Collaborative Research: Evolutionary trends and ecological drivers of eye reduction in bat flies (Hippoboscoidea)

视觉是一种重要的感觉方式，包括人类在内的动物可以通过视觉来感知和处理它们在空间中的方位、辨认形状、感知时间、移动和导航、感知颜色。视觉是复杂的，在动物王国里存在着不同的视觉解决方案，比如昆虫的复眼和人类的单眼。然而，动物视觉的许多特征，如基因、结构和信号传导方法，都是相似的。这就是为什么昆虫是一个有用的模型，可以帮助我们大致理解眼睛功能的形成过程。这个项目的重点是一群昆虫的成员，他们一直生活在低光照下，在食物和配偶很近的地方，不需要在很远的距离上被视觉识别。这些昆虫的眼睛与完全发育的日光版本相比已经大大缩小，但它们仍然具有功能。在研究进化时间框架内这种减少的过程中，该项目旨在了解事件的顺序，哪些刺激导致视觉结构的减少（或丧失），以及维持眼睛功能所需的最低组织和复杂性。这项跨学科研究的结果将有助于我们对复杂生物系统的鲁棒性和适应性的理解。这一研究也与系统发育、进化系统生物学、神经生物学和生物工程等领域直接相关。除了科学进步之外，该项目还将覆盖和培养来自不同教育背景的学生，包括初中/高中、本科生和研究生。研究成果将整合到面向初高中教师的探究式教育模块中。该项目使用系统基因组学、组织学和分子方法来测试几种关于寄生蝙蝠果蝇眼睛进化的假设。蝙蝠蝇是这类研究的理想系统，因为1)所有物种的眼睛都减少或失去了，而且物种之间的减少程度有所不同；2)该类群来源于完全可视的、自由生活的掠食性祖先，现存的物种可以进行比较分析；3)由于该群体的生活史特征，蝙蝠蝇追踪两个不同的生态位-发育生态位（蛹沉积的地方）和寄主生态位（成年蝙蝠与蝙蝠一起出现的地方）-引入了物种之间宿主接近度和光照环境的变化。对物种间宿主和发育生态位的差异进行比较研究，以及在整个系统发育过程中微观和宏观眼睛解剖结构模式的结果，将允许测试以下假设：1)哪些生态特征驱动了眼睛缩小的进化；2)不同的物理领域（如宏观形态、微观形态和基因表达）如何相对于这些驱动力进化。

Vision is an important sensory mode, and through vision, animals including humans can detect and process their orientation in space, make out shapes, sense time, move and navigate, or detect color. Vision is complex, and different solutions for vision exist across the animal kingdom, such as compound eyes in insects versus simple eyes in humans. However, many features enabling vision, such as genes, structures and signaling methods, are similar across animals. This is why insects are a useful model for our general understanding of the processes involved in making eyes functional. This project focuses on members of a group of insects that consistently live at low light levels, in a place where food and mates are close by and need not be visually recognized over large distances. The eyes of these insects have been dramatically reduced from the fully developed daylight version, but they are still functional. In studying the process of this reduction over evolutionary timeframes, this project aims to understand the sequence of events and which stimuli led to the reduction (or loss) of visual structures, and what minimum level of organization and complexity is required to maintain a functional eye. Results of this interdisciplinary research will contribute to our understanding of the robustness and adaptability of complex biological systems. This study is also directly relevant to the fields of phylogenetics, evolutionary systems biology, neurobiology and bioengineering. In addition to scientific advancement, this project will reach and train students from diverse backgrounds at all levels of education, including middle/high school, undergraduate, and graduate students. Research results will be integrated into inquiry-based education modules for middle and high school teachers. This project uses phylogenomic, histological, and molecular methods to test several hypotheses regarding the evolution of reduced, yet functional, eyes in parasitic bat flies. Bat flies are an ideal system for this type of study because 1) all species have reduced or lost eyes, and there are variations among species in the degree of reduction; 2) the group is derived from fully visual, free-living predatory ancestors, and extant species can be studied for comparative analyses; and 3) due to life history characteristics of the group, bat flies trace two distinct ecological niches - the developmental niche (where pupae are deposited) and the host niche (where adult bat flies occur in association with bats) - that introduce variations in host proximity and light environments among species. Comparative studies of the variation in host and developmental niches among species, and the resulting structural patterns in micro- and macro-eye anatomy across the phylogeny will allow for the testing of hypotheses related to 1) which ecological features are driving the evolution of eye reduction and 2) how different physical domains (e.g. macromorphology, micromorphology, and gene expression) evolve relative to these driving forces.