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

视觉是一种重要的感觉模式，包括人类在内的动物通过视觉可以检测和处理它们在空间中的方位，辨别形状，感知时间，移动和导航，或者检测颜色。视觉是复杂的，动物王国中存在不同的视觉解决方案，例如昆虫的复眼和人类的单眼。然而，许多能够实现视觉的特征，如基因、结构和信号传递方法，在动物中是相似的。这就是为什么昆虫是一个有用的模型，可以帮助我们全面了解眼睛的功能。这个项目的重点是一群昆虫的成员，这些昆虫一直生活在低光照下，在一个食物和配偶离得很近的地方，不需要在很远的距离上用视觉识别。与完全发育的日光版相比，这些昆虫的眼睛已经大幅减少，但它们仍然具有功能。在研究进化过程中，这个项目的目的是了解事件的顺序，以及哪些刺激导致视觉结构的减少(或丧失)，以及维持功能眼睛所需的最低组织和复杂性水平。这一跨学科研究的结果将有助于我们理解复杂生物系统的稳健性和适应性。这项研究还直接涉及到系统发育、进化系统生物学、神经生物学和生物工程等领域。除了科学进步，该项目还将接触和培训来自各个教育层次的不同背景的学生，包括初中生、本科生和研究生。研究成果将被整合到初中和高中教师的探究式教育模块中。这个项目使用系统基因组学、组织学和分子学方法来测试几个关于寄生蝙蝠苍蝇眼睛退化但有功能的进化的假说。蝙蝠是这类研究的理想系统，因为1)所有物种都有弱视或失明，不同物种的弱视程度存在差异；2)该类群来自完全视觉的自由生活的捕食祖先，可以对现存物种进行比较分析；3)由于该类群的生活史特征，蝙蝠追踪两个不同的生态位--发育生态位(存放幼虫的地方)和寄主生态位(成虫蝙蝠与蝙蝠联合出现的地方)--这导致了不同物种之间寄主接近和光环境的变化。对物种间寄主和发育生态位差异的比较研究，以及由此产生的跨系统发展的微观和宏观眼睛解剖学的结构模式，将允许检验与以下假设有关的假设：1)哪些生态特征正在推动眼睛减少的进化；2)不同的物理领域(如宏观形态、微形态和基因表达)是如何相对于这些驱动力进化的。

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.