The influence of early-life stress on behaviour, physiology and fitness in the wild.

我的研究通过在野生种群中整合生态学和生理学方法来测试早期生活环境对个体生理、行为和健康的持续影响。早期生活条件可能会对一个人的一生产生深远而持久的影响，然而，对行为、生理和健康的下游影响还没有被很好地理解。众所周知，应激和糖皮质激素对神经系统和下丘脑-垂体-肾上腺(HPA)轴的发育和功能有重要影响。此外，HPA轴是连接有机体与环境的关键生理机制，通过急性反应和长期适应，但压力如何影响野生种群的适应性几乎是未知的。最近的实验室研究表明，出生前或出生后应激和/或糖皮质激素治疗对成年后代的大脑、行为和HPA轴有不利影响。然而，如果父母正在调整后代以最好地匹配未来的环境条件，这些明显的有害影响实际上可能会促进在压力环境中的生存和繁殖。要研究早期生活压力在成年期的表现和世代的持久性，需要有能力在长期种群中跟踪标记的个体。 我和我的学生将通过在两个种群中进行实验田野研究，努力了解早期生活环境的生态和生理长期影响。首先，利用Kent Island NB上长期标记的Savannah麻雀(Passerculus Sandwichensis)种群，我们将通过测量雏鸟在荷尔蒙(糖皮质激素、睾酮、雌二醇)、应激生理和身体状况方面的自然个体差异，来研究早期环境对生理、歌唱行为和健康的影响。对于存活下来并返回岛上繁殖的个体，我们将测量成年应激生理、歌唱行为、存活和生殖输出。我们的第二个一般性研究是在安大略省阿尔冈昆公园的一个明显的鹿鼠种群(Permyscus Manulatus)，在那里我们将测试与出生种群密度、母体行为以及下游对后代行为和生理影响有关的假设。最近对小型哺乳动物的研究表明，种群密度与母体应激激素水平呈正相关，母体行为受到种群密度的影响。虽然众所周知，母体环境对后代的行为影响是表观遗传的，F1在成年后HPA轴发生变化，但目前尚不清楚这些影响是否会在多代人中持续存在，更重要的是，对后代健康的影响是什么。 在这两个种群中，我们还将使用公布的密切相关的传统实验动物(斑马雀和实验室小鼠)的基因组信息来开发尖端的表观遗传学工具，以研究出生前和出生后环境的特征的多代传递的新机制。总体而言，这些都是难得的机会，可以测试与早年生活压力的生理和健康后果相关的独特预测。此外，由于HPA轴是生物体对环境做出反应的主要中介，了解母体应激影响HPA轴发育和功能的机制至关重要，因为越来越多的野生种群暴露在可能影响HPA功能和适应性的人为因素中。

My research tests the persistent effects of the early-life environment on individual physiology, behavior and fitness by integrating ecological and physiological methods in wild populations. Early-life conditions can have profound and lasting effects throughout an individual’s lifetime, however, the downstream influences on behaviour, physiology and fitness are not well understood. Stress and glucocorticoids have well-known and important effects on the development and function of the nervous system and the hypothalamic-pituitary-adrenal (HPA) axis. Moreover, the HPA axis is a key physiological mechanism connecting an organism to its environment, through both acute responses and long-term adaptation, yet how stress influences fitness in wild populations is virtually unknown. Recent laboratory studies indicate that pre- or postnatal stress and/or glucocorticoid treatment have detrimental effects on the brain, behaviour and HPA axis in adult offspring. Although, if parents are adapting offspring to best match future environmental conditions, these apparent detrimental effects may, in fact, facilitate survival and reproduction in a stressful environment. To investigate the manifestation of early life stress in adulthood and the persistence across generations requires the ability to follow marked individuals within long-term populations. My students and I will work to understand the ecological and physiological long term effects of the early life environment by conducting experimental field studies in two populations. First, using a long-term marked population of Savannah sparrows (Passerculus sandwichensis) on Kent Island NB, we will investigate the effect of the early environment on physiology, song behaviour and fitness by measuring natural individual variation among chicks in their hormonal profiles (glucocorticoids, testosterone, estradiol), stress physiology, and body condition. In individuals that survive and return to breed on the island, we will measure adult stress physiology, song behaviour, survival, and reproductive output. Our second general study is a marked population of deer mice (Peromyscus maniculatus) in Algonquin Park, Ontario, where we will test hypotheses related to natal population density, maternal behaviour and downstream effects on offspring behaviour and physiology. Recent work in small mammals has demonstrated that population density is positively correlated with maternal stress hormone levels and that maternal behaviour is affected by population density. And while it is known that behavioural effects in offspring due to the maternal environment are epigenetically transmitted and F1s have an altered HPA axis in adulthood, it is not clear whether these effects persist across multiple generations and, importantly, what the consequences are for offspring fitness. In both of these populations, we will also use published genomic information for closely related conventional lab animals (zebra finch and lab mice) to develop cutting edge epigenetic tools to investigate a novel mechanism for the multigenerational transmission of signatures of the pre- and post-natal environment. Overall, these are rare opportunities to test unique predictions related to physiological and fitness consequences of early life stress. Further, because the HPA axis is a primary mediator of an organism’s response to its environment, understanding the mechanisms by which maternal stress affects HPA axis development and function is critical as more and more wild populations are being exposed to anthropogenic factors that may affect HPA function and influence fitness.