The behavioural ecology of the brain: integrating evolution, behaviour and neuroscience.

不同脊椎动物的大脑在大小和形状上有很大的不同，但这种解剖学上的多样性是如何以及为什么存在的，在很大程度上是未知的。我的研究项目通过理解大脑和行为如何协同进化来解决神经科学中的这个基本问题。更具体地说，我通过对物种内部和跨物种的研究，以及使用一系列神经科学、动物行为和进化生物学技术，来测试进化理论应用于大脑的有效性。在这个资助周期中，我将重点关注与大脑进化有关的生殖行为的两个方面：求爱表现和交配系统。求偶是繁殖的重要组成部分，在鸟类中，不同求偶方式的进化与大脑的解剖变化有关。然而，大多数关于鸟类求偶行为的神经基础研究都集中在发声上，对于大脑如何产生和调节非发声的求偶行为知之甚少。我将通过研究皱巴巴的松鸡（Bonasa umbellus）来解决这一知识差距，皱巴巴的松鸡是一种在求爱时不发声的物种。相反，雄性松鸡会发出低频的鼓声。通过一系列的实地实验，我的实验室将确定松鸡如何产生这种显示器的低频声音特征，并确定产生显示器所需的神经回路。交配系统在大脑的进化过程中也起着重要作用。然而，我们对交配系统与大脑解剖学和进化的关系的理解是基于两种物种的比较，其中一种是非社会性和一夫多妻制，而另一种是社会性和一夫一妻制。这些比较本质上是混乱的，因为不清楚这些差异是归因于社会性还是归因于交配制度。因此，确定大脑区域大小或神经化学是否反映了交配系统，需要分析在社会和交配系统中都存在差异的物种。我之前的研究表明，社会性的、一夫多妻的理查德森地松鼠（Urocitellus Richardson）在海马解剖结构上与其他一夫多妻的啮齿动物有明显不同的季节和性别差异。这表明社会性和其他行为可能在海马体的进化中起着重要作用。在这里，我建议在这个初步工作的基础上，在更大的解剖学细节上量化性别和季节差异，并测试野生和实验室饲养的地松鼠在空间能力上的差异。然而，交配系统也与神经化学有关，特别是神经肽受体的分布。我还将测试理查森地松鼠体内催产素和抗利尿激素受体的分布是否存在显著的性别差异。最后，我将通过对地松鼠和松鸡进行比较测试，来测试海马体中的两性二态性是否在不同的交配系统中有所不同。因为海马体解剖中的两性二态性被认为反映了家庭范围的大小和运动，我预测非社会性地松鼠在海马体中的两性二态性比社会性地松鼠更大。同样，我预计一夫多妻制的松鸡在海马体中会比一夫一妻制的松鸡（Lagopus spp.）有更大的性别二态性。通过这种独特的结合实验室和实地考察以及物种内部和跨物种的研究，我的研究将极大地提高我们对大脑行为关系和进化神经生物学一般原理的理解，这将有助于完善关于大脑如何进化的假设。

The brain differs greatly in size and shape across vertebrate species, but how and why this anatomical diversity exists is largely unknown. My research program addresses this fundamental issue in neuroscience through understanding how brain and behaviour evolve in concert. More specifically, I test the validity of evolutionary theories as applied to the brain through studies within and across species and using a range of neuroscience, animal behaviour and evolutionary biology techniques. In this grant cycle, I will focus on two aspects of reproductive behaviour that are related to how the brain evolves: courtship display and mating system. Courtship is an essential part of reproduction and, in birds, the evolution of different courtship displays is associated with anatomical changes in the brain. However, the majority of studies on the neural basis of avian courtship displays focus on vocalizations and very little is known about how the brain produces and modulates non-vocal courtship displays. I will address this knowledge gap by examining the ruffed grouse (Bonasa umbellus), a species that does not vocalize in its courtship. Instead, male grouse produce a low frequency drumming display. Through a series of field experiments, my lab will determine how grouse generate the low frequency sound characteristic of this display and identify the neural circuitry required to produce the display. Mating systems also play a significant role in how the brain evolves. Our understanding of how mating system is related to brain anatomy and evolution is, however, based on two-species comparisons in which one species is asocial and polygamous whereas the other is social and monogamous. These comparisons are inherently confounded because it is unclear whether the differences are attributable to sociality or mating system. Determining whether brain region size or neurochemistry reflects mating systems or not therefore requires the analysis of species that vary in both sociality and mating system. My previous research showed that the social, polygamous Richardson's ground squirrel (Urocitellus richardsonii) has markedly different seasonal and sex differences in hippocampal anatomy than other polygamous rodents. This suggests that sociality and other behaviours might play a significant role in how the hippocampus evolves. Here, I propose to build upon this initial work and quantify the sex and seasonal differences in greater anatomical detail and test for differences in spatial abilities in both wild and lab-reared ground squirrels. Mating system is, however, also related to neurochemistry, especially the distribution of neuropeptide receptors. I will also test if there are significant sex differences in the distribution of oxytocin and vasopressin receptors in Richardson's ground squirrels. Finally, I will test whether sexual dimorphism in the hippocampus varies across mating systems by performing comparative tests across ground squirrels and grouse. Because sexual dimorphism in hippocampal anatomy is thought to reflect home range sizes and movement, I predict that asocial ground squirrels will have greater sexual dimorphism in the hippocampus than social species. Similarly, I expect that the polygamous ruffed grouse will have greater sexual dimorphism in the hippocampus than the monogamous ptarmigan (Lagopus spp.). Through this unique combination lab and fieldwork and studies within and across species, my research will greatly improve our understanding of brain-behaviour relationships and general principles of evolutionary neurobiology that will help to refine hypotheses about how the brain evolves.