Whitnee Broyles

Document Type

Honors Thesis


Vertebrates exhibit extensive variation in brain size, but why such diversity exists has been an area of interest for decades. Recent selection experiments revealed that the evolution of larger brains enhances survival in the presence of predators; increased predation should thus favor larger brains. This project tested the influence of predator-induced mortality on the evolution of brain size by exploring Trinidadian killifish (Rivulus hartii) from communities that vary in predation intensity for differences in brain size. This work showed that male (but not female) Rivulus from sites that lack predators exhibited significantly larger brains than males from sites with large piscivorous fish capable of eating adult Rivulus. Brain size did not differ between sites that varied in the presence of a gape-limited predator of Rivulus. These results argue that increased male brain size is favored in less risky environments due to fitness benefits of higher cognitive function.

Publication Date






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