DISSERTATION RESEARCH: Discovering the Evolutionary History of Nocturnality in Birds

从历史上看，向夜间生活方式的过渡使一些鸟类能够在捕食者较少、对食物的竞争较少的时候活动。对夜间活动的适应促成了今天所见鸟类的多样性，这种转变可能是从夜视的进化开始的。这项研究将开发一种新的方法来揭示鸟类适应黑暗的方式，从而成为夜行动物。这种方法结合了对所有鸟类视觉遗传基础的详细分析，并将有助于揭示鸟类多样化的其他模式，例如不同羽毛颜色的起源。通过这项研究获得的关于鸟类视觉的见解将适用于人类视觉和视觉疾病（如色盲）的研究。人们对鸟类的夜视知之甚少，但系统发育分析提供了这种特征和夜行性的多个独立起源的证据。在这个提议中开发的DNA序列捕获探针集将允许从任何鸟类的基因组中分离和测序整个光导级联。光传导级联是一个由大约30个基因组成的通路，从视蛋白中光子的吸收开始，导致神经信号的产生。在这个项目中，这些基因将从所有主要的夜间鸟类谱系和它们的白天亲戚中被捕获和测序。对这些数据的分析将确定视蛋白光谱调谐的证据，选择的证据，以及在这个级联中基因的潜在损失或假原化。这些信息将表明夜行性在整个鸟类生命树中进化了多少次，从而深入了解这些适应的进化起源，无论它们是独立衍生的，代表趋同创新，还是由于深度同源性。

Historically, transitioning to a nocturnal lifestyle allowed some birds to operate during a time when fewer predators were active and there was less competition for food. Adaptation to nocturnality contributed to the great diversity of birds seen today and that transition likely began with the evolution of night vision. This research will develop a novel method to uncover the ways that birds adapted to see in the dark, and thus became nocturnal. This method incorporates detailed analyses of the genetic foundation of vision in all birds, and will help uncover other modes of avian diversification, such as the origin of diverse plumage coloration. The insights into bird vision gained through this research will be applicable and relevant to research on human vision and visual diseases, such as colorblindness.Little is known about night vision in birds, but phylogenetic analyses offer evidence of multiple independent origins of this trait and of nocturnality. The DNA sequence capture probe set developed in this proposal will allow isolation and sequencing of the entire phototransduction cascade from the genome of any bird. The phototransduction cascade is a pathway of approximately 30 genes, beginning with the absorption of a photon in an opsin, and resulting in the generation of a neural signal. For this project, these genes will be captured and sequenced from all major nocturnal bird lineages and their diurnal relatives. Analysis of these data will identify evidence of spectral tuning in opsins, evidence for selection, and potential loss or pseudogenization of genes in this cascade. This information will indicate how many times nocturnality has evolved across the avian tree of life, providing insight into the evolutionary origin of those adaptations, whether they were independently derived, represent convergent innovations, or are due to deep homology.