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.
