ORCID Identifier(s)

ORCID 0000-0002-6557-1889

Graduation Semester and Year

Spring 2024



Document Type


Degree Name

Doctor of Philosophy in Biology



First Advisor

Dr. Matthew Walsh

Second Advisor

Dr. Scott Coleman

Third Advisor

Dr. Jeff Demuth

Fourth Advisor

Dr. Luke Frishkoff

Fifth Advisor

Dr. Alison Ravenscraft


Evolutionary theory proposes that increases in brain size confer cognitive and behavioral benefits that offset the expensive investment in brain tissue. However, few studies have examined the relationship between brain size, cognition, and behavior within species. The majority of research has focused on cross-species comparisons, thus there is a need for empirical research within species examining how contrasting ecological pressures select for cognitive and behavioral benefits and how these may evolve in tandem with changes in brain size. My dissertation addresses this gap by examining: 1) Whether selection on brain size is linked to improvements in cognitive ability; 2) How changes in natural selection influences shifts in brain size and behavior in a natural setting; and 3) How different selective forces shape behavioral plasticity in a model system of Trinidadian killifish (Anablepsoides hartii). In my first chapter, I demonstrate that killifish in absence of predators have evolved improved learning and reversal learning in a food reward maze task and examine connections to brain size to determine how evolved brain size influences learning ability. In chapter two, I examine how a change in selection from environments dominated by predation to competition selects for increased aggressive behavior by examining aggression levels in second generation lab reared killifish. I additionally examine how increased brain size influences aggressive behavior and growth in fish originating from high predation locales that have been transplanted into a site without predators. Finally, in chapter three, I test for predator-mediated behavioral plasticity in second generation lab reared fish and wild-caught fish to examine the interplay between genetic background and environmental cues on shifts in behavior.


Aggression, Behavior, Brain size, Cognition, Competition, Ecological drivers, Evolution, Learning, Natural selection, Predation


Behavior and Ethology | Ecology and Evolutionary Biology | Evolution | Population Biology


Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Available for download on Tuesday, May 13, 2025