Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Jamie Theobald

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Robert Lickliter

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Fernando Noriega

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Laura Serbus

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Jeffrey Wells

Fifth Advisor's Committee Title

Committee member


insect vision, behavior, flight, Drosophila, motion perception

Date of Defense



With over 150,000 described species, flies constitute one of the most species-rich groups of animals on earth, and have managed to colonize almost every corner of it. Part of their success comes from their amazing flying skills, which are strongly tied to their visual capabilities. To navigate fast and accurately through their habitats, they must be able to process the inordinate amounts of visual information necessary to sort obstacles, avoid predators and remain on course. Surprisingly, despite their tiny brains, flies have no problem in processing all that information to generate correcting maneuvers in just about 30 ms. To this end, the fly eye is extremely specialized for the perception of motion following the anisotropies of the environment, but that is only part of the story. In my dissertation I investigated whether this regional specialization of the eye extends to other characteristics of the stimulus, those providing structural information about the habitat. I focused on three main questions: (1) do flies regionalize the perception of parallax across regions of the eye? (2) Is there regionalization in the perception of the spatial layout of visual elements during flight? (3) How is this regional processing modified in species adapted to different habitats? Using a virtual reality setup to measure flight behavior with very high precision, I tricked the flies into responding to a sudden and unintended change in position, signaled by strong visual sideslip of their visual environment. I found that, during these disturbances, (1) flies respond to motion parallax only if it is below them, not above; (2) the same pattern of response applies to the layout of visual elements moving during the disturbance; (3) While the basic mechanisms are present across species adapted to different habitats, responses are modulated differently, signaling evolutionary novelties in specialized natural histories. My findings advance our understanding of the ways in which the processing of visual information in flying insects is optimized for speed and accuracy of responses, when neural resources are limited. It also offers insights into how highly conserved behaviors are modulated is species adapted to completely different environments.




Previously Published In

Ruiz C, Theobald JC. 2020 Ventral motion parallax enhances fruit fly steering to visual sideslip. Biol. Lett. 16: 20200046.

Ruiz C, Theobald JC. 2021 Stabilizing responses to sideslip disturbances in Drosophila melanogaster are modulated by the density of moving elements on the ground. Biol. Lett. 20200748.



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