Dataset Information

Predator-driven brain size evolution in natural populations of Trinidadian killifish (Rivulus hartii).

ABSTRACT: Vertebrates exhibit extensive variation in relative brain size. It has long been assumed that this variation is the product of ecologically driven natural selection. Yet, despite more than 100 years of research, the ecological conditions that select for changes in brain size are unclear. Recent laboratory selection experiments showed that selection for larger brains is associated with increased survival in risky environments. Such results lead to the prediction that increased predation should favour increased brain size. Work on natural populations, however, foreshadows the opposite trajectory of evolution; increased predation favours increased boldness, slower learning, and may thereby select for a smaller brain. We tested the influence of predator-induced mortality on brain size evolution by quantifying brain size variation in a Trinidadian killifish, Rivulus hartii, from communities that differ in predation intensity. We observed strong genetic differences in male (but not female) brain size between fish communities; second generation laboratory-reared males from sites with predators exhibited smaller brains than Rivulus from sites in which they are the only fish present. Such trends oppose the results of recent laboratory selection experiments and are not explained by trade-offs with other components of fitness. Our results suggest that increased male brain size is favoured in less risky environments because of the fitness benefits associated with faster rates of learning and problem-solving behaviour.

SUBMITTER: Walsh MR

PROVIDER: S-EPMC4947895 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Predator-driven brain size evolution in natural populations of Trinidadian killifish (Rivulus hartii).

Walsh Matthew R MR Broyles Whitnee W Beston Shannon M SM Munch Stephan B SB

Proceedings. Biological sciences 20160701 1834

Vertebrates exhibit extensive variation in relative brain size. It has long been assumed that this variation is the product of ecologically driven natural selection. Yet, despite more than 100 years of research, the ecological conditions that select for changes in brain size are unclear. Recent laboratory selection experiments showed that selection for larger brains is associated with increased survival in risky environments. Such results lead to the prediction that increased predation should fa ...[more]

PMID: 27412278

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Project description:Abstract Brain size, brain architecture, and eye size vary extensively in vertebrates. However, the extent to which the evolution of these components is intricately connected remains unclear. Trinidadian killifish, Anablepsoides hartii, are found in sites that differ in the presence and absence of large predatory fish. Decreased rates of predation are associated with evolutionary shifts in brain size; males from sites without predators have evolved a relatively larger brain and eye size than males from sites with predators. Here, we evaluated the extent to which the evolution of brain size, brain structure, and eye size covary in male killifish. We utilized wild?caught and common garden?reared specimens to determine whether specific components of the brain have evolved in response to differences in predation and to determine if there is covariation between the evolution of brain size, brain structure, and eye size. We observed consistent shifts in brain architecture in second generation common garden reared, but not wild caught preserved fish. Male killifish from sites that lack predators exhibited a significantly larger telencephalon, optic tectum, cerebellum, and dorsal medulla when compared with fish from sites with predators. We also found positive connections between the evolution of brain structure and eye size but not between overall brain size and eye size. These results provide evidence for evolutionary covariation between the components of the brain and eye size. Such results suggest that selection, directly or indirectly, acts upon specific regions of the brain, rather than overall brain size, to enhance visual capabilities. We evaluated the extent to which the evolution of brain size, brain structure, and eye size covary in male killifish from sites that vary in predation. We found positive connections between the evolution of brain structure and eye size but not between brain size and eye size. We also found that male killifish from sites that lack predators exhibited significantly larger brain structures than those from sites with predators. These results provide evidence for evolutionary covariation between the components of the brain and eye size and that selection, directly or indirectly, acts upon specific regions of the brain, rather than overall brain size, to enhance visual capabilities.

Dataset Information

Predator-driven brain size evolution in natural populations of Trinidadian killifish (Rivulus hartii).

Publications

Predator-driven brain size evolution in natural populations of Trinidadian killifish (Rivulus hartii).

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