Sex-specific evolution of brain size, brain structure, and covariation with eye size in Trinidadian killifish

Links between contrasting ecological conditions and evolutionary shifts in neurosensory components such as brain and eye size are accumulating. Whether selection operates differently on these traits between sexes is unclear. Trinidadian killifish (Anablepsoides hartii) are located in sites with and without predators. Male killifish from sites without predators have evolved larger brains and eyes than males from sites with predators. These differences in brain size are present early in life but disappear in adult size-classes. Here, we evaluated female brain growth allometries to determine if females exhibit similar size-specific brain size differences between sites that differ in predation intensity. We also quantified brain size, structure, and eye size to determine if these structures coevolve in a sex-specific manner. We found that female brain growth allometries did not differ across populations. Yet, female killifish from sites without predators exhibited a larger cerebellum, optic...