步春季迁徙不安，抑制秋季迁徙不安。对诸如捕食者线索和人造毒素等压力源的反应会随季节而变化。我将通过实验室和实地实验研究来解决上述假设。我将利用实验室目前正在开发的一套发育神经可塑性标记物，通过比较一年中不同时期的大脑，以及对已知驱动行为季节性变化的激素的操纵，探索大脑可塑性的季节性和发育机制之间的相似性。我会操纵类固醇激素来确定它们是如何控制大脑解剖结构的季节性变化的。我将利用激素去除和替代实验，以及利用遥测和远程跟踪技术监测圈养和野外的行为，评估性腺类固醇如何影响春季和秋季迁徙强度和方向的差异。我将测试大脑对捕食者线索的反应，以及对甲基汞的生理反应是如何随季节变化的。结合起来，这些研究创造了一个独特的综合研究项目，探索季节表型可塑性是如何调节的。具体来说，我将探讨环境因素如何通过激素信号影响大脑和行为的季节性变化，这对于预测鸟类如何应对不断变化的环境至关重要。

Most organisms exhibit seasonal changes in response to predictable changes in their environment. Seasonally-breeding songbirds show a tremendous degree of such plasticity. Birds adjust social behaviour, reproduction and movement across seasons. They exhibit high degrees of plasticity in the brain, reproductive physiology, and other systems. A bird's fitness depends critically on its ability to appropriately time seasonal changes in behaviour and physiology. A central theme of my research program addresses how birds use environmental cues to regulate seasonal changes in physiology, neurobiology and behaviour. *** The primary objective of my research over the next 5 years will be to explore the environmental physiology of seasonal changes in brain and behaviour. The primary hypotheses of this program include***1. Seasonality recapitulates ontogeny: the cellular mechanisms underlying brain development are regulated to induce seasonal neural plasticity.***2. Androgens, estrogens, and non-steroidal factors, have differential effects on seasonal neurogenesis and other forms of seasonal brain plasticity, and their effects will vary across different seasons.***3. Testosterone regulation, migration behaviour, and dispersal are correlated among individuals as part of a movement syndrome.***4. Endogenous clocks that are synchronized by photoperiod control the timing of migration, but gonadal androgens accelerate and synchronize spring migratory restlessness and inhibit fall migratory restlessness.***5. Responses to stressors such as predator cues and man-made toxins will vary seasonally.*** I will address the above hypotheses through a program of laboratory and field-based experimental studies. Using a suite of markers of developmental neural plasticity currently under development in my lab I will explore the similarities between seasonal and developmental mechanisms of brain plasticity by comparing brains from different times of year and following manipulation of hormones known to drive seasonal changes in behaviour. I will manipulate steroid hormones to determine how they control seasonal changes in brain anatomy. I will assess how gonadal steroids affect differences in migratory intensity and orientation between spring and fall migration using hormone removal and replacement experiments and monitoring behaviour in captivity and in the field using telemetry and remote tracking. I will test how brain responses to predator cues, and physiological responses to methylmercury change with the seasons.*** Combined, these lines of research create a uniquely integrative research program that explores how seasonal phenotypic plasticity is regulated. Specifically, I will explore how environmental factors affect seasonal changes in brain and behaviour via hormone signals, which is critical to predicting how birds will cope with changing environments.