My ResearchMy dissertation research examined how differing ecological factors drive shifts in brain and eye size within a species of killifish, and why larger brains are favored in predator-free, high competition environments. Trinidadian killifish (Rivulus hartii) have evolved differences in brain and eye size across populations in response to various ecological factors (e.g. competition, density, resource availability) driven by changes in predation levels. Previous work found that males from populations without predators evolved larger brains than males from populations with predators. The goal of my dissertation research is to better identify how and why the evolution of a larger brain is associated with declines in predation (i.e. what ecological pressures select for larger brains in the absence of predation?). Therefore, I tested the links between behavior, fitness, and brain size.
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Publications
Tran, S.*, K.J. Howell, M.R. Walsh. 2023 (in revision). Natural Selection favours larger eyes in Trinidadian killifish experimentally tranplanted into low light, hight competition environments. Biology Letters MS ID RSBL- 2023-0060.
Howell, K.J., S. Muh*, B. Parajuli*, M.R. Walsh. 2023 (accepted, in production). Experimental test of the influence of light availability on the evolution of eye size and behavior in Daphnia. Journal of Evolutionary Biology.
Howell, K.J., M.R. Walsh. 2022 . Transplant experiments demonstrate that larger brains are favoured in high-competition environments in Trinidadian killifish. Ecology Letters. https://doi.org/10.1111/ele.14133
Howell, K.J., S.M. Beston, and M.R. Walsh. 2022. Sex-specific evolution of brain size, brain structure, and covariation with eye size in Trinidadian killifish. Biological Journal of the Linnean Society. https://doi.org/10.1093/biolinnean/blac033
Howell, K.J., S.M. Beston, S. Stearns*, and M.R. Walsh. 2021. Coordinated Evolution of Brain Size, Structure, and Eye Size in Trinidadian killifish. Ecology and Evolution. https://doi.org/10.1002/ece3.7051
*indicates undergraduate author
Howell, K.J., S. Muh*, B. Parajuli*, M.R. Walsh. 2023 (accepted, in production). Experimental test of the influence of light availability on the evolution of eye size and behavior in Daphnia. Journal of Evolutionary Biology.
Howell, K.J., M.R. Walsh. 2022 . Transplant experiments demonstrate that larger brains are favoured in high-competition environments in Trinidadian killifish. Ecology Letters. https://doi.org/10.1111/ele.14133
Howell, K.J., S.M. Beston, and M.R. Walsh. 2022. Sex-specific evolution of brain size, brain structure, and covariation with eye size in Trinidadian killifish. Biological Journal of the Linnean Society. https://doi.org/10.1093/biolinnean/blac033
Howell, K.J., S.M. Beston, S. Stearns*, and M.R. Walsh. 2021. Coordinated Evolution of Brain Size, Structure, and Eye Size in Trinidadian killifish. Ecology and Evolution. https://doi.org/10.1002/ece3.7051
*indicates undergraduate author